Research Article

Multiscale Feature Model for Terrain Data Based on Adaptive Spatial Neighborhood

Algorithm 1

The cluster algorithm based on FMRH.
Input: The structure in external storage of FMRH.
Output: The set of cluster .
Description: This algorithm generates the set of cluster
        by traversing the structure of FMRH with depth-first order,
        according to the relationship of static error and threshold.
(1) Initialization:
    (1.1) According to Definition 1, set
         ,
         and make
        
         .
    (1.2) Clear the clusters in aggregation .
(2) Recall the function of Traverse_FMRH (FMRH, , 0).
(3) Generate the index file of clusters, and save the index of data block for each cluster.
(4) The end.
Traverse_FMRH (FMRH, current_Block, level_S)
Function Description: Load static error of data blocks in
FMRH, and decide which cluster it belongs to.
Parameter Description: FMRH is a multi-resolution
        level of structure based on features. The parameter
        current_Block is the current data block. The parameter
        level_S is the index of current data block in the level.
(1) Load the static error of current_Block from FMRH as current_Block.CovSE.
(2) Decide which cluster current_Block belongs to:
    (2.1) Construct intervals according to error
       thresholds   .
    (2.2) Each threshold interval corresponds a cluster from to :
     (2.2.1) Decide the size of current_Block.CovSE, if it meet two constraints:
      ;
       add data block current_Block into the cluster ,
      if there is no ancestor data block of current_Block
      including in the cluster .
     (2.2.2) When current_Block.leaf is false, then, get four data
       blocks in the next level
       from current_Block in FMRH, and recall the function of
       DeepTraverse_FMRH(FMRH, , level_S + 1).
(3) The end.