[GRASS-SVN] r68521 - sandbox/bo/i.segment.gsoc2016/i.segment

[svn_grass at osgeo.org]

Author: hao2309
Date: 2016-05-25 20:30:24 -0700 (Wed, 25 May 2016)
New Revision: 68521

Added:
   sandbox/bo/i.segment.gsoc2016/i.segment/MeanShift_pseudo_2016_05_25_MM
Log:
add pseudo code

Added: sandbox/bo/i.segment.gsoc2016/i.segment/MeanShift_pseudo_2016_05_25_MM
===================================================================
--- sandbox/bo/i.segment.gsoc2016/i.segment/MeanShift_pseudo_2016_05_25_MM	                        (rev 0)
+++ sandbox/bo/i.segment.gsoc2016/i.segment/MeanShift_pseudo_2016_05_25_MM	2016-05-26 03:30:24 UTC (rev 68521)
@@ -0,0 +1,128 @@
+'''
+Module Name:  Meanshift pseudo code
+
+Created on May 24, 2016
+
+ at author: Bo Yang, Moritz Lennert, Markus Metz
+
+GRASS GSoC2016 project, All Rights Reserved
+'''
+
+#==================================================================================
+#               input parameters
+#==================================================================================
+
+# sampling window radius = spatial bandwidth in number of pixels
+radius = 3.5
+
+# range bandwidth (spectral bandwidth) for normalized difference between old and new values
+# must be 0 < range bandwidth < 1
+range_bandwidth = 0.1
+
+# threshold to control when iterations should stop
+# stop if the maximum difference between old and new values is < threshold
+threshold_factor= 0.01
+
+# maximum number of iterations
+max_iter = 20
+
+
+#===================================================================================
+#                       input  Raster
+#===================================================================================
+
+# use existing functions in i.segment
+
+
+#===================================================================================
+#               gaussian weight difference (S=||B1-A1||)
+#===================================================================================
+
+# window size in number of pixels
+window_size = (int)radius * 2 + 1
+
+# initialize
+
+# copy input raster to output raster
+rastout = rastin
+
+# iteration counter
+iter = 0
+
+# number of changed pixels with change > threshold
+n_changes = 1
+
+while (iter < max_iter && n_changes > 0 {
+
+  # make output raster of last iteration input raster of this iteration
+  rasttmp = rastin
+  rastin = rastout
+  rastout = rasttmp
+
+  # go through all rows
+  for (row = 0; row < nrows; row++) {
+
+    # go through all columns
+    for (col = 0; col < ncols; col++) {
+    
+      # figure out moving window, clip to region if necessary
+      mwrow1 = row - (int)radius
+      mwrow2 = mwrow1 + window_size
+      if (mwrow1 < 0)
+        mwrow1 = 0
+      if (mwrow2 > nrows)
+        mwrow2 = nrows
+
+      
+      mwcol1 = col - (int)radius
+      mwcol2 = mwcol1 + window_size
+      if (mwcol1 < 0)
+        mwcol1 = 0
+      if (mwcol2 > ncols)
+        mwcol2 = ncols
+
+      # read band values from rastin for row, col
+
+      sum_of_weights = 0
+      # go through the window
+      for (mwrow = mwrow1; mwrow < mwrow2; mwrow++) {
+        for (mwcol = mwcol1; mwcol < mwcol2; mwcol++) {
+        
+          # check spatial distance
+          if the spatial distance to focus pixel is <= radius {
+
+            # set the weight, here 1, can be changed to gaussian weight
+            weight = 1
+          
+            # read band values from rastin for mrow, mcol as oldvalue
+
+            # check spectral distance
+            if the spectral distance to focus pixel is <= range_bandwidth {
+
+              # adjust the weight, here 1, can be changed to gaussian weight
+              # the weight is a function of the spectral distance, one weight for all bands
+              weight *= 1
+              sum_of_weights += weight
+              for all bands
+                newvalue = oldvalue * weight
+            }
+          }
+        }
+      }
+      # end of moving window
+
+      newvalue /= sum_of_weights
+
+      write newvalue to rastout
+
+      if the spectral distance between old and new value is > threshold
+        # not yet converged
+        n_changes++
+
+    }
+    # end columns
+  }
+  # end rows
+}
+# end iterations
+