71 lines
2.7 KiB
C++
71 lines
2.7 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_FACE_GEOMETRY_LIBS_PROCRUSTES_SOLVER_H_
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#define MEDIAPIPE_FACE_GEOMETRY_LIBS_PROCRUSTES_SOLVER_H_
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#include <memory>
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#include "Eigen/Dense"
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#include "mediapipe/framework/port/status.h"
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namespace mediapipe::face_geometry {
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// Encapsulates a stateless solver for the Weighted Extended Orthogonal
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// Procrustes (WEOP) Problem, as defined in Section 2.4 of
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// https://doi.org/10.3929/ethz-a-004656648.
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//
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// Given the source and the target point clouds, the algorithm estimates
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// a 4x4 transformation matrix featuring the following semantic components:
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//
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// * Uniform scale
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// * Rotation
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// * Translation
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//
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// The matrix maps the source point cloud into the target point cloud minimizing
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// the Mean Squared Error.
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class ProcrustesSolver {
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public:
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virtual ~ProcrustesSolver() = default;
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// Solves the Weighted Extended Orthogonal Procrustes (WEOP) Problem.
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//
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// All `source_points`, `target_points` and `point_weights` must define the
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// same number of points. Elements of `point_weights` must be non-negative.
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//
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// A too small diameter of either of the point clouds will likely lead to
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// numerical instabilities and failure to estimate the transformation.
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//
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// A too small point cloud total weight will likely lead to numerical
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// instabilities and failure to estimate the transformation too.
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//
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// Small point coordinate deviation for either of the point cloud will likely
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// result in a failure as it will make the solution very unstable if possible.
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//
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// Note: the output `transform_mat` argument is used instead of `StatusOr<>`
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// return type in order to avoid Eigen memory alignment issues. Details:
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// https://eigen.tuxfamily.org/dox/group__TopicStructHavingEigenMembers.html
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virtual absl::Status SolveWeightedOrthogonalProblem(
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const Eigen::Matrix3Xf& source_points, //
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const Eigen::Matrix3Xf& target_points, //
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const Eigen::VectorXf& point_weights, //
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Eigen::Matrix4f& transform_mat) const = 0;
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};
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std::unique_ptr<ProcrustesSolver> CreateFloatPrecisionProcrustesSolver();
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} // namespace mediapipe::face_geometry
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#endif // MEDIAPIPE_FACE_GEOMETRY_LIBS_PROCRUSTES_SOLVER_H_
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