110 lines
4.4 KiB
C++
110 lines
4.4 KiB
C++
// Copyright 2020 The MediaPipe Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef MEDIAPIPE_MODULES_OBJECTRON_CALCULATORS_DECODER_H_
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#define MEDIAPIPE_MODULES_OBJECTRON_CALCULATORS_DECODER_H_
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#include <vector>
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#include "Eigen/Dense"
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#include "absl/status/status.h"
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#include "mediapipe/framework/port/opencv_core_inc.h"
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#include "mediapipe/modules/objectron/calculators/annotation_data.pb.h"
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#include "mediapipe/modules/objectron/calculators/belief_decoder_config.pb.h"
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namespace mediapipe {
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// Decodes 3D bounding box from heatmaps and offset maps. In the future,
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// if we want to develop decoder for generic skeleton, then we need to
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// generalize this class, and make a few child classes.
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class Decoder {
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public:
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static const int kNumOffsetmaps;
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explicit Decoder(const BeliefDecoderConfig& config) : config_(config) {
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epnp_alpha_ << 4.0f, -1.0f, -1.0f, -1.0f, 2.0f, -1.0f, -1.0f, 1.0f, 2.0f,
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-1.0f, 1.0f, -1.0f, 0.0f, -1.0f, 1.0f, 1.0f, 2.0f, 1.0f, -1.0f, -1.0f,
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0.0f, 1.0f, -1.0f, 1.0f, 0.0f, 1.0f, 1.0f, -1.0f, -2.0f, 1.0f, 1.0f,
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1.0f;
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}
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// Decodes bounding boxes from predicted heatmap and offset maps.
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// Input:
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// heatmap: a single channel cv::Mat representing center point heatmap
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// offsetmap: a 16 channel cv::Mat representing the 16 offset maps
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// (2 for each of the 8 vertices)
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// Output:
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// Outputs 3D bounding boxes 2D vertices, represented by 'point_2d' field
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// in each 'keypoints' field of object annotations.
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FrameAnnotation DecodeBoundingBoxKeypoints(const cv::Mat& heatmap,
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const cv::Mat& offsetmap) const;
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// Lifts the estimated 2D projections of bounding box vertices to 3D.
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// This function uses the EPnP approach described in this paper:
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// https://icwww.epfl.ch/~lepetit/papers/lepetit_ijcv08.pdf .
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// Input:
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// projection_matrix: the projection matrix from 3D coordinate
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// to screen coordinate.
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// The 2D screen coordinate is defined as: u is along the long
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// edge of the device, pointing down; v is along the short edge
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// of the device, pointing right.
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// portrait: a boolen variable indicating whether our images are
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// obtained in portrait orientation or not.
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// estimated_box: annotation with point_2d field populated with
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// 2d vertices.
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// Output:
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// estimated_box: annotation with point_3d field populated with
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// 3d vertices.
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absl::Status Lift2DTo3D(
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const Eigen::Matrix<float, 4, 4, Eigen::RowMajor>& projection_matrix,
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bool portrait, FrameAnnotation* estimated_box) const;
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private:
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struct BeliefBox {
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float belief;
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std::vector<std::pair<float, float>> box_2d;
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};
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std::vector<cv::Point> ExtractCenterKeypoints(
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const cv::Mat& center_heatmap) const;
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// Decodes 2D keypoints at the peak point.
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void DecodeByPeak(const cv::Mat& offsetmap, int center_x, int center_y,
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float offset_scale_x, float offset_scale_y,
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BeliefBox* box) const;
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// Decodes 2D keypoints by voting around the peak.
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void DecodeByVoting(const cv::Mat& heatmap, const cv::Mat& offsetmap,
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int center_x, int center_y, float offset_scale_x,
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float offset_scale_y, BeliefBox* box) const;
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// Returns true if it is a new box. Otherwise, it may replace an existing box
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// if the new box's belief is higher.
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bool IsNewBox(std::vector<BeliefBox>* boxes, BeliefBox* box) const;
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// Returns true if the two boxes are identical.
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bool IsIdentical(const BeliefBox& box_1, const BeliefBox& box_2) const;
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BeliefDecoderConfig config_;
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// Following equation (1) in this paper
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// https://icwww.epfl.ch/~lepetit/papers/lepetit_ijcv08.pdf,
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// this variable denotes the coefficients for the 4 control points
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// for each of the 8 3D box vertices.
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Eigen::Matrix<float, 8, 4, Eigen::RowMajor> epnp_alpha_;
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};
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} // namespace mediapipe
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#endif // MEDIAPIPE_MODULES_OBJECTRON_CALCULATORS_DECODER_H_
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