Fredrik Viksten

Comparison of local image descriptors for full 6 degree-of-freedom pose estimation

Recent years have seen advances in the estimation of full 6 degree-of-freedom object pose from a single 2D image. These advances have often been presented as a result of, or together with, a new local image descriptor. This paper examines how the performance for such a system varies with choice of local descriptor. This is done by comparing the performance of a full 6 degree-of-freedom pose estimation system for fourteen types of local descriptors. The evaluation is done on a database with photos of complex objects with simple and complex backgrounds and varying lighting conditions. From the experiments we can conclude that duplet features, that use pairs of interest points, improve pose estimation accuracy, and that affine covariant features do not work well in current pose estimation frameworks. The data sets and their ground truth is available on the web to allow future comparison with novel algorithms.

Increasing pose estimation performance using multi-cue integration

We have developed a system which integrates the information output from several pose estimation algorithms and from several views of the scene. It is tested in a real setup with a robotic manipulator. It is shown that integrating pose estimates from several algorithms increases the overall performance of the pose estimation accuracy as well as the robustness as compared to using only a single algorithm. It is shown that increased robustness can be achieved by using pose estimation algorithms based on complementary features, so called algorithmic multi-cue integration (AMC). Furthermore it is also shown that increased accuracy can be achieved by integrating pose estimation results from different views of the scene, so-called temporal multi-cue integration (TMC). Temporal multi-cue integration is the most interesting aspect of this paper

Point-of-interest detection for range data

Point-of-interest detection is a way of reducing the amount of data that needs to be processed in a certain application and is widely used in 2D image analysis. In 2D image analysis, point-of-interest detection is usually related to extraction of local descriptors for object recognition, classification, registration or pose estimation. In analysis of range data however, some local descriptors have been published in the last decade or so, but most of them do not mention any kind of point-of-interest detection. We here show how to use an extended Harris detector on range data and discuss variants of the Harris measure. All described variants of the Harris detector for 3D should also be usable in medical image analysis, but we focus on the range data case. We do present a performance evaluation of the described variants of the Harris detector on range data.

Local single-patch features for pose estimation using the log-polar transform

This paper presents a local image feature, based on the log-polar transform which renders it invariant to orientation and scale variations. It is shown that this feature can be used for pose estimation of 3D objects with unknown pose, with cluttered background and with occlusion. The proposed method is compared to a previously published one and the new feature is found to be about as good or better as the old one for this task.

A Geometry-Based Local Descriptor for Range Data

We present a novel local descriptor for range data that can describe one or more planes or lines in a local region. It is possible to recover the geometry of the described local region and extract the size, position and orientation of each local plane or line-like structure from the descriptor. This gives the descriptor a property that other popular local descriptors for range data, such as spin images or point signatures, does not have. The estimation of the descriptor is dependant on estimation of surface normals but does not depend on the specific normal estimation method used. It is shown that is possible to extract how many planar surface regions the descriptor represents and that this could be used as a point-of-interest detector.

Motion based estimation and representation of 3D surfaces and boundaries

This paper presents a novel representation for 3D shapes in terms of planar surface patches and their boundaries. The representation is based on a tensor formalism similar to the usual orientation tensor but extends this concept by using projective spaces and a fourth order tensor, even though the practical computations can be made in normal matrix algebra. This paper also discusses the possibility of estimating the proposed representation from motion field which are generated by a calibrated camera moving in the scene. One method based on 3D spatio-temporal orientation tensors is presented and results from this method are included.