Feature Migration

Choice on Raster GIS menu, migration over time submenu.  Designed for sequential time surveys of features like dunes.

Select two feature grids (created with ID features). These can have different numbers of features, but must have the same extent and grid spacing.

  • Boxes at the top let you select the maximum lags to test, from each point in a feature.  These are in grid units.  In this case we know the migration should be to the NE, so the values to the south and west are 0.
  • All features: For each feature in the original grid, the algorithm will attempt to find a corresponding point in the migrated grid.  The score will be the percentage of points that had a match, with the largest percentage being the computed shift.  If several shifts have the same score, the computed shift will be the centroid of the points with the tied score.
  • Reverse (all):  flips the original and migrated grids, the box containing the lags to test, and the resulting lags.  This basically finds the motion that must be reversed to go from the migrated feature to an original feature.
Table, which includes:
  • ID of the feature
  • Number of points for the feature in the grid
  • Centroid location of the feature
  • Shift in meters
  • PC is the percentage of the points in the feature which have a point at the new location
  • NAVG is the number of shifts with the same PC, which were averaged to get the shift.

Last revision 5/14/2014