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2026-07-13 12:40:42 +08:00

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// Copyright (c) 2022 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/phi/kernels/matrix_nms_kernel.h"
#include "paddle/common/ddim.h"
#include "paddle/phi/backends/cpu/cpu_context.h"
#include "paddle/phi/core/dense_tensor.h"
#include "paddle/phi/core/kernel_registry.h"
namespace phi {
template <class T>
static inline T BBoxArea(const T* box, const bool normalized) {
if (box[2] < box[0] || box[3] < box[1]) {
// If coordinate values are invalid
// (e.g. xmax < xmin or ymax < ymin), return 0.
return static_cast<T>(0.);
} else {
const T w = box[2] - box[0];
const T h = box[3] - box[1];
if (normalized) {
return w * h;
} else {
// If coordinate values are not within range [0, 1].
return (w + 1) * (h + 1);
}
}
}
template <class T>
static inline T JaccardOverlap(const T* box1,
const T* box2,
const bool normalized) {
if (box2[0] > box1[2] || box2[2] < box1[0] || box2[1] > box1[3] ||
box2[3] < box1[1]) {
return static_cast<T>(0.);
} else {
const T inter_xmin = std::max(box1[0], box2[0]);
const T inter_ymin = std::max(box1[1], box2[1]);
const T inter_xmax = std::min(box1[2], box2[2]);
const T inter_ymax = std::min(box1[3], box2[3]);
T norm = normalized ? static_cast<T>(0.) : static_cast<T>(1.);
T inter_w = inter_xmax - inter_xmin + norm;
T inter_h = inter_ymax - inter_ymin + norm;
const T inter_area = inter_w * inter_h;
const T bbox1_area = BBoxArea<T>(box1, normalized);
const T bbox2_area = BBoxArea<T>(box2, normalized);
return inter_area / (bbox1_area + bbox2_area - inter_area);
}
}
template <typename T, bool gaussian>
struct decay_score;
template <typename T>
struct decay_score<T, true> {
T operator()(T iou, T max_iou, T sigma) {
return std::exp((max_iou * max_iou - iou * iou) * sigma);
}
};
template <typename T>
struct decay_score<T, false> {
T operator()(T iou, T max_iou, T sigma UNUSED) {
return (1. - iou) / (1. - max_iou);
}
};
template <typename T, bool gaussian>
void NMSMatrix(const DenseTensor& bbox,
const DenseTensor& scores,
const T score_threshold,
const T post_threshold,
const float sigma,
const int64_t top_k,
const bool normalized,
std::vector<int>* selected_indices,
std::vector<T>* decayed_scores) {
int64_t num_boxes = bbox.dims()[0];
int64_t box_size = bbox.dims()[1];
auto score_ptr = scores.data<T>();
auto bbox_ptr = bbox.data<T>();
std::vector<int32_t> perm(num_boxes);
std::iota(perm.begin(), perm.end(), 0);
auto end = std::remove_if(
perm.begin(), perm.end(), [&score_ptr, score_threshold](int32_t idx) {
return score_ptr[idx] <= score_threshold;
});
auto sort_fn = [&score_ptr](int32_t lhs, int32_t rhs) {
return score_ptr[lhs] > score_ptr[rhs];
};
int64_t num_pre = std::distance(perm.begin(), end);
if (num_pre <= 0) {
return;
}
if (top_k > -1 && num_pre > top_k) {
num_pre = top_k;
}
std::partial_sort(perm.begin(), perm.begin() + num_pre, end, sort_fn);
std::vector<T> iou_matrix((num_pre * (num_pre - 1)) >> 1);
std::vector<T> iou_max(num_pre);
iou_max[0] = 0.;
for (int64_t i = 1; i < num_pre; i++) {
T max_iou = 0.;
auto idx_a = perm[i];
for (int64_t j = 0; j < i; j++) {
auto idx_b = perm[j];
auto iou = JaccardOverlap<T>(
bbox_ptr + idx_a * box_size, bbox_ptr + idx_b * box_size, normalized);
max_iou = std::max(max_iou, iou);
iou_matrix[i * (i - 1) / 2 + j] = iou;
}
iou_max[i] = max_iou;
}
if (score_ptr[perm[0]] > post_threshold) {
selected_indices->push_back(perm[0]);
decayed_scores->push_back(score_ptr[perm[0]]);
}
decay_score<T, gaussian> decay_fn;
for (int64_t i = 1; i < num_pre; i++) {
T min_decay = 1.;
for (int64_t j = 0; j < i; j++) {
auto max_iou = iou_max[j];
auto iou = iou_matrix[i * (i - 1) / 2 + j];
auto decay = decay_fn(iou, max_iou, sigma);
min_decay = std::min(min_decay, decay);
}
auto ds = min_decay * score_ptr[perm[i]];
if (ds <= post_threshold) continue;
selected_indices->push_back(perm[i]);
decayed_scores->push_back(ds);
}
}
template <typename T>
size_t MultiClassMatrixNMS(const DenseTensor& scores,
const DenseTensor& bboxes,
std::vector<T>* out,
std::vector<int>* indices,
int start,
int64_t background_label,
int64_t nms_top_k,
int64_t keep_top_k,
bool normalized,
T score_threshold,
T post_threshold,
bool use_gaussian,
float gaussian_sigma) {
std::vector<int> all_indices;
std::vector<T> all_scores;
std::vector<T> all_classes;
all_indices.reserve(scores.numel());
all_scores.reserve(scores.numel());
all_classes.reserve(scores.numel());
size_t num_det = 0;
auto class_num = scores.dims()[0];
DenseTensor score_slice;
for (int64_t c = 0; c < class_num; ++c) {
if (c == background_label) continue;
score_slice = scores.Slice(c, c + 1);
if (use_gaussian) {
NMSMatrix<T, true>(bboxes,
score_slice,
score_threshold,
post_threshold,
gaussian_sigma,
nms_top_k,
normalized,
&all_indices,
&all_scores);
} else {
NMSMatrix<T, false>(bboxes,
score_slice,
score_threshold,
post_threshold,
gaussian_sigma,
nms_top_k,
normalized,
&all_indices,
&all_scores);
}
for (size_t i = 0; i < all_indices.size() - num_det; i++) {
all_classes.push_back(static_cast<T>(c));
}
num_det = all_indices.size();
}
if (num_det <= 0) {
return num_det;
}
if (keep_top_k > -1) {
auto k = static_cast<size_t>(keep_top_k);
if (num_det > k) num_det = k;
}
std::vector<int32_t> perm(all_indices.size());
std::iota(perm.begin(), perm.end(), 0);
std::partial_sort(perm.begin(),
perm.begin() + num_det, // NOLINT
perm.end(),
[&all_scores](int lhs, int rhs) {
return all_scores[lhs] > all_scores[rhs];
});
for (size_t i = 0; i < num_det; i++) {
auto p = perm[i];
auto idx = all_indices[p];
auto cls = all_classes[p];
auto score = all_scores[p];
auto bbox = bboxes.data<T>() + idx * bboxes.dims()[1];
(*indices).push_back(start + idx);
(*out).push_back(cls);
(*out).push_back(score);
for (int j = 0; j < bboxes.dims()[1]; j++) {
(*out).push_back(bbox[j]);
}
}
return num_det;
}
template <typename T, typename Context>
void MatrixNMSKernel(const Context& dev_ctx,
const DenseTensor& bboxes,
const DenseTensor& scores,
float score_threshold,
int nms_top_k,
int keep_top_k,
float post_threshold,
bool use_gaussian,
float gaussian_sigma,
int background_label,
bool normalized,
DenseTensor* out,
DenseTensor* index,
DenseTensor* roisnum) {
auto score_dims = vectorize<int>(scores.dims());
auto batch_size = score_dims[0];
auto num_boxes = score_dims[2];
auto box_dim = bboxes.dims()[2];
auto out_dim = box_dim + 2;
DenseTensor boxes_slice, scores_slice;
size_t num_out = 0;
std::vector<size_t> offsets = {0};
std::vector<T> detections;
std::vector<int> indices;
std::vector<int> num_per_batch;
detections.reserve(out_dim * num_boxes * batch_size);
indices.reserve(num_boxes * batch_size);
num_per_batch.reserve(batch_size);
for (int i = 0; i < batch_size; ++i) {
scores_slice = scores.Slice(i, i + 1);
scores_slice.Resize({score_dims[1], score_dims[2]});
boxes_slice = bboxes.Slice(i, i + 1);
boxes_slice.Resize({score_dims[2], box_dim});
int start = i * score_dims[2];
num_out = MultiClassMatrixNMS(scores_slice,
boxes_slice,
&detections,
&indices,
start,
background_label,
nms_top_k,
keep_top_k,
normalized,
static_cast<T>(score_threshold),
static_cast<T>(post_threshold),
use_gaussian,
gaussian_sigma);
offsets.push_back(offsets.back() + num_out);
num_per_batch.emplace_back(num_out);
}
int64_t num_kept = static_cast<int64_t>(offsets.back());
if (num_kept == 0) {
out->Resize({0, out_dim});
dev_ctx.template Alloc<T>(out);
index->Resize({0, 1});
dev_ctx.template Alloc<int>(index);
} else {
out->Resize({num_kept, out_dim});
dev_ctx.template Alloc<T>(out);
index->Resize({num_kept, 1});
dev_ctx.template Alloc<int>(index);
std::copy(detections.begin(), detections.end(), out->data<T>());
std::copy(indices.begin(), indices.end(), index->data<int>());
}
if (roisnum != nullptr) {
roisnum->Resize({batch_size});
dev_ctx.template Alloc<int>(roisnum);
std::copy(num_per_batch.begin(), num_per_batch.end(), roisnum->data<int>());
}
}
} // namespace phi
PD_REGISTER_KERNEL(
matrix_nms, CPU, ALL_LAYOUT, phi::MatrixNMSKernel, float, double) {
kernel->OutputAt(1).SetDataType(phi::DataType::INT32);
kernel->OutputAt(2).SetDataType(phi::DataType::INT32);
}