IV. RESULT AND DISCUSSION
4.1. Digital Image Processing
4.1.1. Radiometric Correction
Complete result of radiometric correction on all channels is shown in Table 4.1.
Table 4.1. Radiometric correction on digital imagery data
Channel First Image
Last Image Min. Value
Max.Value Min. Value
Max.Value TM1 57
255 198
TM2 34 255
221 TM3 23
255 232
TM4 9 255
246 TM5 8
255 247
TM7 7 255
248
As shown in Table 4.1, channels TM1 has highest atmosphere bias effect, followed by band 2, 3, 4, 5, and 7, respectively. These minimum values were then
used to subtract the corresponding channel band so that the minimum value of each band become 0 zero. In other words, to reduce this bias effect, all spectral
values will be reduced by its minimum value itself in each bands become 0 zero.
4.1.2. Geometric Correction
The Indonesian marine environment map was used for image geometric correction as referencing. A polynomial rectification with linear order was
selected and applied using 12 reference points Ground Control Points GCPs. The number of GCPs was used 12 points only, because the area is relatively flat.
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The accuracy of each point is shown in Table 4.2 and the resulting image in Fig 4.1.
Based on the accuracy of geometric correction criteria Jensen, 1996, the accuracy of the geometric correction result is high. This can be seen in the
resulting average and sum of the RMS errors. The smaller RMS value indicated that the accuracy of geometric correction is better.
Table 4.2. Ground control point for geometric correction
Points Cell-X
Cell-Y To Easting
To Northing RMS
1 2546.711 5533.989
119.5180335 -4.8883093
0.0055 2 2621.178
5567.783 119.5382321
-4.897333 0.0181
3 2530.979 5408.919
119.5136389 -4.8544314
0.0663 4 2537.823
5765.27 119.5158577
-4.9510444 0.0515
5 2456.489 5981.818
119.4940305 -5.0099084
0.0742 6 2854.153
6014.394 119.6017439
-5.0180051 0.0713
7 2915.855 5796.818
119.6182746 -4.9588557
0.07 8 2757.009
5231.63 119.5747164
-4.805899 0.0487
9 2979.684 5538.059
119.6353348 -4.8885764
0.0848 10 2790.131
5567.768 119.5839864
-4.8970075 0.0487
11 2815.506 5706.634
119.5909849 -4.9346274
0.0899 12 2851.713
5169.397 119.6003013
-4.7888497 0.009
Average RMS error : 0.053
Total RMS error : 0.638
Before Geometric Correction After Geometric Correction
Fig 4.1. Landsat TM image of Maros before and after geometric correction
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4.2. Characteristics of Coastal Region 4.2.1. Land Characteristics
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