Model-based 3-D Shape and Motion Estimation Using Sliding Textures

Given an accurate 3-D shape model of a scene, the motion parameters of a moving camera can be recovered with high accuracy using model-based motion estimation techniques. Shape errors, however, reduce the accuracy of this kind of motion estimation considerably. In this paper, model-based motion estimation is combined with simultaneous object shape refinement. A deformable 3-D shape model of low dimensionality is employed to approximate the object shape. Camera position and orientation for all views as well as object shape refinements are estimated simultaneously from the image data using an optical-flow-based approach. In comparison to traditional flexible body motion estimation, our formulation of the shape deformation allows the object texture to slide on the object surface. Experimental results illustrate that combined shape and motion estimation using sliding textures improves the calibration data of the individual views in comparison to fixed-shape modelbased camera motion estimation.

Multi-Stream Voice over IP Using Packet Path Diversity

We propose multi-stream transmission of real-time voice over best-effort packet networks such as today's Internet, where multiple redundant descriptions of the voice stream are sent over independent network paths. At the receiver, multi-stream adaptive playout scheduling is employed to improve the tradeoff among delay, late loss rate, and speech quality. Experiments over the Internet suggest largely uncorrelated statistical characteristics, such as erasure probability and delay jitter, for different network paths, which leads to a noticeable path diversity gain. We have obtained significant reductions in mean end-to-end latency and loss rates compared to FEC protected single-path transmission at the same data rate. The speech quality perceived by the receiver is evaluated using the recently standardized objective quality measure PESQ. In our experiments, we observe gains of more than 0.4 PESQ score for voice transmission with packet path diversity

Real-time Voice Communication over the Internet Using Packet Path Diversity

The quality of real-time voice communication over best-effort networks is mainly determined by the delay and loss characteristics observed along the network path. Excessive playout buffering at the receiver is prohibitive and significantly delayed packets have to be discarded and considered as late loss. We propose to improve the tradeoff among delay, late loss rate, and speech quality using multi-stream transmission of real-time voice over the Internet, where multiple redundant descriptions of the voice stream are sent over independent network paths. Scheduling the playout of the received voice packets is based on a novel multi-stream adaptive playout scheduling technique that uses a Lagrangian cost function to trade delay versus loss. Experiments over the Internet suggest largely uncorrelated packet erasure and delay jitter characteristics for different network paths which leads to a noticeable path diversity gain. We observe significant reductions in mean end-to-end latency and loss rates as well as improved speech quality when compared to FEC protected single-path transmission at the same data rate. In addition to our Internet measurements, we analyze the performance of the proposed multi-path voice communication scheme using the ns network simulator for different network topologies, including shared network links

Bounding Box Disparity: 3D Metrics for Object Detection With Full Degree of Freedom

The most popular evaluation metric for object detection in 2D images is Intersection over Union (IoU). Existing implementations of the IoU metric for 3D object detection usually neglect one or more degrees of freedom. In this paper, we first derive the analytic solution for three dimensional bounding boxes. As a second contribution, a closed-form solution of the volume-to-volume distance is derived. Finally, the Bounding Box Disparity is proposed as a combined positive continuous metric. We provide open source implementations of the three metrics as standalone python functions, as well as extensions to the Open3D library and as ROS nodes.Comment: 4 pages+1 Page references, 4 Figures, Accepted for ICIP202