add option for nearest neighbor interpolation to gtRotateVolume

Signed-off-by: Wolfgang Ludwig <wolfgang.ludwig@esrf.fr>

4_grains/gtGrainRotateStructure.m

-function [structure, proj] = gtGrainRotateStructure(structure, proj, type,  parameters, rot_tensor_angles, rot_axes)
+function [structure, proj] = gtGrainRotateStructure(structure, proj, type,  parameters, rot_tensor_angles, rot_axes, interpolation)
     if (any([size(rot_tensor_angles, 1), size(rot_tensor_angles, 2)] == 1))
         rot_angles = rot_tensor_angles;
-        if (~exist('rot_axis', 'var'))
+        if (~exist('rot_axes', 'var') || isempty(rot_axes))
             rot_axes = [0 0 1];
         end
         rot_tensor = gtMathsRotationTensorComposite(rot_axes, rot_angles);
     else
         rot_tensor = rot_tensor_angles;
     end
+    if (~exist('interpolation','var') || isempty(interpolation))
+        interpolation = 'linear';
+    end
 
-    structure.intensity = gtRotateVolume(structure.intensity, rot_tensor);
+    structure.intensity = gtRotateVolume(structure.intensity, rot_tensor, [], [], interpolation);
 
     switch (upper(type))
         case 'ODF6D'
             dmvol = structure.voxels_avg_R_vectors;
-            dmvol(:, :, :, 1) = gtRotateVolume(dmvol(:, :, :, 1), rot_tensor);
-            dmvol(:, :, :, 2) = gtRotateVolume(dmvol(:, :, :, 2), rot_tensor);
-            dmvol(:, :, :, 3) = gtRotateVolume(dmvol(:, :, :, 3), rot_tensor);
+            dmvol(:, :, :, 1) = gtRotateVolume(dmvol(:, :, :, 1), rot_tensor, [], [], interpolation);
+            dmvol(:, :, :, 2) = gtRotateVolume(dmvol(:, :, :, 2), rot_tensor, [], [], interpolation);
+            dmvol(:, :, :, 3) = gtRotateVolume(dmvol(:, :, :, 3), rot_tensor, [], [], interpolation);
             structure.voxels_avg_R_vectors = dmvol;
         case 'VOL3D'
     end

zUtil_Imaging/gtRotateVolume.m

-function vol = gtRotateVolume(vol, rot_tensor_angle, rot_axis, rot_center)
+function vol = gtRotateVolume(vol, rot_tensor_angle, rot_axis, rot_center, interpolation)
 % function vol = gtRotateVolume(vol, rot_tensor_angle, rot_axis, rot_center)
     if (any([size(rot_tensor_angle, 1), size(rot_tensor_angle, 2)] == 1))
         rot_angle = rot_tensor_angle;
-        if (~exist('rot_axis', 'var'))
+        if (~exist('rot_axis', 'var') || isempty(rot_axis))
             rot_axis = [0 0 1];
         end
         rot_tensor = eye(3);
@@ -18,7 +18,9 @@ function vol = gtRotateVolume(vol, rot_tensor_angle, rot_axis, rot_center)
     if (~exist('rot_center', 'var') || isempty(rot_center))
         rot_center = (vol_size + 1) / 2;
     end
-
+    if (~exist('interpolation', 'var') || isempty('interpolation'))
+        interpolation = 'linear';
+    end
     T1 = eye(4);
     T1(4, 1:3) = -rot_center;
 
@@ -37,6 +39,6 @@ function vol = gtRotateVolume(vol, rot_tensor_angle, rot_axis, rot_center)
     % Old version. NOTE that rot_tensor should be un-transposed if this
     % version was to be used.
     tform = maketform('affine', T);
-    R = makeresampler('linear', 'fill');
+    R = makeresampler(interpolation, 'fill');
     vol = tformarray(vol, tform, R, [1 2 3], [1 2 3], vol_size, [], 0);
 end