Evaluating and Grading Students in Large-Scale Image Processing Courses.

In undergraduate practical courses, it is common to work with groups of 100 or more students. These large-scale courses bring their own challenges. For example, course problems are too small and lack "the big picture"; grading becomes burdensome and repetitive for the teaching staff; and it is difficult to detect cheating. Based on their experience with a traditional large-scale practical course in image processing, the authors developed a novel course approach to teaching "Introduction to Digital Image Processing" (or EDBV, from the German course title Einführung in die Digitale Bild-Verarbeitung) for all undergraduate students of media informatics and visual computing and medical informatics at the TU Wien.

Comparison of three-dimensional surface-imaging systems.

BACKGROUND: In recent decades, three-dimensional (3D) surface-imaging technologies have gained popularity worldwide, but because most published articles that mention them are technical, clinicians often have difficulties gaining a proper understanding of them. This article aims to provide the reader with relevant information on 3D surface-imaging systems. In it, we compare the most recent technologies to reveal their differences. METHODS: We have accessed five international companies with the latest technologies in 3D surface-imaging systems: 3dMD, Axisthree, Canfield, Crisalix and Dimensional Imaging (Di3D; in alphabetical order). We evaluated their technical equipment, independent validation studies and corporate backgrounds. RESULTS: The fastest capturing devices are the 3dMD and Di3D systems, capable of capturing images within 1.5 and 1 ms, respectively. All companies provide software for tissue modifications. Additionally, 3dMD, Canfield and Di3D can fuse computed tomography (CT)/cone-beam computed tomography (CBCT) images into their 3D surface-imaging data. 3dMD and Di3D provide 4D capture systems, which allow capturing the movement of a 3D surface over time. Crisalix greatly differs from the other four systems as it is purely web based and realised via cloud computing. CONCLUSION: 3D surface-imaging systems are becoming important in today's plastic surgical set-ups, taking surgeons to a new level of communication with patients, surgical planning and outcome evaluation. Technologies used in 3D surface-imaging systems and their intended field of application vary within the companies evaluated. Potential users should define their requirements and assignment of 3D surface-imaging systems in their clinical as research environment before making the final decision for purchase.

Evolution of the 3-dimensional video system for facial motion analysis: ten years' experiences and recent developments.

Since the implementation of the computer-aided system for assessing facial palsy in 1999 by Frey et al (Plast Reconstr Surg. 1999;104:2032-2039), no similar system that can make an objective, three-dimensional, quantitative analysis of facial movements has been marketed. This system has been in routine use since its launch, and it has proven to be reliable, clinically applicable, and therapeutically accurate. With the cooperation of international partners, more than 200 patients were analyzed. Recent developments in computer vision--mostly in the area of generative face models, applying active--appearance models (and extensions), optical flow, and video-tracking-have been successfully incorporated to automate the prototype system. Further market-ready development and a business partner will be needed to enable the production of this system to enhance clinical methodology in diagnostic and prognostic accuracy as a personalized therapy concept, leading to better results and higher quality of life for patients with impaired facial function.

Hierarchical spatio-temporal extraction of models for moving rigid parts.

This paper presents a method to extract a part-based model of an observed scene from a video sequence. Independent motion is a strong cue that two points belong to different "rigid" entities. Conversely, things that move together throughout the whole video belong together and define a "rigid" object or part. Successfully tracked features indicate trajectories of salient points in the scene. A triangulated graph connects the salient points and encodes their local neighborhood in the first frame. The length variation of the triangle edges is used to label them as relevant (on an object) or separating (connecting different objects). A following grouping process uses the motion of the triangles marked as relevant as a cue to identify the "rigid" parts of the foreground or the background. The choice of the motion-based grouping criterion depends on the type of motion: in the image plane or out of the image plane. The result is a hierarchical description (graph pyramid) of the scene, where each vertex in the top level of the pyramid represents a "rigid" part of the foreground or the background, and encloses to the salient features used to describe it. Promising experimental results show the potential of the approach.

Multi-scale 2D tracking of articulated objects using hierarchical spring systems.

This paper presents a flexible framework to build a target-specific, part-based representation for arbitrary articulated or rigid objects. The aim is to successfully track the target object in 2D, through multiple scales and occlusions. This is realized by employing a hierarchical, iterative optimization process on the proposed representation of structure and appearance. Therefore, each rigid part of an object is described by a hierarchical spring system represented by an attributed graph pyramid. Hierarchical spring systems encode the spatial relationships of the features (attributes of the graph pyramid) describing the parts and enforce them by spring-like behavior during tracking. Articulation points connecting the parts of the object allow to transfer position information from reliable to ambiguous parts. Tracking is done in an iterative process by combining the hypotheses of simple trackers with the hypotheses extracted from the hierarchical spring systems.