In this section, synthetic and real hyperspectral image experiments were conducted to substantiate and validate the utility of ATGP-FCLS in size estimation of subpixel targets. The data to be used for experiments was the HYDICE image shown in Figure 1.15(a) with ground truth map of Figure 1.15(b).
30.3.1 Synthetic Image Experiments
In order to evaluate our approach, we simulated a synthetic image scene based on Figure 1.15(a) and (b) and the five panel signatures in Figure 1.16. First of all, 400 grass samples extracted from Figure 1.15(a) were used to simulate the image background. Two panel signatures, p1 and p2 were used to simulate two sets of target panels, p11, p12, p13 and p21p22, p23, respectively. The three panels in each set had size ranging from 100%, 50%, and 25% of pixel size (i.e., GSD = 1.5 m), namely, 2.25 m2, 1.125 m2, and 0.5625 m2, respectively. Figure 30.1(a) and (b) shows how the target panels p12 and p13 with size being 50% and 25% of pixel size were simulated. For example, in order to simulate the panel p12, we first simulated 2-pixel vectors specified by the grass signature and 2-pixel vectors specified by the panel signature p1 to form a 4-pixel square panel where each of 4-pixel vectors in the panel had size of 2.25 m2 and the resulting 4-pixel square panel had size of 9 m2. This 4-pixel square panel was then shrunk to its ¼ size by averaging all 4-pixel vectors to reduce the 4-pixel square panel with size of 9 m2 to a 4-pixel square panel ...