Simplify picodet postprocess (#5650)

configs/picodet/_base_/picodet_320_reader.yml

 worker_num: 6
+eval_height: &eval_height 320
+eval_width: &eval_width 320
+eval_size: &eval_size [*eval_height, *eval_width]
+
 TrainReader:
   sample_transforms:
   - Decode: {}
@@ -18,7 +22,7 @@ TrainReader:
 EvalReader:
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [320, 320], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
   batch_transforms:
@@ -29,13 +33,10 @@ EvalReader:
 
 TestReader:
   inputs_def:
-    image_shape: [1, 3, 320, 320]
+    image_shape: [1, 3, *eval_height, *eval_width]
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [320, 320], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
-  batch_transforms:
-  - PadBatch: {pad_to_stride: 32}
   batch_size: 1
-  shuffle: false

configs/picodet/_base_/picodet_416_reader.yml

 worker_num: 6
+eval_height: &eval_height 416
+eval_width: &eval_width 416
+eval_size: &eval_size [*eval_height, *eval_width]
+
 TrainReader:
   sample_transforms:
   - Decode: {}
@@ -18,7 +22,7 @@ TrainReader:
 EvalReader:
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [416, 416], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
   batch_transforms:
@@ -29,13 +33,10 @@ EvalReader:
 
 TestReader:
   inputs_def:
-    image_shape: [1, 3, 416, 416]
+    image_shape: [1, 3, *eval_height, *eval_width]
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [416, 416], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
-  batch_transforms:
-  - PadBatch: {pad_to_stride: 32}
   batch_size: 1
-  shuffle: false

configs/picodet/_base_/picodet_640_reader.yml

 worker_num: 6
+eval_height: &eval_height 640
+eval_width: &eval_width 640
+eval_size: &eval_size [*eval_height, *eval_width]
+
 TrainReader:
   sample_transforms:
   - Decode: {}
@@ -18,7 +22,7 @@ TrainReader:
 EvalReader:
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [640, 640], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
   batch_transforms:
@@ -29,13 +33,10 @@ EvalReader:
 
 TestReader:
   inputs_def:
-    image_shape: [1, 3, 640, 640]
+    image_shape: [1, 3, *eval_height, *eval_width]
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [640, 640], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
-  batch_transforms:
-  - PadBatch: {pad_to_stride: 32}
   batch_size: 1
-  shuffle: false

configs/picodet/legacy_model/_base_/picodet_320_reader.yml

 worker_num: 6
+eval_height: &eval_height 320
+eval_width: &eval_width 320
+eval_size: &eval_size [*eval_height, *eval_width]
+
 TrainReader:
   sample_transforms:
   - Decode: {}
@@ -18,7 +22,7 @@ TrainReader:
 EvalReader:
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [320, 320], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
   batch_transforms:
@@ -29,13 +33,10 @@ EvalReader:
 
 TestReader:
   inputs_def:
-    image_shape: [1, 3, 320, 320]
+    image_shape: [1, 3, *eval_height, *eval_width]
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [320, 320], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
-  batch_transforms:
-  - PadBatch: {pad_to_stride: 32}
   batch_size: 1
-  shuffle: false

configs/picodet/legacy_model/_base_/picodet_416_reader.yml

 worker_num: 6
+eval_height: &eval_height 416
+eval_width: &eval_width 416
+eval_size: &eval_size [*eval_height, *eval_width]
+
 TrainReader:
   sample_transforms:
   - Decode: {}
@@ -18,7 +22,7 @@ TrainReader:
 EvalReader:
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [416, 416], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
   batch_transforms:
@@ -29,13 +33,10 @@ EvalReader:
 
 TestReader:
   inputs_def:
-    image_shape: [1, 3, 416, 416]
+    image_shape: [1, 3, *eval_height, *eval_width]
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [416, 416], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
-  batch_transforms:
-  - PadBatch: {pad_to_stride: 32}
   batch_size: 1
-  shuffle: false

configs/picodet/legacy_model/_base_/picodet_640_reader.yml

 worker_num: 6
+eval_height: &eval_height 640
+eval_width: &eval_width 640
+eval_size: &eval_size [*eval_height, *eval_width]
+
 TrainReader:
   sample_transforms:
   - Decode: {}
@@ -18,7 +22,7 @@ TrainReader:
 EvalReader:
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [640, 640], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
   batch_transforms:
@@ -29,13 +33,10 @@ EvalReader:
 
 TestReader:
   inputs_def:
-    image_shape: [1, 3, 640, 640]
+    image_shape: [1, 3, *eval_height, *eval_width]
   sample_transforms:
   - Decode: {}
-  - Resize: {interp: 2, target_size: [640, 640], keep_ratio: False}
+  - Resize: {interp: 2, target_size: *eval_size, keep_ratio: False}
   - NormalizeImage: {is_scale: true, mean: [0.485,0.456,0.406], std: [0.229, 0.224,0.225]}
   - Permute: {}
-  batch_transforms:
-  - PadBatch: {pad_to_stride: 32}
   batch_size: 1
-  shuffle: false

ppdet/modeling/architectures/picodet.py

@@ -67,10 +67,9 @@ class PicoDet(BaseArch):
         if self.training or not self.export_post_process:
             return head_outs, None
         else:
-            im_shape = self.inputs['im_shape']
             scale_factor = self.inputs['scale_factor']
             bboxes, bbox_num = self.head.post_process(
-                head_outs, im_shape, scale_factor, export_nms=self.export_nms)
+                head_outs, scale_factor, export_nms=self.export_nms)
             return bboxes, bbox_num
 
     def get_loss(self, ):

ppdet/modeling/heads/gfl_head.py

@@ -79,7 +79,9 @@ class Integral(nn.Layer):
                 offsets from the box center in four directions, shape (N, 4).
         """
         x = F.softmax(x.reshape([-1, self.reg_max + 1]), axis=1)
-        x = F.linear(x, self.project).reshape([-1, 4])
+        x = F.linear(x, self.project)
+        if self.training:
+            x = x.reshape([-1, 4])
         return x
 
 

ppdet/modeling/heads/pico_head.py

@@ -194,7 +194,7 @@ class PicoHead(OTAVFLHead):
         'conv_feat', 'dgqp_module', 'loss_class', 'loss_dfl', 'loss_bbox',
         'assigner', 'nms'
     ]
-    __shared__ = ['num_classes']
+    __shared__ = ['num_classes', 'eval_size']
 
     def __init__(self,
                  conv_feat='PicoFeat',
@@ -210,7 +210,8 @@ class PicoHead(OTAVFLHead):
                  feat_in_chan=96,
                  nms=None,
                  nms_pre=1000,
-                 cell_offset=0):
+                 cell_offset=0,
+                 eval_size=None):
         super(PicoHead, self).__init__(
             conv_feat=conv_feat,
             dgqp_module=dgqp_module,
@@ -239,6 +240,7 @@ class PicoHead(OTAVFLHead):
         self.nms = nms
         self.nms_pre = nms_pre
         self.cell_offset = cell_offset
+        self.eval_size = eval_size
 
         self.use_sigmoid = self.loss_vfl.use_sigmoid
         if self.use_sigmoid:
@@ -282,12 +284,50 @@ class PicoHead(OTAVFLHead):
                         bias_attr=ParamAttr(initializer=Constant(value=0))))
                 self.head_reg_list.append(head_reg)
 
+        # initialize the anchor points
+        if self.eval_size:
+            self.anchor_points, self.stride_tensor = self._generate_anchors()
+
     def forward(self, fpn_feats, export_post_process=True):
         assert len(fpn_feats) == len(
             self.fpn_stride
         ), "The size of fpn_feats is not equal to size of fpn_stride"
-        cls_logits_list = []
-        bboxes_reg_list = []
+
+        if self.training:
+            return self.forward_train(fpn_feats)
+        else:
+            return self.forward_eval(
+                fpn_feats, export_post_process=export_post_process)
+
+    def forward_train(self, fpn_feats):
+        cls_logits_list, bboxes_reg_list = [], []
+        for i, fpn_feat in enumerate(fpn_feats):
+            conv_cls_feat, conv_reg_feat = self.conv_feat(fpn_feat, i)
+            if self.conv_feat.share_cls_reg:
+                cls_logits = self.head_cls_list[i](conv_cls_feat)
+                cls_score, bbox_pred = paddle.split(
+                    cls_logits,
+                    [self.cls_out_channels, 4 * (self.reg_max + 1)],
+                    axis=1)
+            else:
+                cls_score = self.head_cls_list[i](conv_cls_feat)
+                bbox_pred = self.head_reg_list[i](conv_reg_feat)
+
+            if self.dgqp_module:
+                quality_score = self.dgqp_module(bbox_pred)
+                cls_score = F.sigmoid(cls_score) * quality_score
+
+            cls_logits_list.append(cls_score)
+            bboxes_reg_list.append(bbox_pred)
+
+        return (cls_logits_list, bboxes_reg_list)
+
+    def forward_eval(self, fpn_feats, export_post_process=True):
+        if self.eval_size:
+            anchor_points, stride_tensor = self.anchor_points, self.stride_tensor
+        else:
+            anchor_points, stride_tensor = self._generate_anchors(fpn_feats)
+        cls_logits_list, bboxes_reg_list = [], []
         for i, fpn_feat in enumerate(fpn_feats):
             conv_cls_feat, conv_reg_feat = self.conv_feat(fpn_feat, i)
             if self.conv_feat.share_cls_reg:
@@ -307,50 +347,68 @@ class PicoHead(OTAVFLHead):
             if not export_post_process:
                 # Now only supports batch size = 1 in deploy
                 # TODO(ygh): support batch size > 1
-                cls_score = F.sigmoid(cls_score).reshape(
+                cls_score_out = F.sigmoid(cls_score).reshape(
                     [1, self.cls_out_channels, -1]).transpose([0, 2, 1])
                 bbox_pred = bbox_pred.reshape([1, (self.reg_max + 1) * 4,
                                                -1]).transpose([0, 2, 1])
-            elif not self.training:
-                cls_score = F.sigmoid(cls_score.transpose([0, 2, 3, 1]))
+            else:
+                b, _, h, w = fpn_feat.shape
+                l = h * w
+                cls_score_out = F.sigmoid(
+                    cls_score.reshape([b, self.cls_out_channels, l]))
                 bbox_pred = bbox_pred.transpose([0, 2, 3, 1])
-                stride = self.fpn_stride[i]
-                b, cell_h, cell_w, _ = paddle.shape(cls_score)
-                y, x = self.get_single_level_center_point(
-                    [cell_h, cell_w], stride, cell_offset=self.cell_offset)
-                center_points = paddle.stack([x, y], axis=-1)
-                cls_score = cls_score.reshape([b, -1, self.cls_out_channels])
-                bbox_pred = self.distribution_project(bbox_pred) * stride
-                bbox_pred = bbox_pred.reshape([b, cell_h * cell_w, 4])
-
-                # NOTE: If keep_ratio=False and image shape value that 
-                # multiples of 32, distance2bbox not set max_shapes parameter
-                # to speed up model prediction. If need to set max_shapes,
-                # please use inputs['im_shape']. 
-                bbox_pred = batch_distance2bbox(
-                    center_points, bbox_pred, max_shapes=None)
+                bbox_pred = self.distribution_project(bbox_pred)
+                bbox_pred = bbox_pred.reshape([b, l, 4])
 
-            cls_logits_list.append(cls_score)
+            cls_logits_list.append(cls_score_out)
             bboxes_reg_list.append(bbox_pred)
 
+        if export_post_process:
+            cls_logits_list = paddle.concat(cls_logits_list, axis=-1)
+            bboxes_reg_list = paddle.concat(bboxes_reg_list, axis=1)
+            bboxes_reg_list = batch_distance2bbox(anchor_points,
+                                                  bboxes_reg_list)
+            bboxes_reg_list *= stride_tensor
+
         return (cls_logits_list, bboxes_reg_list)
 
-    def post_process(self,
-                     gfl_head_outs,
-                     im_shape,
-                     scale_factor,
-                     export_nms=True):
-        cls_scores, bboxes_reg = gfl_head_outs
-        bboxes = paddle.concat(bboxes_reg, axis=1)
-        mlvl_scores = paddle.concat(cls_scores, axis=1)
-        mlvl_scores = mlvl_scores.transpose([0, 2, 1])
+    def _generate_anchors(self, feats=None):
+        # just use in eval time
+        anchor_points = []
+        stride_tensor = []
+        for i, stride in enumerate(self.fpn_stride):
+            if feats is not None:
+                _, _, h, w = feats[i].shape
+            else:
+                h = math.ceil(self.eval_size[0] / stride)
+                w = math.ceil(self.eval_size[1] / stride)
+            shift_x = paddle.arange(end=w) + self.cell_offset
+            shift_y = paddle.arange(end=h) + self.cell_offset
+            shift_y, shift_x = paddle.meshgrid(shift_y, shift_x)
+            anchor_point = paddle.cast(
+                paddle.stack(
+                    [shift_x, shift_y], axis=-1), dtype='float32')
+            anchor_points.append(anchor_point.reshape([-1, 2]))
+            stride_tensor.append(
+                paddle.full(
+                    [h * w, 1], stride, dtype='float32'))
+        anchor_points = paddle.concat(anchor_points)
+        stride_tensor = paddle.concat(stride_tensor)
+        return anchor_points, stride_tensor
+
+    def post_process(self, head_outs, scale_factor, export_nms=True):
+        pred_scores, pred_bboxes = head_outs
         if not export_nms:
-            return bboxes, mlvl_scores
+            return pred_bboxes, pred_scores
         else:
             # rescale: [h_scale, w_scale] -> [w_scale, h_scale, w_scale, h_scale]
-            im_scale = scale_factor.flip([1]).tile([1, 2]).unsqueeze(1)
-            bboxes /= im_scale
-            bbox_pred, bbox_num, _ = self.nms(bboxes, mlvl_scores)
+            scale_y, scale_x = paddle.split(scale_factor, 2, axis=-1)
+            scale_factor = paddle.concat(
+                [scale_x, scale_y, scale_x, scale_y],
+                axis=-1).reshape([-1, 1, 4])
+            # scale bbox to origin image size.
+            pred_bboxes /= scale_factor
+            bbox_pred, bbox_num, _ = self.nms(pred_bboxes, pred_scores)
             return bbox_pred, bbox_num
 
 
@@ -374,10 +432,9 @@ class PicoHeadV2(GFLHead):
         'conv_feat', 'dgqp_module', 'loss_class', 'loss_dfl', 'loss_bbox',
         'static_assigner', 'assigner', 'nms'
     ]
-    __shared__ = ['num_classes']
+    __shared__ = ['num_classes', 'eval_size']
 
-    def __init__(
-            self,
+    def __init__(self,
                  conv_feat='PicoFeatV2',
                  dgqp_module=None,
                  num_classes=80,
@@ -396,7 +453,8 @@ class PicoHeadV2(GFLHead):
                  nms_pre=1000,
                  cell_offset=0,
                  act='hard_swish',
-            grid_cell_scale=5.0, ):
+                 grid_cell_scale=5.0,
+                 eval_size=None):
         super(PicoHeadV2, self).__init__(
             conv_feat=conv_feat,
             dgqp_module=dgqp_module,
@@ -432,6 +490,7 @@ class PicoHeadV2(GFLHead):
         self.grid_cell_scale = grid_cell_scale
         self.use_align_head = use_align_head
         self.cls_out_channels = self.num_classes
+        self.eval_size = eval_size
 
         bias_init_value = -math.log((1 - self.prior_prob) / self.prior_prob)
         # Clear the super class initialization
@@ -478,11 +537,22 @@ class PicoHeadV2(GFLHead):
                         act=self.act,
                         use_act_in_out=False))
 
+        # initialize the anchor points
+        if self.eval_size:
+            self.anchor_points, self.stride_tensor = self._generate_anchors()
+
     def forward(self, fpn_feats, export_post_process=True):
         assert len(fpn_feats) == len(
             self.fpn_stride
         ), "The size of fpn_feats is not equal to size of fpn_stride"
 
+        if self.training:
+            return self.forward_train(fpn_feats)
+        else:
+            return self.forward_eval(
+                fpn_feats, export_post_process=export_post_process)
+
+    def forward_train(self, fpn_feats):
         cls_score_list, reg_list, box_list = [], [], []
         for i, (fpn_feat, stride) in enumerate(zip(fpn_feats, self.fpn_stride)):
             b, _, h, w = get_static_shape(fpn_feat)
@@ -498,15 +568,6 @@ class PicoHeadV2(GFLHead):
             else:
                 cls_score = F.sigmoid(cls_logit)
 
-            if not export_post_process and not self.training:
-                # Now only supports batch size = 1 in deploy
-                cls_score_list.append(
-                    cls_score.reshape([1, self.cls_out_channels, -1]).transpose(
-                        [0, 2, 1]))
-                box_list.append(
-                    reg_pred.reshape([1, (self.reg_max + 1) * 4, -1]).transpose(
-                        [0, 2, 1]))
-            else:
             cls_score_out = cls_score.transpose([0, 2, 3, 1])
             bbox_pred = reg_pred.transpose([0, 2, 3, 1])
             b, cell_h, cell_w, _ = paddle.shape(cls_score_out)
@@ -519,23 +580,60 @@ class PicoHeadV2(GFLHead):
             bbox_pred = bbox_pred.reshape([b, cell_h * cell_w, 4])
             bbox_pred = batch_distance2bbox(
                 center_points, bbox_pred, max_shapes=None)
-                if not self.training:
-                    cls_score_list.append(cls_score_out)
-                    box_list.append(bbox_pred)
-                else:
-                    cls_score_list.append(
-                        cls_score.flatten(2).transpose([0, 2, 1]))
+            cls_score_list.append(cls_score.flatten(2).transpose([0, 2, 1]))
             reg_list.append(reg_pred.flatten(2).transpose([0, 2, 1]))
             box_list.append(bbox_pred / stride)
 
-        if not self.training:
-            return cls_score_list, box_list
-        else:
         cls_score_list = paddle.concat(cls_score_list, axis=1)
         box_list = paddle.concat(box_list, axis=1)
         reg_list = paddle.concat(reg_list, axis=1)
         return cls_score_list, reg_list, box_list, fpn_feats
 
+    def forward_eval(self, fpn_feats, export_post_process=True):
+        if self.eval_size:
+            anchor_points, stride_tensor = self.anchor_points, self.stride_tensor
+        else:
+            anchor_points, stride_tensor = self._generate_anchors(fpn_feats)
+        cls_score_list, box_list = [], []
+        for i, (fpn_feat, stride) in enumerate(zip(fpn_feats, self.fpn_stride)):
+            b, _, h, w = fpn_feat.shape
+            # task decomposition
+            conv_cls_feat, se_feat = self.conv_feat(fpn_feat, i)
+            cls_logit = self.head_cls_list[i](se_feat)
+            reg_pred = self.head_reg_list[i](se_feat)
+
+            # cls prediction and alignment
+            if self.use_align_head:
+                cls_prob = F.sigmoid(self.cls_align[i](conv_cls_feat))
+                cls_score = (F.sigmoid(cls_logit) * cls_prob + eps).sqrt()
+            else:
+                cls_score = F.sigmoid(cls_logit)
+
+            if not export_post_process:
+                # Now only supports batch size = 1 in deploy
+                cls_score_list.append(
+                    cls_score.reshape([1, self.cls_out_channels, -1]).transpose(
+                        [0, 2, 1]))
+                box_list.append(
+                    reg_pred.reshape([1, (self.reg_max + 1) * 4, -1]).transpose(
+                        [0, 2, 1]))
+            else:
+                l = h * w
+                cls_score_out = cls_score.reshape([b, self.cls_out_channels, l])
+                bbox_pred = reg_pred.transpose([0, 2, 3, 1])
+                bbox_pred = self.distribution_project(bbox_pred)
+                bbox_pred = bbox_pred.reshape([b, l, 4])
+                cls_score_list.append(cls_score_out)
+                box_list.append(bbox_pred)
+
+        if export_post_process:
+            cls_score_list = paddle.concat(cls_score_list, axis=-1)
+            box_list = paddle.concat(box_list, axis=1)
+            box_list = batch_distance2bbox(anchor_points, box_list)
+            box_list *= stride_tensor
+
+        return cls_score_list, box_list
+
     def get_loss(self, head_outs, gt_meta):
         pred_scores, pred_regs, pred_bboxes, fpn_feats = head_outs
         gt_labels = gt_meta['gt_class']
@@ -644,20 +742,41 @@ class PicoHeadV2(GFLHead):
 
         return loss_states
 
-    def post_process(self,
-                     gfl_head_outs,
-                     im_shape,
-                     scale_factor,
-                     export_nms=True):
-        cls_scores, bboxes_reg = gfl_head_outs
-        bboxes = paddle.concat(bboxes_reg, axis=1)
-        mlvl_scores = paddle.concat(cls_scores, axis=1)
-        mlvl_scores = mlvl_scores.transpose([0, 2, 1])
+    def _generate_anchors(self, feats=None):
+        # just use in eval time
+        anchor_points = []
+        stride_tensor = []
+        for i, stride in enumerate(self.fpn_stride):
+            if feats is not None:
+                _, _, h, w = feats[i].shape
+            else:
+                h = math.ceil(self.eval_size[0] / stride)
+                w = math.ceil(self.eval_size[1] / stride)
+            shift_x = paddle.arange(end=w) + self.cell_offset
+            shift_y = paddle.arange(end=h) + self.cell_offset
+            shift_y, shift_x = paddle.meshgrid(shift_y, shift_x)
+            anchor_point = paddle.cast(
+                paddle.stack(
+                    [shift_x, shift_y], axis=-1), dtype='float32')
+            anchor_points.append(anchor_point.reshape([-1, 2]))
+            stride_tensor.append(
+                paddle.full(
+                    [h * w, 1], stride, dtype='float32'))
+        anchor_points = paddle.concat(anchor_points)
+        stride_tensor = paddle.concat(stride_tensor)
+        return anchor_points, stride_tensor
+
+    def post_process(self, head_outs, scale_factor, export_nms=True):
+        pred_scores, pred_bboxes = head_outs
         if not export_nms:
-            return bboxes, mlvl_scores
+            return pred_bboxes, pred_scores
         else:
             # rescale: [h_scale, w_scale] -> [w_scale, h_scale, w_scale, h_scale]
-            im_scale = scale_factor.flip([1]).tile([1, 2]).unsqueeze(1)
-            bboxes /= im_scale
-            bbox_pred, bbox_num, _ = self.nms(bboxes, mlvl_scores)
+            scale_y, scale_x = paddle.split(scale_factor, 2, axis=-1)
+            scale_factor = paddle.concat(
+                [scale_x, scale_y, scale_x, scale_y],
+                axis=-1).reshape([-1, 1, 4])
+            # scale bbox to origin image size.
+            pred_bboxes /= scale_factor
+            bbox_pred, bbox_num, _ = self.nms(pred_bboxes, pred_scores)
             return bbox_pred, bbox_num