containment threshold

lib/templates/image_to_fields.rb

@@ -297,7 +297,7 @@ module Templates
       [img_array.reshape(1, 3, resolution, resolution), transform_info]
     end
 
-    def nms(boxes, scores, iou_threshold = 0.5)
+    def nms(boxes, scores, iou_threshold = 0.5, containment_threshold = 0.7)
       return Numo::Int32[] if boxes.shape[0].zero?
 
       x1 = boxes[true, 0]
@@ -328,7 +328,11 @@ module Templates
 
         iou = intersection / (areas[i] + areas[order[1..]] - intersection)
 
-        inds = iou.le(iou_threshold).where
+        other_areas = areas[order[1..]]
+        containment = intersection / (other_areas + 1e-6)
+
+        suppress_mask = iou.gt(iou_threshold) | containment.gt(containment_threshold)
+        inds = suppress_mask.eq(0).where
 
         order = order[inds + 1]
       end