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#include "roi_align_op.h"
#include "caffe2/utils/eigen_utils.h"
#include "caffe2/utils/math.h"
namespace caffe2 {
namespace {
template <typename T>
struct PreCalc {
int pos1;
int pos2;
int pos3;
int pos4;
T w1;
T w2;
T w3;
T w4;
};
template <typename T>
void pre_calc_for_bilinear_interpolate(
const int height,
const int width,
const int pooled_height,
const int pooled_width,
const int iy_upper,
const int ix_upper,
T roi_start_h,
T roi_start_w,
T bin_size_h,
T bin_size_w,
int roi_bin_grid_h,
int roi_bin_grid_w,
std::vector<PreCalc<T>>& pre_calc) {
int pre_calc_index = 0;
for (int ph = 0; ph < pooled_height; ph++) {
for (int pw = 0; pw < pooled_width; pw++) {
for (int iy = 0; iy < iy_upper; iy++) {
const T yy = roi_start_h + ph * bin_size_h +
static_cast<T>(iy + .5f) * bin_size_h /
static_cast<T>(roi_bin_grid_h); // e.g., 0.5, 1.5
for (int ix = 0; ix < ix_upper; ix++) {
const T xx = roi_start_w + pw * bin_size_w +
static_cast<T>(ix + .5f) * bin_size_w /
static_cast<T>(roi_bin_grid_w);
T x = xx;
T y = yy;
// deal with: inverse elements are out of feature map boundary
if (y < -1.0 || y > height || x < -1.0 || x > width) {
// empty
PreCalc<T> pc;
pc.pos1 = 0;
pc.pos2 = 0;
pc.pos3 = 0;
pc.pos4 = 0;
pc.w1 = 0;
pc.w2 = 0;
pc.w3 = 0;
pc.w4 = 0;
pre_calc[pre_calc_index] = pc;
pre_calc_index += 1;
continue;
}
if (y <= 0) {
y = 0;
}
if (x <= 0) {
x = 0;
}
int y_low = (int)y;
int x_low = (int)x;
int y_high;
int x_high;
if (y_low >= height - 1) {
y_high = y_low = height - 1;
y = (T)y_low;
} else {
y_high = y_low + 1;
}
if (x_low >= width - 1) {
x_high = x_low = width - 1;
x = (T)x_low;
} else {
x_high = x_low + 1;
}
T ly = y - y_low;
T lx = x - x_low;
T hy = 1. - ly, hx = 1. - lx;
T w1 = hy * hx, w2 = hy * lx, w3 = ly * hx, w4 = ly * lx;
// save weights and indeces
PreCalc<T> pc;
pc.pos1 = y_low * width + x_low;
pc.pos2 = y_low * width + x_high;
pc.pos3 = y_high * width + x_low;
pc.pos4 = y_high * width + x_high;
pc.w1 = w1;
pc.w2 = w2;
pc.w3 = w3;
pc.w4 = w4;
pre_calc[pre_calc_index] = pc;
pre_calc_index += 1;
}
}
}
}
}
template <typename T>
void ROIAlignForward(
const int nthreads,
const T* bottom_data,
const T& spatial_scale,
const int channels,
const int height,
const int width,
const int pooled_height,
const int pooled_width,
const int sampling_ratio,
const T* bottom_rois,
int roi_cols,
T* top_data,
StorageOrder order) {
DCHECK(roi_cols == 4 || roi_cols == 5);
int n_rois = nthreads / channels / pooled_width / pooled_height;
#ifdef _OPENMP
#pragma omp parallel for
#endif
for (int n = 0; n < n_rois; n++) {
int index_n = n * channels * pooled_width * pooled_height;
// roi could have 4 or 5 columns
const T* offset_bottom_rois = bottom_rois + n * roi_cols;
int roi_batch_ind = 0;
if (roi_cols == 5) {
roi_batch_ind = offset_bottom_rois[0];
offset_bottom_rois++;
}
// Do not using rounding; this implementation detail is critical
T roi_start_w = offset_bottom_rois[0] * spatial_scale;
T roi_start_h = offset_bottom_rois[1] * spatial_scale;
T roi_end_w = offset_bottom_rois[2] * spatial_scale;
T roi_end_h = offset_bottom_rois[3] * spatial_scale;
// T roi_start_w = round(offset_bottom_rois[0] * spatial_scale);
// T roi_start_h = round(offset_bottom_rois[1] * spatial_scale);
// T roi_end_w = round(offset_bottom_rois[2] * spatial_scale);
// T roi_end_h = round(offset_bottom_rois[3] * spatial_scale);
// Force malformed ROIs to be 1x1
T roi_width = std::max(roi_end_w - roi_start_w, (T)1.);
T roi_height = std::max(roi_end_h - roi_start_h, (T)1.);
T bin_size_h = static_cast<T>(roi_height) / static_cast<T>(pooled_height);
T bin_size_w = static_cast<T>(roi_width) / static_cast<T>(pooled_width);
// We use roi_bin_grid to sample the grid and mimic integral
int roi_bin_grid_h = (sampling_ratio > 0)
? sampling_ratio
: ceil(roi_height / pooled_height); // e.g., = 2
int roi_bin_grid_w =
(sampling_ratio > 0) ? sampling_ratio : ceil(roi_width / pooled_width);
// We do average (integral) pooling inside a bin
const T count = roi_bin_grid_h * roi_bin_grid_w; // e.g. = 4
// we want to precalculate indeces and weights shared by all chanels,
// this is the key point of optimiation
std::vector<PreCalc<T>> pre_calc(
roi_bin_grid_h * roi_bin_grid_w * pooled_width * pooled_height);
pre_calc_for_bilinear_interpolate(
height,
width,
pooled_height,
pooled_width,
roi_bin_grid_h,
roi_bin_grid_w,
roi_start_h,
roi_start_w,
bin_size_h,
bin_size_w,
roi_bin_grid_h,
roi_bin_grid_w,
pre_calc);
if (order == StorageOrder::NCHW) {
for (int c = 0; c < channels; c++) {
int index_n_c = index_n + c * pooled_width * pooled_height;
const T* offset_bottom_data =
bottom_data + (roi_batch_ind * channels + c) * height * width;
int pre_calc_index = 0;
for (int ph = 0; ph < pooled_height; ph++) {
for (int pw = 0; pw < pooled_width; pw++) {
int index = index_n_c + ph * pooled_width + pw;
T output_val = 0.;
for (int iy = 0; iy < roi_bin_grid_h; iy++) {
for (int ix = 0; ix < roi_bin_grid_w; ix++) {
PreCalc<T> pc = pre_calc[pre_calc_index];
output_val += pc.w1 * offset_bottom_data[pc.pos1] +
pc.w2 * offset_bottom_data[pc.pos2] +
pc.w3 * offset_bottom_data[pc.pos3] +
pc.w4 * offset_bottom_data[pc.pos4];
pre_calc_index += 1;
}
}
output_val /= count;
top_data[index] = output_val;
} // for pw
} // for ph
} // for c
} // if nchw
if (order == StorageOrder::NHWC) {
const T* offset_bottom_data =
bottom_data + roi_batch_ind * channels * height * width;
int pre_calc_index = 0;
for (int ph = 0; ph < pooled_height; ph++) {
for (int pw = 0; pw < pooled_width; pw++) {
EVecXf output_vals = EVecXf::Zero(channels);
for (int iy = 0; iy < roi_bin_grid_h; iy++) {
for (int ix = 0; ix < roi_bin_grid_w; ix++) {
PreCalc<T> pc = pre_calc[pre_calc_index];
ConstEigenVectorMap<T> data_1(
offset_bottom_data + channels * pc.pos1, channels);
ConstEigenVectorMap<T> data_2(
offset_bottom_data + channels * pc.pos2, channels);
ConstEigenVectorMap<T> data_3(
offset_bottom_data + channels * pc.pos3, channels);
ConstEigenVectorMap<T> data_4(
offset_bottom_data + channels * pc.pos4, channels);
output_vals += pc.w1 * data_1 + pc.w2 * data_2 + pc.w3 * data_3 +
pc.w4 * data_4;
pre_calc_index += 1;
}
}
output_vals /= count;
int index_nhw = index_n + (ph * pooled_width + pw) * channels;
std::memcpy(
top_data + index_nhw, output_vals.data(), channels * sizeof(T));
} // for pw
} // for ph
} // if nhwc
} // for n
}
} // namespace
template <>
bool RoIAlignOp<float, CPUContext>::RunOnDevice() {
auto& X = Input(0); // Input data to pool, NCHW
auto& R = Input(1); // RoIs
if (R.numel() == 0) {
std::vector<int64_t> sizes;
// Handle empty rois
if (order_ == StorageOrder::NCHW) {
sizes = {0, X.dim32(1), pooled_height_, pooled_width_};
} else if (order_ == StorageOrder::NHWC) {
sizes = {0, pooled_height_, pooled_width_, X.dim32(3)};
}
// Output Tensor is inititalized with proper sizes and data type
Output(0, sizes, at::dtype<float>());
return true;
}
CAFFE_ENFORCE_EQ(R.dim(), 2);
// if R has 5 columns, the first column is the index, otherwise 0
CAFFE_ENFORCE(R.dim32(1) == 4 || R.dim32(1) == 5);
assert(sampling_ratio_ >= 0);
if (order_ == StorageOrder::NCHW) {
auto* Y = Output(
0,
{R.dim32(0), X.dim32(1), pooled_height_, pooled_width_},
at::dtype<float>()); // RoI pooled data
int output_size = Y->numel();
ROIAlignForward<float>(
output_size,
X.data<float>(),
spatial_scale_,
X.dim32(1),
X.dim32(2),
X.dim32(3),
pooled_height_,
pooled_width_,
sampling_ratio_,
R.data<float>(),
R.dim32(1),
Y->template mutable_data<float>(),
order_);
} else if (order_ == StorageOrder::NHWC) {
auto* Y = Output(
0,
{R.dim32(0), pooled_height_, pooled_width_, X.dim32(3)},
at::dtype<float>()); // RoI pooled data
int output_size = Y->numel();
ROIAlignForward<float>(
output_size,
X.data<float>(),
spatial_scale_,
X.dim32(3),
X.dim32(1),
X.dim32(2),
pooled_height_,
pooled_width_,
sampling_ratio_,
R.data<float>(),
R.dim32(1),
Y->template mutable_data<float>(),
order_);
}
return true;
}
REGISTER_CPU_OPERATOR(RoIAlign, RoIAlignOp<float, CPUContext>);
// Input: X, rois; Output: Y
OPERATOR_SCHEMA(RoIAlign)
.NumInputs(2)
.NumOutputs(1)
.SetDoc(R"DOC(
Region of Interest (RoI) align operation as used in Mask R-CNN.
)DOC")
.Arg(
"spatial_scale",
"(float) default 1.0; Spatial scale of the input feature map X "
"relative to the input image. E.g., 0.0625 if X has a stride of 16 "
"w.r.t. the input image.")
.Arg("pooled_h", "(int) default 1; Pooled output Y's height.")
.Arg("pooled_w", "(int) default 1; Pooled output Y's width.")
.Arg(
"sampling_ratio",
"(int) default -1; number of sampling points in the interpolation grid "
"used to compute the output value of each pooled output bin. If > 0, "
"then exactly sampling_ratio x sampling_ratio grid points are used. If "
"<= 0, then an adaptive number of grid points are used (computed as "
"ceil(roi_width / pooled_w), and likewise for height).")
.Input(0, "X", "4D feature map input of shape (N, C, H, W).")
.Input(
1,
"RoIs",
"2D input of shape (R, 4 or 5) specifying R RoIs "
"representing: batch index in [0, N - 1], x1, y1, x2, y2. The RoI "
"coordinates are in the coordinate system of the input image. For "
"inputs corresponding to a single image, batch index can be excluded "
"to have just 4 columns.")
.Output(
0,
"Y",
"4D output of shape (R, C, pooled_h, pooled_w). The r-th batch element "
"is a pooled feature map cooresponding to the r-th RoI.");
} // namespace caffe2