ry[3,4,6], 
n aspect- 
attribute 
de, face- 
relational 
indicate 
which is 
group of 
ammetry 
ect from 
| of the 
ognizing 
aratively 
haracters 
zed are 
ided. 
novelty 
kind of 
of this 
nted to 
rimitives 
s well as 
ct-graph 
nted. 
ing was 
ed. 
)N 
1 of 3-D 
rimitives 
different) 
imber of 
location 
volume- 
, which 
corresponds to a 2-D projection of 3-D primitive. We choose a set of usual primitives from CAD 
So a volume-primitive corresponds to a 3-D system[Fig. 1], its probable projection to be 
primitive. A number of volume-primitives happened is shows in Fig. 2 when view point is 
constructs an object in reasonable disposition. located in general position. We take the face 
The edge, face, volume-primitive and object projected by 3-D surface as element, then 
form a tree construction, we call interpretation- analyze, study and deliberate these faces, finally 
tree. Every layer in this tree describes a kind of refine out eleven visual faces, which contain 
state of projection of object. We call aspect. i.e. some characters as follows: / 
the aspect is used as representing the projection 
of a 3-D object. So the decomposed state of (ze 
projection corresponds to edge-aspect, face- 
aspect,  primitive-aspect and  object-aspect 
respectively. This decomposed process imitates (0) @) G) (9) 6) 
the human recognizing process[1]. If the aspects 
are connected by acre, we call aspect-graph, Ca to nd 
which is in fact the attribute relational graph S irt 
(6) 0) (8) ©) 
(ARG) [2,18,19]. It shows the property of i 
connection among aspect On the basis of (10) 
analysis above, the author presents recognizing Fig. 1 Ten usual primitives 
the primitives by model matching based on face] It consists of four edges, all edges are 
aspect-interpretation. straight line and each pair of opposite edge is 
In aspect-graph, in order to recognize parallel. 
primitives, the node may be defined as standing face2 It consists of four edges, all edges are 
for the primitive-aspect, and the branch may be straight line. One pair of opposite edge is 
defined as standing for connected relation parallel, another pair of opposite edge converges 
between neighbor  primitive-aspect. The à same point. 
advantages in this way lie in a) the volume- fjce3 It consists of four edges, one pair of 
primitive consisting object is numbered; b) the opposite edge is straight line, and another pair of 
matching process can directly research due to opposite edge is curve. Both pairs of opposite 
the independence of primitive in CAD system, c) edges are parallel. 
mainly, the LP soft-package can directly be face4 It consists of four edges, one pair of curve 
useful for measurement. opposite edge is parallel, and another pair of 
Aspect-graph constructed in this way above is straight opposite edge converge a same point. 
only describing the volume-primitive and their face5 |t consists of four curve edges, each pair 
connected relation. During the intersection of of two curve opposite edges is parallel. 
between primitives, a face of primitive feature face6 It consists of three edges, the bottom is 
may be divided into several disconnected straight line, two other edges are curve. 
components thus creating new faces. face7 It consists of three straight edges. 
Furthermore, two intersecting faces of a face8 It consists of three edges, the bottom edge 
primitive may not be adjacent. In merging is curve, two other edges are straight line. 
between primitives, there are still analogous face9 Its shape is an ellipse. 
case above. So in order to describe faces and face10 Its shape is a circle. 
their connected relations, we take faces as node feel] The face is constructed by two curve 
(element), their connected relations as branch to edges. 
construct face-aspect-graph (called also attribute The eleven visual faces are taken as the 
graph here). With the help of face-aspect- foundation of face-aspect-interpretation, we 
interpretation, we further construct primitive represent them with the ordinal numbers 1, 2, 3, 
graph, which describes volume-primitives, and 4, 5, 6, 7, 8, 9, 10, 11[Fig. 3]. Each ordinal 
then construct attribute hypergraphy through number corresponds to a fixed visual face. Each 
describing connected relations between volume- face corresponds to a fixed code. Their coding 
primitives. principles are suggested as follows: 
1) The amount of edges in face-aspect is defined 
2.1 Face-aspect Coding Principle as first-figure number of coding. For example, if 
1019 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996