We present a model of curvilinear grouping using piecewise linear representations of contours and a conditional random field to capture continuity and the frequency of different junction types. Potential completions are generated by building a constrained Delaunay triangulation (CDT) over the set of contours found by a local edge detector. Maximum likelihood parameters for the model are learned from human labeled groundtruth. Using held out test data, we measure how the model, by incorporating continuity structure, improves boundary detection over the local edge detector. We also compare performance with a baseline local classifier that operates on pairs of edgels. Both algorithms consistently dominate the low-level boundary detector at all thresholds. To our knowledge, this is the first time that curvilinear continuity has been shown quantitatively useful for a large variety of natural images. Better boundary detection has immediate application in the problem of object detection and recognition.
For example, X. Ren et al. REF uses constrained Delaunay triangulation over the set of contours detected by local edge detectors to remove gaps and clutters present in the extracted edges.
Scale-invariant contour completion using conditional random fields
Tenth IEEE International Conference on Computer Vision (ICCV'05) Volume 1
Tenth IEEE International Conference on Computer Vision (ICCV'05) Volume 1
Computer Science