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from observed images Fig 5 shows the results getting averaged image of three images. It shows<br />

that the cars observed in the image of March 25 and people observed m the image of April 6 are<br />

removed in the averaged image.<br />

3.2.2 Removing shadows in observed Images<br />

<strong>The</strong>re exist shadows of many objects such as trees, cars, and buildings in observed images.<br />

<strong>The</strong>se have possibility recognized as the physical recovery during image processing <strong>The</strong><br />

observed images have been composed from three colors, red, blue, and green. Each color has its<br />

own charactenstics against shadows. <strong>The</strong> method to remove shadows using these characteristics<br />

was developed. <strong>The</strong> procedure of this process is as follows.<br />

a Observed images are recomposed to law data of red, blue, and green (Fig 5)<br />

b <strong>The</strong> value of each color is adjusted into the value that does not have effects from the<br />

sunlight<br />

R'=(R-G/R+G)xlOO (1)<br />

B'=(B-G/B+G)xlOO (2)<br />

R' value has characteristic that effects from shadows is weak And R' value is used for die<br />

following analysis.<br />

c Comparing two sets of adjusted image according to following formulation.<br />

AR'=|RO'-R1'| (3)<br />

AR': Comparison result, RO'* Base Averaged Image , Rl': Reference Averaged image<br />

d. <strong>The</strong> compared images (acquired from process of c) are classified into two values, black and<br />

white according to a threshold. Threshold value 5 is used in this analysis. Acquired image<br />

will be shown in Fig.6.<br />

3/25 10 00 4/6 10 00 4/20 10 00<br />

Averaged image of 3/25 4/6 and 20 Averaged image of 5/181 Sand 20<br />

Red Value Green Value Blue Value<br />

Fig.5 Removing Moving objects<br />

Fig.6 Shadows removed image<br />

3.3 Acquiring amount of physical recovery<br />

<strong>The</strong>re still exist many noises without physical recovery (ref. Fig6). <strong>The</strong>se noises are<br />

generated from the effect of sunlight against existing buildings and the edge of roads. <strong>The</strong>se<br />

noises are removed by the method of smoothing. <strong>The</strong> result is shown in Fig.7. And acquired<br />

results will convert to the GIS data. About the method for conversion will be discussed another<br />

paper.

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