remove uint8 cast in weight calculation for boundary CE loss and fix ZeroDivisionError

Summary: The uint8 cast means that the floating point non_bd_weight is never assigned

Reviewed By: wat3rBro

Differential Revision: D30176377

fbshipit-source-id: 013602bb4313393f220ee0f1510bf1ff83bd56fc

tests/modeling/test_trimap.py

+#!/usr/bin/env python3
+# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
+
+
+import numpy as np
+import unittest
+
+from d2go.modeling.trimap import generate_boundary_weight_mask
+
+
+class TestTrimap(unittest.TestCase):
+
+    def test_generate_boundary_weight_mask(self):
+        # smallest size mask to not give dilation too small warning
+        mask_gt = np.zeros((115, 252))
+        mask_gt[54:60, 123:128] = 1
+
+        mask_dt = np.zeros((115, 252))
+        mask_dt[55:61, 124:129] = 1
+
+        weights = generate_boundary_weight_mask(mask_gt, mask_dt, non_bd_weight=0.1)
+        unique_values = np.unique(weights)
+        self.assertEqual(unique_values.size, 2)
+        self.assertEqual(10 * unique_values[0], unique_values[1])
+
+    def test_generate_boundary_weight_mask_from_negative_img_mask(self):
+        # smallest size mask to not give dilation too small warning
+        mask_gt = np.zeros((115, 252))
+        mask_dt = np.zeros((115, 252))
+
+        try:
+            generate_boundary_weight_mask(mask_gt, mask_dt, non_bd_weight=0.0)
+        except ZeroDivisionError:
+            self.fail(
+                "generate_boundary_weight_mask raised ZeroDivisionError unexpectedly")