Add affine grid generator op (#12238)

* Add affine grid generator.

* fix ffine grid.

* Add unitest.

* Add CPU kernel and fix unitest.

* Fix CPU kernel.

* Refine code.
test=develop

* Fix python api.
test=develop

* Update python api.
test=develop

* Fix comment.
test=develop

* Rename affine_grid_generator to affine_grid and enhence unitest.
test=develop

* Fix unitest.
test=develop

paddle/fluid/API.spec

@@ -174,6 +174,7 @@ paddle.fluid.layers.mean ArgSpec(args=['x', 'name'], varargs=None, keywords=None
 paddle.fluid.layers.mul ArgSpec(args=['x', 'y', 'x_num_col_dims', 'y_num_col_dims', 'name'], varargs=None, keywords=None, defaults=(1, 1, None))
 paddle.fluid.layers.sigmoid_cross_entropy_with_logits ArgSpec(args=['x', 'label', 'name'], varargs=None, keywords=None, defaults=(None,))
 paddle.fluid.layers.maxout ArgSpec(args=['x', 'groups', 'name'], varargs=None, keywords=None, defaults=(None,))
+paddle.fluid.layers.affine_grid ArgSpec(args=['theta', 'out_shape', 'name'], varargs=None, keywords=None, defaults=(None,))
 paddle.fluid.layers.sequence_reverse ArgSpec(args=['x', 'name'], varargs=None, keywords=None, defaults=(None,))
 paddle.fluid.layers.affine_channel ArgSpec(args=['x', 'scale', 'bias', 'data_layout', 'name'], varargs=None, keywords=None, defaults=(None, None, 'NCHW', None))
 paddle.fluid.layers.hash ArgSpec(args=['input', 'hash_size', 'num_hash', 'name'], varargs=None, keywords=None, defaults=(1, None))

paddle/fluid/operators/affine_grid_cudnn_op.cu.cc

+/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#include "paddle/fluid/framework/op_registry.h"
+#include "paddle/fluid/platform/cudnn_helper.h"
+
+namespace paddle {
+namespace operators {
+
+using Tensor = framework::Tensor;
+using ScopedSpatialTransformerDescriptor =
+    platform::ScopedSpatialTransformerDescriptor;
+
+template <typename T>
+class CUDNNAffineGridOpKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    PADDLE_ENFORCE(platform::is_gpu_place(ctx.GetPlace()),
+                   "It must use CUDAPlace.");
+    auto& dev_ctx = ctx.template device_context<platform::CUDADeviceContext>();
+    auto handle = dev_ctx.cudnn_handle();
+    auto* theta = ctx.Input<Tensor>("Theta");
+    auto* output = ctx.Output<Tensor>("Output");
+    const T* theta_data = theta->data<T>();
+
+    int n = theta->dims()[0];
+    auto size_attr = ctx.Attr<std::vector<int>>("output_shape");
+    Tensor h_sizes;
+    int* h_size_data;
+    if (size_attr.size() == 0) {
+      auto* output_shape = ctx.Input<Tensor>("OutputShape");
+      framework::TensorCopy(*output_shape, platform::CPUPlace(), &h_sizes);
+      h_size_data = h_sizes.data<int>();
+    } else {
+      h_size_data = h_sizes.mutable_data<int>({4}, platform::CPUPlace());
+      h_size_data[0] = n;
+      h_size_data[1] = size_attr[1];
+      h_size_data[2] = size_attr[2];
+      h_size_data[3] = size_attr[3];
+    }
+
+    T* output_data = output->mutable_data<T>(
+        {n, h_size_data[2], h_size_data[3], 2}, ctx.GetPlace());
+    ScopedSpatialTransformerDescriptor st_desc;
+    cudnnSpatialTransformerDescriptor_t cudnn_st_desc =
+        st_desc.descriptor<T>(4, h_size_data);
+
+    PADDLE_ENFORCE(platform::dynload::cudnnSpatialTfGridGeneratorForward(
+        handle, cudnn_st_desc, theta_data, output_data));
+  }
+};
+
+template <typename T>
+class CUDNNAffineGridGradOpKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    PADDLE_ENFORCE(platform::is_gpu_place(ctx.GetPlace()),
+                   "It must use CUDAPlace.");
+    auto& dev_ctx = ctx.template device_context<platform::CUDADeviceContext>();
+    auto handle = dev_ctx.cudnn_handle();
+    auto output_grad = ctx.Input<Tensor>(framework::GradVarName("Output"));
+    auto theta_grad = ctx.Output<Tensor>(framework::GradVarName("Theta"));
+
+    int n = output_grad->dims()[0];
+    auto size_attr = ctx.Attr<std::vector<int>>("output_shape");
+    Tensor h_sizes;
+    int* h_size_data;
+    if (size_attr.size() == 0) {
+      auto* output_shape = ctx.Input<Tensor>("OutputShape");
+      framework::TensorCopy(*output_shape, platform::CPUPlace(), &h_sizes);
+      h_size_data = h_sizes.data<int>();
+    } else {
+      h_size_data = h_sizes.mutable_data<int>({4}, platform::CPUPlace());
+      h_size_data[0] = n;
+      h_size_data[1] = size_attr[1];
+      h_size_data[2] = size_attr[2];
+      h_size_data[3] = size_attr[3];
+    }
+
+    ScopedSpatialTransformerDescriptor st_desc;
+    cudnnSpatialTransformerDescriptor_t cudnn_st_desc =
+        st_desc.descriptor<T>(4, h_size_data);
+
+    const T* output_grad_data = output_grad->data<T>();
+    T* theta_grad_data = theta_grad->mutable_data<T>(ctx.GetPlace());
+
+    PADDLE_ENFORCE(platform::dynload::cudnnSpatialTfGridGeneratorBackward(
+        handle, cudnn_st_desc, output_grad_data, theta_grad_data));
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace plat = paddle::platform;
+REGISTER_OP_KERNEL(affine_grid, CUDNN, plat::CUDAPlace,
+                   paddle::operators::CUDNNAffineGridOpKernel<float>,
+                   paddle::operators::CUDNNAffineGridOpKernel<double>);
+REGISTER_OP_KERNEL(affine_grid_grad, CUDNN, plat::CUDAPlace,
+                   paddle::operators::CUDNNAffineGridGradOpKernel<float>,
+                   paddle::operators::CUDNNAffineGridGradOpKernel<double>);

paddle/fluid/operators/affine_grid_op.cc

+/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#include "paddle/fluid/operators/affine_grid_op.h"
+#include <string>
+#include "paddle/fluid/framework/op_registry.h"
+#ifdef PADDLE_WITH_CUDA
+#include "paddle/fluid/platform/cudnn_helper.h"
+#endif
+
+namespace paddle {
+namespace operators {
+
+using Tensor = framework::Tensor;
+
+template <typename T>
+struct Linspace<paddle::platform::CPUDeviceContext, T> {
+  framework::Tensor operator()(T start, T end, int count,
+                               const framework::ExecutionContext& ctx) {
+    Tensor numbers;
+    T* number_data = numbers.mutable_data<T>({count}, platform::CPUPlace());
+    T slice = (end - start) / (T)(count - 1);
+    for (int i = 0; i < count; ++i) {
+      number_data[i] = start + (T)i * slice;
+    }
+    return numbers;
+  }
+};
+
+class AffineGridOp : public framework::OperatorWithKernel {
+ public:
+  using framework::OperatorWithKernel::OperatorWithKernel;
+  void InferShape(framework::InferShapeContext* ctx) const override {
+    PADDLE_ENFORCE(ctx->HasInput("Theta"),
+                   "Input(Theta) of AffineGridOp should not be null.");
+    PADDLE_ENFORCE(ctx->HasOutput("Output"),
+                   "Output(Output) of AffineGridOp should not be null.");
+    auto theta_dims = ctx->GetInputDim("Theta");
+    PADDLE_ENFORCE(theta_dims.size() == 3,
+                   "AffineGrid's Input(Theta) should be 3-D tensor.");
+
+    auto output_shape = ctx->Attrs().Get<std::vector<int>>("output_shape");
+    if (output_shape.size() == 0) {
+      PADDLE_ENFORCE(ctx->HasInput("OutputShape"),
+                     "Input(OutputShape) of AffineGridOp should not be null if "
+                     "attr(output_shape) is not configured.");
+      auto output_shape_dims = ctx->GetInputDim("OutputShape");
+      PADDLE_ENFORCE(output_shape_dims.size() == 1,
+                     "AffineGrid's Input(OutputShape) should be 1-D tensor.");
+    } else {
+      PADDLE_ENFORCE(output_shape.size() == 4,
+                     "The size of attr(output_shape) should be 4.");
+    }
+
+    PADDLE_ENFORCE(theta_dims[1] == 2, "Input(theta) dims[1] should be 2.");
+    PADDLE_ENFORCE(theta_dims[2] == 3, "Input(theta) dims[2] should be 3.");
+    // N * H * W * 2
+    ctx->SetOutputDim("Output",
+                      framework::make_ddim({theta_dims[0], -1, -1, 2}));
+    ctx->ShareLoD("Theta", "Output");
+  }
+
+ protected:
+  framework::OpKernelType GetExpectedKernelType(
+      const framework::ExecutionContext& ctx) const override {
+    framework::LibraryType library{framework::LibraryType::kPlain};
+#ifdef PADDLE_WITH_CUDA
+    if (platform::CanCUDNNBeUsed(ctx)) {
+      library = framework::LibraryType::kCUDNN;
+    }
+#endif
+    auto data_type = framework::ToDataType(ctx.Input<Tensor>("Theta")->type());
+    return framework::OpKernelType(data_type, ctx.GetPlace(),
+                                   framework::DataLayout::kAnyLayout, library);
+  }
+};
+
+class AffineGridOpMaker : public framework::OpProtoAndCheckerMaker {
+ public:
+  void Make() override {
+    AddInput(
+        "Theta",
+        "(Tensor) A batch of affine transform parameters with shape [N, 2, 3]. "
+        "It is used to transform coordinate (x_0, y_0) to coordinate (x_1, "
+        "y_1).");
+    AddInput("OutputShape",
+             "(Tensor) The shape of target image with format [N, C, H, W].")
+        .AsDispensable();
+    AddOutput("Output", "(Tensor) Output Tensor with shape [N, H, W, 2].");
+    AddAttr<bool>(
+        "use_cudnn",
+        "(bool, default false) Only used in cudnn kernel, need install cudnn")
+        .SetDefault(true);
+    AddAttr<std::vector<int>>(
+        "output_shape",
+        "The target output image shape with format [N, C, H, W].")
+        .SetDefault(std::vector<int>());
+
+    AddComment(R"DOC(
+    It generates a grid of (x,y) coordinates using the parameters of the
+    affine transformation that correspond to a set of points where the input
+    feature map should be sampled to produce the transformed output feature map.
+
+    Given:
+        Theta = [[[x_11, x_12, x_13]
+                  [x_14, x_15, x_16]]
+                 [[x_21, x_22, x_23]
+                  [x_24, x_25, x_26]]]
+    
+        OutputShape = [2, 3, 5, 5]
+
+    Step 1:
+
+        Generate relative coordinates according to OutputShape.
+        The values of relative coordinates are in the interval between -1 and 1.
+        The shape of the relative coordinates is [2, H, W] as below:
+    
+        C = [[[-1.  -1.  -1.  -1.  -1. ]
+              [-0.5 -0.5 -0.5 -0.5 -0.5]
+              [ 0.   0.   0.   0.   0. ]
+              [ 0.5  0.5  0.5  0.5  0.5]
+              [ 1.   1.   1.   1.   1. ]] 
+             [[-1.  -0.5  0.   0.5  1. ]
+              [-1.  -0.5  0.   0.5  1. ]
+              [-1.  -0.5  0.   0.5  1. ]
+              [-1.  -0.5  0.   0.5  1. ]
+              [-1.  -0.5  0.   0.5  1. ]]]
+        C[0] is the coordinates in height axis and  C[1] is the coordinates in width axis.
+    
+    Step2:
+        Tanspose and reshape C to shape [H * W, 2] and append ones to last dimension. The we get:
+        C_ = [[-1.  -1.   1. ]
+              [-0.5 -1.   1. ]
+              [ 0.  -1.   1. ]
+              [ 0.5 -1.   1. ]
+              [ 1.  -1.   1. ]
+              [-1.  -0.5  1. ]
+              [-0.5 -0.5  1. ]
+              [ 0.  -0.5  1. ]
+              [ 0.5 -0.5  1. ]
+              [ 1.  -0.5  1. ]
+              [-1.   0.   1. ]
+              [-0.5  0.   1. ]
+              [ 0.   0.   1. ]
+              [ 0.5  0.   1. ]
+              [ 1.   0.   1. ]
+              [-1.   0.5  1. ]
+              [-0.5  0.5  1. ]
+              [ 0.   0.5  1. ]
+              [ 0.5  0.5  1. ]
+              [ 1.   0.5  1. ]
+              [-1.   1.   1. ]
+              [-0.5  1.   1. ]
+              [ 0.   1.   1. ]
+              [ 0.5  1.   1. ]
+              [ 1.   1.   1. ]]
+    Step3:
+        Compute output by equation $$Output[i] = C_ * Theta[i]^T$$
+    )DOC");
+  }
+};
+
+class AffineGridOpGrad : public framework::OperatorWithKernel {
+ public:
+  using framework::OperatorWithKernel::OperatorWithKernel;
+  void InferShape(framework::InferShapeContext* ctx) const override {
+    auto theta_dims = ctx->GetInputDim("Theta");
+    if (ctx->HasOutput(framework::GradVarName("Theta"))) {
+      ctx->SetOutputDim(framework::GradVarName("Theta"), theta_dims);
+    }
+  }
+
+ protected:
+  framework::OpKernelType GetExpectedKernelType(
+      const framework::ExecutionContext& ctx) const override {
+    framework::LibraryType library_{framework::LibraryType::kPlain};
+#ifdef PADDLE_WITH_CUDA
+    if (platform::CanCUDNNBeUsed(ctx)) {
+      library_ = framework::LibraryType::kCUDNN;
+    }
+#endif
+    return framework::OpKernelType(
+        framework::ToDataType(ctx.Input<Tensor>("Theta")->type()),
+        ctx.GetPlace(), framework::DataLayout::kAnyLayout, library_);
+  }
+};
+
+class AffineGridGradMaker : public framework::SingleGradOpDescMaker {
+ public:
+  using framework::SingleGradOpDescMaker::SingleGradOpDescMaker;
+
+ protected:
+  std::unique_ptr<framework::OpDesc> Apply() const override {
+    auto* op = new framework::OpDesc();
+    op->SetType("affine_grid_grad");
+    op->SetInput("Theta", Input("Theta"));
+    op->SetInput("OutputShape", Input("OutputShape"));
+    op->SetInput(framework::GradVarName("Output"), OutputGrad("Output"));
+
+    op->SetAttrMap(Attrs());
+
+    op->SetOutput(framework::GradVarName("Theta"), InputGrad("Theta"));
+    return std::unique_ptr<framework::OpDesc>(op);
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+REGISTER_OPERATOR(affine_grid, ops::AffineGridOp, ops::AffineGridOpMaker,
+                  ops::AffineGridGradMaker);
+REGISTER_OPERATOR(affine_grid_grad, ops::AffineGridOpGrad);
+
+REGISTER_OP_CPU_KERNEL(
+    affine_grid,
+    ops::AffineGridOpKernel<paddle::platform::CPUDeviceContext, float>,
+    ops::AffineGridOpKernel<paddle::platform::CPUDeviceContext, double>);
+REGISTER_OP_CPU_KERNEL(
+    affine_grid_grad,
+    ops::AffineGridGradOpKernel<paddle::platform::CPUDeviceContext, float>,
+    ops::AffineGridGradOpKernel<paddle::platform::CPUDeviceContext, double>);

paddle/fluid/operators/affine_grid_op.h

+/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#pragma once
+#include <vector>
+#include "paddle/fluid/framework/eigen.h"
+#include "paddle/fluid/framework/op_registry.h"
+#include "paddle/fluid/operators/math/blas.h"
+#include "paddle/fluid/operators/math/math_function.h"
+
+namespace paddle {
+namespace operators {
+
+using Tensor = framework::Tensor;
+template <typename T, size_t D, int MajorType = Eigen::RowMajor,
+          typename IndexType = Eigen::DenseIndex>
+using EigenTensor = framework::EigenTensor<T, D, MajorType, IndexType>;
+
+using Array1 = Eigen::DSizes<int64_t, 1>;
+using Array2 = Eigen::DSizes<int64_t, 2>;
+using Array3 = Eigen::DSizes<int64_t, 3>;
+using Array4 = Eigen::DSizes<int64_t, 4>;
+
+/**
+ *Return a tensor with evenly spaced numbers over a specified interval.
+ */
+template <typename DeviceContext, typename T>
+struct Linspace {
+  framework::Tensor operator()(T start, T end, int count,
+                               const framework::ExecutionContext& ctx);
+};
+
+template <typename DeviceContext, typename T>
+class AffineGridOpKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto& place = *ctx.template device_context<DeviceContext>().eigen_device();
+    auto* theta = ctx.Input<Tensor>("Theta");
+    int n = theta->dims()[0];
+
+    auto size_attr = ctx.Attr<std::vector<int>>("output_shape");
+    int h = 0;
+    int w = 0;
+    if (size_attr.size() == 0) {
+      auto* output_shape = ctx.Input<Tensor>("OutputShape");
+      Tensor h_sizes;
+      framework::TensorCopy(*output_shape, platform::CPUPlace(), &h_sizes);
+      const int* h_size_data = h_sizes.data<int>();
+      h = h_size_data[2];
+      w = h_size_data[3];
+    } else {
+      h = size_attr[2];
+      w = size_attr[3];
+    }
+
+    auto* output = ctx.Output<Tensor>("Output");
+    output->mutable_data<T>({n, h, w, 2}, ctx.GetPlace());
+
+    math::SetConstant<DeviceContext, T>()(
+        ctx.template device_context<DeviceContext>(), output,
+        static_cast<T>(0));
+
+    Linspace<DeviceContext, T> linspace;
+    // Get indexes of height with shape [height, width, 1]
+    auto h_idx = linspace((T)-1, (T)1, h, ctx);
+    auto h_idx_t = EigenTensor<T, 1>::From(h_idx);
+    // Get indexes of width with shape [height, width, 1]
+    auto w_idx = linspace((T)-1, (T)1, w, ctx);
+    auto w_idx_t = EigenTensor<T, 1>::From(w_idx);
+    // Get constant ones tensor with shape [height, width, 1]
+    Tensor ones;
+    ones.mutable_data<T>({h, w, 1}, ctx.GetPlace());
+    auto ones_t = EigenTensor<T, 3>::From(ones).setConstant((T)1);
+    // Get grid tensor with shape [n, h, w, 3] by concatenating h_idx, w_idx and
+    // ones
+    Tensor grid;
+    grid.mutable_data<T>({n, h, w, 3}, ctx.GetPlace());
+    auto grid_t = EigenTensor<T, 4>::From(grid);
+
+    grid_t.device(place) = w_idx_t.reshape(Array2(1, w))
+                               .broadcast(Array2(h, 1))
+                               .reshape(Array3(h, w, 1))
+                               .concatenate(h_idx_t.reshape(Array2(1, h))
+                                                .broadcast(Array2(w, 1))
+                                                .shuffle(Array2(1, 0))
+                                                .reshape(Array3(h, w, 1)),
+                                            2)
+                               .eval()
+                               .concatenate(ones_t, 2)
+                               .reshape(Array4(1, h, w, 3))
+                               .broadcast(Array4(n, 1, 1, 1));
+
+    // output = grid * theta.T
+    // TODO(wanghaoshuang): Refine batched matrix multiply
+    auto blas = math::GetBlas<DeviceContext, T>(ctx);
+    for (int i = 0; i < n; ++i) {
+      Tensor sliced_grid = grid.Slice(i, i + 1).Resize({h * w, 3});
+      Tensor sliced_theta = theta->Slice(i, i + 1).Resize({2, 3});
+      Tensor sliced_out = output->Slice(i, i + 1).Resize({h * w, 2});
+      blas.MatMul(sliced_grid, false, sliced_theta, true, T(1), &sliced_out,
+                  T(0));
+    }
+  }
+};
+
+template <typename DeviceContext, typename T>
+class AffineGridGradOpKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto& place = *ctx.template device_context<DeviceContext>().eigen_device();
+    auto output_grad = ctx.Input<Tensor>(framework::GradVarName("Output"));
+    auto theta_grad = ctx.Output<Tensor>(framework::GradVarName("Theta"));
+
+    int n = output_grad->dims()[0];
+    auto size_attr = ctx.Attr<std::vector<int>>("output_shape");
+    int h = 0;
+    int w = 0;
+    if (size_attr.size() == 0) {
+      auto* output_shape = ctx.Input<Tensor>("OutputShape");
+      Tensor h_sizes;
+      framework::TensorCopy(*output_shape, platform::CPUPlace(), &h_sizes);
+      const int* h_size_data = h_sizes.data<int>();
+      h = h_size_data[2];
+      w = h_size_data[3];
+    } else {
+      h = size_attr[2];
+      w = size_attr[3];
+    }
+
+    theta_grad->mutable_data<T>({n, 2, 3}, ctx.GetPlace());
+
+    math::SetConstant<DeviceContext, T>()(
+        ctx.template device_context<DeviceContext>(), theta_grad,
+        static_cast<T>(0));
+
+    Linspace<DeviceContext, T> linspace;
+
+    // Get indexes of height with shape [height, width, 1]
+    auto h_idx = linspace((T)-1, (T)1, h, ctx);
+    auto h_idx_t = EigenTensor<T, 1>::From(h_idx);
+    // Get indexes of width with shape [height, width, 1]
+    auto w_idx = linspace((T)-1, (T)1, w, ctx);
+    auto w_idx_t = EigenTensor<T, 1>::From(w_idx);
+    // Get constant ones tensor with shape [height, width, 1]
+    Tensor ones;
+    ones.mutable_data<T>({h, w, 1}, ctx.GetPlace());
+    auto ones_t = EigenTensor<T, 3>::From(ones).setConstant((T)1);
+    // Get grid tensor with shape [n, h, w, 3] by concatenating h_idx, w_idx and
+    // ones
+    Tensor grid;
+    grid.mutable_data<T>({n, h, w, 3}, ctx.GetPlace());
+    auto grid_t = EigenTensor<T, 4>::From(grid);
+    grid_t.device(place) = w_idx_t.reshape(Array2(1, w))
+                               .broadcast(Array2(h, 1))
+                               .reshape(Array3(h, w, 1))
+                               .concatenate(h_idx_t.reshape(Array2(1, h))
+                                                .broadcast(Array2(w, 1))
+                                                .shuffle(Array2(1, 0))
+                                                .reshape(Array3(h, w, 1)),
+                                            2)
+                               .eval()
+                               .concatenate(ones_t, 2)
+                               .reshape(Array4(1, h, w, 3))
+                               .broadcast(Array4(n, 1, 1, 1));
+    // output = grid * theta.T
+    // TODO(wanghaoshuang): Refine batched matrix multiply
+    auto blas = math::GetBlas<DeviceContext, T>(ctx);
+    for (int i = 0; i < n; ++i) {
+      Tensor sliced_grid = grid.Slice(i, i + 1).Resize({h * w, 3});
+      Tensor sliced_out_grad = output_grad->Slice(i, i + 1).Resize({h * w, 2});
+      Tensor sliced_theta_grad = theta_grad->Slice(i, i + 1).Resize({2, 3});
+      blas.MatMul(sliced_out_grad, true, sliced_grid, false, T(1),
+                  &sliced_theta_grad, T(0));
+    }
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle

paddle/fluid/platform/cudnn_helper.h

@@ -341,6 +341,28 @@ class ScopedPoolingDescriptor {
   DISABLE_COPY_AND_ASSIGN(ScopedPoolingDescriptor);
 };
 
+class ScopedSpatialTransformerDescriptor {
+ public:
+  ScopedSpatialTransformerDescriptor() {
+    PADDLE_ENFORCE(dynload::cudnnCreateSpatialTransformerDescriptor(&desc_));
+  }
+  ~ScopedSpatialTransformerDescriptor() {
+    PADDLE_ENFORCE(dynload::cudnnDestroySpatialTransformerDescriptor(desc_));
+  }
+
+  template <typename T>
+  inline cudnnSpatialTransformerDescriptor_t descriptor(const int nbDims,
+                                                        const int dimA[]) {
+    PADDLE_ENFORCE(dynload::cudnnSetSpatialTransformerNdDescriptor(
+        desc_, CUDNN_SAMPLER_BILINEAR, CudnnDataType<T>::type, nbDims, dimA));
+    return desc_;
+  }
+
+ private:
+  cudnnSpatialTransformerDescriptor_t desc_;
+  DISABLE_COPY_AND_ASSIGN(ScopedSpatialTransformerDescriptor);
+};
+
 inline bool CanCUDNNBeUsed(const framework::ExecutionContext& ctx) {
   bool use_cudnn = ctx.Attr<bool>("use_cudnn");
   use_cudnn &= paddle::platform::is_gpu_place(ctx.GetPlace());

paddle/fluid/platform/dynload/cudnn.h

@@ -90,6 +90,13 @@ extern void EnforceCUDNNLoaded(const char* fn_name);
   __macro(cudnnSetConvolutionNdDescriptor);          \
   __macro(cudnnGetConvolutionNdDescriptor);          \
   __macro(cudnnDeriveBNTensorDescriptor);            \
+  __macro(cudnnCreateSpatialTransformerDescriptor);  \
+  __macro(cudnnSetSpatialTransformerNdDescriptor);   \
+  __macro(cudnnDestroySpatialTransformerDescriptor); \
+  __macro(cudnnSpatialTfGridGeneratorForward);       \
+  __macro(cudnnSpatialTfGridGeneratorBackward);      \
+  __macro(cudnnSpatialTfSamplerForward);             \
+  __macro(cudnnSpatialTfSamplerBackward);            \
   __macro(cudnnCreate);                              \
   __macro(cudnnDestroy);                             \
   __macro(cudnnSetStream);                           \

python/paddle/fluid/layers/nn.py

@@ -154,6 +154,7 @@ __all__ = [
     'mul',
     'sigmoid_cross_entropy_with_logits',
     'maxout',
+    'affine_grid',
     'sequence_reverse',
     'affine_channel',
     'hash',
@@ -6140,6 +6141,124 @@ def crop(x, shape=None, offsets=None, name=None):
     return out
 
 
+def affine_grid(theta, out_shape, name=None):
+    """
+    It generates a grid of (x,y) coordinates using the parameters of
+    the affine transformation that correspond to a set of points where
+    the input feature map should be sampled to produce the transformed
+    output feature map.
+
+    .. code-block:: text
+
+        * Case 1:
+
+          Given:
+
+              theta = [[[x_11, x_12, x_13]
+                        [x_14, x_15, x_16]]
+                       [[x_21, x_22, x_23]
+                        [x_24, x_25, x_26]]]
+      
+              out_shape = [2, 3, 5, 5]
+      
+          Step 1:
+      
+              Generate normalized coordinates according to out_shape.
+              The values of the normalized coordinates are in the interval between -1 and 1.
+              The shape of the normalized coordinates is [2, H, W] as below:
+      
+              C = [[[-1.  -1.  -1.  -1.  -1. ]
+                    [-0.5 -0.5 -0.5 -0.5 -0.5]
+                    [ 0.   0.   0.   0.   0. ]
+                    [ 0.5  0.5  0.5  0.5  0.5]
+                    [ 1.   1.   1.   1.   1. ]]
+                   [[-1.  -0.5  0.   0.5  1. ]
+                    [-1.  -0.5  0.   0.5  1. ]
+                    [-1.  -0.5  0.   0.5  1. ]
+                    [-1.  -0.5  0.   0.5  1. ]
+                    [-1.  -0.5  0.   0.5  1. ]]]
+              C[0] is the coordinates in height axis and  C[1] is the coordinates in width axis.
+
+          Step2:
+
+              Tanspose and reshape C to shape [H * W, 2] and append ones to last dimension. The we get:
+              C_ = [[-1.  -1.   1. ]
+                    [-0.5 -1.   1. ]
+                    [ 0.  -1.   1. ]
+                    [ 0.5 -1.   1. ]
+                    [ 1.  -1.   1. ]
+                    [-1.  -0.5  1. ]
+                    [-0.5 -0.5  1. ]
+                    [ 0.  -0.5  1. ]
+                    [ 0.5 -0.5  1. ]
+                    [ 1.  -0.5  1. ]
+                    [-1.   0.   1. ]
+                    [-0.5  0.   1. ]
+                    [ 0.   0.   1. ]
+                    [ 0.5  0.   1. ]
+                    [ 1.   0.   1. ]
+                    [-1.   0.5  1. ]
+                    [-0.5  0.5  1. ]
+                    [ 0.   0.5  1. ]
+                    [ 0.5  0.5  1. ]
+                    [ 1.   0.5  1. ]
+                    [-1.   1.   1. ]
+                    [-0.5  1.   1. ]
+                    [ 0.   1.   1. ]
+                    [ 0.5  1.   1. ]
+                    [ 1.   1.   1. ]]
+          Step3:
+              Compute output by equation $$Output[i] = C_ * Theta[i]^T$$
+
+    Args:
+        theta (Variable): A batch of affine transform parameters with shape [N, 2, 3].
+        out_shape (Variable | list | tuple): The shape of target output with format [N, C, H, W].
+        out_shape can be a Variable or a list or tuple.
+        name(str|None): A name for this layer(optional). If set None, the layer
+                        will be named automatically.
+
+    Returns:
+        Variable: The output with shape [N, H, W, 2].
+
+    Raises:
+        ValueError: If the type of arguments is not supported.
+
+    Examples:
+
+        .. code-block:: python
+            theta = fluid.layers.data(name="x", shape=[2, 3], dtype="float32")
+            out_shape = fluid.layers.data(name="y", shape=[-1], dtype="float32")
+            data = fluid.layers.affine_grid(theta, out_shape)
+
+            # or
+            data = fluid.layers.affine_grid(theta, [5, 3, 28, 28])
+
+    """
+    helper = LayerHelper('affine_grid')
+
+    if not (isinstance(out_shape, list) or isinstance(out_shape, tuple) or \
+        isinstance(out_shape, Variable)):
+        raise ValueError("The out_shape should be a list, tuple or Variable.")
+
+    if not isinstance(theta, Variable):
+        raise ValueError("The theta should be a Variable.")
+
+    out = helper.create_variable_for_type_inference(theta.dtype)
+    ipts = {'Theta': theta}
+    attrs = {}
+    if isinstance(out_shape, Variable):
+        ipts['OutputShape'] = out_shape
+    else:
+        attrs['output_shape'] = out_shape
+
+    helper.append_op(
+        type='affine_grid',
+        inputs=ipts,
+        outputs={'Output': out},
+        attrs=None if len(attrs) == 0 else attrs)
+    return out
+
+
 def rank_loss(label, left, right, name=None):
     """
     **Rank loss layer for RankNet**

python/paddle/fluid/tests/unittests/test_affine_grid_op.py

+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+import numpy as np
+from op_test import OpTest
+
+
+def AffineGrid(theta, size):
+    n = size[0]
+    w = size[3]
+    h = size[2]
+    h_idx = np.repeat(
+        np.linspace(-1, 1, h)[np.newaxis, :], w, axis=0).T[:, :, np.newaxis]
+    w_idx = np.repeat(
+        np.linspace(-1, 1, w)[np.newaxis, :], h, axis=0)[:, :, np.newaxis]
+    grid = np.concatenate(
+        [w_idx, h_idx, np.ones([h, w, 1])], axis=2)  # h * w * 3
+    grid = np.repeat(grid[np.newaxis, :], size[0], axis=0)  # n * h * w *3
+
+    ret = np.zeros([n, h * w, 2])
+    theta = theta.transpose([0, 2, 1])
+    for i in range(len(theta)):
+        ret[i] = np.dot(grid[i].reshape([h * w, 3]), theta[i])
+
+#    print ret.reshape([h * w, 2]).astype("float32")    
+    return ret.reshape([n, h, w, 2]).astype("float32")
+
+
+class TestAffineGridOp(OpTest):
+    def setUp(self):
+        self.initTestCase()
+        self.op_type = "affine_grid"
+        theta = np.random.randint(1, 3, self.theta_shape).astype("float32")
+        theta = np.ones(self.theta_shape).astype("float32")
+        self.inputs = {'Theta': theta}
+        self.attrs = {"use_cudnn": True}
+        if self.dynamic_shape:
+            self.inputs['OutputShape'] = self.output_shape
+        else:
+            self.attrs['output_shape'] = self.output_shape
+        self.outputs = {'Output': AffineGrid(theta, self.output_shape)}
+
+    def test_check_output(self):
+        self.check_output()
+
+    def test_check_grad_normal(self):
+        self.check_grad(
+            ['Theta'],
+            'Output',
+            no_grad_set=['OutputShape'],
+            max_relative_error=0.006)
+
+    def initTestCase(self):
+        self.theta_shape = (3, 2, 3)
+        self.output_shape = np.array([3, 2, 5, 7]).astype("int32")
+        self.dynamic_shape = False
+
+
+class TestAffineGridOpCase1(TestAffineGridOp):
+    def initTestCase(self):
+        self.theta_shape = (3, 2, 3)
+        self.output_shape = np.array([3, 2, 5, 7]).astype("int32")
+        self.dynamic_shape = True
+
+
+if __name__ == '__main__':
+    unittest.main()

python/paddle/fluid/tests/unittests/test_layers.py

@@ -865,6 +865,22 @@ class TestBook(unittest.TestCase):
             self.assertIsNotNone(out)
         print(str(program))
 
+    def test_affine_grid(self):
+        program = Program()
+        with program_guard(program):
+            data = layers.data(name='data', shape=[2, 3, 3], dtype="float32")
+            out, ids = layers.argsort(input=data, axis=1)
+
+            theta = layers.data(name="theta", shape=[2, 3], dtype="float32")
+            out_shape = layers.data(
+                name="out_shape", shape=[-1], dtype="float32")
+            data_0 = layers.affine_grid(theta, out_shape)
+            data_1 = layers.affine_grid(theta, [5, 3, 28, 28])
+
+            self.assertIsNotNone(data_0)
+            self.assertIsNotNone(data_1)
+        print(str(program))
+
 
 if __name__ == '__main__':
     unittest.main()