Application of the Referencing Method over water surfaces
Because of the relatively small dynamic range of TM data it was felt that the Referencing Method may not be entirely successful over low reflected energy targets such as wetlands and water. The Brine Concentration ponds at Dampier Salt (Karratha,WA) were chosen as the average reflectance in the best water-penetrating band (DMSV Band 1 – 450nm) was of the order of 5%. The following example is from a salt evaporation pond, and demonstrates the Referencing Method over water surfaces. The purpose for the data acquisition was to map the condition of the benthic algae.
Figure 12 show the narrow (25nm) DMSV bands 1 (450nm) 2 (550nm) and 3 (650nm) centres and Figure 13 the TM modelled surfaces.
Figure 12: DMSV Band 1, 2 and 3 of DMSV image ds8al showing a part of the brine concentration ponds.
Figure 13: Brightness surfaces of band 1, 2 and 3 of DMSV image ds8al.
| Correlation | TM1(450-520) | TM2(520-600) | TM3(630-690) | TM4(760-900) | V1(438-462) | V2(538-562) | V3(638-662) | V4(758-782) |
| TM1(450-520) |
1 |
0.982 |
0.949 |
0.678 |
0.775 |
0.78 |
0.71 |
0.454 |
| TM2(520-600) |
0.982 |
1 |
0.965 |
0.721 |
0.743 |
0.754 |
0.701 |
0.493 |
| TM3(630-690) |
0.949 |
0.965 |
1 |
0.852 |
0.712 |
0.725 |
0.769 |
0.642 |
| TM4(760-900) |
0.678 |
0.721 |
0.852 |
1 |
0.5 |
0.52 |
0.693 |
0.786 |
| V1(438-462) |
0.775 |
0.743 |
0.712 |
0.5 |
1 |
0.963 |
0.83 |
0.456 |
| V2(538-562) |
0.78 |
0.754 |
0.725 |
0.52 |
0.963 |
1 |
0.852 |
0.49 |
| V3(638-662) |
0.71 |
0.701 |
0.769 |
0.693 |
0.83 |
0.852 |
1 |
0.758 |
| V4(758-782) |
0.454 |
0.493 |
0.642 |
0.786 |
0.456 |
0.49 |
0.758 |
1 |
Table 1: Correlation matrix for Landsat TM acquired on 03.10.95 and DMSV acquired on 16.11.95.
Figure 14: LEFT: Mosaic of DMSV images acquired on 16.11.95 before correction. CENTRE: Landsat TM image acquired on 03.10.95. RIGHT: Mosaic of DMSV images acquired on 16.11.95 corrected using the Referencing Method.