Hans Jørgen Andersen - Academia.edu (original) (raw)

Papers by Hans Jørgen Andersen

Experiment and Results Experiments have been done both in simulation and in real world. The simul... more Experiment and Results Experiments have been done both in simulation and in real world. The simulation tests the capability of the Case Base Reasoning module, and the real world experiment tests the movement pattern of the robot. The simulation has been done using the robotic software framework Player/Stage, and the real world experiment has been done using a FESTO Robotino robot platform equipped with a laser range finder and a camera for detecting persons. In the simulation an extra simulated robot was used to represent a person. Experiments were made with persons both interested and not interested in interaction.

Sampling based techniques for robot motion planning have become more widespread during the last d... more Sampling based techniques for robot motion planning have become more widespread during the last decade. The algorithms however, still struggle with for example narrow passages in the configuration space and suffer from high number of necessary samples, especially in higher dimensions. A widely used method is Rapidly-exploring Random Trees (RRT’s). One problem with this method is the nearest neighbour search time, which grows significantly when adding a large number of vertices. We propose an algorithm which decreases the computation time, such that more vertices can be added in the same amount of time to generate better trajectories. The algorithm is based on subdividing the configuration space into boxes, where only specific boxes needs to be searched to find the nearest neighbour. It is shown that the computational complexity is lowered from a theoretical point of view. The result is an algorithm that can provide better trajectories within a given time period, or alternatively com...

International Journal of Architectural Computing, 2020

This study seeks to identify key aspects for increased integration of interactive robotics within... more This study seeks to identify key aspects for increased integration of interactive robotics within the creative design process. Through its character as foundational research, the study aims to contribute to the advancement of new explorative design methods to support architects in their exploration of fabrication and assembly of an integrated performance-driven architecture. The article describes and investigates a proposed design framework for supporting an interactive human–robot design process. The proposed framework is examined through a 3-week architectural studio, with university master students exploring the design of a brick construction with the support of an interactive robotic platform. Evaluation of the proposed framework was done by triangulation of the authors’ qualitative user observations, quantitative logging of the students’ individual design processes, and through questionnaires completed after finishing the studies. The result suggests that interactive human–robo...

International Journal of Computer Applications in Technology, 2016

In the modern world, cities need to keep up with the demand for mobility, efficient infrastructur... more In the modern world, cities need to keep up with the demand for mobility, efficient infrastructure and environmental sustainability. The future smart cities use intelligent information and communication technologies to raise the quality of life. This includes computer vision as one of the main technologies. It can observe and analyse human activities from a distance in a noninvasive manner. Traditional computer vision utilises RGB cameras, but problems with this sensor include its light dependency, and the privacy issues that can be raised by people being observed. In this paper, we propose the use of thermal imaging in real-time smart city applications. Thermal cameras operate independently of light and measure the radiated infrared waves representing the temperature of the scene. In order to showcase the possibilities, we present five different applications which use thermal imaging only. These include both indoor and outdoor scenarios with the purposes of people detection, counting and tracking, as well as one application for traffic safety evaluation.

This paper presents and discusses perspectives extracted from two interviews conducted during the... more This paper presents and discusses perspectives extracted from two interviews conducted during the experiments Urban Responsive Lighting. The two experts embody two different fields related to city lighting: architecture & public lighting industry. The representatives were invited to the test-site, where 15 LED RGB Park lamps, controlled driven by a wind sensor, mobile phone applications or by thermal camera tracking. According to the specialists are the social and aesthetical dimensions more interesting than the energy use cases and efficiency. This motivates an interdisciplinary discussion on applied technologies and responsive light design in the contemporary cities.

In this article we introduce a novel method for detecting multi-scale salient regions around edge... more In this article we introduce a novel method for detecting multi-scale salient regions around edges using a graph based image compression algorithm. Images are recursively decomposed into triangles arranged into a binary tree using linear interpolation. The entropy of any local region of the image is inherent in the areas of the triangles and tree depth. We introduce twin leaves as nodes whose sibling share the same characteristics. Triangles corresponding to the twin leaves are filtered out from the binary tree. Graph connectivity is exploited to get clusters of triangles followed by ellipse fitting to estimate regions. Salient regions are thus formed as stable regions around edges. Tree hierarchy is then used to generate multi-scale regions. We evaluate our detector by performing image retrieval tests on our building database which shows that combined with Spin Images (Lazebnik et al., 2003), their performance is comparable to SIFT (Lowe, 2004).We also show that when they are used together with MSERs (Matas et al., 2002), the performance of MSERs is boosted.

This paper aims at evaluating multi-camera configurations as a function of the descriptive parame... more This paper aims at evaluating multi-camera configurations as a function of the descriptive parameters of complex biological objects. Multi-baseline Stereo has potential to handle projective distortion at large baselines. Being close to the observed object and the orientation of object surfaces pointing toward the camera increase the projection distortion. An example is 3D reconstruction of plants where the leaves can be pointing steeply toward the cameras, while, sub-leaf reconstruction needs high depth resolution, because the leaves overlap closely to each other. The paper presents a new dissimilarity measure, called Sums of Individual Sums of Squared Differences (SISSD). It takes projection distortion and changing specular highlights into account by learning the gradual changing of the feature window. The method was included in the comparative study that used realistic ray traced plant models, where the descriptive parameters of the objects could be controlled. Other configurations in the experiment were the commonly used Multi-baseline Sum of the Sums of Squared Differences (SSSD), the popular binocular graph cuts, and two trinocular correlation techniques. Comparison is in regard to leaf type, texture and orientation, proportion of occlusion and proportion of changing highlights by computing the overall-, occluded-, and highlighted-percentage of bad matching pixels (pbmp, pbmpocc, and pbmp high). The results showed a complicated relationship of trade-offs that points toward further development combining the strengths of the individual configurations.

2012 16th International Symposium on Wearable Computers, 2012

Communications in Computer and Information Science, 2009

2009 IEEE International Conference on Robotics and Automation, 2009

This paper introduces a new method to determine a person's pose based on laser range measurements... more This paper introduces a new method to determine a person's pose based on laser range measurements. Such estimates are typically a prerequisite for any human-aware robot navigation, which is the basis for effective and timeextended interaction between a mobile robot and a human. The robot uses observed information from a laser range finder to detect persons and their position relative to the robot. This information together with the motion of the robot itself is fed through a Kalman filter, which utilizes a model of the human kinematic movement to produce an estimate of the person's pose. The resulting pose estimates are used to identify humans who wish to be approached and interacted with. The behaviour of the robot is based on adaptive potential functions adjusted accordingly such that the persons social spaces are respected. The method is tested in experiments that demonstrate the potential of the combined pose estimation and adaptive behaviour approach.

2010 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2010

This paper presents a trajectory planning algorithm for a robot operating in dynamic human enviro... more This paper presents a trajectory planning algorithm for a robot operating in dynamic human environments. Environments such as pedestrian streets, hospital corridors, train stations or airports. We formulate the problem as planning a minimal cost trajectory through a potential field, defined from the perceived position and motion of persons in the environment. A Rapidly-exploring Random Tree (RRT) algorithm is proposed as a solution to the planning problem, and a new method for selecting the best trajectory in the RRT, according to the cost of traversing a potential field, is presented. The RRT expansion is enhanced to account for the kinodynamic robot constraints by using a robot motion model and a controller to add a reachable vertex to the tree. Instead of executing a whole trajectory, when planned, the algorithm uses a Model Predictive Control (MPC) approach, where only a short segment of the trajectory is executed while a new iteration of the RRT is computed. The planning algorithm is demonstrated in a simulated pedestrian street environment.

ISPRS Journal of Photogrammetry and Remote Sensing, 2014

In this article we analyze the response of Time of Flight cameras (active sensors) for close rang... more In this article we analyze the response of Time of Flight cameras (active sensors) for close range imaging under three different illumination conditions and compare the results with stereo vision (passive) sensors. Time of Flight sensors are sensitive to ambient light and have low resolution but deliver high frame rate accurate depth data under suitable conditions. We introduce some metrics for performance evaluation over a small region of interest. Based on these metrics, we analyze and compare depth imaging of leaf under indoor (room) and outdoor (shadow and sunlight) conditions by varying exposures of the sensors. Performance of three different time of flight cameras (PMD CamBoard, PMD CamCube and SwissRanger SR4000) is compared against selected stereo-correspondence algorithms (local correlation and graph cuts). PMD CamCube has better cancellation of sunlight, followed by CamBoard, while SwissRanger SR4000 performs poorly under sunlight. stereo vision is more robust to ambient illumination and provides high resolution depth data but it is constrained by texture of the object along with computational efficiency. Graph cut based stereo correspondence algorithm can better retrieve the shape of the leaves but is computationally much more expensive as compared to local correlation. Finally, we propose a method to increase the dynamic range of the ToF cameras for a scene involving both shadow and sunlight exposures at the same time using camera flags (PMD) or confidence matrix (SwissRanger).

Lecture Notes in Computer Science, 2008

Existing local feature detectors such as Scale Invariant Feature Transform (SIFT) usually produce... more Existing local feature detectors such as Scale Invariant Feature Transform (SIFT) usually produce a large number of features per image. This is a major disadvantage in terms of the speed of search and recognition in a run-time application. Besides, not all detected features are equally important in the search. It is therefore essential to select informative descriptors. In this paper, we propose a new approach to selecting a subset of local feature descriptors. Uniqueness is used as a filtering criterion in selecting informative features. We formalize the notion of uniqueness and show how it can be used for selection purposes. To evaluate our approach, we carried out experiments in urban building recognition domains with different datasets. The results show a significant improvement not only in recognition speed, as a result of using fewer features, but also in the performance of the system with selected features.

Image Processing, Image Quality, Image Capture Systems Conference, 2003

Building intelligent traffic guide systems has been an interesting subject recently. A good syste... more Building intelligent traffic guide systems has been an interesting subject recently. A good system should be able to observe all important visual information to be able to analyze the context of the scene. To do so, signs in general, and traffic signs in particular, are usually taken into account as they contain rich information to these systems. Therefore, many researchers have put an effort on sign recognition field. Sign localization or sign detection is the most important step in the sign recognition process. This step filters out non informative area in the scene, and locates candidates in later steps. In this paper, we apply a new approach in detecting sign locations using a new color invariant model. Experiments are carried out with different datasets introduced in other works where authors claimed the difficulty in detecting signs under unfavorable imaging conditions. Our method is simple, fast and most importantly it gives a high detection rate in locating signs.

Computer vision (image analysis) is used increasingly for research and development of sensors. Th... more Computer vision (image analysis) is used increasingly for research and development of sensors. The price of cameras has during the last decades fallen dramatically and in the meantime the performance has increased. This is a development that is expected to continue in the coming years. In this presentation the focus will be on the possibilities, considerations, and limitations using computer vision under outdoor illumination conditions. How the image formation may be modelled and how this may be used for detection of suitable measurement locations will be presented. Finally, at the end the problem of second order reflection and how these may be modelled is briefly introduced. The ambition of the presentation is to give an overview and understanding of some of the conditions that influence images of vegetation captured under outdoor conditions. For modelling of the image formation process it will be demonstrated how the dichromatic reflection and CIE daylight standard might be used f...

Seamless mobile navigation will reinforce social inclusion of people with Mild Cognitive Impairme... more Seamless mobile navigation will reinforce social inclusion of people with Mild Cognitive Impairment (MCI) and will lower their anxiety levels when mobile in their usual habitats as they have at hand a means to support them in cases such as where they lose their way or forget where they were going. We have continued development from existing studies of vibrotactile displays (Van Erp, 2007), for our first prototype of a wearable assistive navigation device that gives a range of sensitive haptic feedback as part of an intended larger project. The larger project will develop methods and technology that provide 'companion navigators', which are of significant importance for social inclusion for people with navigation problems (Hansen et al, 2009). In addition, we add the concept of PeerCare as developed by Riche & MacKay (2010) in order to create a system that enhances the ability of elderly peers to communicate with and care for each other (Hutchinson et al, 2003). We describe h...