The goals of verification are:
However, as tolerances are needed to allow for segmentation variations, position parameter misestimation, and obscured surface reconstruction, some invalid verifications are expected. Some invalid SURFACEs are verified because of variability in surface shape matching and having no other constraints on their identity at this point. The effect of these hypotheses is reduced performance rates and increased chances of invocation of higher level false objects. However, verified higher false hypotheses are not likely to occur as the surfaces must then meet grouping, relative orientation and location constraints in hypothesis construction, and the verification constraints discussed in this chapter.
Table 10.1 summarizes the causes for rejection of SURFACE hypotheses, and Table 10.2 summarizes the causes for rejection of ASSEMBLY hypotheses. The tables record the rejection criterion as given here, except for those designated by "", which means rejection by a modeled numerical constraint, by "", which means failure to establish a reference frame (Chapter 9), or by "" which means all slots that should have been filled were not.
Some rejected curved SURFACE hypotheses had the correct identity but an
inconsistent reference frame.
Some false ASSEMBLY hypotheses were rejected in hypothesis construction because no
consistent reference frame could be found for them.
These hypotheses are included in the analysis of rejected hypotheses
|ASSEMBLY||IMAGE REGIONS||REJECTION RULE||INSTANCES||NOTE|
|+1||valid hypothesis rejection because of geometric reasoning error|
|MODEL USED||TRUE MODEL||IMAGE REGIONS||NOTE|
|+1||true model similar to invoked model|
|+2||symmetric model gives match with another reference frame|
|+3||error because substantially obscured|
Table 10.3 lists and analyzes all remaining verified hypotheses that were not "correct". The most common causes of incorrectly verified hypotheses were symmetric models, leading to multiple reference frames, and nearly identical models. The incorrect models normally were not used in larger ASSEMBLYs, because of reference frame inconsistencies.
These results show that verification worked well.
Two true ASSEMBLY hypotheses were rejected because of deficiencies in
All verified false hypotheses were reasonable, usually arising from
either a similar or symmetric object model.
Most rejected SURFACE hypotheses failed the value constraint (usually
surface area - see Appendix A).
Curved SURFACEs were rejected when their curvature axis was inconsistent
with other orientation estimates.
Most ASSEMBLYs were rejected because no consistent reference frame
could be found.
(Many of these hypotheses arose because hypothesis construction has a
combinatorial aspect during initial hypothesis construction.)