A New Skeleton Feature Extraction Method for Terrain Model Using Profile Recognition and Morphological Simplification

Algorithm 4

Evaluate and process the big rings.

Input: Segments set seg_res without polygons and

   small rings.

Output: Segments set seg_br and segments set

   seg_res that has been disassembled.

1. Traverse segments set seg_res. If all the segments

 have been traversed, then go to step 5.

2. Let 𝑠∈seg_res as the current segment:

 2.1 Find the adjacent points of 𝑠 as Figure 7, and

   evaluate the filling intensities ins of these

   points, if ins<criterion, then go to step 1;

 2.2 Evaluate whether 𝑠 satisfies the Rule (2) in

   Section 3.3.

3. If the points (Figure 7) on the both sides of 𝑠 are

 non-target points according to the original target

 points set, and then:

 3.1 Disassemble the rings and remove 𝑠 from

    seg_res;

 3.2 Otherwise, denote 𝑠 as the segment of the

    stable ring and put it into seg_br.

4. If there is no any change for the segments set

 seg_res, then go to step 5.

5. Algorithm end.