e The amount of share edge is taken as 
ep (4) attribute value. 
5 ef | 39 e The type of share edge is taken as attribute 
| value. Straight line is 1, or 0. 
(a) (D (6) e The slope of straight line is taken as attribute 
Fig. 8 Object and aspect value. 
3.1 ‘Image Aspect-graph Constructing ° The curvature of curve is taken as attribute 
Regulation value. 
j e The information of two end-points of share 
It may be completely different when edge is taken as attribute value. 
constructing the aspect-graph duo to varioUS jt is convenient to construct 2-D attribute 
tasks and aims. Since our aim is to recognize relation graph in term to proposal above. With 
primitive, it is a key work to construct the the help of aspect-interpretation, we can further 
primitive attribute graph and — attribute construct primitive attribute graph and attribute 
hypergraph. But they are on the basis of pyperoraph, It is sometimes necessary to 
describing face-aspect-graph, so we have to take describe the connected relation of two primitive 
face. as an element(node). The regulation of „44ribute graphs in attribute hypergraph, the 
constructing attribute graph is attribute value is suggested as follows. 
1) A face-aspect is taken as a node[Fig.9a]. e The primitives recognized by  aspect- 
2) A share edge between neighbor face-aspect iS interpretation is taken as attribute value. 
taken as a branch[Fig. 9b]. e The code of face-aspect or face-aspect 
3) The information in face-aspect, such as type, mergence is taken as attribute value. 
area, etc. is taken as subset of node [Fig.9c]. With the regulation proposed above, we can 
4) The information of ring, such as internal or construct an attribute relational graph, primitive 
external ring, is taken as subset of node [Fig. 9d]. attribute graph and attribute hypergraph, which 
5) The information of share edge is taken as correspond face-aspect, primitive-aspect and 
  
   
   
  
  
   
   
   
  
  
   
   
   
    
  
   
  
  
   
    
   
      
    
  
   
   
    
  
subset of branch [Fig. 9e]. 
6) The information of two end-points in share 
edge is taken as subset of branch [Fig. 9f]. 
[7 vh s 4 f£ 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
(a) (b) (c) 
1 
/1 "A 
1 
x 
(4) (e) ® 
Fig. 9 The regulation of attribute graph 
In addition, the attribute values are still 
suggested as follows: 
1) The regulations to nodes are 
e The area of face-aspect is taken as attribute 
value. : 
e The perimeter of face-aspect is taken as 
attribute value. 
e The mass center coordinates(Xc, Yc) of face- 
aspect is taken as attribute value. 
e The direction angle of face-aspectg is taken 
as attribute value. where  x,- Mjo/ Mog 
Ye = Mio/ Mog*9 - 1/2atan[2 Mj1/( M29 - Mo2)] 
M, j is i, j-order moment, m, nr sao cn 
2) The regulations to branch are 
object-aspect respectively for a complex object. 
The whole process is illustrated in Fig. 10. 
  
nput image 
  
    
  
    
    
   
     
Imags Segment ‚(Interpretation using 
; {| Face-aspect code. 
  
Attribute 
relational graph 
  
   
  
  
  
Interpretation using. 
: Face-aspect rietgence code 
  
    
  
    
  
Primitive 
attribute graph 
  
  
  
  
  
  
Attribute 2 38 nterpretation using 
hypergraph Fe ce-aspect split codé 
  
  
  
  
  
  
Fig. 10 The flow char of attribute graph constructing 
4. FROM CAD to MODEL ASPECT- 
GRAPH 
That we only have image aspect graph can not 
correctly recognize the primitive yet since a part 
possibly is occluded by another part or an object 
is occluded by another object. Therefore we 
must use prior CAD knowledge. Since the 
object is represented by data structure in CAD 
system, it is necessary to look for a relation 
between image aspect-graph and the data 
structure. Generally, it is very difficult to realize 
directly matching data structure with graph. So 
we have to study how to transfer data structure 
into attribute graph. 
1022 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996