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AffineGridGenerator.cpp
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AffineGridGenerator.cpp
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#define TORCH_ASSERT_ONLY_METHOD_OPERATORS
#include <ATen/core/Tensor.h>
#include <ATen/TensorOperators.h>
#ifndef AT_PER_OPERATOR_HEADERS
#include <ATen/Functions.h>
#include <ATen/NativeFunctions.h>
#else
#include <ATen/ops/affine_grid_generator_backward_native.h>
#include <ATen/ops/affine_grid_generator_native.h>
#include <ATen/ops/empty.h>
#include <ATen/ops/linspace.h>
#include <ATen/ops/tensor.h>
#endif
namespace at { namespace native {
static at::Tensor linspace_from_neg_one(const Tensor& grid, int64_t num_steps,
bool align_corners) {
if (num_steps <= 1) {
return at::tensor(0, grid.options());
}
auto range = at::linspace(-1, 1, num_steps, grid.options());
if (!align_corners) {
range = range * (num_steps - 1) / num_steps;
}
return range;
}
static Tensor make_base_grid_4D(
const Tensor& theta,
int64_t N,
int64_t C,
int64_t H,
int64_t W,
bool align_corners) {
auto base_grid = at::empty({N, H, W, 3}, theta.options());
base_grid.select(-1, 0).copy_(linspace_from_neg_one(theta, W, align_corners));
base_grid.select(-1, 1).copy_(linspace_from_neg_one(theta, H, align_corners).unsqueeze_(-1));
base_grid.select(-1, 2).fill_(1);
return base_grid;
}
static Tensor make_base_grid_5D(
const Tensor& theta,
int64_t N,
int64_t C,
int64_t D,
int64_t H,
int64_t W,
bool align_corners) {
auto base_grid = at::empty({N, D, H, W, 4}, theta.options());
base_grid.select(-1, 0).copy_(linspace_from_neg_one(theta, W, align_corners));
base_grid.select(-1, 1).copy_(linspace_from_neg_one(theta, H, align_corners).unsqueeze_(-1));
base_grid.select(-1, 2).copy_(linspace_from_neg_one(theta, D, align_corners).unsqueeze_(-1).unsqueeze_(-1));
base_grid.select(-1, 3).fill_(1);
return base_grid;
}
static Tensor affine_grid_generator_4D(
const Tensor& theta,
int64_t N,
int64_t C,
int64_t H,
int64_t W,
bool align_corners) {
Tensor base_grid = make_base_grid_4D(theta, N, C, H, W, align_corners);
auto grid = base_grid.view({N, H * W, 3}).bmm(theta.transpose(1, 2));
return grid.view({N, H, W, 2});
}
static Tensor affine_grid_generator_5D(
const Tensor& theta,
int64_t N,
int64_t C,
int64_t D,
int64_t H,
int64_t W,
bool align_corners) {
Tensor base_grid = make_base_grid_5D(theta, N, C, D, H, W, align_corners);
auto grid = base_grid.view({N, D * H * W, 4}).bmm(theta.transpose(1, 2));
return grid.view({N, D, H, W, 3});
}
Tensor affine_grid_generator(const Tensor& theta, IntArrayRef size, bool align_corners) {
TORCH_CHECK(
size.size() == 4 || size.size() == 5,
"AffineGridGenerator needs 4d (spatial) or 5d (volumetric) inputs.");
if (size.size() == 4) {
return affine_grid_generator_4D(
theta, size[0], size[1], size[2], size[3], align_corners);
} else {
return affine_grid_generator_5D(
theta, size[0], size[1], size[2], size[3], size[4], align_corners);
}
}
static Tensor affine_grid_generator_4D_backward(
const Tensor& grad_grid,
int64_t N,
int64_t C,
int64_t H,
int64_t W,
bool align_corners) {
auto base_grid = make_base_grid_4D(grad_grid, N, C, H, W, align_corners);
AT_ASSERT(grad_grid.sizes() == IntArrayRef({N, H, W, 2}));
auto grad_theta = base_grid.view({N, H * W, 3})
.transpose(1, 2)
.bmm(grad_grid.view({N, H * W, 2}));
return grad_theta.transpose(1, 2);
}
static Tensor affine_grid_generator_5D_backward(
const Tensor& grad_grid,
int64_t N,
int64_t C,
int64_t D,
int64_t H,
int64_t W,
bool align_corners) {
auto base_grid = make_base_grid_5D(grad_grid, N, C, D, H, W, align_corners);
AT_ASSERT(grad_grid.sizes() == IntArrayRef({N, D, H, W, 3}));
auto grad_theta = base_grid.view({N, D * H * W, 4})
.transpose(1, 2)
.bmm(grad_grid.view({N, D * H * W, 3}));
return grad_theta.transpose(1, 2);
}
Tensor affine_grid_generator_backward(const Tensor& grad, IntArrayRef size, bool align_corners) {
TORCH_CHECK(
size.size() == 4 || size.size() == 5,
"AffineGridGenerator needs 4d (spatial) or 5d (volumetric) inputs.");
if (size.size() == 4) {
return affine_grid_generator_4D_backward(
grad, size[0], size[1], size[2], size[3], align_corners);
} else {
return affine_grid_generator_5D_backward(
grad, size[0], size[1], size[2], size[3], size[4], align_corners);
}
}
}} // namespace at::native