[core][imageregistration][shift_detection] Fix bug when h is 0

darfix/core/imageRegistration.py

@@ -231,6 +231,8 @@ def shift_detection(data, steps, shift_approach="linear"):
     v = normalize(shift)
     v_ = 2 * shift / len(data)
     h = numpy.sqrt(v_[0]**2 + v_[1]**2)
+    if not h:
+        return numpy.outer([0, 0], numpy.arange(len(data)))
     epsilon = 2 * h
     h = improve_linear_shift(data, v, h, epsilon, steps, shift_approach=shift_approach)
     return numpy.outer(h * v, numpy.arange(len(data)))