revert fit for resize_nearest scale. (#2242)

PaddleCV/yolov3/README.md

@@ -12,7 +12,7 @@
 
 ## Installation
 
-Running sample code in this directory requires PaddelPaddle Fluid v.1.5 and later. If the PaddlePaddle on your device is lower than this version, please follow the instructions in [installation document](http://www.paddlepaddle.org/documentation/docs/en/1.4/beginners_guide/install/index_en.html) and make an update.
+Running sample code in this directory requires PaddelPaddle Fluid v.1.4 and later. If the PaddlePaddle on your device is lower than this version, please follow the instructions in [installation document](http://www.paddlepaddle.org/documentation/docs/en/1.4/beginners_guide/install/index_en.html) and make an update.
 
 ## Introduction
 

PaddleCV/yolov3/README_cn.md

@@ -12,7 +12,7 @@
 
 ## 安装
 
-在当前目录下运行样例代码需要PadddlePaddle Fluid的v.1.5或以上的版本。如果你的运行环境中的PaddlePaddle低于此版本，请根据[安装文档](http://paddlepaddle.org/documentation/docs/zh/1.4/beginners_guide/install/index_cn.html)中的说明来更新PaddlePaddle。
+在当前目录下运行样例代码需要PadddlePaddle Fluid的v.1.4或以上的版本。如果你的运行环境中的PaddlePaddle低于此版本，请根据[安装文档](http://paddlepaddle.org/documentation/docs/zh/1.4/beginners_guide/install/index_cn.html)中的说明来更新PaddlePaddle。
 
 ## 简介
 

PaddleCV/yolov3/models/yolov3.py

@@ -46,9 +46,19 @@ def yolo_detection_block(input, channel, is_test=True, name=None):
     return route, tip
 
 def upsample(input, scale=2,name=None):
+    # get dynamic upsample output shape
+    shape_nchw = fluid.layers.shape(input)
+    shape_hw = fluid.layers.slice(shape_nchw, axes=[0], starts=[2], ends=[4])
+    shape_hw.stop_gradient = True
+    in_shape = fluid.layers.cast(shape_hw, dtype='int32')
+    out_shape = in_shape * scale
+    out_shape.stop_gradient = True
+
+    # reisze by actual_shape
     out = fluid.layers.resize_nearest(
         input=input,
-        scale=float(scale),
+        scale=scale,
+        actual_shape=out_shape,
         name=name)
     return out