Segmentation of object outlines into parts: A large-scale integrative study
Section snippets
The minima rule (Hoffman & Richards, 1984)
Hoffman and Richards (1984) proposed that objects are segmented according to the minima rule. Because in their view object segmentation into parts precedes object recognition, it must be based on very generic regularities that hold for almost any object. These regularities are found in the transversality and singularity principle. The transversality principle entails that a concave crease on the surface of an object is a very likely candidate for the segmentation of two forms. The singularity
Aims
In the light of the above state-of-the-art, we thus believe that the field would benefit from a study in which a large set of outlines is segmented by a large number of subjects. In such a benchmark data set, the relative strengths and weaknesses of the different models would be easier to evaluate, and even relatively rare types of parts could reveal themselves. To provide such a benchmark data set is the most important goal of this paper.
We investigate how people segment outlines of existing
Subjects
Two hundred and one subjects, all first-year psychology students at the University of Leuven, participated in this study as a mandatory component of their curriculum. It took place in a large movie theatre used as a lecture hall, following two hours of lectures on the history of philosophy and metaphysics. Our study was only part of a longer session of several (unrelated) paper-and-pencil tests and experiments. It is important to note that these conditions are not ideal to motivate subjects for
Results and discussion
A fairly large number of data was excluded from analysis. There were three categories of faults that led to exclusion. (1) The segmentation line did not cut two points on the outline. Sometimes this was true for the majority of the 22 outlines, sometimes for only a number of outlines per subject. (2) Some stimuli were not segmented at all. (3) There was also a rest category of other ‘errors’, like filling-in the inner details of an outline (e.g. drawing an eye on the horse). In addition to
General discussion
This study started out by formulating three aims. The first goal of this study was to supplement the large literature on object segmentation into parts with good (i.e. reliable and valid) benchmark data. The current literature consists of a wealth of different segmentation principles and rules for part formation but relatively little strong empirical evidence. Most of the experiments so far had used only a small number of subjects and stimuli (mostly meaningless outline shapes). Using outlines
Acknowledgements
This research was supported by a research grant from the University Research Council (OT/00/007) and from the Fund for Scientific Research (FWO-Vlaanderen G.0189.02) to JW. This study is part of a larger research program with financial support from the University Research Council (GOA/2005/03-TBA) to the Laboratory of Experimental Psychology. We would also like to thank Felix Wichmann, Sven Panis, Donald Hoffman and an anonymous reviewer for their helpful comments on a previous draft.
We would
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2019, Computer Vision and Image UnderstandingCitation Excerpt :Comparing to the conventional definition, which requires part-cuts to cross an axis of local symmetry (Singh and Hoffman, 2001), this is a stronger definition in agreement with the definition of necks (Siddiqi and Kimia, 1995). We actually show that this can be in accordance to psychophysical evidence (De Winter and Wagemans, 2006) in some cases. In general, some ground-truth cuts may be lost but we introduce a way to recover them.