Hyperspectral Data Processing: Algorithm Design and Analysis

30.2 Size Estimation of Subpixel Targets

Prior to size estimation detection must be performed to find targets of interest. When an image scene is unknown such a detection must be carried out in an unsupervised manner. The algorithm to be used for this purpose is ATGP which is similar to ATGP-EEA developed in Section 8.5.1, and can be described as follows.

Algorithm for Automatic Target Generation Process

1. Initial condition:

Select a pixel with maximal vector length as an initial target signature of interest denoted by t₀. Let ε be the prescribed error threshold and U⁽⁰⁾ = [t⁽⁰⁾].

Set .

2. At iteration, apply via (2.78) to all data sample vectors r and find the kth data sample vector t^(k), which has the maximum orthogonal projection defined by

(30.1)

where is the data matrix and if .

3. Calculate

(30.2)

and compare η_k to a prescribed threshold ε.

4. Stopping rule:

If , go to ...