Vanishing point Research Papers - Academia.edu (original) (raw)

A framework is presented for estimating the pose of a camera based on images extracted from a single omnidirectional image of an urban scene, given a 2D map with building outlines with no 3D geometric information nor appearance data. The framework attempts to identify vertical corner edges of buildings in the query image, which we term VCLH, as well as the neighboring plane normals, through vanishing point analysis. A bottom-up process further groups VCLH into elemental planes and subsequently into 3D structural fragments modulo a similarity transformation. A geometric hashing lookup allows us to rapidly establish multiple candidate correspondences between the structural fragments and the 2D map building contours. A voting-based camera pose estimation method is then employed to recover the correspondences admitting a camera pose solution with high consensus. In a dataset that is even challenging for humans, the system returned a top-30 ranking for correct matches out of 3600 camera pose hypotheses (0.83% selectivity) for 50.9% of queries.

- by
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- Computer Vision, Data Mining, Computational Geometry, Image Analysis

Perspective is a fundamental structure that is found to some extent in most images that reflect 3D structure. It is thought to be an important factor in the human visual system for obtaining understanding and extracting semantics from visual material. This paper describes a method of detecting vanishing points in images that does not require prior assumptions about the image being analysed. It enables 3D information to be inferred from 2D images. The approach is derived from earlier work on visual attention that identifies salient regions and translational symmetries.

- by Fred Stentiford
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- Visual attention, Machine Vision, D structure, Vanishing point

Camera calibration has been studied extensively in computer vision and photogrammetry and the proposed techniques in the literature include those using 3D apparatus (two or three planes orthogonal to each other or a plane undergoing a pure translation, etc.), 2D objects (planar patterns undergoing unknown motions), and 0D features (self-calibration using unknown scene points). Yet, this paper proposes a new calibration technique using 1D objects (points aligned on a line), thus filling the missing dimension in calibration. In particular, we show that camera calibration is not possible with free-moving 1D objects, but can be solved if one point is fixed. A closed-form solution is developed if six or more observations of such a 1D object are made. For higher accuracy, a nonlinear technique based on the maximum likelihood criterion is then used to refine the estimate. Singularities have also been studied. Besides the theoretical aspect, the proposed technique is also important in practice especially when calibrating multiple cameras mounted apart from each other, where the calibration objects are required to be visible simultaneously.

- by Zhengyou Zhang
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- Information Systems, Algorithms, Computer Vision, Photogrammetry

We present a novel drawing system for composing and rendering perspective scenes. Our approach uses a projective 2D representation for primitives rather than a conventional 3D description. This allows drawings to be composed with the same ease as traditional illustrations, while providing many of the advantages of a 3D model. We describe a range of user-interface tools and interaction techniques that give our system its 3D-like capabilities. We provide vanishing point guides and perspective grids to aid in drawing freehand strokes and composing perspective scenes. Our system also has tools for intuitive navigation of a virtual camera, as well as methods for manipulating drawn primitives so that they appear to undergo 3D translations and rotations. We also support automatic shading of primitives using either realistic or non-photorealistic styles. Our system supports drawing and shading of extrusion surfaces with automatic hidden surface removal and highlighted silhouettes. Casting shadows from an infinite light source is also possible with minimal user intervention.

- by Leonard McMillan
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- User Interface, Non-photorealistic rendering, Euclidean space, Vanishing point

3D object recognition is a difficult and yet an important problem in computer vision. A 3D object recognition system has two major components, namely: an object modeller and a system that performs the matching of stored representations to those derived from the sensed image. The performance of systems wherein the construction of object models is done by training from one or more images of the objects, has not been very satisfactory. Although objects used in a robotic workcell or in assembly processes have been designed using a CAD system, the vision systems used for recognition of these objects are independent of the CAD database. This paper proposes a scheme for interfacing the CAD database of objects and the computer vision processes used for recognising these objects. CAD models of objects are processed to generate vision oriented features that appear in the different views of the object and the same features are extracted from images of the object to identify the object and its pose.

In the paper, we propose a robust lane detection
method using an adaptive road mask with edge
based techniques. The adaptive road mask is
generated by applying the fast vanishing-point
detection scheme. Our method is highly
computationally efficient, robust to lane detection,
and adaptive to the captured road scenario.
Experimental results demonstrate the promising
characteristics of the proposed method.

- by SDIWC Organization
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- Computer Vision, Edge Detection, Lane Detection, Vanishing point

In this article a new method for the calibration of a vision system which consists of two (or more) cameras is presented. The proposed method, which uses simple properties of vanishing points, is divided into two steps. In the first step, the intrinsic parameters of each camera, that is, the focal length and the location of the intersection between the optical axis and the image plane, are recovered from a single image of a cube. In the second step, the extrinsic parameters of a pair of cameras, that is, the rotation matrix and the translation vector which describe the rigid motion between the coordinate systems fixed in the two cameras, are estimated from an image stereo pair of a suitable planar pattern. Firstly, by matching the corresponding vanishing points in the two images the rotation matrix can be computed, then the translation vector is estimated by means of a simple triangulation. The robustness of the method against noise is discussed, and the conditions for optimal estimation of the rotation matrix are derived. Extensive experimentation shows that the precision that can be achieved with the proposed method is sufficient to efficiently perform machine vision tasks that require camera calibration, like depth from stereo and motion from image sequence.

- by Bruno Caprile
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- Computer Vision, Machine Vision, Stereopsis, Algorithm
- by Aini Hussain
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- Bone, IEEE, Vanishing point, Tracking system

الجشطالتThe Project is “One Point controls everything in the room”.
Installation NO. 1 “Everything belongs to One Source in this Universe”
Installation NO. 2“The diameter of the circle is impossible to become parallel lines”.
“The parallel lines meeting at one source “
Installation NO. 3lines meeting in a one-point in everyplace even the spare places in the room

Rotation estimation is a fundamental step for various robotic applications such as automatic control of ground/aerial vehicles, motion estimation and 3D reconstruction. However it is now well established that traditional navigation equipments, such as global positioning systems (GPSs) or inertial measurement units (IMUs), suffer from several disadvantages. Hence, some vision-based works have been proposed recently. Whereas interesting results can be obtained, the existing methods have non-negligible limitations such as a difficult feature matching (e.g. repeated textures, blur or illumination changes) and a high computational cost (e.g. analyze in the frequency domain). Moreover, most of them utilize conventional perspective cameras and thus have a limited field of view. In order to overcome these limitations, in this paper we present a novel rotation estimation approach based on the extraction of vanishing points in omnidirectional images. The first advantage is that our rotation estimation is decoupled from the translation computation, which accelerates the execution time and results in a better control solution. This is made possible by our complete framework dedicated to omnidirectional vision, whereas conventional vision has a rotation/translation ambiguity. Second, we propose a top-down approach which maintains the important constraint of vanishing point orthogonality by inverting the problem: instead of performing a difficult line clustering preliminary step, we directly search for the orthogonal vanishing points. Finally, experimental results on various data sets for diverse robotic applications have demonstrated that our novel framework is accurate, robust, maintains the orthogonality of the vanishing points and can run in real-time.

- by Cédric Demonceaux
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- Mechanical Engineering, Automatic Control, Motion estimation, Feature matching

When observers localize the vanishing point of a moving target, localizations are reliably displaced beyond the final position, in the direction the stimulus was traveling just prior to its offset. We examined modulations of this phenomenon through eye movements and action control over the vanishing point. In Experiment 1 with pursuit eye movements, localization errors were in movement direction, but less pronounced when the vanishing point was self-determined by a keypress of the observer. In contrast, in Experiment 2 with fixation instruction, localization errors were opposite movement direction and independent from action control. This pattern of results points at the role of eye movements, which were gathered in Experiment 3. That experiment showed that the eyes lagged behind the target at the point in time, when it vanished from the screen, but that the eyes continued to drift on the targets' virtual trajectory. It is suggested that the perceived target position resulted from the spatial lag of the eyes and of the persisting retinal image during the drift.

- by Jochen Müsseler
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- Psychology, Cognitive Science, Visual Cognition, Eye Movement

In this paper, a methodology for the calculation of rough exterior orientation (EO) parameters of multiple large-scale overlapping oblique aerial images, in the case that GPS/INS information is not available (e.g., for old datasets), is presented. It consists of five main steps; (a) the determination of the overlapping image pairs and the single image in which four ground control points have to be measured; (b) the computation of the transformation parameters from every image to the coordinate reference system; (c) the rough estimation of the camera interior orientation parameters; (d) the estimation of the true horizon line and the nadir point of each image; (e) the calculation of the rough EO parameters of each image. A developed software suite implementing the proposed methodology is tested using a set of UAV multi-perspective oblique aerial images. Several tests are performed for the assessment of the errors and show that the estimated EO parameters can be used either as initial approximations for a bundle adjustment procedure or as rough georeferencing information for several applications, like 3D modelling, even by non-photogrammetrists, because of the minimal user intervention needed. Finally, comparisons with a commercial software are made, in terms of automation and correctness of the computed EO parameters.

- by Styliani Verykokou
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- Computer Vision, Photogrammetry, Georeferencing, Unmanned Aerial Vehicles
- by Kadi Bouatouch
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- Cognitive Science, Augmented Reality, Camera Calibration, 3-D Reconstruction

The purpose of this project is to verify that the artist Johannes Vermeer painted The Music Lesson and A Lady Standing at a Virginal in the same room. The main objective is to elucidate the methods used by Tomas Garcia-Salgado by calculating the numerical values mentioned in his paper and compare the calculations with the findings in Aditya Liviandi's thesis.

- by Helmer Aslaksen
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- Projective Geometry, Vanishing point

Image based video generation paradigms have recently emerged as an interesting problem in the field of
robotics. This paper focuses on the problem of automatic video generation of both indoor and outdoor
scenes. Automatic 3D view generation of indoor scenes mainly consist of orthogonal planes and outdoor
scenes consist of vanishing point. The algorithm infers frontier information directly from the images using
a geometric context-based segmentation scheme that uses the natural scene structure. The presence of
floor is a major cue for obtaining the termination point for the video generation of the indoor scenes and
vanishing point plays an important role in case of outdoor scenes. In both the cases, we create the
navigation by cropping the image to the desired size upto the termination point. Our approach is fully
automatic, since it needs no human intervention and finds applications, mainly in assisting autonomous
cars, virtual walk through ancient time images, in architectural sites and in forensics. Qualitative and
quantitative experiments on nearly 250 images in different scenarios show that the proposed algorithms
are more efficient and accurate.

- by International Journal on Computational Science & Applications (IJCSA) and +1
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- Hough Transform, Vanishing point, Canny Edge Detector

In this paper, we present an analytical method for computing the globally optimal estimates of orthogonal vanishing points in a “Manhattan world” with a calibrated camera. We formulate this as constrained least-squares problem whose optimality conditions form a multivariate polynomial system. We solve this system analytically to compute all the critical points of the least-squares cost function, and hence the global minimum, i.e., the globally optimal estimate for the orthogonal vanishing points. The same optimal estimator is used in conjunction with RANSAC to generate orthogonal-vanishing-point hypotheses (from triplets of lines) and thus classify lines into parallel and mutually orthogonal groups. The proposed method is validated experimentally on the York Urban Database.

- by Mirza Ahmad Faraz
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- Mathematics, Computer Science, Image Processing, Iterative Methods

A calibrated camera is essential for computer vision systems: the prime reason being that such a camera acts as an angle measuring device. Once the camera is calibrated, applications like three-dimensional reconstruction or metrology or other applications requiring real world information from the video sequences can be envisioned. Motivated by this, we address the problem of calibrating multiple cameras, with

- by Imran Junejo
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- Cognitive Science, Computer Vision, Camera Calibration, Motion Capture

KNAW Narcis. Back to search results. Publication The Arnolfini Portrait in 3d: Creating Virtual World of a Painting... (2007). Pagina-navigatie: Main. Title, The Arnolfini Portrait in 3d: Creating Virtual World of a Painting with... more

- by Zsofia Ruttkay
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- Computer Science, Image Processing, Virtual Worlds, Scientific Computing

In this paper we present a multi-camera system, which serves as the primary vision apparatus for a ceiling based swinging service robotic platform. To facilitate a smooth and unimpeded movement of the swinging platform the knowledge of the working environment is essential. To this end we examine the 3D scene reconstruction by concurrent multiple views from the distinct cameras located at the upper corners of a room for volume calculation of objects in everyday indoor environments. The 3D scene reconstruction is used to determine the working volume where the swinging robot will be able to operate. At first, we detect lines across the views using the hough transformation while the computation of multiple vanishing points serves as the platform to distinguish regions across the multi camera system. We thereafter obtain correspondences across the multiple views of the test room and finally we determine the 3D volumes of objects across the scene. The preliminary experimental results show that the volume computation is very accurate and reasonably time consuming.

- by Antonios Gasteratos
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- Computer Vision, Machine Vision, Work Environment, Mobile Robots

Beliz Güçbilmez Modern Turkish Theatre has been widely classified as a westernized theatre, which means that it is modeled on the grounding principles of the western-or with a more accurate definition-the European theatre. The westernization of the Turkish theatre began with the Reformation period, Tanzimat back in 1836, and caused a serious conflict between the existing forms, and the " new " found ones. The old forms like Karagöz, Ortaoyunu and Meddah (a form named after the story teller) had been condemned for their immoral, rude and naughty character during the fervent days of Reformation period and these traditional forms had been consigned to oblivion. This first westernization period of the theatre is marked with the melodramas written by some of the most politic figures of the era, like Namık Kemal, faintly or strongly reminiscent of Shakespeare and Hugo. During late 1920's, the second westernization period took place right after the proclamation of the republic, disowning the heritage of the Ottomans, and remodeling the western oriented Reformation theatre without really adding anything new to the idea or the way of westernization, apart from shifting the model from melodrama to realist theatre. The republican theatre bureaucracy had pointed the Ibsenite realism out, 2 but the playwriting practice had somehow fallen short of expectations. The structure of Ibsen's plays that might be formulated as something had happened in the past, and it has its consequences in the present or a present with a past shadow has been employed scarcely in Turkish plays. What is accepted widely in Turkish realist theatre has been another formula; suddenly something happens and the action develops. The difference between the intention of the Republican cultural policy and the experience of the playwright is deeper than it might be perceived at first sight. I'd like to examine this difference more closely, in order to demonstrate that it is not so easy to define Turkish realist theatre as a westernized form of writing and try to read these alleged realist plays as miniatures which owe their ground to the Eastern culture more than the Western culture. In order to do this I'd like to point out to the link between the theatre and the memory briefly, and then the importance of the past in Ibsen's theatre as the advised model of Turkish theatre. This route will –I

- by Beliz Güçbilmez
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- Dramaturgy, Turkish Theatre, Perspective, Story Telling

We describe how 3D affine measurements may be computed from a single perspective view of a scene given only minimal geometric information determined from the image. This minimal information is typically the vanishing line of a reference plane, and a vanishing point for a direction not parallel to the plane. It is shown that affine scene structure may then be determined from the image, without knowledge of the camera's internal calibration (e.g. focal length), nor of the explicit relation between camera and world (pose). In particular, we show how to (i) compute the distance between planes parallel to the reference plane (up to a common scale factor); (ii) compute area and length ratios on any plane parallel to the reference plane; (iii) determine the camera's location. Simple geometric derivations are given for these results. We also develop an algebraic representation which unifies the three types of measurement and, amongst other advantages, permits a first order error propagation analysis to be performed, associating an uncertainty with each measurement. We demonstrate the technique for a variety of applications, including height measurements in forensic images and 3D graphical modelling from single images.

- by Andrew Zisserman
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- Forensics, Computer Vision, Image Processing, Photogrammetry

This paper presents two new, efficient solutions to the two-view, relative pose problem from three image point correspondences and one common reference direction. This three-plus-one problem can be used either as a substitute for the classic five-point algorithm, using a vanishing point for the reference direction, or to make use of an inertial measurement unit commonly available on robots and mobile devices where the gravity vector becomes the reference direction. We provide a simple, closed-form solution and a solution based on algebraic geometry which offers numerical advantages. In addition, we introduce a new method for computing visual odometry with RANSAC and four point correspondences per hypothesis. In a set of real experiments, we demonstrate the power of our approach by comparing it to the five-point method in a hypothesizeand-test visual odometry setting.

- by Xun Zhou
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- Information Systems, Robotics, Algebraic Geometry, Algorithms

This paper explores the combination of inertial sensor data with vision. Visual and inertial sensing are two sensory modalities that can be explored to give robust solutions on image segmentation and recovery of 3D structure from images, increasing the capabilities of autonomous robots and enlarging the application potential of vision systems. In biological systems, the information provided by the vestibular system is fused at a very early processing stage with vision, playing a key role on the execution of visual movements such as gaze holding and tracking, and the visual cues aid the spatial orientation and body equilibrium. In this paper, we set a framework for using inertial sensor data in vision systems, and describe some results obtained. The unit sphere projection camera model is used, providing a simple model for inertial data integration. Using the vertical reference provided by the inertial sensors, the image horizon line can be determined. Using just one vanishing point and the vertical, we can recover the camera's focal distance and provide an external bearing for the system's navigation frame of reference. Knowing the geometry of a stereo rig and its pose from the inertial sensors, the collineation of level planes can be recovered, providing enough restrictions to segment and reconstruct vertical features and leveled planar patches.

- by Jorge Dias
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- Information Systems, Computer Vision, Image segmentation, Vestibular System

Unmanned aerial vehicles (UAVs) are increasingly replacing manned systems in situations that are dangerous, remote, or difficult for manned aircraft to access. Its control tasks are empowered by computer vision technology. Visual sensors are robustly used for stabilization as primary or at least secondary sensors. Hence, UAV stabilization by attitude estimation from visual sensors is a very active research area. Vision based techniques are proving their effectiveness and robustness in handling this problem. In this work a comprehensive review of UAV vision based attitude estimation approaches is covered, starting from horizon based methods and passing by vanishing points, optical flow, and stereoscopic based techniques. A novel segmentation approach for UAV attitude estimation based on polarization is proposed. Our future insightes for attitude estimation from uncalibrated catadioptric sensors are also discussed.

- by Olivier Morel and +2
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- Cognitive Science, Optical Flow, Intelligent, Vanishing point

“…the I is invisible, as when H. Masud Taj reflects on insight, blindness and the chance symmetries between nature and architecture, in ‘The Clock Tower, the Skyscraper and the Moon’: The clock tower is a cyclops The skyscraper is blind,... more

- by H. Masud Taj
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- Poetry, Pilgrimage, Black Holes, Photosynthesis

According to the Perceptual Symbols Theory of cognition (Barsalou, 1999), modality-specific simulations underlie the representation of concepts. A strong prediction of this view is that perceptual processing affects conceptual processing. In this study, participants performed a perceptual detection task and a conceptual property-verification task in alternation. Responses on the property-verification task were slower for those trials that were preceded by a perceptual trial in a different modality than for those that were preceded by a perceptual trial in the same modality. This finding of a modality-switch effect across perceptual processing and conceptual processing supports the hypothesis that perceptual and conceptual representations are partially based on the same systems.

- by René Zeelenberg
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- Psychology, Cognitive Science, Optics, Perception

When participants control the horizontal movements of a stimulus and indicate its vanishing point after it unexpectedly vanishes, the perceived vanishing point is displaced beyond the actual vanishing point, and the size of the displacement is directly related to the action-effect extrapolations one has to generate to successfully control the stimulus. The present experiments examined whether learning a pattern of action-effect extrapolation would later impact one's perception of moving stimuli. While one participant (the controller) controlled a dot's movements across a computer screen, another (the observer), who could neither see nor hear the controller, watched the dot's movements on a separate monitor. When the dot unexpectedly vanished, the observer indicated the vanishing point. After 40 trials, participants switched roles. While serving as observers, all participants generated forward displacements, but those who did so after acquiring control experience produced larger displacement. Subsequent experiments indicated the larger displacement was due to action-effect extrapolations the participants learned while either controlling the dot or observing another do so.

- by Scott Jordan
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- Psychology, Cognitive Science, Perception, Cognition

Camera parameters estimation is an important issue in machine vision. This study proposes a new method to find translation and rotation matrix of camera in a sport scene based on points at infinity. Vanishing point (point at infinity) of parallel lines is the image of the point at infinity, which corresponds to the projection of the intersection of parallel lines at infinity. According to projective geometry constraint, camera rotation of the projection matrix is directly computed using two vanishing points and rotation matrix of camera extracted from those points at infinity. Computer simulation and real data experiments are carried out to validate the proposed method.

This paper describes a system for structure from motion using vanishing points and three-dimensional lines extracted from omni-directional video sequences. To track lines, we use a novel dynamic programming approach to improve ambiguity resolution, and we use delayed states to aid in the initialization of landmarks. By reobserving vanishing points we get direct measurements of the robot's three-dimensional attitude that are independent of its position. Using vanishing points simplifies the representation since parallel lines share the same direction states. We show the performance of the system in various indoor and outdoor environments and include comparisons with independent two-dimensional reference maps for each experiment.

- by Michael Bosse
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- Cognitive Science, State Estimation, Structure from Motion, Kalman Filter
- by Brian D. Warner
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- Spectrum, Vanishing point

- by Charalampos Ioannidis
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- Computer Vision, Remote Sensing, Photogrammetry, Georeferencing

The paper describes a system for 6 degree of freedom intertemporal stochastic mapping of an unknown environment using only odometery and omni-directional vision. The method uses a feature-based stochastic map where vanishing points and line segments are extracted and tracked in the omni-directional video sequence. To track lines, we use a novel dynamic programming approach to improve ambiguity resolution, and we use delayed states to aid in the initialization of landmarks in the scene. By reobserving vanishing points we get a direct measurement of the robot's 3-D attitude that is independent from its translation. Furthermore using vanishing points simplifies the representation since parallel lines share the same direction states. We show the performance of the system in various indoor and outdoor environments and compare the generated 3-D map with a 2-D map generated from a gyro-laser based system. 1

- by Michael Bosse
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- Structure from Motion, Degree of Freedom, Vanishing point

The judged final position of a moving stimulus has been suggested to be shifted in the direction of motion because of mental extrapolation (representational momentum). However, a perceptual explanation is possible: The eyes overshoot the final position of the target, and because of a foveal bias, the judged position is shifted in the direction of motion. To test this hypothesis, the authors replicated previous studies, but instead of having participants indicate where the target vanished, the authors probed participants' perceptual focus by presenting probe stimuli close to the vanishing point. Identification of probes in the direction of target motion was more accurate immediately after target offset than it was with a delay. Another experiment demonstrated that judgments of the final position of a moving target are affected by whether the eyes maintain fixation or follow the target. The results are more consistent with a perceptual explanation than with a memory aecount.

- by Jochen Müsseler and +1
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- Psychology, Cognitive Science, Visual perception, Motion perception

We present a novel perception-driven approach to low-cost tele-presence systems, to support immersive experience in continuity between projected video and conferencing room. We use geometry and spectral correction to impart for perceptual continuity to the whole scene. The geometric correction comes from a learning-based approach to identifying horizontal and vertical surfaces. Our method redraws the projected video to match its vanishing point with that of the conference room in which it is projected. We quantify intuitive concepts such as the depth-of-field using a Gabor filter analysis of overall images of the conference room. We equalise spectral features across the projected video and the conference room, for spectral continuity between the two.

- by Lopamudra Choudhury
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- Pattern Recognition, Geometric correction, Depth of Field, Gabor Filter

Road modeling is the first step towards environment perception within driver assistance video-based systems. Typically, lañe modeling allows applications such as lañe departure warning or lañe invasión by other vehicles. In this paper, a new monocular image processing strategy that achieves a robust múltiple lañe model is proposed. The identification of múltiple lañes is done by firstly detecting the own lañe and estimating its geometry under perspective distortion. The perspective analysis and curve fitting allows to hypothesize adjacent lañes assuming some a priori knowledge about the road. The verification of these hypotheses is carried out by a confidence level analysis. Several types of sequences have been tested, with different illumination conditions, presence of shadows and significant curvature, all performing in realtime. Results show the robustness of the system, delivering accurate múltiple lañe road models in most situations.

- by Luis Salgado
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- Image Processing, A Priori Knowledge, Real Time, Curve fitting

Vision systems play an important role in many intelligent transportation systems (ITS) applications, such as traffic monitoring, traffic law reinforcement, driver assistance, and automatic vehicle guidance. These systems installed in either outdoor environments or vehicles have often suffered from image instability. In this paper, a video stabilization technique for a camcorder mounted on a moving vehicle is presented. The proposed approach takes full advantage of the a priori information of traffic images, significantly reducing the computational and time complexities. There are four major steps involved in the proposed approach: global feature extraction, camcorder motion estimation, motion taxonomy, and image compensation. We begin with extracting the global features of lane lines and the road vanishing point from the input image. The extracted features are then combined with those detected in previous images to compute the camcorder motion corresponding to the current input image. The computed motion consists of both expected and unexpected components. They are discriminated and the expected motion component is further smoothed. The resulting motion is next integrated with a predicted motion, which is extrapolated from the previous desired camcorder motions, leading to the desired camcorder motion associated with the input image under consideration. The current input image is finally stabilized based on the computed desired camcorder motion using an image transformation technique. A series of experiments with both real and synthetic data have been conducted. The experimental results have revealed the effectiveness of the proposed technique.

- by Sei-Wang Chen
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- Engineering, Technology, Intelligent Transport System, Stability

Whereas some methods for plane extraction have been proposed, this problem still remains an open issue due to the complexity of the task. This paper especially focuses on the extraction of points lying on a plane (such as the ground and buildings walls) in sequences acquired by a central omnidirectional camera. Our approach is based on the epipolar constraint for planar scenes (i.e. homography) on a pair of omnidirectional images to detect some interest points belonging to a plane. Our main contribution is the introduction of a new method, called "2-point algorithm for homography", that imposes some constraints on the homography using vanishing point (VP) information. Compared to the widely used DLT (4-point) algorithm, experiments on real data demonstrated that the proposed "2-point algorithm for homography" is more robust to noise and false matching, even when the plane to extract is not dominant in the image. Finally, we show that our system provides key clues for ground segmentation by GrabCut.

In recent years, oblique aerial images are involved in various photogrammetric processes and are used not only for interpretation or visualization purposes but also in metric applications. This paper describes an approach for the computation of vertical and horizontal distances from a single low oblique aerial image. The proposed methodology can be applied in the case where the camera exterior orientation is unknown. It relies on the automatic determination of the nadir point using edge detection and line extraction algorithms, combined with robust model fitting and least-squares techniques, taking into account the underlying geometry of oblique imagery. The workflow and the mathematical model used are presented in detail and the effect of different variables (flying height, camera constant, tilt of the camera axis, length of the line segment, error in the determination of the flying height and error due to lack of ground elevation information) on the errors of both measured vertica...

- by Charalampos Ioannidis
- •
- Photogrammetry, Aerial Photogrammetry, Aerial Photography, Accuracy

This paper describes a system for structure-from-motion using vanishing points and three-dimensional lines extracted from omni-directional video sequences. To track lines, we use a novel dynamic programming approach to improve ambiguity resolution, and we use delayed states to aid in the initialization of landmark. By reobserving vanishing points we get direct measurements of the robot's 3-D attitude that are independent of its position. Using vanishing points simplifies the representation since parallel lines share the same direction states. We show the performance of the system in various indoor and outdoor environments and include comparisons with independent 2-D reference maps for each experiment.

- by Michael Bosse
- •
- Image Processing, Dynamic programming, Structure from Motion, Navigation

- by Xun Zhou
- •
- Information Systems, Robotics, Algebraic Geometry, Algorithms

We present two components of a vision-based approach to autonomous driving on and near rural and desert roads. The first component comprises fast processing of live vehicle camera video to robustly extract linear direction and midline estimates of marginal roads. The second uses satellite imagery immediately surrounding the vehicle's GPS position to trace the road ahead for curve and corner anticipation, and to inform the vehicle planner of a nearby road when traveling cross-country. The algorithms are built upon Gabor wavelet filters for texture analysis: on-board, they are employed to find ruts and tracks from which the road vanishing point can be inferred via Houghstyle voting, and aerially, they localize the edges of low-contrast road contours. Mechanisms for both modules to determine whether the vehicle is currently on-or off-road are also explained. Our system's efficacy is illustrated for several difficult datasets, including a log from one vehicle's run during the 2004 DARPA Grand Challenge.

- by Christopher Rasmussen and +1
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- Computer Vision and Pattern Recognition, Satellite Imagery, Texture Analysis, Vanishing point

Scenes that contain every-day man-made objects often possess sets of parallel lines and orthogonal planes, the projective features of which possess enough structural information to constrain possible scene element geometries as well as a camera's intrinsic and extrinsic parameters. In particular, in a scene with three mutually orthogonal sets of parallel lines, detection of the corresponding three vanishing points of

- by Shawn Becker
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- Line Detection, Lens Distortion, Multiple Views, Vanishing point

- by Styliani Verykokou
- •
- Computer Vision, Photogrammetry, Aerial Photogrammetry, Edge Detection

In this paper we describe a flexible approach for determining the relative orientation of the camera with respect to the scene. The main premise of the approach is the fact that in man-made environments, the majority of lines is aligned with the principal orthogonal directions of the world coordinate frame. We exploit this observation towards efficient detection and estimation of vanishing points, which provide strong constraints on camera parameters and relative orientation of the camera with respect to the scene. By combining efficient image processing techniques in the line detection and initialization stage we demonstrate that simultaneous grouping and estimation of vanishing directions can be achieved in the absence of internal parameters of the camera. Constraints between vanishing points are then used for partial calibration and relative rotation estimation. The algorithm has been tested in a variety of indoors and outdoors scenes and its efficiency and automation makes it amenable for implementation on robotic platforms.

- by Jana Kosecka
- •
- Computer Science, Line Detection, Image processing techniques, Vanishing point

In this paper, we describe how an effective vanishing point detector can be applied to photogrammetry when only a single view of an architectural environment is available. Our method performs automatic segment clustering in projective space-a direct transformation from the image space-instead of the traditional bounded accumulator space. Experiments on real images show the effectiveness of the proposed detector in finding all vanishing points, as well as its application in a photogrammetry algorithm, by recovering the vertical direction of the scene and the vanishing line for the ground plane.

- by Gabriel Taubin
- •
- Vanishing point, projective space
- by Nicolas Paparoditis
- •
- Computer Vision, Mobile Mapping, Real Time, Pose Estimation

This paper presents a way to design a lateral controller for an automated vehicle using information gained through image processing with the control objective being to stay on a desired path. Two possible ways to obtain the information necessary for lateral control by image processing ure presented, one based on pixel intensity summation and the other on vanishing point calculations. The paper also describes two algorithms for the actual lateral control, one based on classical control theory and the other on modern H, control. The resulting control algorithms were implemented on a scaled autonomous vehicle system.

- by Pushkin Kachroo
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- Computer Vision, Image Processing, Control Theory, Process Control

These 6 experiments explored the ability of moving random dot patterns to attract attention, as measured by a simple probe-detection task. Each trial began with random motion (i.e., dots linearly moved in random directions). After 1 s motion in 1 hemifield became gradually coherent (i.e., all dots moved up-, down-, left-, or rightwards, or either towards or away from a vanishing point). The results show that only looming motion attracted attention, even when the task became a more demanding discrimination task. This effect is not due to an apparent magnification of stimuli presented in the focus of expansion. When the coherent motion started abruptly, all types of motion attracted attention at a short stimulus onset asynchrony. The looming motion effect only disappeared when attention was drawn to the target location by an arrow. These results suggest that looming motion plays a unique role in guiding spatial attention.

- by Alejandro Lleras
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- Psychology, Cognitive Science, Psychophysics, Visual attention