Devrim Akca | Swiss Federal Institute of Technology (ETH) (original) (raw)

Journal Papers by Devrim Akca

The Photogrammetric Record, 2016

A reduced complexity model, which simulates the process of fluvial inland-delta formation, has be... more A reduced complexity model, which simulates the process of fluvial inland-delta formation, has been developed in a previous study. The results have been compared and validated with a laboratory experiment. This work elaborates the laboratory investigation in which an experimental inland delta is generated and its eroding topography is measured using a structured-light 3D scanner. The least squares 3D (LS3D) co-registration and comparison method is used for alignment as well as for comparing data epochs both spatially and temporally. A spatial precision value of around AE50 lm (1/20 000) is achieved. A series of high-quality digital elevation models (DEMs) are generated and the space-time evolution of the inland delta is monitored and analysed, in terms of slope and topography dynamics, in the consecutive DEM layers. The combination of high-resolution scanning together with high-precision co-registration techniques allows investigation of the details of the space-time variability of the sedimentation-deposition patterns to be used for geomorphological analysis.
Keywords: co-registration, digital elevation model (DEM), geomorphology,
structured-light system, 3D comparison, 3D scanning.

Geophysical Research Letters, 2010

The topography of inland deltas is influenced by the water‐sediment balance in distributary chan... more The topography of inland deltas is influenced by the
water‐sediment balance in distributary channels and local
evaporation and seepage rates. In this letter a reduced
complexity model is applied to simulate inland delta
formation, and results are compared with the Okavango
Delta, Botswana and with a laboratory experiment. We show
that water loss in inland deltas produces fundamentally
different dynamics of water and sediment transport than
coastal deltas, especially deposition associated with
expansion‐contraction dynamics at the channel head. These
dynamics lead to a systematic decrease in the mean
topographic slope of the inland delta with distance from the
apex following a power law with exponent a = −0.69 ± 0.02
where the data for both simulation and experiment can be
collapsed onto a single curve. In coastal deltas, on the
contrary, the slope increases toward the end of the deposition
zone.
Citation: Seybold, H. J., P. Molnar, D. Akca, M. Doumi,
M. Cavalcanti Tavares, T. Shinbrot, J. S. Andrade Jr., W. Kinzelbach,
and H. J. Herrmann (2010), Topography of inland deltas: Observations,
modeling, and experiments, Geophys. Res. Lett., 37, L08402,
doi:10.1029/2009GL041605.

Mediterranean Archaeology and Archaeometry, 2012

3D modeling of cultural heritage objects is an expanding application area. The selection of the ... more 3D modeling of cultural heritage objects is an expanding application area. The selection
of the right technology is very important and strictly related to the project requirements,
budget and user’s experience. The triangulation based active sensors, e.g. structured light systems are used for many kinds of 3D object reconstruction tasks and in particular for 3D recording of cultural heritage objects. This study presents the experiences in the results of two such projects in which a close-range structured light system is used for the 3D digitization. The paper includes the essential steps of the 3D object modeling pipeline, i.e. digitization, registration, surface triangulation, editing, texture mapping and visualization. The capabilities of the used hardware and software are addressed. Particular emphasis is given to a coded structured light system as an option for data acquisition.

KEYWORDS: active sensors, 3D point cloud, scanning, registration, surface triangulation,
visualization

The Photogrammetric Record, 2013

An artificial rainfall event was applied to a forested slope in Ruedlingen, northern Switzerland... more An artificial rainfall event was applied to a forested slope in Ruedlingen,
northern Switzerland. The experiment triggered a landslide which resulted in
mobilising about 130 m3 of debris. The event was monitored by a photogrammetric
network of four cameras, operating at 5 to 8 frames per second, in order to
quantify spatial and temporal changes by tracking tennis balls pegged into the
ground. Image measurements were performed using automated image matching
methods, implemented through a software package developed in-house. Three dimensional coordinates of the target points were estimated by running a
customised type of bundle adjustment, achieving a positioning precision of 1.8 cm.

Keywords: bundle adjustment, camera synchronisation, high speed camera,
landslide monitoring, network design, photogrammetric network simulation.

The Photogrammetric Record, 2009

This paper examines the potential of mobile phones to be used as front-end sensors for photogramm... more This paper examines the potential of mobile phones to be used as front-end sensors for photogrammetric procedures and applications. For this purpose, two mobile phone cameras (Sony Ericsson K750i and Nokia N93) were calibrated over an indoor 3D testfield, using a self-calibrating bundle adjustment. Geometric accuracy tests were carried out in order to evaluate their metric performances and to compare the results with respect to two off-the-shelf digital still video cameras (Sony DSC W100 and Sony DSC F828). The geometric accuracy evaluation comprised an absolute accuracy test, JPEG test and temporal stability test. The radiometric capabilities of all cameras (except that the DSC W100 was replaced with a DSC T100 camera) were also evaluated and compared by carrying out modulation transfer function (MTF) analysis, image noise analysis and an operating range test. Substantial systematic errors were diagnosed in some systems. However, with proper calibration it is believed that these devices can be used for many photogrammetric tasks.

Keywords: geometric accuracy, image noise, JPEG test, mobile phone cameras,
modulation transfer function (MTF), operating range, self-calibration, temporal
stability.

The Photogrammetric Record, 2010

Three-dimensional building models are often now produced from lidar and photogrammetric data. Th... more Three-dimensional building models are often now produced from lidar and
photogrammetric data. The quality control of these models is a relevant issue both
from the scientific and practical points of view. This work presents a method for
the quality control of such models. The input model (3D building data) is
co-registered to the verification data using a 3D surface matching method. The 3D
surface matching evaluates the Euclidean distances between the verification and
input data-sets. The Euclidean distances give appropriate metrics for the 3D model
quality. This metric is independent of the method of data capture. The proposed
method can favourably address the reference system accuracy, positional accuracy
and completeness. Three practical examples of the method are provided for
demonstration.
Keywords: 3D building model, 3D comparison, lidar, point cloud, quality
assessment, surface co-registration

Isprs Journal of Photogrammetry and Remote Sensing, 2007

3D surface matching would be an ill conditioned problem when the curvature of the object surface ... more 3D surface matching would be an ill conditioned problem when the curvature of the object surface is either homogenous or
isotropic, e.g. for plane or spherical types of objects. A reliable solution can only be achieved if supplementary information or
functional constraints are introduced. In a previous paper, an algorithm for the least squares matching of overlapping 3D surfaces,
which were digitized/sampled point by point using a laser scanner device, by the photogrammetric method or other techniques, was
proposed [Gruen, A., and Akca, D., 2005. Least squares 3D surface and curve matching. ISPRS Journal of Photogrammetry and
Remote Sensing 59 (3), 151–174.]. That method estimates the transformation parameters between two or more fully 3D surfaces,
minimizing the Euclidean distances instead of z-differences between the surfaces by least squares. In this paper, an extension to the
basic algorithm is given, which can simultaneously match surface geometry and its attribute information, e.g. intensity, colour,
temperature, etc. under a combined estimation model. Three experimental results based on terrestrial laser scanner point clouds are
presented. The experiments show that the basic algorithm can solve the surface matching problem provided that the object surface
has at least the minimal information. If not, the laser scanner derived intensities are used as supplementary information to find a
reliable solution. The method derives its mathematical strength from the least squares image matching concept and offers a high
level of flexibility for many kinds of 3D surface correspondence problem.

Photogrammetric Engineering & Remote Sensing, 2010

A method for the automatic co-registration of 3D surfaces is presented. The method utilizes the ... more A method for the automatic co-registration of 3D surfaces is
presented. The method utilizes the mathematical model of
Least Squares 2D image matching and extends it for solving
the 3D surface matching problem. The transformation parameters
of the search surfaces are estimated with respect to a
template surface. The solution is achieved when the sum of
the squares of the 3D spatial (Euclidean) distances between
the surfaces are minimized. The parameter estimation is
achieved using the Generalized Gauss-Markov model. Execution
level implementation details are given. Apart from the
co-registration of the point clouds generated from spaceborne,
airborne and terrestrial sensors and techniques, the proposed
method is also useful for change detection, 3D comparison,
and quality assessment tasks. Experiments using terrain data
examples show the capabilities of the method.

Isprs Journal of Photogrammetry and Remote Sensing, 2005

The automatic co-registration of point clouds, representing 3D surfaces, is a relevant problem in... more The automatic co-registration of point clouds, representing 3D surfaces, is a relevant problem in 3D modeling. This multiple
registration problem can be defined as a surface matching task. We treat it as least squares matching of overlapping surfaces.
The surface may have been digitized/sampled point by point using a laser scanner device, a photogrammetric method or other
surface measurement techniques. Our proposed method estimates the transformation parameters of one or more 3D search
surfaces with respect to a 3D template surface, using the Generalized Gauss–Markoff model, minimizing the sum of squares of
the Euclidean distances between the surfaces. This formulation gives the opportunity of matching arbitrarily oriented 3D surface
patches. It fully considers 3D geometry. Besides the mathematical model and execution aspects we address the further
extensions of the basic model. We also show how this method can be used for curve matching in 3D space and matching of
curves to surfaces. Some practical examples based on the registration of close-range laser scanner and photogrammetric point
clouds are presented for the demonstration of the method. This surface matching technique is a generalization of the least
squares image matching concept and offers high flexibility for any kind of 3D surface correspondence problem, as well as
statistical tools for the analysis of the quality of final matching results.

Isprs Journal of Photogrammetry and Remote Sensing, 2005

写真測量とリモートセンシング, Sep 7, 2012

A Study on Accuracy Investigation of Point Clouds Generated by the Mobile Mapping System (MMS) ... more A Study on Accuracy Investigation of Point Clouds Generated by the Mobile Mapping System (MMS)

Koji MANO, Kazunori ISHII, Masataka HIRAO, Kikuo TACHIBANA, Mitsunori YOSHIMURA, Devrim AKCA and Armin GRUEN

Abstract : This paper describes on an accuracy investigation of point clouds which generated by MMS (Mobile Mapping System). In recent years 3D measurement technologies have advanced significantly. At the same time, MMS have become common measurement instruments for 3D application fields such as road facility management and related fields.We have to consider that the necessity of establishment positional accuracy evaluation methodology stands on the measurement mechanism of MMS point clouds. The aim of this study is to establish positional accuracy evaluation methodology for MMS point cloud measurement data and examine our LS3D (Least Squares 3D Surface matching)approach in practical experiments.Our proposed evaluation methodology consists of⑴ Data Quality Assessment,⑵ Precision Assessment,⑶ Absolute Accuracy Assessment,⑷ Relative Assessment,⑸ Cross -sensor Accuracy Assessment. In order to examine our evaluation methodology,we had been carried out an actual MMS run and MMS point clouds generation at Minato-Mirai,Yokohama.Through our practical experiments and
an actual evaluation,we confirmed that our proposed positional accuracy evaluation methodology is good enough procedures. As farther works, we have to accumulate much more evaluations than this moment.

Journal of the Japan society of photogrammetry and remote sensing, 2012

A Study on Accuracy Investigation of Point Clouds Generated by the Mobile Mapping System (MMS) K... more A Study on Accuracy Investigation of Point Clouds Generated by the Mobile Mapping System (MMS)
Koji MANO, Kazunori ISHII, Masataka HIRAO, Kikuo TACHIBANA, Mitsunori YOSHIMURA, Devrim AKCA and Armin GRUEN

Abstract : This paper describes on an accuracy investigation of point clouds which generated by MMS (Mobile
Mapping System). In recent years 3D measurement technologies have advanced significantly. At the same time,
MMS have become common measurement instruments for 3D application fields such as road facility management
and related fields.We have to consider that the necessity of establishment positional accuracy evaluation methodology
stands on the measurement mechanism of MMS point clouds. The aim of this study is to establish positional
accuracy evaluation methodology for MMS point cloud measurement data and examine our LS3D (Least Squares
3D Surface matching)approach in practical experiments.Our proposed evaluation methodology consists of⑴ Data
Quality Assessment,⑵ Precision Assessment,⑶ Absolute Accuracy Assessment,⑷ Relative Assessment,⑸ Cross
-sensor Accuracy Assessment. In order to examine our evaluation methodology,we had been carried out an actual
MMS run and MMS point clouds generation at Minato-Mirai,Yokohama.Through our practical experiments and
an actual evaluation,we confirmed that our proposed positional accuracy evaluation methodology is good enough
procedures. As farther works, we have to accumulate much more evaluations than this moment.

9th Asian Conference on Remote Sensing (ACRS'08), Colombo, Sri Lanka, November 10-14 (only on CD-ROM), 2008

The radiometric capabilities of two mobile phone cameras are examined and compared against two ... more The radiometric capabilities of two mobile phone cameras are examined
and compared against two off-the-shelf digital cameras. The radiometric performances
are measured in terms of resolution by MTF analysis, noise analysis and linearity test.
All tests are conducted with the use of a Siemens Star chart.

Harita Dergisi, 2002

ÖZET Ana bileşenler dönüşümü (principal components transformation), aralarında yüksek korelasyon ... more ÖZET Ana bileşenler dönüşümü (principal components transformation), aralarında yüksek korelasyon bulunan çok değişkenli verileri, aralarında korelasyon olmayan yeni bir koordinat sistemine dönüştüren istatistiksel bir veri dönüşümü yöntemidir. Bu dönüşüm, farklı disiplinlerce çok değişkenli (çok boyutlu) verilerin analizinde (multivariate analysis) kullanılmaktadır. Özellikle sinyallerin iletiminde sıkça kullanılan bu dönüşüm, sayısal görüntülerin de sinyal olarak yorumlanabilmesi sayesinde, görüntü işleme uygulamalarında da sıkça kullanılmaktadır. Bu çalışmada, sayısal görüntülerde ana bileşenler dönüşümü anlatılmış ve 24 bpp'lik bir test görüntüsü üzerinde yapılan uygulama sunulmuştur. Uygulama, makalenin yazarları tarafından Borland C++ Builder programlama dilinde yazılmış bir bilgisayar programı tarafından gerçekleştirilmiştir. Makalenin sonunda, programın temel fonksiyonlarının kaynak kodları verilmiştir.
ABSTRACT The principal components transformation is a statistical data transformation which maps the high correlated multivariate data to a new coordinate system where the data is uncorrelated. This transformation is used by various disciplines. The principal components transformation is especially used in the transmission theory of digital signals. Since digital images can also be interpreted as of special type digital signals, this transformation is also used in digital image processing frequently, for various purposes. In this paper, the principal components transformation has been explained and a sample application has been performed on 24 bpp test image, has been presented. This sample application has been performed with a computer program written by the authors, and has been coded in Borland C++ Builder programming language. At the end of the paper, source codes of the basic functions of the program have also been given. Whole of the original program can be downloaded from:

Conf. Papers & Proceedings by Devrim Akca

ISPRS Commission V Symposium 'Image Engineering and Vision Metrology', Dresden, September 25-27. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XXXVI, part 5, pp. 14-19. , 2006

ABSTRACT: This paper presents the results of a study in which a close-range structured light sys... more ABSTRACT:
This paper presents the results of a study in which a close-range structured light system is used for the digitization of a cultural
heritage object. A Herakles statue, named “Weary Herakles” and located in the Antalya Museum, Turkey was scanned by a
Breuckmann optoTOP-HE system. The work comprises the essential steps of the 3D object modeling pipeline, i.e. digitization,
registration, surface triangulation, editing, texture mapping and visualization. 3D recording, modeling and visualization of cultural
heritage objects is an expanding application area. This paper addresses the capabilities of some of the current technology in this
field. Particular emphasis is given to a coded structured light system as an option for data acquisition.
KEY WORDS: Herakles, cultural heritage, structured light, laser scanning, digitization, registration, modeling, visualization

Videometrics IX, Proc. of SPIE-IS&T Electronic Imaging, San Jose (California), USA, January 29-30, SPIE vol. 6491, pp. 64910V-1-12., 2007

ABSTRACT 3D documentation and visualization of Cultural Heritage objects is an expanding applica... more ABSTRACT
3D documentation and visualization of Cultural Heritage objects is an expanding application area. The selection of the
right technology for these kinds of applications is very important and strictly related to the project requirements, budget
and user’s experience. Active sensors, i.e. triangulation based laser scanners and structured light systems are used for
many kinds of 3D object reconstruction tasks and in particular for 3D documentation of cultural heritage objects. This
study presents some experiences in the results of two case studies in which a close-range structured light system is used
for the 3D digitization. The paper includes all necessary steps of the 3D object modeling pipeline from data acquisition
to 3D visualization.

Keywords: Active sensor, digitization, cultural heritage, modeling, visualization

In: Gruen, A., Kahmen, H. (Eds.), Optical 3-D Measurement Techniques VII, Vienna, Austria, October 3-5, vol. II, pp. 197-206., 2005

Abstract: We present an algorithm for the least squares matching of overlapping 3D surfaces. It ... more Abstract: We present an algorithm for the least squares matching of overlapping 3D surfaces.
It estimates the transformation parameters between two or more fully 3D surfaces, using the
Generalized Gauss-Markoff model, minimizing the sum of squares of the Euclidean distances
between the surfaces. This formulation gives the opportunity of matching arbitrarily oriented
3D surfaces simultaneously, without using explicit tie points. Besides the mathematical model
of the procedure, we discuss the computational aspects. We give practical examples to
demonstrate the method.

2nd International Conference on Remote Sensing in Archaeology, Rome, Italy, December 4-7, pp.375-382. , 2006

Recording and modeling of cultural heritage objects with coded structured light projection system... more Recording and modeling of cultural heritage objects with coded structured light projection systems
Devrim Akca, Fabio Remondino, David Novák, Thomas Hanusch, Gerhard Schrotter,
Armin Gruen
Institute of Geodesy and Photogrammetry, ETH Zurich, CH-8093 Zurich, Switzerland
http://www.photogrammetry.ethz.ch

Conclusions
Nowadays active sensors are often used for many kinds
of 3D object reconstruction tasks, one important area of
which is 3D documentation of cultural heritage objects.
This study presents the results of 3D modeling of two
cultural heritage objects, where a close-range coded
structured light system was used for digitization. In fact
active sensing with coded structured light systems is a
mature technology and allows high resolution
documentation of cultural heritage objects.
The used instruments have acquired high quality point
cloud data of the statues. The results of the processing
(accuracy of about 50 micron and better) are in good
agreement with the system specifications and project
requirements. The heaviest user interaction is needed in
the editing steps, e.g. for filling the data holes. We have
used two commercial software packages in order to carry
out the modeling. Each software package has its own
particular advantages and functions. A unique package,
which fulfills all requirements with sophisticated and
automatic editing capabilities, is not yet available. In our
opinion, the use of both packages can give the optimal
modeling results. Texture mapping is another issue,
which is not fully supported by either software.

ISPRS "Panoramic Photogrammetry Workshop", Dresden, Germany, February 19-22. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XXXIV, part 5/W16 (on CD-ROM)., 2004

ABSTRACT: The automatic co-registration of point clouds, representing 3D surfaces, is a relevant... more ABSTRACT:
The automatic co-registration of point clouds, representing 3D surfaces, is a relevant problem in 3D modeling. This registration
problem can be defined as a surface matching problem. We treat it as least squares matching of overlapping surfaces. The point
cloud may have been digitized/sampled point by point using a laser scanner device, a photogrammetric method or other surface
measurement techniques. In the past, several efforts have been made concerning the registration of 3D point clouds. One of the most
popular methods is the Iterative Closest Point (ICP) algorithm. Several variations and improvements of the ICP method have been
proposed. In photogrammetry there have been some studies on the absolute orientation of stereo models using DEMs (Digital
Elevation Model) as control information. These works are known as DEM matching, which corresponds mathematically with least
squares image matching. The DEM matching concept is only applied to 2.5D surfaces. 2.5D surfaces have limited value, especially
in close range applications. Our proposed method estimates the 3D similarity transformation parameters between two or more fully
3D surface patches, minimizing the Euclidean distances between the surfaces by least squares. This formulation gives the
opportunity of matching arbitrarily oriented 3D surface patches. An observation equation is written for each surface element on the
template surface patch, i.e. for each sampled point. The geometric relationship between the conjugate surface patches is defined as a
7-parameter 3D similarity transformation. The constant term of the adjustment is given by the observation vector whose elements are
the Euclidean distances between the template and search surface elements. Since the functional model is non-linear, the solution is
iteratively approaching to a global minimum. The unknown transformation parameters are treated as stochastic quantities using
proper weights. This extension of the mathematical model gives control over the estimation parameters. Furthermore, some
experimental results based on registration of close-range laser scanner and photogrammetric point clouds will be presented. This new
surface matching technique is a generalization of the least squares image matching concept and offers high flexibility for any kind of
3D surface correspondence problem, as well as statistical tools for the analysis of the quality of the final results.

KEY WORDS: Least squares 3D surface matching, point clouds, registration, laser scanning.

ASPRS 2005 Annual Conference, Baltimore (Maryland), USA, March 7-11 (on CD-ROM). , 2005

ABSTRACT An algorithm for the least squares matching of overlapping 3D surfaces is presented. It... more ABSTRACT
An algorithm for the least squares matching of overlapping 3D surfaces is presented. It estimates the transformation
parameters between two or more fully 3D surfaces, using the Generalized Gauss-Markoff model, minimizing the
sum of squares of the Euclidean distances between the surfaces. This formulation gives the opportunity of matching
arbitrarily oriented 3D surfaces simultaneously, without using explicit tie points. Besides the mathematical model
and execution aspects we give further extension of the basic model. The first extension is the simultaneous matching
of sub-surface patches, which are selected in cooperative surface areas. It provides a computationally effective
solution, since it matches only relevant multi-subpatches rather than the whole overlapping areas. The second
extension is the matching of surface geometry and its attribute information, e.g. reflectance, color, temperature, etc.,
under a combined estimation model. We give practical examples for the demonstration of the basic method and the
extensions.

The Photogrammetric Record, 2016

Geophysical Research Letters, 2010

Mediterranean Archaeology and Archaeometry, 2012

KEYWORDS: active sensors, 3D point cloud, scanning, registration, surface triangulation,
visualization

The Photogrammetric Record, 2013

Keywords: bundle adjustment, camera synchronisation, high speed camera,
landslide monitoring, network design, photogrammetric network simulation.

The Photogrammetric Record, 2009

Keywords: geometric accuracy, image noise, JPEG test, mobile phone cameras,
modulation transfer function (MTF), operating range, self-calibration, temporal
stability.

The Photogrammetric Record, 2010

Isprs Journal of Photogrammetry and Remote Sensing, 2007

Photogrammetric Engineering & Remote Sensing, 2010

Isprs Journal of Photogrammetry and Remote Sensing, 2005

写真測量とリモートセンシング, Sep 7, 2012

A Study on Accuracy Investigation of Point Clouds Generated by the Mobile Mapping System (MMS) ... more A Study on Accuracy Investigation of Point Clouds Generated by the Mobile Mapping System (MMS)

Koji MANO, Kazunori ISHII, Masataka HIRAO, Kikuo TACHIBANA, Mitsunori YOSHIMURA, Devrim AKCA and Armin GRUEN

Journal of the Japan society of photogrammetry and remote sensing, 2012

Abstract : This paper describes on an accuracy investigation of point clouds which generated by MMS (Mobile
Mapping System). In recent years 3D measurement technologies have advanced significantly. At the same time,
MMS have become common measurement instruments for 3D application fields such as road facility management
and related fields.We have to consider that the necessity of establishment positional accuracy evaluation methodology
stands on the measurement mechanism of MMS point clouds. The aim of this study is to establish positional
accuracy evaluation methodology for MMS point cloud measurement data and examine our LS3D (Least Squares
3D Surface matching)approach in practical experiments.Our proposed evaluation methodology consists of⑴ Data
Quality Assessment,⑵ Precision Assessment,⑶ Absolute Accuracy Assessment,⑷ Relative Assessment,⑸ Cross
-sensor Accuracy Assessment. In order to examine our evaluation methodology,we had been carried out an actual
MMS run and MMS point clouds generation at Minato-Mirai,Yokohama.Through our practical experiments and
an actual evaluation,we confirmed that our proposed positional accuracy evaluation methodology is good enough
procedures. As farther works, we have to accumulate much more evaluations than this moment.

9th Asian Conference on Remote Sensing (ACRS'08), Colombo, Sri Lanka, November 10-14 (only on CD-ROM), 2008

Harita Dergisi, 2002

Videometrics IX, Proc. of SPIE-IS&T Electronic Imaging, San Jose (California), USA, January 29-30, SPIE vol. 6491, pp. 64910V-1-12., 2007

Keywords: Active sensor, digitization, cultural heritage, modeling, visualization

In: Gruen, A., Kahmen, H. (Eds.), Optical 3-D Measurement Techniques VII, Vienna, Austria, October 3-5, vol. II, pp. 197-206., 2005

2nd International Conference on Remote Sensing in Archaeology, Rome, Italy, December 4-7, pp.375-382. , 2006

KEY WORDS: Least squares 3D surface matching, point clouds, registration, laser scanning.

ASPRS 2005 Annual Conference, Baltimore (Maryland), USA, March 7-11 (on CD-ROM). , 2005

ISPRS Workshop on Laser Scanning 2007 and SilviLaser 2007, Espoo, Finland, September 12-14. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XXXVI, part 3 / W52, pp. 1-7., 2007

ABSTRACT: A method for the simultaneous co-registration and georeferencing of multiple 3D pointc... more ABSTRACT:
A method for the simultaneous co-registration and georeferencing of multiple 3D pointclouds and associated intensity information is
proposed. It is a generalization of the 3D surface matching problem. The simultaneous co-registration provides for a strict solution to
the problem, as opposed to sequential pairwise registration. The problem is formulated as the Least Squares matching of overlapping
3D surfaces. The parameters of 3D transformations of multiple surfaces are simultaneously estimated, using the Generalized GaussMarkoff
model, minimizing the sum of squares of the Euclidean distances among the surfaces. An observation equation is written
for each surface-to-surface correspondence. Each overlapping surface pair contributes a group of observation equations to the design
matrix. The parameters are introduced into the system as stochastic variables, as a second type of (fictitious) observations. This
extension allows to control the estimated parameters. Intensity information is introduced into the system in the form of quasisurfaces
as the third type of observations. Reference points, defining an external (object) coordinate system, which are imaged in additional
intensity images, or can be located in the pointcloud, serve as the fourth type of observations. They transform the whole block of
“models” to a unique reference system. Furthermore, the given coordinate values of the control points are treated as observations.
This gives the fifth type of observations. The total system is solved by applying the Least Squares technique, provided that
sufficiently good initial values for the transformation parameters are given. This method can be applied to data sets generated from
aerial as well as terrestrial laser scanning or other pointcloud generating methods.

KEY WORDS: Surface matching, co-registration, multiple surfaces, 3D surface, pointcloud, georeferencing.

ISPRS Hannover Workshop 2007, "High Resolution Earth Imaging for Geospatial Information", Hannover, Germany, May 29- June 1, (on CD-ROM)., 2007

ABSTRACT: The Institute of Geodesy and Photogrammetry (IGP) is participating in the Cartosat-1 e... more ABSTRACT:
The Institute of Geodesy and Photogrammetry (IGP) is participating in the Cartosat-1 evaluation program, a common initiative of
ISRO (India) and ISPRS. Within this program various test sites with reference data have been established and Cartosat-1 images
have been acquired over these sites. Here, we will report about our investigations at the Rome and Mausanne test sites. First, we
report on radiometric problems encountered with the images and preprocessing for their improvement. These include artefacts,
unfocussing in the forward channel and scale differences to aft, jitter at horizontal edges, interlacing errors and pattern noise. We
show examples and also preprocessing methods that can be employed in order to improve image quality, with aim especially to
automatically generate a DSM with less blunders (due to noise and artefacts) and more match points. Then, we report on sensor
modelling and the 3D point positioning accuracy that can be achieved, as well as various problems encountered with the Rational
Polynomial Coefficients (RPCs). The orientation results were produced using various options regarding image preprocessing, sensor
model, number and distribution of GCPs and GCP image mensuration methods. The best results led to a planimetric and height
accuracy (RMSE) of about 1.3 m. The absolute geolocation accuracy varies greatly from dataset to dataset and can be worse than a
few thousand meters, making Cartosat-1 unsuitable for generation of global mapping products without use of GCPs. Finally, we
present the results of automatic DSM generation using our own Sat-PP program package. Various DSMs were generated with 10m
grid spacing. The results were checked both visually and were compared using the provided reference data. In the best case, the
achieved accuracy is about 2.7 m without any manual editing and in spite of 3-year difference between matching and reference
DSM. In spite of several aspects that could and should be improved, Cartosat-1 is a useful sensor for mapping and especially
generation of DSMs.
KEY WORDS: Cartosat-1, image quality, image preprocessing, sensor modelling, RPCs, 3D point positioning, DSM generation,
performance evaluation

Yerel Yönetimlerde Kent Bilgi Sistemi Uygulamaları Sempozyumu, Trabzon, 13-15 Ekim 1999, 1999

ÖZET : Bu çalışmada, Trabzon ili Merkez ilçesi ve Maçka ilçesi idari sınırları içerisinde kalan D... more ÖZET : Bu çalışmada, Trabzon ili Merkez ilçesi ve Maçka ilçesi idari sınırları içerisinde kalan Değirmendere Vadisinde; Trabzon Valiliği tarafından desteklenen ve Karadeniz Teknik Üniversitesi'nce yürütülen " Trabzon-Değirmendere Vadisi Çevre Düzenleme Projesi (DEVAÇED) " kapsamında yapılan Coğrafi Bilgi Sistemi uygulamaları anlatılacaktır. Özellikle havzanın; coğrafi yapısı yanında, evsel atık ve sanayi atığı üreterek vadiyi kirleten suni yapılarla ilgili grafik-sözel bilgiler ve uydu görüntüleri, değişik kaynaklardan toplanarak, ARC/INFO-ArcView Coğrafi Bilgi Sistemi yazılımlarıyla değerlendirilmiş ve havzanın sayısal modeli oluşturulmuştur.

In: Gruen, A., Kahmen, H. (Eds.), Optical 3-D Measurement Techniques VI, Zurich, Switzerland, September 22-25, vol. I, pp. 330-337., 2003

ABSTRACT The registration of point clouds that are acquired from different laser scanner standpo... more ABSTRACT
The registration of point clouds that are acquired from different laser scanner standpoints is an
essential task in the environment modelling works. In this paper, a full automatic point cloud
registration scheme is presented. Special targets attached onto the object(s) are used as landmarks
and their 3-D coordinates are measured with a theodolite in a ground coordinate system before the
scanning process. The presented registration scheme can automatically find these targets in the
point clouds using radiometric and geometric information (shape, size, and planarity). At the last
step, targets are labelled using the consistent labelling by discrete relaxation in order to find the
actual names of the points in the ground control points list.

KEY WORDS : Laser Scanning, Point Cloud, Registration, Consistent Labeling, 3-D Similarity
Transformation

19th CIPA International Symposium, Antalya, Turkey, September 30-October 4. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XXXIV, part 5/C15, pp. 55-60. , 2003

ABSTRACT: A stack of 66 historical Indian palm leaves, which were produced in the 8th Century AD... more ABSTRACT:
A stack of 66 historical Indian palm leaves, which were produced in the 8th Century AD, is kept in the Museum Rietberg, Zuerich.
On the leaves, there are figures and a long poem, inscribed in ancient Sanskrit language and narrating a love story. The original
sequence of the leaves was lost long time ago. At one point in history, the stack of the leaves was damaged by a mouse biting pieces
off. Only the first 18 leaves have their pages numbered in Sanskrit language, but the rest of them got out of order. If it is assumed
that the mouse chewed at the leaves in a regular manner, the geometry of the leaf perimeter, as left over after eating, should bear
useful information to find the original sequence. After acquiring digital images of the leaves and a pre-processing phase, an inner
boundary-tracing algorithm was applied to all leaves in order to segment them. The fundamental data used in this work are boundary
coordinates of the leaves. In order to obtain quantitative shape similarity measures, two different Boundary Based Shape Descriptor
algorithms were applied to the boundary data: Fourier descriptors and a rotation-translation invariant boundary intersection-based
shape descriptor. Shape descriptors indicate the similarity of different leaves. These similarity measures among all of the leaf pairs
were arranged in form of a symmetric square matrix. With this matrix and a threshold similarity value one can determine the most
probable ancestor and successor leaves for a pointed leaf. In the final step, a Tree Search scheme that starts from the 18th (fixed) leaf
and ends at the 66th (relaxed) leaf was established to generate the most probable sequence. Every node in the tree was defined as a
leaf and branched to the most probable neighbor leaves. The similarity measures were expressed as costs of the arcs, which connect
two nodes in the tree. The sequence which has minimum total path cost was proposed as the most probable original sequence.

KEY WORDS: Cultural Heritage, Image Analysis, Boundary-tracing, Fourier descriptors, shape similarity measures, Tree-Search,
Visualization

0th ISPRS Congress, Istanbul, Turkey, July 12-23. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XXXV, part B7, pp. 960-965., 2004

ABSTRACT: A new algorithm for least squares matching of overlapping 3D surfaces, digitized/sampl... more ABSTRACT:
A new algorithm for least squares matching of overlapping 3D surfaces, digitized/sampled point by point using a laser scanner
device, the photogrammetric method or other techniques, is proposed. In photogrammetry, the problem statement of surface patch
matching and its solution method was first addressed by Gruen (1985a) as a straight application of Least Squares Matching. There
have been some studies on the absolute orientation of stereo models using DEMs as control information. These works have been
known as DEM matching. Furthermore, techniques for 2.5D DEM surface matching have been developed, which correspond
mathematically with least squares image matching. 2.5D surfaces have limited value, especially in close range applications. Our
proposed method estimates the transformation parameters between two or more fully 3D surface patches, minimizing the Euclidean
distances instead of Z-differences between the surfaces by least squares. This formulation gives the opportunity of matching
arbitrarily oriented surface patches. An observation equation is written for each surface element on the template surface patch, i.e. for
each sampled point. The geometric relationship between the conjugate surface patches is defined as a 7-parameter 3D similarity
transformation. The Least Squares observations of the adjustment are defined by the observation vector whose elements are
Euclidean distances between the template and search surface elements. The unknown transformation parameters are treated as
stochastic quantities using proper weights. This extension of the functional model gives control over the estimation parameters. The
details of the mathematical modelling of the proposed method, the convergence behavior, and statistical analysis of the theoretical
precision of the estimated parameters are explained. Furthermore, some experimental results based on registration of close-range
laser scanner and photogrammetric point clouds are presented. This new surface matching technique derives its mathematical
strength from the least squares image matching concept and offers high level flexibility for any kind of 3D surface correspondence
problem, as well as statistical tools for the analysis of the quality of the final results.

KEY WORDS: Surface matching, Least Squares Matching, Point clouds, Registration, Laser scanning.

Videometrics VIII, Proc. of SPIE-IS&T Electronic Imaging, San Jose (California), USA, January 18-20, SPIE vol. 5665, pp.184-195., 2005

An algorithm for the least squares matching of overlapping 3D surfaces is presented. It estimates... more An algorithm for the least squares matching of overlapping 3D surfaces is presented. It estimates the transformation
parameters between two or more fully 3D surfaces, using the Generalized Gauss-Markoff model, minimizing the sum of
squares of the Euclidean distances between the surfaces. This formulation gives the opportunity of matching arbitrarily
oriented 3D surfaces simultaneously, without using explicit tie points. Besides the mathematical model and execution
aspects we give further extension of the basic model. The first extension is the simultaneous matching of sub-surface
patches, which are selected in cooperative surface areas. It provides a computationally effective solution, since it matches
only relevant multi-subpatches rather than the whole overlapping areas. The second extension is the matching of surface
geometry and its attribute information, e.g. reflectance, color, temperature, etc., under a combined estimation model. We
give practical examples for the demonstration of the basic method and the extensions.

Keywords: Least squares 3D surface matching, point clouds, registration, laser scanning, intensity matching.

International Workshop on Recording, Modeling and Visualization of Cultural Heritage, Ascona, Switzerland, May 22-27, E. Baltsavias, A. Gruen, L. Van Gool, M. Pateraki (Eds.), Taylor & Francis/Balkema, Leiden, pp. 115-126., 2005

An algorithm for the least squares matching of overlapping 3D surfaces is pre- sented. It estimat... more An algorithm for the least squares matching of overlapping 3D surfaces is pre- sented. It estimates the transformation parameters between two or more fully 3D surfaces, using the Generalized Gauss-Markoff model, minimizing the sum of squares of the Euclidean dis- tances between the surfaces. This formulation gives the opportunity of matching arbitrarily ori- ented 3D surfaces simultaneously, without using explicit tie points. Besides the mathematical model and execution aspects we give further extensions of the basic model: simultaneous matching of multi sub-surface patches, and matching of surface geometry and its attribute in- formation, e.g. reflectance, color, temperature, etc. under a combined estimation model. We give practical examples for the demonstration of the basic method and the extensions.

ISPRS Workshop on "Tools and Techniques for E-Learning", Potsdam, Germany, June 1-3. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XXXVI, part 6/W30 (on CD-ROM)., 2005

ABSTRACT: This paper presents a user-friendly Windows-based educational software system for expl... more ABSTRACT:
This paper presents a user-friendly Windows-based educational software system for explanation and demonstration of the procedure
of digital monoplotting. The software system named Digital Monoplotting Teaching Program (DiMoTeP) is primarily designed to be
used by teaching personnel in lectures to bring over this particular topic of photogrammetry to master students in an attractive way.
The program consists of two parts: an HTML-based animated tutorial presenting the theoretical background of the method and a
practical part demonstrating the procedure with the real data. The theoretical part of the program is a web-based tutorial covering
explanation of the topic, i.e. definition and background of monoplotting, required data, methods used in the process and application
areas. The demonstration tool is a Windows® software implemented in C/C++ programming language that performs the basic
functions of the procedure, i.e. import the DTM and image data, recording the point or line features as well as visualization. The
students’ feedback showed that the overall structure provides an easy and didactic tool for teaching.

KEY WORDS: E-Learning, Educational Software, Photogrammetry, Digital Monoplotting.

ISPRS Workshop Laser scanning 2005, Enschede, the Netherlands, September 12-14. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XXXVI, part 3/W19, pp. 186-191., 2005

ABSTRACT: An algorithm for least squares matching of overlapping 3D surfaces is presented. It es... more ABSTRACT:
An algorithm for least squares matching of overlapping 3D surfaces is presented. It estimates the transformation parameters between
two or more fully 3D surfaces, using the Generalized Gauss-Markoff model, minimizing the sum of squares of the Euclidean
distances between the surfaces. This formulation gives the opportunity of matching arbitrarily oriented 3D surfaces simultaneously,
without using explicit tie points. Besides the mathematical model and execution aspects we pay particular interest to the reduction of
the computational expenses. An efficient space partitioning method is implemented in order to speed up the correspondence search,
which is the main portion of the computational efforts. The simultaneous matching of sub-surface patches is given as another
strategy. It provides a computationally effective solution, since it matches only relevant multi-subpatches rather then the whole
overlapping area. A practical example including computation times is given for the demonstration of the method.

KEY WORDS: Least squares 3D surface matching, Point clouds, Registration, Laser scanning, Correspondence searching.

5th International Symposium Turkish-German Geodetic Days, Berlin, March 28-31, (only on CD-ROM)., 2006

ABSTRACT: A Herakles statue, named “Weary Herakles” and located in the Antalya Museum, Turkey wa... more ABSTRACT:
A Herakles statue, named “Weary Herakles” and located in the Antalya Museum, Turkey was scanned by a Breuckmann structural
light system. The work comprises all the necessary steps of the 3D object modeling pipeline, i.e. digitization, registration, surface
wrapping, editing and visualization. 3D documentation and visualization of cultural heritage objects is an expanding application
area. This paper presents the capabilities of some of the current technology in this field.

KEY WORDS: Herakles, cultural heritage, laser scanning, digitization, registration, modeling, visualization

ISPRS Commission I Symposium, Paris, July 3-6, (only on CD-ROM). , 2006

ABSTRACT: The Cartographic Institute of Catalonia (ICC) has acquired a DMC digital camera and ha... more ABSTRACT:
The Cartographic Institute of Catalonia (ICC) has acquired a DMC digital camera and has performed some first investigations
regarding radiometric performance and geometric accuracy potential. In this cooperation with the Institute of Geodesy and
Photogrammetry (IGP), ETH Zurich various aspects are analysed. The investigations make use of recent test flights near Tortosa, a
plane region with varying landcover. For the quantitative analysis of the DMC results, a ground control points and lidar data exist,
which have been simultaneously acquired with the DMC images. The first part of the investigations focusses on geometric sensor
modeling and aerial triangulation. Preliminary results of ICC have shown that when standard additional parameters, like the 12
Ebner parameters, are used in AT, significant systematic errors remain and each of the 4 subimages that form the virtual
panchromatic image has a different pattern of image deformations. In these investigations, we do not perform analysis of additional
parameters in order to model these deformations, as this has been done in another ICC work. The results are analysed using GCPs
established in the above mentioned testfield, using two different bundle adjustment programs.. Another part of our investigations
regarding AT deals with automatic point transfer using a high quality multi-image, multi-primitive matching method developed at
IGP, initially for automatic DSM generation. Different aspects like number, distribution and accuracy of the tie points are analysed,
as well number of rays per tie point. The second part of the paper focuses on automatic DSM generation. Although digital cameras
offer characteristics, like better image quality, that could be used favourably in automated DSM generation, almost all commercial
systems employ matching methods with limitations, like no support of multi-image matching. In these investigations, we briefly
introduce the above mentioned IGP multi-image matching and present the matching results. Initial results with other digital cameras
and images with large forward and side overlap have shown that this matching approach can produce DSMs at least as dense as those
produced by airborne laser scanning and almost as accurate, preserving also very well surface discontinuities. The processing and
DSM control was performed by IGP using lidar data provided by ICC, while ICC made an independent control of the aerial
triangulation using the software programs at ICC.

KEY WORDS: Aerial digital cameras, DMC, Sensor modelling, Triangulation, Digital Surface Models, Accuracy analysis

Dreiländertagung SGPBF, DGPF und OVG, Muttenz, Switzerland, June 19-21, DGPF Tagungsband 16 / 2007, pp. 441-451. , 2007

Abstract: This paper examines the potential of mobile phones to be used as a front-end sensor fo... more Abstract:
This paper examines the potential of mobile phones to be used as a front-end sensor for
photogrammetric procedures and applications. For this purpose we are currently calibrating
various mobile phones over our indoor 3D testfield, using self-calibration. In some systems
we have diagnosed substantial systematic errors. We are currently also in the process of
checking the stability of the interior orientation over time.
Using the same testfield we are performing accuracy tests in order to evaluate the metric
performance. This paper reports about first experiences in calibration and accuracy
validation of mobile phone cameras. We believe that with a proper performance these
devices can be used for many photogrammetric tasks in the future.

$Research paper thumbnail of Modeling fractional shrub/tree cover and multi-temporal changes in mire ecosystems using high-resolution digital surface models and CIR aerial images$

2007 IEEE International Geoscience and Remote Sensing Symposium, 2007

Internal Technical Report at IGP - ETH, Zurich, June, 23 pages. , 2003

SWISS FEDERAL INSTITUTE OF TECHNOLOGY Institute of Geodesy and Photogrammetry ETH-Hoenggerberg,... more SWISS FEDERAL INSTITUTE OF TECHNOLOGY
Institute of Geodesy and Photogrammetry
ETH-Hoenggerberg, Zuerich
GENERALIZED PROCRUSTES ANALYSIS AND ITS
APPLICATIONS IN PHOTOGRAMMETRY
Prepared for:
Praktikum in Photogrammetrie, Fernerkundung und GIS
Presented to:
Prof. Armin W. GRUEN
Prepared by:
M. Devrim AKCA
June, 2003

The Procrustes analysis is a least-squares method to estimate the unknown similarity
transformation parameters among two or more than two model points matrices up to their
maximal agreement. Because the estimation model is linear, it does not require the initial
approximations of the unknowns. In geodetic sciences, we are very familiar to solve the
k = 2,3 dimensional similarity transformations by means of conventional least-squares
adjustment. In fact, these two different methods offer two different ways to achieve the same
solution.
In this report, a survey on Procrustes analysis, its theory, algorithms, and related works has
been given. Also, its applications in photogrammetry has been addressed. The previous
section (3.4.) gives a comparison between the Procrustes analysis and the conventional least
squares adjustment.
The most important disadvantage of the Procrustes method is lack of reliability criterion in
order to detect and localize the blunders, which might be included by the data set. Without
such a tool, the results that produced by the Procrustes method can be wrong in the case of
existence of blunders in the data set.

Internal Technical Report at IGP - ETH, Zurich, July, 21 pages., 2005

CO-REGISTRATION OF LARGE VOLUME LASER SCANNER POINT CLOUDS: THE PINCHANGO ALTO (PERU) DATA SET I... more CO-REGISTRATION OF LARGE VOLUME LASER SCANNER POINT CLOUDS: THE PINCHANGO ALTO (PERU) DATA SET
Internal Technical Report
by
Devrim Akca
Group of Photogrammetry and Remote Sensing (P+F), ETH Zurich
www.photogrammetry.ethz.ch

Presented to
Prof. Dr. Armin Gruen
Prepared for the project
3D Modeling of the pre-Inkaic site Pinchango Alto, Peru
a cooperation of
Group of Photogrammetry and Remote Sensing of ETH Zurich
and
German Institute of Archaeology (KAVA, Bonn, Germany)
Swiss Federal Institute of Technology (ETH) Zurich
Institute of Geodesy and Photogrammetry
ETH-Hoenggerberg, CH-8093 Zurich
July 2005

Conclusions
The disadvantages of the target based registration of the laser scanning point clouds are well known. Adopting a target based registration approach requires more fieldwork and personnel, i.e. setting up those targets to the site and measuring them using a theodolite or a GPS system. It is apparent that additional geodetic measurement devices increase the equipment cost as well. The target based registration methods cannot exploit the full accuracy potential of the data, due to additional errors introduced by the geodetic measurements. Although the laser data naturally has very high level of redundancy, the target based registration techniques use only a very small portion of the data. This is the second reason causing to degrade the accuracy potential.
Surface based registration techniques stand as efficient and versatile alternative to the target based techniques. They offer better registration results while keeping the project cost lower. In this study we showed the capabilities our surface based registration method applying to the Pinchango Alto laser scanning data set. Our proposed method, the Least Squares 3D Surface Matching (LS3D), estimates the transformation parameters between two or more fully 3D surfaces, using the Generalized Gauss Markoff model, minimizing the sum of squares of the Euclidean distances between the surfaces. The mathematical model is a generalization of the least squares image matching method and offers high flexibility for any kind of 3D surface correspondence problem. The least squares concept allows for the monitoring of the quality of the final results by means of precision and reliability
criterions.
The Pinchango Alto data set stands as a special case due to the huge volume and many occlusions on the data. The practical example shows that our proposed method can provide successful matching results in reasonable processing times. It exploits the full accuracy potential of the data owing to its powerful mathematical model.
The following up step surface modeling was performed by use of commercial software packages. However, it was not possible to model in the original resolution. Due to not efficient memory management capabilities of the software packages, the modeling had to be performed at reduced resolution. The modeling of 3D laser scanner point clouds is still a troublesome step and sophisticated algorithms need to be developed with real 3D capabilities.

The time-of-flight (TOF) principle is a well known technology to acquire a scene in all three dim... more The time-of-flight (TOF) principle is a well known technology to acquire a scene in all three dimensions. The advantages of the knowledge of the third dimension are obvious for many kinds of applications. The distance information within the scene renders automatic information-processing systems more robust and much less complex or even enables completely new solutions. A solid-state image sensor containing 124x160 pixels and the corresponding 3D-camera, the so-called SwissRanger camera has already been ...

Journal of Spatial Science, Mar 1, 2017

International journal of environment and geoinformatics, Mar 2, 2015

Harita Dergisi, 2002

ÖZET Ana bileşenler dönüşümü (principal components transformation), aralarında yüksek korelasyon ... more ÖZET Ana bileşenler dönüşümü (principal components transformation), aralarında yüksek korelasyon bulunan çok değişkenli verileri, aralarında korelasyon olmayan yeni bir koordinat sistemine dönüştüren istatistiksel bir veri dönüşümü yöntemidir. Bu dönüşüm, farklı disiplinlerce çok değişkenli (çok boyutlu) verilerin analizinde (multivariate analysis) kullanılmaktadır. Özellikle sinyallerin iletiminde sıkça kullanılan bu dönüşüm, sayısal görüntülerin de sinyal olarak yorumlanabilmesi sayesinde, görüntü işleme uygulamalarında da sıkça kullanılmaktadır. Bu çalışmada, sayısal görüntülerde ana bileşenler dönüşümü anlatılmış ve 24 bpp'lik bir test görüntüsü üzerinde yapılan uygulama sunulmuştur. Uygulama, makalenin yazarları tarafından Borland C++ Builder programlama dilinde yazılmış bir bilgisayar programı tarafından gerçekleştirilmiştir. Makalenin sonunda, programın temel fonksiyonlarının kaynak kodları verilmiştir. ABSTRACT The principal components transformation is a statistical data transformation which maps the high correlated multivariate data to a new coordinate system where the data is uncorrelated. This transformation is used by various disciplines. The principal components transformation is especially used in the transmission theory of digital signals. Since digital images can also be interpreted as of special type digital signals, this transformation is also used in digital image processing frequently, for various purposes. In this paper, the principal components transformation has been explained and a sample application has been performed on 24 bpp test image, has been presented. This sample application has been performed with a computer program written by the authors, and has been coded in Borland C++ Builder programming language. At the end of the paper, source codes of the basic functions of the program have also been given. Whole of the original program can be downloaded from:

Photogrammetric Record, Apr 26, 2013

An artificial rainfall event was applied to a forested slope in Ruedlingen, northern Switzerland... more An artificial rainfall event was applied to a forested slope in Ruedlingen,
northern Switzerland. The experiment triggered a landslide which resulted in
mobilising about 130 m3 of debris. The event was monitored by a photogrammetric
network of four cameras, operating at 5 to 8 frames per second, in order to
quantify spatial and temporal changes by tracking tennis balls pegged into the
ground. Image measurements were performed using automated image matching
methods, implemented through a software package developed in-house. Threedimensional coordinates of the target points were estimated by running a
customised type of bundle adjustment, achieving a positioning precision of 18 cm.

FORSAT is a software platform for the extraction of 3D geometric information and automatic change... more FORSAT is a software platform for the extraction of 3D geometric information and automatic change detection from HR (high resolution) and VHR (very-high resolution) imagery from satellite optical sensors. This single-source 3D forest information solution was developed during a two-year research project (2012 â€“ 2014) co-funded by the national funding authorities of the participating countries, namely Austria, Cyprus, Spain, Switzerland and Turkey, under EUROSTARS funding scheme and the European Commission. FORSAT includes two main units. The first one is dedicated to the geometric and radiometric processing of satellite optical imagery and 2D/3D information extraction, that is: image radiometric pre-processing, image and ground point measurement, improvement of geometric sensor orientation, quasi-epipolar image derivation for 3D stereo measurements; Digital Surface Models (DSMs) extraction by using a precise and robust image matching approach specially designed for HR/VHR satellite...

Videometrics, Range Imaging, and Applications XIV, 2017

The Photogrammetric Record, 2016

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2016

Quick and economical ways of detecting of planimetric and volumetric changes of forest areas are ... more Quick and economical ways of detecting of planimetric and volumetric changes of forest areas are in high demand. A research platform, called FORSAT (A satellite processing platform for high resolution forest assessment), was developed for the extraction of 3D geometric information from VHR (very-high resolution) imagery from satellite optical sensors and automatic change detection. This 3D forest information solution was developed during a Eurostars project. FORSAT includes two main units. The first one is dedicated to the geometric and radiometric processing of satellite optical imagery and 2D/3D information extraction. This includes: image radiometric pre-processing, image and ground point measurement, improvement of geometric sensor orientation, quasiepipolar image generation for stereo measurements, digital surface model (DSM) extraction by using a precise and robust image matching approach specially designed for VHR satellite imagery, generation of orthoimages, and 3D measureme...

2019 9th International Conference on Recent Advances in Space Technologies (RAST)

Earth surface changes are often computed by comparing the sequences of digital elevation models (... more Earth surface changes are often computed by comparing the sequences of digital elevation models (DEMs) so called the DEM of difference (DoD) method. We present an operational DEM generation, co-registration and DoD comparison software in which the surface changes are quantified in metric units of volume. A practical method, which is based on the law of error propagation, is developed to estimate the theoretical precisions of volumetric changes. The proposed pipeline can estimate the change of object volumes (in terms of loss and gain) together with their precision numbers. Change of the forest volume in a fire effected region in a test site is analyzed for the validation. The method can be used for various change detection applications related to forestry as well as other topics such as earthworks, geomorphology, mining, and urbanization.

The Photogrammetric Record, 2010