EI I 
[Esl 
Ld 
— 
à 
duc EN E 
lard 
ing 
een 
nge 
ons 
ion 
ime 
nge 
da 
nge 
/ of 
this 
nge 
om 
2-3, 
ent 
age 
ing 
een 
S-2 
eT 
(2) 
-T, 
(3) 
| to 
    
The above process results in two images; first image contains 
moving vehicles of the MS-1 image and second image contains 
moving vehicles of the MS-2 image. 
  
Figure 2: Second principal component of MS-1 image (MS-1: 
PCA2) 
  
Figure 3: Second principal component of MS-2 image (MS-2: 
PCA2) 
  
Figure 4: Second principal component of MS image (MS: 
PCA2). In this figure, two positions of the same vehicle are 
available. 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
2.6 Post-Processing 
Although thresholds used in equations 2 and 3 significantly 
reduced the outliers, still there are false alarms (structures other 
than the vehicles) present in the resulting images. To eliminate 
the false alarms, c/ean filter, majority filter, hole filling filters, 
and opening/closing morphological operators discussed in 
Sharma et al.(2006) have been used. In the above filters, (1) 
Clean filter removes the one pixel size structure surrounded by 
Os. (2) Majority filter sets a pixel to 1, if five or more pixels in a 
3x3 neighbourhood are 1s; otherwise, it sets to the pixel to 0. 
(3) Hole filling filter fills isolated pixels, such as centre pixels. 
(4) Opening/closing morphological operation removes one or 
two pixel wide interconnections between two pixel groups. 
After filtering operations, Otsu threshold method (Otsu, 1979) 
has been used to convert gray level image into binary (black and 
white) image. An algorithm has been developed to count 
vehicles from the generated binary images. The final result of 
moving vehicle detection is shown in Figure 5 and 6. Figure 5 
shows the moving vehicles detected from the MS-1 image and 
Figure 6 shows the moving vehicles detected from the MS-2 
image. 
  
    
Figure 6: Result of vehicles detected from MS-2 image 
2.7 Results of vehicle detection 
The experiment results are based on WorldView-2 imagery of a 
part of Moncton, a city in New Brunswick, Canada. A very 
small part of the results have been shown in the figures due to 
space limitation. The whole image was taken as input to the