Gonen Eren

Scanning from heating: 3D shape estimation of transparent objects from local surface heating

Today, with quality becoming increasingly important, each product requires three-dimensional in-line quality control. On the other hand, the 3D reconstruction of transparent objects is a very difficult problem in computer vision due to transparency and specularity of the surface. This paper proposes a new method, called Scanning From Heating (SFH), to determine the surface shape of transparent objects using laser surface heating and thermal imaging. Furthermore, the application to transparent glass is discussed and results on different surface shapes are presented.

Evaluation of video activity localizations integrating quality and quantity measurements

Evaluating the performance of computer vision algorithms is classically done by reporting classification error or accuracy, if the problem at hand is the classification of an object in an image, the recognition of an activity in a video or the categorization and labeling of the image or video. If in addition the detection of an item in an image or a video, and/or its localization are required, frequently used metrics are Recall and Precision, as well as ROC curves. These metrics give quantitative performance values which are easy to understand and to interpret even by non-experts. However, an inherent problem is the dependency of quantitative performance measures on the quality constraints that we need impose on the detection algorithm. In particular, an important quality parameter of these measures is the spatial or spatio-temporal overlap between a ground-truth item and a detected item, and this needs to be taken into account when interpreting the results. We propose a new performance metric addressing and unifying the qualitative and quantitative aspects of the performance measures. The performance of a detection and recognition algorithm is illustrated intuitively by performance graphs which present quantitative performance values, like Recall, Precision and F-Score, depending on quality constraints of the detection. In order to compare the performance of different computer vision algorithms, a representative single performance measure is computed from the graphs, by integrating out all quality parameters. The evaluation method can be applied to different types of activity detection and recognition algorithms. The performance metric has been tested on several activity recognition algorithms participating in the ICPR 2012 HARL competition.

3-D Scanning of Nonopaque Objects by Means of Imaging Emitted Structured Infrared Patterns

Three-dimensional surface acquisition is a subject that has been studied to a large extent; a significant number of techniques for acquiring shapes have been proposed, and a wide range of commercial solutions is available. Nevertheless, todays systems still have difficulties when digitizing objects that are transparent or semitransparent in the visible range. In this paper, some of the issues of traditional scanning systems are addressed by considering the radiative properties of materials. As a result, an infrared laser light-based scanner is presented for successfully acquiring the shape of complex surfaces by analyzing heat patterns that are emitted by the object.

Three-dimensional scanning of specular and diffuse metallic surfaces using an infrared technique

For the past two decades, the need for three-dimensional (3-D) scanning of industrial objects has increased significantly and many experimental techniques and commercial solutions have been proposed. However, difficulties remain for the acquisition of optically non-cooperative surfaces, such as transparent or specular surfaces. To address highly reflective metallic surfaces, we propose the extension of a technique that was originally dedicated to glass objects. In contrast to conventional active triangulation techniques that measure the reflection of visible radiation, we measure the thermal emission of a surface, which is locally heated by a laser source. Considering the thermophysical properties of metals, we present a simulation model of heat exchanges that are induced by the process, helping to demonstrate its feasibility on specular metallic surfaces and predicting the settings of the system. With our experimental device, we have validated the theoretical modeling and computed some 3-D point clouds from specular surfaces of various geometries. Furthermore, a comparison of our results with those of a conventional system on specular and diffuse parts will highlight that the accuracy of the measurement no longer depends on the roughness of the surface.

Activity recognition with volume motion templates and histograms of 3D gradients

We propose a new method for activity recognition based on a view independent representation of human motion. Robust 3D volume motion templates (VMTs) are calculated from tracklets. View independence is achieved through a rotation with respect to a canonical orientation. From this volumes, features based on 3D gradients are extracted, projected to a codebook and pooled into a bags-of-words model classified with an SVM classifier. Experiments show that the method outperforms the original HoG3D method.

The importance of customized advertisement delivery using 3D tracking and facial recognition

Interactive technologies impact on every facet of our everyday lives including marketing systems. Digital displays used in advertisement are capable of providing more information about customers hence allow producers to gather a wide ranging database about the number and the attention patterns of the audience. This research proposes a system that engages audience to the advertisement through interactive applications and provides data to the advertiser/producer about their audience.

Estimation of surface normal vectors based on 3D scanning from heating approach

The Scanning From Heating is a 3D scanning approach initially developed to realise 3D acquisition of transparent or specular surfaces. A laser source is used to create a local heating point. An infrared camera is used to observe the IR radiation emitted by the scene. The 2D coordinates of the heated point are computed in the 2D image of the camera. Knowing the parameters of the system (which are obtained by a previous calibration), the 3D coordinates of the point are computed using triangulation method. In this article we will present an extension of this technique. We propose here to analyse the shape of the hot spot observed by the IR camera, and, from the analysis to determine information on the local orientation of the surface at each measured point.

Multi-view Pose Estimation with Flexible Mixtures-of-Parts

We propose a new method for human pose estimation which leverages information from multiple views to impose a strong prior on the articulated pose. The novelty of the method concerns the types of coherence modeled. Consistency is maximized over the different views through different terms modeling classical geometric information (coherence of the resulting poses) as well as appearance information which is modeled as latent variables in the global energy function. Experiments on the HumanEva dataset show that the proposed method significantly decreases the estimation error compared to single-view results and attains a 3D PCP score of 86%.

Multi-view pose estimation with mixtures-of-parts and adaptive viewpoint selection

We propose a new method for human pose estimation which leverages information from multiple views to impose a strong prior on articulated pose. The novelty of the method concerns the types of coherence modelled. Consistency is maximised over the different views through different terms modelling classical geometric information (coherence of the resulting poses) as well as appearance information which is modelled as latent variables in the global energy function. Moreover, adequacy of each view is assessed and their contributions are adjusted accordingly. Experiments on the HumanEva and UMPM datasets show that the proposed method significantly decreases the estimation error compared to single-view results.

Development of system supervision and control software for a micromanipulation system

This paper presents the realization of a modular software architecture that is capable of handling the complex supervision structure of a multi degree of freedom open architecture and reconfigurable micro assembly workstation. This software architecture initially developed for a micro assembly workstation is later structured to form a framework and design guidelines for precise motion control and system supervision tasks explained subsequently through an application on a micro assembly workstation. The software is separated by design into two different layers, one for real-time and the other for non-realtime. These two layers are composed of functional modules that form the building blocks for the precise motion control and the system supervision of complex mechatronics systems.