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

Algorithm 3

Connected domain judgment.

Input: Non-feature points set 𝑉_𝑛.

Output: The connected domain matrix DOM, and its

   filling intensity Ins_𝑖, 𝑖=1,2,3,….

1. Set Ins_𝑖=0, 𝑖=1,2,3,….

2. Set 𝑖=0 and DOM(𝑟,𝑐)=0, 0≤𝑟,𝑐≤𝑚,

 where 𝑚 is the scale of original data.

3. Find one point that is neither target point, nor

 marked point from 𝑉_𝑛, let 𝑣_𝑟,𝑐∈𝑉_𝑛 as the

  current non-feature point, 𝑖=𝑖+1 and mark it, go to

  step 3.1; there is no such point go to step 4:

 3.1 Initialize array A;

 3.2 Set 𝑘=1 and 𝐴[𝑘]=𝑣_𝑟,𝑐;

 3.3 Set Ins_𝑖=Ins_𝑖+1 and DOM(𝑟,𝑐)=𝑖;

 3.4 Find one point that is neither target point, nor

    the marked point in eight adjacent points of

    current point, let 𝑣_{𝑟𝑟,𝑐𝑐} be the point which is

    found at this time, if find the point go to

    step 3.6; if there is no such point, 𝑘=𝑘−1,

    𝑣_𝑟,𝑐=𝐴[𝑘], go to step 3.5.

 3.5 If 𝑘=1, go to step 4.

 3.6 Mark 𝑣_{𝑟𝑟,𝑐𝑐}, 𝑘=𝑘+1, 𝐴[𝑘]=𝑣_{𝑟𝑟,𝑐𝑐}, 𝑣_𝑟,𝑐 = 𝑣_{𝑟𝑟,𝑐𝑐},

     go to step 3.3.

4. Algorithm end.