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yolox.cpp
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yolox.cpp
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//
// Created by DefTruth on 2021/7/20.
//
#include "yolox.h"
#include "lite/ort/core/ort_utils.h"
#include "lite/utils.h"
using ortcv::YoloX;
Ort::Value YoloX::transform(const cv::Mat &mat_rs)
{
cv::Mat canvas;
cv::cvtColor(mat_rs, canvas, cv::COLOR_BGR2RGB);
// resize without padding, (Done): add padding as the official Python implementation.
// cv::resize(canva, canva, cv::Size(input_node_dims.at(3),
// input_node_dims.at(2)));
// (1,3,640,640) 1xCXHXW
ortcv::utils::transform::normalize_inplace(canvas, mean_vals, scale_vals); // float32
// Note !!!: Comment out this line if you use the newest YOLOX model.
// There is no normalization for the newest official C++ implementation
// using ncnn. Reference:
// [1] https://github.com/Megvii-BaseDetection/YOLOX/blob/main/demo/ncnn/cpp/yolox.cpp
// ortcv::utils::transform::normalize_inplace(canva, mean_vals, scale_vals); // float32
return ortcv::utils::transform::create_tensor(
canvas, input_node_dims, memory_info_handler,
input_values_handler, ortcv::utils::transform::CHW);
}
void YoloX::resize_unscale(const cv::Mat &mat, cv::Mat &mat_rs,
int target_height, int target_width,
YoloXScaleParams &scale_params)
{
if (mat.empty()) return;
int img_height = static_cast<int>(mat.rows);
int img_width = static_cast<int>(mat.cols);
mat_rs = cv::Mat(target_height, target_width, CV_8UC3,
cv::Scalar(114, 114, 114));
// scale ratio (new / old) new_shape(h,w)
float w_r = (float) target_width / (float) img_width;
float h_r = (float) target_height / (float) img_height;
float r = std::min(w_r, h_r);
// compute padding
int new_unpad_w = static_cast<int>((float) img_width * r); // floor
int new_unpad_h = static_cast<int>((float) img_height * r); // floor
int pad_w = target_width - new_unpad_w; // >=0
int pad_h = target_height - new_unpad_h; // >=0
int dw = pad_w / 2;
int dh = pad_h / 2;
// resize with unscaling
cv::Mat new_unpad_mat;
// cv::Mat new_unpad_mat = mat.clone(); // may not need clone.
cv::resize(mat, new_unpad_mat, cv::Size(new_unpad_w, new_unpad_h));
new_unpad_mat.copyTo(mat_rs(cv::Rect(dw, dh, new_unpad_w, new_unpad_h)));
// record scale params.
scale_params.r = r;
scale_params.dw = dw;
scale_params.dh = dh;
scale_params.new_unpad_w = new_unpad_w;
scale_params.new_unpad_h = new_unpad_h;
scale_params.flag = true;
}
void YoloX::detect(const cv::Mat &mat, std::vector<types::Boxf> &detected_boxes,
float score_threshold, float iou_threshold,
unsigned int topk, unsigned int nms_type)
{
if (mat.empty()) return;
const int input_height = input_node_dims.at(2);
const int input_width = input_node_dims.at(3);
int img_height = static_cast<int>(mat.rows);
int img_width = static_cast<int>(mat.cols);
// resize & unscale
cv::Mat mat_rs;
YoloXScaleParams scale_params;
this->resize_unscale(mat, mat_rs, input_height, input_width, scale_params);
// 1. make input tensor
Ort::Value input_tensor = this->transform(mat_rs);
// 2. inference scores & boxes.
auto output_tensors = ort_session->Run(
Ort::RunOptions{nullptr}, input_node_names.data(),
&input_tensor, 1, output_node_names.data(), num_outputs
);
// 3. rescale & exclude.
std::vector<types::Boxf> bbox_collection;
this->generate_bboxes(scale_params, bbox_collection, output_tensors, score_threshold, img_height, img_width);
// 4. hard|blend|offset nms with topk.
this->nms(bbox_collection, detected_boxes, iou_threshold, topk, nms_type);
}
// Issue: https://github.com/DefTruth/lite.ai/issues/9
// Note!!!: The implementation of Anchor generation in Lite.AI is slightly different
// with the official one in order to fix the inference error for non-square input shape.
// Official: https://github.com/Megvii-BaseDetection/YOLOX/blob/main/demo/ncnn/cpp/yolox.cpp
/** Official implementation. It assumes that the input shape must be a square.
* When you use the YOLOX model that was trained by yourself, but the input tensor of
* the model is not square, you will encounter an error. So, I decided to extend the
* official implementation for compatibility with square and non-square input.
*
* static void generate_grids_and_stride(const int target_size, std::vector<int>& strides,
* std::vector<GridAndStride>& grid_strides)
* {
* for (auto stride : strides)
* {
* int num_grid = target_size / stride;
* for (int g1 = 0; g1 < num_grid; g1++)
* {
* for (int g0 = 0; g0 < num_grid; g0++)
* {
* grid_strides.push_back((GridAndStride){g0, g1, stride});
* }
* }
* }
* }
*/
void YoloX::generate_anchors(const int target_height,
const int target_width,
std::vector<int> &strides,
std::vector<YoloXAnchor> &anchors)
{
for (auto stride: strides)
{
int num_grid_w = target_width / stride;
int num_grid_h = target_height / stride;
for (int g1 = 0; g1 < num_grid_h; ++g1)
{
for (int g0 = 0; g0 < num_grid_w; ++g0)
{
#ifdef LITE_WIN32
YoloXAnchor anchor;
anchor.grid0 = g0;
anchor.grid1 = g1;
anchor.stride = stride;
anchors.push_back(anchor);
#else
anchors.push_back((YoloXAnchor) {g0, g1, stride});
#endif
}
}
}
}
void YoloX::generate_bboxes(const YoloXScaleParams &scale_params,
std::vector<types::Boxf> &bbox_collection,
std::vector<Ort::Value> &output_tensors,
float score_threshold, int img_height,
int img_width)
{
Ort::Value &pred = output_tensors.at(0); // (1,n,85=5+80=cxcy+cwch+obj_conf+cls_conf)
auto pred_dims = output_node_dims.at(0); // (1,n,85)
const unsigned int num_anchors = pred_dims.at(1); // n = ?
const unsigned int num_classes = pred_dims.at(2) - 5;
const float input_height = static_cast<float>(input_node_dims.at(2)); // e.g 640
const float input_width = static_cast<float>(input_node_dims.at(3)); // e.g 640
std::vector<YoloXAnchor> anchors;
std::vector<int> strides = {8, 16, 32}; // might have stride=64
this->generate_anchors(input_height, input_width, strides, anchors);
float r_ = scale_params.r;
int dw_ = scale_params.dw;
int dh_ = scale_params.dh;
bbox_collection.clear();
unsigned int count = 0;
for (unsigned int i = 0; i < num_anchors; ++i)
{
float obj_conf = pred.At<float>({0, i, 4});
if (obj_conf < score_threshold) continue; // filter first.
float cls_conf = pred.At<float>({0, i, 5});
unsigned int label = 0;
for (unsigned int j = 0; j < num_classes; ++j)
{
float tmp_conf = pred.At<float>({0, i, j + 5});
if (tmp_conf > cls_conf)
{
cls_conf = tmp_conf;
label = j;
}
} // argmax
float conf = obj_conf * cls_conf; // cls_conf (0.,1.)
if (conf < score_threshold) continue; // filter
const int grid0 = anchors.at(i).grid0;
const int grid1 = anchors.at(i).grid1;
const int stride = anchors.at(i).stride;
float dx = pred.At<float>({0, i, 0});
float dy = pred.At<float>({0, i, 1});
float dw = pred.At<float>({0, i, 2});
float dh = pred.At<float>({0, i, 3});
float cx = (dx + (float) grid0) * (float) stride;
float cy = (dy + (float) grid1) * (float) stride;
float w = std::exp(dw) * (float) stride;
float h = std::exp(dh) * (float) stride;
float x1 = ((cx - w / 2.f) - (float) dw_) / r_;
float y1 = ((cy - h / 2.f) - (float) dh_) / r_;
float x2 = ((cx + w / 2.f) - (float) dw_) / r_;
float y2 = ((cy + h / 2.f) - (float) dh_) / r_;
types::Boxf box;
box.x1 = std::max(0.f, x1);
box.y1 = std::max(0.f, y1);
box.x2 = std::min(x2, (float) img_width - 1.f);
box.y2 = std::min(y2, (float) img_height - 1.f);
box.score = conf;
box.label = label;
box.label_text = class_names[label];
box.flag = true;
bbox_collection.push_back(box);
count += 1; // limit boxes for nms.
if (count > max_nms)
break;
}
#if LITEORT_DEBUG
std::cout << "detected num_anchors: " << num_anchors << "\n";
std::cout << "generate_bboxes num: " << bbox_collection.size() << "\n";
#endif
}
void YoloX::nms(std::vector<types::Boxf> &input, std::vector<types::Boxf> &output,
float iou_threshold, unsigned int topk, unsigned int nms_type)
{
if (nms_type == NMS::BLEND) lite::utils::blending_nms(input, output, iou_threshold, topk);
else if (nms_type == NMS::OFFSET) lite::utils::offset_nms(input, output, iou_threshold, topk);
else lite::utils::hard_nms(input, output, iou_threshold, topk);
}