Chen Yuen Teoh 
  
Attributes 
Pictorial Illustration 
Property of Road Model Addressed 
E 
  
Separation between a 
pair of edges 
———————— 
D 
+X 
ZN 
Seperation = x 
Deals with basic road properties that a 
road segment must have a minimum and 
a maximum of width 
  
Difference in Spatial 
direction 
E E 
dir y 
Difference = (dir x - dir y) 
The road property that a road segment 
must be running in parallel direction or 
near parallel direction 
  
Difference in Gradient 
direction 
oradient dir X 
— 
gradient dir x 
Difference = (gradient dir x - 
gradient dir y) 
The road property that a road segment 
has opposite gradient directions 
  
Average enclosed 
intensity 
Intensity — 
Average Intensity 
= avg(Intensity of all pixels 
within the enclosed 
boundary) 
Image property for road model, by having 
smooth higher intensity from border 
to border. within a road segment 
  
Difference in 
intensity with the 
surrounding 
  
  
  
Intensity y 
Intensity x 
Difference = (intensity x - 
intensity y) 
(a) Level 
Addressing the fact that road surfaces 
have higher colour intensity than other 
surface material 
  
  
— 
  
Attributes 
Pictorial Illustration 
Property of Road Model Addressed 
  
Minimum Seperation 
Minimum Seperation = 
max(x, y) 
Deals with basic road property that 
2 linkng road segments should have 
minimal separation, normally caused 
by noise. 
  
Gap Difference 
Difference = max(x, y) 
Deal with basic road properties that 
2 linking road segments should not have 
big difference in width. 
  
  
Spatial Direction dir a dirc | Deals with basic road property that 
ee »- € t . 
Difference 2 linking road segments should have 
Er c — — | similar spatial direction, i.e.: changes is 
dir b dir d angle or direction should be minimal. 
Difference = 
max((dir a-dir c),(dir b-dir d)) 
Width Difference Ep T TW Deals with basic road properties that 
Ix Y y 2 linking road segments should not have 
MN ES —— 
wide changes in width .. 
  
Intensity Difference 
  
intensity x 
intensity y 
Intensity — (Intensity x - 
  
  
Intensity y) 
(b) Level 2 
Figure 2: Features targeted at Different Levels 
  
  
  
  
  
Exp. | Combination Level | L1 | L2 || Figure 
Z| LU/LI/LZ/L3 NE | NE | NE # 
Preprocessed 6481 3 (b) 
CL/No/No/No 
CL/ML/No/No 
CL/ML/ML/No 
WN — 
  
  
  
2644 
2644 
2644 
252 
252 
  
  
2 (a) 
2 (b) 
86 2 (c) 
  
  
  
  
Deals with image property of road 
model that linking two road segments, 
the intensity of these two candidates 
should have similar intensity, i.e.: 
minimal intensity difference. 
  
Table 1: Result SummaryML: Machine Learning; CL: Clustering; Li: Level i of the System; NE: Number of Edges 
  
884 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000.