I found a improved version for the ear index finder, which completely…

mesh2hrtf/Mesh2Input/Meshes/AssignMaterials/AssignMaterials.py

@@ -46,7 +46,10 @@ class AssignMaterials(bpy.types.Operator):
     ear : StringProperty
         The ear canals to assign the materials to. Can be ``'Both ears'``,
         ``'Left ear'`` or ``'Right ear'``. The default is 'Both ears'.
-
+    tolerance_mode : StringProperty
+        Mode of tolerance.
+        ``'y_distance'`` minimizes xz_distance and tolerates deviation along the y axis,
+        ``'xz_distance'`` minimizes abs(y) and tolerates radial deviation normal to the y axis.
     '''
     bl_idname = "object.assignmaterials"
     bl_label = "AssignMaterials"
@@ -63,6 +66,13 @@ class AssignMaterials(bpy.types.Operator):
                        The default is 'Both ears'.",
         default = "Both ears",
         )
+    tolerance_mode: StringProperty(
+        name = "tolerance_mode",
+        description = "Mode of tolerance. \
+        ``'y_distance'`` minimizes xz_distance and tolerates deviation along the y axis, \
+        ``'xz_distance'`` minimizes abs(y) and tolerates radial deviation normal to the y axis.",
+        default = "y_distance",
+        )
 
     def execute(self, context):
         # unit = 'mm'
@@ -96,66 +106,88 @@ def setup_materials(obj):
         bpy.context.object.active_material.name = name
 
 
-def get_ear_indices(bm, obj, tolerance, ear):
-    '''Return indicees of faces at the entrance to the ear channels'''
+def get_ear_indices(bm, obj, tolerance, ear, tolerance_mode="y_distance"):
+    '''Return indices of faces at the entrance to the ear channels'''
 
     bm.verts.ensure_lookup_table()
     bm.faces.ensure_lookup_table()
 
-    # initialize helper variables
-    left_indices = []
-    left_xy_distance = []
-    left_y = []
-    right_indices = []
-    right_xy_distance = []
-    right_y = []
+    # initialize helper variable
     min_y = [1000, 1000]
-
-    # world matrix for obtaining vertex positions in world coorindates
-    world = obj.matrix_world
-
-    # find possible faces at the ear channel entrances
-    for face in bm.faces:
-
-        # current face location in world coordinates
-        xyz = world @ face.calc_center_median()
-        # distance from y axis, and y-value
-        xy_distance = abs(xyz[0]) + abs(xyz[2])
-        y = xyz[1]
-
-        # potential left ear
-        if y > 0 and abs(xyz[0]) < tolerance and abs(xyz[2]) < tolerance:
-            left_indices.append(face.index)
-            left_xy_distance.append(xy_distance)
-            left_y.append(abs(y))
-            if abs(y) < min_y[0]:
-                min_y[0] = abs(y)
-        # potential right ear
-        elif y < 0 and abs(xyz[0]) < tolerance and abs(xyz[2]) < tolerance:
-            right_indices.append(face.index)
-            right_xy_distance.append(xy_distance)
-            right_y.append(abs(y))
-            if abs(y) < min_y[1]:
-                min_y[1] = abs(y)
-
-    # find left ear element and try to exclude faces at the tragus
     left_index = None
-    if ear in ("Both ears", "Left ear"):
-        min_xy_dist = 1000
-        for n in range(len(left_indices)):
-            if left_y[n] < min_y[0] + tolerance and left_xy_distance[n] < \
-                    min_xy_dist:
-                min_xy_dist = left_xy_distance[n]
-                left_index = left_indices[n]
-    # find left ear element and try to exclude faces at the tragus
     right_index = None
-    if ear in ("Both ears", "Right ear"):
-        min_xy_dist = 1000
-        for n in range(len(right_indices)):
-            if right_y[n] < min_y[1] + tolerance and right_xy_distance[n] < \
-                    min_xy_dist:
-                min_xy_dist = right_xy_distance[n]
-                right_index = right_indices[n]
+
+    if tolerance_mode == "y_distance":
+        # minimizes xz_distance and tolerates deviation along the y axis
+        # initialize helper variables
+        left_indices = []
+        left_xy_distance = []
+        left_y = []
+        right_indices = []
+        right_xy_distance = []
+        right_y = []
+
+        # world matrix for obtaining vertex positions in world coorindates
+        world = obj.matrix_world
+
+        # find possible faces at the ear channel entrances
+        for face in bm.faces:
+
+            # current face location in world coordinates
+            xyz = world @ face.calc_center_median()
+            # distance from y axis, and y-value
+            xy_distance = abs(xyz[0]) + abs(xyz[2])
+            y = xyz[1]
+
+            # potential left ear
+            if y > 0 and abs(xyz[0]) < tolerance and abs(xyz[2]) < tolerance:
+                left_indices.append(face.index)
+                left_xy_distance.append(xy_distance)
+                left_y.append(abs(y))
+                if abs(y) < min_y[0]:
+                    min_y[0] = abs(y)
+            # potential right ear
+            elif y < 0 and abs(xyz[0]) < tolerance and abs(xyz[2]) < tolerance:
+                right_indices.append(face.index)
+                right_xy_distance.append(xy_distance)
+                right_y.append(abs(y))
+                if abs(y) < min_y[1]:
+                    min_y[1] = abs(y)
+
+        # find left ear element and try to exclude faces at the tragus
+        left_index = None
+        if ear in ("Both ears", "Left ear"):
+            min_xy_dist = 1000
+            for n in range(len(left_indices)):
+                if left_y[n] < min_y[0] + tolerance and left_xy_distance[n] < \
+                        min_xy_dist:
+                    min_xy_dist = left_xy_distance[n]
+                    left_index = left_indices[n]
+        # find left ear element and try to exclude faces at the tragus
+        right_index = None
+        if ear in ("Both ears", "Right ear"):
+            min_xy_dist = 1000
+            for n in range(len(right_indices)):
+                if right_y[n] < min_y[1] + tolerance and right_xy_distance[n] < \
+                        min_xy_dist:
+                    min_xy_dist = right_xy_distance[n]
+                    right_index = right_indices[n]
+
+    elif tolerance_mode == "xz_distance":
+        # find optimal faces for left and right mic position
+        # by choosing the face with min y value in the area around the y axis with radius=tolerance
+        for f in bm.faces:
+            f_median= f.calc_center_median()  # compute face location
+            xz_distance = np.sqrt(f_median.x**2 + f_median.z**2)  # compute distance to y axis
+            if xz_distance < tolerance:
+                if f_median.y > 0 and ear in ("Both ears", "Left ear"):  # Left
+                    if f_median.y < min_y[0]:
+                        min_y[0] = f_median.y
+                        left_index = f.index
+                elif f_median.y < 0 and ear in ("Both ears", "Right ear"):  # Right
+                    if abs(f_median.y) < min_y[1]:
+                        min_y[1] = abs(f_median.y)
+                        right_index = f.index
 
     return left_index, right_index
 
@@ -172,11 +204,11 @@ def assign_material(obj, tolerance, ear):
     bm = bmesh.new()
     bm.from_mesh(obj.data)
 
-    # get indicees
+    # get indices
     print(f"Search tolerance: {tolerance} blender units")
     left_index, right_index = get_ear_indices(bm, obj, tolerance, ear)
 
-    # assign indicees
+    # assign indices
     if ear in ("Both ears", "Left ear"):
         if left_index is not None:
             bm.faces[left_index].material_index = 1