Comparison of jers-1 and radarsat synthetic aperture
Radar data for mapping mangrove and its biomass
Results and Discussion
Classification of mangrove and species determination
Unsupervised-supervised approach with maximum likelihood classifier was
performed on JERS-1 and Radarsat image (Figure 2). Seven classes can be defined
from JERS-1 and five classes from Radarsat. In both images, Rhizophora are still the
dominant species where it covers 45.2 % of JERS-1 and 55.4 % of Radarsat data.
Accuracy points were carefully selected to avoid error and confusion due to inclusion
of mixed, border/edge pixels (Table 2).
Error matrix were created and figures for User’s Accuracy, Producer’s Accuracy, and
Combined Accuracy (kappa statistic) compiled to evaluate the quality of each
classification. User’s Accuracy is a ratio statistic compiled by dividing the number of
pixels correctly assigned to a category by the total number of pixels to the category.
Producer’s Accuracy is calculated by dividing the number of accuracy pixels correctly
assigned to a category by the number of accuracy pixels selected for that category.
These two measures are useful in defining the type of classifications errors made and
provide differents perspectives of accuracy. Results show Radarsat that (5.6 cm
wavelength) is less sensitive compare with JERS-1 (23.5 cm). The lower accuracy
existence in mangrove classification mapping especially in study area due to the
mixed species.
Table 2: Error matrix of classification statistic for JERS-1 SAR and Radarsat
| Dataset Classes | JERS-1 SAR | Radarsat |
| User’s Accuracy | Producer’s Accuracy | User’s Accuracy | Producer’s Accuracy |
| Muddy plants and Sonneratia sp | 100% | 67% | 100% | 50% |
| Bareland and small mangroves | 50% | 44% | - | - |
| Avicennia sp and others small mangroves | - | - | 40% | 67% |
| Avicennia sp and Ceriops sp | 50% | 75% | - | - |
| Small mangroves | 50% | 38% | - | - |
| Rhizophora sp | 60% | 46% | 50% | 38% |
| Mature Rhizophora | 45% | 71% | 43% | 30% |
| Bruguiera sp and Xylocarpus sp | 43% | 50% | 45% | 45% |
| Overall Accuracy | 52 | 46 |
| KHAT | 43 | 30 |
(a)
(b)
Figure 2:
Mangrove species classified from (a) JERS-1 SAR, and (b) Radarsat
