Robert van Liere

Robert van Liere
Centrum Wiskunde & Informatica | CWI

About

190
Publications
23,466
Reads
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2,535
Citations
Citations since 2016
16 Research Items
715 Citations
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2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120

Publications

Publications (190)
Article
Full-text available
Detection of unwanted ('foreign') objects within products is a common procedure in many branches of industry for maintaining production quality. X-ray imaging is a fast, non-invasive and widely applicable method for foreign object detection. Deep learning has recently emerged as a powerful approach for recognizing patterns in radiographs (i.e., X-r...
Article
Full-text available
Covered tightly by a thin leather skin, three early seventeenth-century cornetts from the collection of the Rijksmuseum were examined with the focus on their construction and manufacturing. One cornett of the three unexpectedly turned out to have a peculiar construction and to be made out of two sections of different wood species. The question aros...
Preprint
Full-text available
Detection of unwanted (`foreign') objects within products is a common procedure in many branches of industry for maintaining production quality. X-ray imaging is a fast, non-invasive and widely applicable method for foreign object detection. Deep learning has recently emerged as a powerful approach for recognizing patterns in radiographs (i.e., X-r...
Article
TOP-CT (Trajectory with Overlapping Projections X-ray Computed Tomography) is a new class of CT scanning geometries for high throughput industrial CT scanning. In TOP-CT multiple objects move with a constant spacing over the same trajectory between a stationary X-ray source and detector. The projections of multiple objects can overlap, which provid...
Article
An important question in cultural heritage concerns the make process of an artifact. Understanding the make process provides insight related to the origin, techniques and craftsmanship used to make the artifact. Searching for tool marks or traces left by the artist's hand is one way of retrieving clues related to the make process. X-ray computed to...
Article
Full-text available
Fingerprints play a central role in any field where person identification is required. In forensics and biometrics, three-dimensional fingerprint-based imaging technologies, and corresponding recognition methods, have been vastly investigated. In cultural heritage, preliminary studies provide evidence that the three-dimensional impressions left on...
Article
Full-text available
X-ray imaging is a widely used technique for non-destructive inspection of agricultural food products. One application of X-ray imaging is the autonomous, in-line detection of foreign objects in food samples. Examples of such inclusions are bone fragments in meat products, plastic and metal debris in fish, and fruit infestations. This article prese...
Preprint
X-ray imaging is a widely used technique for non-destructive inspection of agricultural food products. One application of X-ray imaging is the autonomous, in-line detection of foreign objects in food samples. Examples of such inclusions are bone fragments in meat products, plastic and metal debris in fish, fruit infestations. This article presents...
Article
Full-text available
Computed Tomography (CT) has proven itself as a powerful technique for analysing the internal structure of cultural heritage objects. The process followed by conservators and technical art historians for investigating an object is explorative: each time a new question is asked based on the outcome of the previous investigation. This workflow howeve...
Conference Paper
X-ray plenoptic apparatuses acquire multi-view single-shot radiographs, but their development is challenging. We present a physical emulation setup for rapidly and inexpensively exploring their design parameter-space, that only uses a flexible laboratory X-ray scanner.
Cover Page
Full-text available
X-ray plenoptic cameras acquire multi-view X-ray transmission images in a single exposure (light field). Their development is challenging: designs have appeared only recently, and they are still affected by important limitations. Concurrently, the lack of available real X-ray light field data hinders dedicated algorithmic development. We present a...
Article
Full-text available
X-ray plenoptic cameras acquire multi-view X-ray transmission images in a single exposure (light-field). Their development is challenging: designs have appeared only recently, and they are still affected by important limitations. Concurrently, the lack of available real X-ray light-field data hinders dedicated algorithmic development. Here, we pres...
Article
Full-text available
An important challenge in hyperspectral imaging tasks is to cope with the large number of spectral bins. Common spectral data reduction methods do not take prior knowledge about the task into account. Consequently, sparsely occurring features that may be essential for the imaging task may not be preserved in the data reduction step. Convolutional n...
Article
Full-text available
Computer Tomography (CT) scanners for research applications are often designed to facilitate flexible acquisition geometries. Making full use of such CT scanners requires advanced reconstruction software that can (i) deal with a broad range of geometrical scanning settings, (ii) allows for customization of processing algorithms, and (iii) has the c...
Article
Full-text available
Recently we have shown that light-field photography images can be interpreted as limited-angle cone-beam tomography acquisitions. Here, we use this property to develop a direct-space tomographic refocusing formulation that allows one to refocus both unfocused and focused light-field images. We express the reconstruction as a convex optimization pro...
Article
Full-text available
Current computational methods for light field photography model the ray-tracing geometry inside the plenoptic camera. This representation of the problem, and some common approximations, can lead to errors in the estimation of object sizes and positions. We propose a representation that leads to the correct reconstruction of object sizes and distanc...
Book
Virtual reality (VR) is a multidisciplinary area of research aimed at interactive human–computer-mediated simulations of artificial environments. An important aspect of VR-based systems is the stimulation of the human senses – usually sight, sound, and touch – in such a way that a user feels a sense of presence in the virtual environment. Sometimes...
Article
Lien sur le site éditeur : http://drops.dagstuhl.de/opus/volltexte/2013/4257/pdf/dagrep_v003_i006_p038_s13241.pdf
Article
Full-text available
Models of interaction tasks are quantitative descriptions of relationships between human temporal performance and the spatial characteristics of the interactive tasks. Examples include Fitts' law for modeling the pointing task and Accot and Zhai's steering law for the path steering task. Interaction models can be used as guidelines to design effici...
Article
Full-text available
The law of path steering, as proposed by Accot and Zhai, describes a quantitative relationship between human temporal performance and the path's spatial characteristics. The steering law is formulated as a continuous goal crossing task, in which a large number of goals are crossed along the path. The steering law has been verified empirically for l...
Conference Paper
Full-text available
Models of interaction tasks are quantitative descriptions of relationships between human temporal performance and the spatial characteristics of the interactive tasks. Examples include Fitts' law for modeling the pointing task and Accot and Zhai's steering law for the path steering task, etc. Models can be used as guidelines to design efficient use...
Conference Paper
Full-text available
Path steering is an interaction task of how quickly one may navigate through a path. The steering law, proposed by Accot and Zhai [AZ97], is a predictive model which describes the time to accomplish a 2D steering task as a function of the path length and width. In this paper, we study a 3D steering task in the presence of force feedback. Our goal i...
Article
Full-text available
Path steering is an interaction task that requires a user to navigate through a path of a given length and width. In 1997, Accot and Zhai developed the steering law for modeling 2D steering tasks. Recently, we extended the steering law for 3D manipulation tasks, by introducing path curvature as an additional factor to the steering law. The extensio...
Article
Full-text available
In addition to experimental studies, computational models provide valuable information about colony development in scleractinian corals. Using our simulation model, we show how environmental factors such as nutrient distribution and light availability affect growth patterns of coral colonies. To compare the simulated coral growth forms with those o...
Conference Paper
Full-text available
The law of path steering, as proposed by Accot and Zhai, describes a quantitative relationship between human temporal performance and the path's spatial characteristics. The steering law is formulated as a continuous goal crossing task, in which a large number of goals are crossed along the path. The steering law has been verified empirically for l...
Article
Display systems typically operate at a minimum rate of 60 Hz. However, existing VR-architectures generally produce application updates at a lower rate. Consequently, the display is not updated by the application every display frame. This causes a number of undesirable perceptual artifacts. We describe an architecture that provides a programmable di...
Article
Full-text available
In this article, we investigate the perception of optically simulated haptic feedback. The perception of optically and mechanically simulated bumps and holes was tested experimentally. In an earlier article, we have described the active cursor technique, a method to simulate haptic feedback optically without resorting to special mechanical force fe...
Article
Designing low end-to-end latency system architectures for virtual reality is still an open and challenging problem. We describe the design, implementation and evaluation of a client-server depth-image warping architecture that updates and displays the scene graph at the refresh rate of the display. Our approach works for scenes consisting of dynami...
Conference Paper
The output resolution of imaging mass spectrometers is increasing rapidly due to advances in engineering and the use of tiling. Imaging-MS data is often displayed as a total-ion-count (TIC) image; however, anatomical structures are not easily identifiable from TIC images. For this purpose, additional high-resolution images that originate from diffe...
Conference Paper
Full-text available
Path steering is a primitive D interaction task that requires the user to navigate through a path of a given length and width. In a previous paper, we have conducted controlled experiments in which users operated a pen input device to steer a cursor through a 3D path subject to fixed path properties, such as path length, width, curvature and orient...
Article
Full-text available
In this paper, we explore the use of printed tangible props as input devices for scientific visualization. Three-dimensional printing technology is used to create a physical representation of data. The object is then used as a tangible input prop, which exactly matches the data. In addition, two-handed interaction with a stylus is performed on the...
Article
Full-text available
Existing measures for evaluating user performance on interaction tasks in virtual environments don't often provide sufficient information for improving these interactions. A new method for analyzing 3D goal-directed movements divides them into meaningful phases. The authors applied this method to experimental data collected for a 3D task resembling...
Article
We present novel techniques for knowledge-assisted annotation and computer-assisted interpretation of seismic data for oil and gas exploration. We describe the existing procedure for oil and gas search which consists of manually extracting information ...
Chapter
The book starts with the chapter presenting a comprehensive overview of Interactive Visualization. The chapter introduces fundamentals of Interactive Visualization, surveys research in the field, examines existing challenges and provides information about popular frameworks that can be used for the development of interactive data visualizations. K...
Article
Full-text available
The measures that are currently used to evaluate users' performances on interaction tasks in virtual environments often do not provide sufficient information for how to improve these interactions. The current paper proposes a new method for analyzing 3D goal-directed movements based on dividing them into meaningful phases. We apply the method to ex...
Article
We describe a software framework to evaluate the performance of model-based optical trackers in virtual environments. The framework can be used to evaluate and compare the performance of different trackers under various conditions, to study the effects of varying intrinsic and extrinsic camera properties, and to study the effects of environmental c...
Article
We describe a software framework to evaluate the performance of model-based optical trackers in virtual environments. The framework can be used to evaluate and compare the performance of different trackers under various conditions, to study the effects ...
Conference Paper
Full-text available
The study of aimed movements has a long history, starting at least as far back as 1899 when Wood-worth proposed a two-component model in which aimed movements are broken into an initial ballistic phase and an additional control phase. In this paper, we use Wood-worth's model for experimentally comparing aimed movements in the real world with those...
Conference Paper
Full-text available
ABSTRACT Designing low end-to-end latency system architectures for virtual reality is still an open and challenging problem. We describe the de- sign, implementation and evaluation of a client-server depth-image warping architecture that updates and displays the scene graph at the refresh rate of the display. Our approach works for scenes con- sist...
Article
Full-text available
In visualization, we use the terms data, information and knowledge extensively, often in an interrelated context. In many cases, they indicate different levels of abstraction, understanding, or truthfulness. For example, "visualization is concerned with exploring data and information," "the primary objective in data visualization is to gain insight...
Conference Paper
Full-text available
The two-component model is a human movement model in which an aimed movement is broken into a voluntary ballistic movement followed by a corrective movement. Recently, experimental evidence has shown that 3D aimed movements in virtual environments can be modeled using the two-component model. In this paper, we use the two-component model for design...
Article
Interactive Visualization enables the development of new scientific techniques to view data, and to use interaction capabilities to interrogate and navigate through datasets and better communicate the results. A wide range of topics are covered in this important new book, representing the state of the art in this research area and providing a spec...
Book
This unique, multi-disciplinary volume provides an insight into an active and vital area of research – Interactive Visualization. Interactive Visualization enables the development of new scientific techniques to view data, and to use interaction capabilities to interrogate and navigate through datasets and better communicate the results. A wide ra...
Article
High-resolution imaging mass spectrometry of large biological samples is the goal of several research groups. In mosaic imaging, the most common method, the large sample is divided into a mosaic of small areas that are then analyzed with high resolution. Here we present an automated alignment routine that uses principal component analysis to reduce...
Article
Efficient navigation requires a good representation of body position/orientation in the environment and an accurate updating of this representation when the body-environment relationship changes. We tested here whether the visual flow alone - i.e., no landmark - can be used to update this representation when the visual scene is rotated, and whether...
Conference Paper
Full-text available
We have used a tangible input device to control 3D widgets in a 3D VR environment. This can be a more efficient input method than unrestricted 6-DOF manipulation, since many 3D widgets impose some restrictions on how they can be manipulated. In particular for tasks that are in essence two-dimensional, such as drawing a contour on a surface, tangibl...
Article
Full-text available
Imaging mass spectrometry is a technique to determine of which materials a small, physical sample is made. Current feature extraction techniques fail to extract certain small, high resolution characteristics from these multi-spectral datacubes. Causes are a low signal-to-noise ratio, the presence of dominant but uninteresting features, and the huge...
Conference Paper
We describe a software framework to evaluate the performance of model-based optical trackers in virtual environments. The framework can be used to evaluate and compare the performance of different trackers under various conditions, to study the effects of varying intrinsic and extrinsic camera properties, and to study the effects of environmental c...
Conference Paper
In this paper we explore the usage of tangible controllers for the manipulation of 3D widgets in scientific visualization applications. Tangible controllers can be more efficient than unrestricted 6-DOF devices, since many 3D widgets impose some restrictions on how they can be manipulated. In particular for tasks that are in essence two-dimensional...
Conference Paper
Full-text available
We describe an architecture that provides a programmable display layer in order to allow the execution of custom programs on consec- utive display frames. This replaces the default display behavior of repeating application frames until an update is available. The archi- tecture is implemented using a multi-GPU system. We will show three application...
Article
Full-text available
Analysing users in their context of work and finding out how and why they use different information resources is essential to provide interactive visualisation systems that match their goals and needs. Designers should actively involve the intended users throughout the whole process. This chapter presents a user-centered approach for the design of...
Article
Full-text available
Morphological variation in marine sessile organisms is frequently related to environmental factors. Quantifying such variation is relevant in a range of ecological studies. For example, analyzing the growth form of fossil organisms may indicate the state of the physical environment in which the organism lived. A quantitative morphological compariso...
Article
Full-text available
The object oriented Visualization Toolkit (VTK) is widely used for sci- entific visualization. VTK is a visualization library that provides a large number of functions for presenting three-dimensional data. Interaction with the visualized data is controlled with two-dimensional input devices, such as mouse and keyboard. Support for real three-dimen...
Conference Paper
Stereo displays suffer from crosstalk, an effect that reduces or even inhibits the viewer's ability to correctly perceive depth. Previous work on software crosstalk reduction focussed on the preprocessing of static scenes which are viewed from a fixed viewpoint. However, in virtual environments scenes are dynamic, and are viewed from various viewpo...
Article
The large size of the hyperspectral datasets that are produced with modern mass spectrometric imaging techniques makes it difficult to analyze the results. Unsupervised statistical techniques are needed to extract relevant information from these datasets and reduce the data into a surveyable overview. Multivariate statistics are commonly used for t...
Article
In this paper, we describe a new optical tracking algorithm for pose estimation of interaction devices in virtual and augmented reality. Given a 3D model of the interaction device and a number of camera images, the primary difficulty in pose reconstruction is to find the correspondence between 2D image points and 3D model points. Most previous meth...
Conference Paper
An imaging mass spectrometer is an analytical instrument that can determine the spatial distribution of chemical compounds on complex surfaces. The output of the device is a multi-spectral datacube; a three-dimensional (3D) dataset in which the xy-dimension represents the surface position and the z-dimension represents the mass spectral distributio...