Toward Consistent Descriptions in Vision Systems

To reduce these amb igu i t i es , a second k ind of i n fo rmat ion f lowfeedbacki s necessary. Concept u a l l y , t h i s a l lows in fo rmat ion to move both hor i z o n t a l l y 'across a l l p o s i t i o n s a t a s i n g l e l e v e l o f abs t rac t i on and v e r t i c a l l y across a l l l e ve l s o f abs t r ac t i on a t a s i ng le p ro jec ted p o s i t i o n . Diagonal k inds of feedback, which f l ow across both p o s i t i o n and l e v e l of a b s t r a c t i o n , can be expressed in terms of these two or thogonal f l o w s . 3. Relaxat ion Processes f o r Dot Label ing and Grouping Feedback can be implemented un i fo rm ly in both d i r e c t i o n s by r e l a x a t i o n l a b e l i n g processes (RLPs). These are p a r a l l e l , i t e r a t i v e schemes f o r using consistency o r c o m p a t i b i l i t y r e l a t i o n s h i p s t o r e duce l o c a l amb igu i t i es . In order to apply RLPs to dot l a b e l i n g and g roup ing , a h i e r a r c h i c a l ar rangement of two h o r i z o n t a l RLPs and one v e r t i c a l RLP must be de f i ned . One h o r i z o n t a l process attempts to disambiguate the assignment o f f u n c t i o n a l l abe l s from the set {EDGE, INTERIOR, NOISE} onto i n d i v i d ua l do ts . I t i t e r a t e s toward h o r i z o n t a l ( i . e . , s p a t i a l ) consistency between the labe ls at tached to neighbor ing do t s . The second h o r i z o n t a l process performs the grouping opera t ion by l abe l i ng the l i n k s between dots as e i t h e r CONNECTED or NOTCONNECTED. The v e r t i c a l RLP al lows i n t e r a c t i o n s between the l i n k l abe l s and the dot l a b e l s . I t i t e r a t e s toward desc r i p t i ons which are cons is ten t across both l e v e l s of a b s t r a c t i o n . (For example, a CONNECTED l i n k is cons is ten t w i t h two neighbor ing INTERIOR do ts . )