improved converte, now with test

still needs to figure out how +P is handled

PRIVATE

@@ -1 +1 @@
-Subproject commit 8deb37dd4526fb5e1425fe1d2360508d01b6ac3e
+Subproject commit 144e729811024fd5f99225fa10b6d8fa40e7d492

processing/pre/geom_fromDREAM3D.py

@@ -95,7 +95,7 @@ for name in filenames:
     except:
       errors.append('Pointwise orientation data ({}) not found'.format(dataset))
       
-    texture = [damask.Rotation.fromQuaternion(q,P=+1) for q in quats]
+    texture = [damask.Rotation.fromQuaternion(q,True,P=+1) for q in quats]
 
     dataset = os.path.join(group_pointwise,options.phase)
     try:
@@ -118,7 +118,7 @@ for name in filenames:
     
     dataset = os.path.join(group_average,options.quaternion)
     try:
-      texture = [damask.Rotation.fromQuaternion(q,P=+1) for q in inFile[dataset][...][1:]]          # skip first entry (unindexed)
+      texture = [damask.Rotation.fromQuaternion(q,True,P=+1) for q in inFile[dataset][...][1:]]     # skip first entry (unindexed)
     except:
       errors.append('Average orientation data ({}) not found'.format(dataset))
       

python/damask/orientation.py

@@ -301,11 +301,15 @@ class Rotation:
     @classmethod
     def fromQuaternion(cls,
                        quaternion,
+                       acceptHomomorph = False,
                        P = -1):
 
       qu = quaternion if isinstance(quaternion, np.ndarray) else np.array(quaternion)
       if P > 0: qu[1:4] *= -1                                                                       # convert from P=1 to P=-1
       if qu[0] < 0.0:
+        if acceptHomomorph:
+          qu *= -1.
+        else:
           raise ValueError('Quaternion has negative first component.\n{}'.format(qu[0]))
       if not np.isclose(np.linalg.norm(qu), 1.0):
         raise ValueError('Quaternion is not of unit length.\n{} {} {} {}'.format(*qu))