Heinz Hügli

Heinz Hügli
École Polytechnique Fédérale de Lausanne | EPFL · Institute of Microengineering

Professor Emeritus

About

110
Publications
14,865
Reads
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1,688
Citations
Additional affiliations
December 1981 - January 2008
Université de Neuchâtel
Position
  • Professor (Associate)
Description
  • Laboratoire de reconnaissance des formes (PARLAB)

Publications

Publications (110)
Article
In this paper we present a computational model of dynamic visual attention on the sphere which combines static (intensity,chromaticity, orientation) and motion features in order to detect salient locations in omnidirectional image sequences while working directly in spherical coordinates. We build the motion pyramid on the sphere by applying block...
Article
Full-text available
D images from time-of-flight (TOF) cameras may suffer from false depth readings caused by light scattering. In order to reduce such scattering artifacts, a scattering compensation procedure is proposed. Assuming a space invariant point spread function as a model for the scattering leads to a solution in a form of a deconvolution scheme. The improve...
Article
Human visual system makes an extensive use of visual attention in order to select the most relevant informations and speed-up the vision process. Inspired by visual attention, several computer models have been developped and many computer vision applications rely today on such models. But the actual algorithms are not suitable to omnidirectional im...
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Recent time of flight cameras deliver range images (2.5D) in realtime, and can be considered as a significant improvement when compared to conventional (2D) cameras. However, the range map produced has only a limited extent, and suffers from occlusions. In this paper, we investigate fusion methods for partially overlapping range images, aiming to a...
Article
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Range imagers provide useful information for part inspection, robot control, or human safety applications in industrial environments. However, some applications may require more information than range data from a single viewpoint. Therefore, multiple range images must be combined to create a three-dimensional representation of the scene. Although s...
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Industrial inspection of micro-devices is often a very challenging task, especially when those devices are produced in large quantities using micro-fabrication techniques. In the case of microlenses, millions of lenses are produced on the same substrate, thus forming a dense array. In this article, we investigate a possible automation of the microl...
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Defined as an attentive process in the context of visual sequences, dynamic visual attention refers to the selection of the most informative parts of video sequence. This paper investigates the contribution of motion in dynamic visual attention, and specifically compares computer models designed with the motion component expressed either as the spe...
Article
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Computational visual attention (VA) has been widely investigated during the last three decades but the conventional algorithms are not suitable for omnidirectional images which often contain a significant amount of radial distortion. Only recently a computational approach was proposed that processes images in the spherical (non-Euclidian) space and...
Article
Range imagers provide useful information for part inspection, robot control, or human safety applications in industrial environments. However, some applications may require more information than range data from a single viewpoint. Therefore, multiple range images must be combined to create a three-dimensional representation of the scene. Although s...
Article
Full-text available
Recent time-of-flight (TOF) cameras allow for real-time acquisition of range maps with good performance. However, the accuracy of the measured range map may be limited by secondary light reflections. Specifically, the range measurement is affected by scattering, which consists in parasitic signals caused by multiple reflections inside the camera de...
Conference Paper
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The computer model of visual attention derives an interest or saliency map from an input image in a process that encompasses several data combination steps. While several combination strategies are possible, not all perform equally well. This paper compares main cue combination strategies by measuring the performance of the considered models with r...
Article
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Visual attention models mimic the ability of a visual system, to detect potentially relevant parts of a scene. This process of attentional selection is a prerequisite for higher level tasks such as object recognition. Given the high relevance of temporal aspects in human visual attention, dynamic information as well as static information must be co...
Conference Paper
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Remote detection by camera offers a versatile means for recording people activities. Relying principally on changes in video images, the method tends to fail in presence of shadows and illumination changes. This paper explores a possible remedy to these problems by using range cameras instead of conventional video cameras. As range is an intrinsic...
Article
Full-text available
Defined as attentive process in presence of visual sequences, dynamic visual attention responds to static and motion features as well. For a computer model, a straightforward way to integrate these features is to combine all features in a competitive scheme: the saliency map contains a contribution of each feature, static and motion. Another way of...
Article
Full-text available
3D images from time-of-flight cameras may suffer from false depth readings caused by light scattering. In order to reduce such scattering artifacts, a scattering compensation procedure is proposed. First, scattering is analysed and expressed as a linear transform of a complex image. Then, a simple scattering model is formulated. Assuming a space in...
Article
Full-text available
Visual attention, defined as the ability of a biological or artificial vision system to rapidly detect potentially relevant parts of a visual scene, provides a general purpose solution for low level feature detection in a vision architecture. Well considered for its universal detection behaviour, the general model of visual attention is suited for...
Article
Full-text available
Machine vision plays an important role in automated assembly. However, present vision systems are not adequate for robot control in an assembly environment where individual components have sizes in the range of 1 to 100 micrometers, since current systems do not provide sufficient resolution in the whole workspace when they are fixed, and they are t...
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The paper provides considerations relative to the application of D vision methods and presents some lessons learnt in this respect by presenting four D vision tasks and discussing the selection of vision sensing devices meant to solving the task. After a short reminder of D vision methods of interest for optical range imaging for microvision and ma...
Conference Paper
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In the heart of the computer model of visual attention, an interest or saliency map is derived from an input image in a process that encompasses several data combination steps. While several combination strategies are possible and the choice of a method influences the final saliency substantially, there is a real need for a performance comparison f...
Chapter
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Manual object digitizing is a tedious task and can be replaced by 3D scanners which provide an accurate and fast way to digitize solid objects. Since only one view of an object can be captured at once, several views have to be combined in order to obtain a description of the complete surface. In this paper a digitizing system is proposed which capt...
Conference Paper
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In visual-based robot navigation, panoramic vision emerges as a very attractive candidate for solving the lo- calization task. Unfortunately, current systems rely on spe- cific feature selection processes that do not cover the re- quirements of general purpose robots. In order to fulfill new requirements of robot versatility and robustness to envir...
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Saliency-based visual attention models provide visual saliency by combining the conspicuity maps relative to var-ious visual cues. Because the cues are of different nature, the maps to be combined show distinct dynamic ranges and a normalization scheme is therefore required. The normal-ization scheme used traditionally is an instantaneous peak-to-p...
Article
In the heart of the computer model of visual attention, an interest or saliency map is derived from an input image in a process that encompasses several data combination steps. While several combination strategies are possible and the choice of a method influences the final saliency substantially, there is a real need for a performance comparison f...
Article
Visual attention is the ability of a vision system, be it biological or artificial, to rapidly detect potentially relevant parts of a visual scene, on which higher level vision tasks, such as object recognition, can focus. The saliency-based model of visual attention represents one of the main attempts to simulate this visual mechanism on computers...
Article
The aim of this study was to investigate how oculomotor behaviour depends on the availability of colour information in pictorial stimuli. Forty study participants viewed complex images in colour or grey-scale, while their eye movements were recorded. We found two major effects of colour. First, although colour increases the complexity of an image,...
Conference Paper
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This paper presents a robot self-localization method based on visual attention. This method takes advantage of the saliency-based model of attention to automatically learn configurations of salient visual landmarks along a robot path. During navigation, the visual attention algorithms detect a set of conspicuous visual features which are compared w...
Conference Paper
Full-text available
Visual attention is the ability of a vision system, be it biological or artificial, to rapidly detect potentially relevant parts of a visual scene. The saliency-based model of visual attention is widely used to simulate this visual mechanism on computers. Though biologically inspired, this model has been only partially assessed in comparison with h...
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This paper considers the task of automatic stamping side detection and presents a method that uses the statistics of features extracted from oblique lighted edges to compute a discriminating intensity ratio that performs stamping side detection in a very robust way.
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This paper reports a landmark-based localization method relying on visual attention. In a learning phase, the multi-cue, multi-scale saliency-based model of visual attention is used to automatically acquire robust visual landmarks that are integrated into a topological map of the navigation environment. During navigation, the same visual attention...
Conference Paper
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A large number of 3D cameras suffer from so-called holes in the data, i.e. the measurement lattice is affected by invalid measurements and the range image has undefined values. Conventional image filters used for removing the holes perform not well in presence of holes with large varying hole sizes. The novel hole-filling method presented in this p...
Conference Paper
Full-text available
Visual attention refers to the ability of a vision system to rapidly detect visually salient locations in a given scene. On the other hand, the selection of robust visual landmarks of an environment rep- resents a cornerstone of reliable vision-based robot navigation systems. Indeed, can salient scene locations provided by visual attention be usefu...
Article
Full-text available
Visual attention refers to the ability of a vision system to rapidly detect visually salient locations in a given scene. On the other hand, the selection of robust visual landmarks of an environment represents a cornerstone of reliable vision-based robot navigation systems. Indeed, can salient scene locations provided by visual attention be useful...
Conference Paper
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The depth from focus measurement principle relies on the detection of the optimal focusing distance for measuring the depth map of an object and finding its 3D shape. The principle is most effective at microscopic ranges where it is usually found implemented around a z-controlled microscope and sometimes named multifocus 3D microscopy. As such, the...
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The research described in this paper aims at assessing the contribution of depth to visual attention. It reports the measurement of depth induced human visual attention derived from fixation patterns and preliminary results of a quantitative comparison with visual attention as modeled by different versions of a computational model. More specificall...
Article
Full-text available
Visual attention is the ability of the human vision system to detect salient parts of the scene, on which higher vision tasks, such as recognition, can focus. In human vision, it is believed that visual attention is intimately linked to the eye movements and that the fixation points correspond to the location of the salient scene parts. In computer...
Conference Paper
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The iterative closest point (ICP) algorithm is widely used for the registration of 3D geometric data. One of the main drawbacks of the algorithm is its quadratic time complexity O(N<sup>2</sup>) with the number of points N. Consequently, several methods have been proposed to accelerate the process. We present a new solution for the speeding up of t...
Conference Paper
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This paper reports a novel Multiscale Attention-based Pre-Segmentation method (MAPS) which is built around the multi-feature, multiscale, saliency-based model of visual attention. From the saliency map, provided by the attention algorithm, MAPS first derives the spatial locations of salient regions that will be considered further in the segmentatio...
Conference Paper
Full-text available
Visual attention is the ability to rapidly detect the interest- ing parts of a given scene on which higher level computer vision tasks can focus. This paper reports a computational model of dynamic visual attention which combines static and dynamic features to detect salient locations in natural image sequences. Therefore, the model computes a map...
Article
Visual attention is the ability to rapidly detect the visually salient parts of a given scene on which higher level vision tasks, such as object recognition, can focus. Found in biological vision, this mechanism represents a fundamental tool for computer vision. This paper reports the first real-time implementation of the complete visual attention...
Conference Paper
Full-text available
Visual attention is the ability to rapidly detect the visually salient parts of a given scene. Inspired by biological vision, the saliency-based algorithm efficiently models the visual attention process. Due to its complexity, the saliency-based model of visual attention needs, for a real time implementation, higher computation resources than avail...
Conference Paper
Full-text available
Shape registration plays an important role in applications such as 3D object modeling or object recognition. The iterative closest point (ICP) algorithm is widely used for the registration of geometric data. One of its main drawback is its time complexity O(N2), quadratic with the shape size N, which implies long processing time, especially when us...
Conference Paper
Full-text available
The iterative closest point (ICP) algorithm is widely used for the registration of geometric data. One of its main drawbacks is its quadratic time complexity O(N<sup>2</sup>) with the shape number of points N, which implies long processing time, especially when using high resolution data. This paper proposes to accelerate the process by a coarse to...
Conference Paper
Full-text available
This paper reports an adaptive still color image compression method which produces automatically selected ROI with a higher reconstruction quality with respect to the rest of the input image. The ROI are generated on-the fly with a purely data-driven technique based on visual attention. Inspired from biological vision, the multicue visual attention...
Conference Paper
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The ”seeded region growing” (SRG) is a segmentation technique which performs an image segmentation with respect to a set of initial points, known as seeds. Given a set of seeds, SRG then grows the regions around each seed, based on the conventional region growing postulate of similarity of pixels within regions. The choice of the seeds is considere...
Article
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There exist many techniques for the measurement of micro and nano surfaces and also several conventional ways to represent the resulting data, such as pseudo color or isometric 3D. This paper addresses the problem of building complete 3D micro-object models from measurements in the submicrometric range. More specifically, it considers measurements...
Article
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Nowadays, vision-based inspection systems are present in many stages of the industrial manufacturing process. Their versatility, which permits to accommodate a broad range of inspection requirements, is however limited by the time consuming system setup performed at each production change. This work aims at providing a configuration assistant that...
Article
Nowadays, vision-based inspection systems are present in many stages of the industrial manufacturing process. Their versatility, which permits us to accommodate a broad range of inspection requirements, is, however, limited by the time consuming system setup performed at each production change. This work aims at providing a configuration assistant...
Article
Full-text available
A specific configuration for liquid flow metrology consists of a flow of falling drops coupled with a preferred measuring method that derives the flow directly from the drop count. Given the inaccuracy of this counting method, alternative methods have been proposed that measure the volume of each falling drop. The principle consists in deriving the...
Conference Paper
Full-text available
Visual attention is the ability to rapidly detect the interesting parts of a given scene. Inspired by biological vision, the principle of visual attention is used with a similar goal in computer vision. Several previous works deal with the computation of visual attention from images provided by standard video cameras, but little attention has been...
Article
The behavioral approach to robot navigation, characterized by a representation of the environment that is topological and robot-environmental interactions that are reactive, is preferable to purely geometrical navigation because it is far more robust against unpredictable changes of the environment. Nevertheless, there is still a need to obtain geo...
Conference Paper
Full-text available
ABSTRACT This paper deals with the problem of capturing the color information of physical 3D objects thanks to a class of digitizers providing color and range data, like range finders based on structured lighting. It appears typically in a modeling procedure that aims at building a realistic virtual 3D model. The color data delivered by such,scanne...
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. In this paper, we present the implementation of an autonomous mobile robot controller based on a behavioural architecture. This architecture is composed of three layers: sensori-motor, behavioural, sequencing. The paper describes its general structure and the function of its main elements. It further analyses the development of an example task pr...
Article
This paper investigates a new approach for the recognition of 3D objects of arbitrary shape. The proposed solution follows the principle of model-based recognition using geometric 3D models and geometric matching. It is an alternative to the classical segmentation and primitive extraction approach and provides a perspective to escape some of its di...
Article
. This paper presents the analysis of vision-based homing behaviors that provide selfpositioning of a mobile robot. The control schemes of the homing behaviors are based on a new approach that describes robot moves in terms of regulation by image features, hence avoiding the usual step of three-dimensional reconstruction of the scene with respect t...
Article
This paper investigates a new approach for the recognition of 3D objects of arbitrary shape. The proposed solution follows the principle of model-based recognition using geometric 3D models and geometric matching. It is an alternative to the classical segmentation and primitive extraction approach and provides a perspective to escape some of its di...
Article
Full-text available
In this paper, we present the implementation of an autonomous mobile robot controller developed according to the principle of a multi-layered hybrid architecture. This architecture is composed of four layers: sensori-motor, behavioral, sequencing, and strategic. The paper describes its general structure and the function of its main elements. It fur...
Article
We present a model-based 3D object recognition architecture that combines pose estimation derived from range images and hypothesis verification derived from intensity images. The architecture takes advantage of the geometrical nature of range images for generating a number of hypothetical poses of objects. Pose and object models are then used to re...
Conference Paper
Full-text available
Applications such as object digitizing, object recognition and object inspection need efficient surface matching algorithms. Several variants of an iterative closest point (ICP) matching algorithm have been proposed for such tasks. This paper proposes and analyzes a multi-feature ICP matching algorithm that includes the surface color and the surfac...
Article
The behavioral approach to robot navigation, characterized by a representation of the environment that is topological and robot-environmental interactions that are reactive, is preferable to the pure geometrical navigation because it is far more robust to unpredictable changes of the environment. Nevertheless, there is still a need to obtain geomet...
Article
Full-text available
For modeling 3D objects, the object geometry is often not sufficient. Better appearance can be obtained by texture mapping which efficiently combines good appearance resolution with small geometric complexity. This paper presents a way to create such texture mapped 3D models of free-form objects, by integrating textured views obtained from range im...
Conference Paper
Full-text available
The increasing use of virtual object representations for several applications creates a need for fast and simple object digitizing systems. Range finders provide a convenient way to digitize solid objects and permit the accurate and fast scanning of an object shape without any probe contact. However, only one view of an object can be captured at on...
Conference Paper
Full-text available
This paper considers the matching of 3D objects by a geometric approach based on the iterative closest point algorithm (ICP), which, starting from an initial configuration of two rigid objects, iteratively finds their best correspondence. The algorithm does not converge always to the best solution. It can be trapped in a local minimum and miss the...
Article
Full-text available
This paper proposes range imaging as a means to improve object registration in an augmented reality environment. The addressed problem deals with virtual world construction from complex scenes using object models. During reconstruction, the scene view is augmented by superimposing virtual object representations from a model database. The main diffi...