filter invalid segmentation in data source (#1630)

ppdet/data/source/coco.py

@@ -137,7 +137,12 @@ class COCODataSet(DataSet):
                     y1 = max(0, y)
                     x2 = min(im_w - 1, x1 + max(0, box_w - 1))
                     y2 = min(im_h - 1, y1 + max(0, box_h - 1))
-                    if x2 >= x1 and y2 >= y1:
+                    if 'segmentation' in inst and len(inst[
+                            'segmentation']) == 0:
+                        logger.warn(
+                            'Found an empty segmentation in annotations: im_id: {}.'.
+                            format(img_id))
+                    elif x2 >= x1 and y2 >= y1:
                         inst['clean_bbox'] = [x1, y1, x2, y2]
                         bboxes.append(inst)
                     else: