VoxelGrid.h

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// ----------------------------------------------------------------------------
// -                        Open3D: www.open3d.org                            -
// ----------------------------------------------------------------------------
// Copyright (c) 2018-2024 www.open3d.org
// SPDX-License-Identifier: MIT
// ----------------------------------------------------------------------------
 
#pragma once
 
#include <Eigen/Core>
#include <memory>
#include <unordered_map>
#include <vector>
 
#include "open3d/geometry/Geometry3D.h"
#include "open3d/utility/Helper.h"
#include "open3d/utility/Logging.h"
 
namespace open3d {
 
namespace camera {
class PinholeCameraParameters;
}
 
namespace geometry {
 
class PointCloud;
class TriangleMesh;
class Octree;
class Image;
 
class Voxel {
public:
    Voxel() {}
    Voxel(const Eigen::Vector3i &grid_index) : grid_index_(grid_index) {}
    Voxel(const Eigen::Vector3i &grid_index, const Eigen::Vector3d &color)
        : grid_index_(grid_index), color_(color) {}
    ~Voxel() {}
 
public:
    Eigen::Vector3i grid_index_ = Eigen::Vector3i(0, 0, 0);
    Eigen::Vector3d color_ = Eigen::Vector3d(0, 0, 0);
};
 
class VoxelGrid : public Geometry3D {
public:
    VoxelGrid() : Geometry3D(Geometry::GeometryType::VoxelGrid) {}
    VoxelGrid(const VoxelGrid &src_voxel_grid);
    ~VoxelGrid() override {}
 
    VoxelGrid &Clear() override;
    bool IsEmpty() const override;
    Eigen::Vector3d GetMinBound() const override;
    Eigen::Vector3d GetMaxBound() const override;
    Eigen::Vector3d GetCenter() const override;
 
    std::vector<Eigen::Vector3d> GetAllVoxelCorners() const;
    AxisAlignedBoundingBox GetAxisAlignedBoundingBox() const override;
 
    OrientedBoundingBox GetOrientedBoundingBox(
            bool robust = false) const override;
 
    OrientedBoundingBox GetMinimalOrientedBoundingBox(
            bool robust = false) const override;
 
    VoxelGrid &Transform(const Eigen::Matrix4d &transformation) override;
    VoxelGrid &Translate(const Eigen::Vector3d &translation,
                         bool relative = true) override;
    VoxelGrid &Scale(const double scale,
                     const Eigen::Vector3d &center) override;
    VoxelGrid &Rotate(const Eigen::Matrix3d &R,
                      const Eigen::Vector3d &center) override;
 
    VoxelGrid &operator+=(const VoxelGrid &voxelgrid);
    VoxelGrid operator+(const VoxelGrid &voxelgrid) const;
 
    bool HasVoxels() const { return voxels_.size() > 0; }
    bool HasColors() const {
        return true;  // By default, the colors are (0, 0, 0)
    }
    Eigen::Vector3i GetVoxel(const Eigen::Vector3d &point) const;
 
    Eigen::Vector3d GetVoxelCenterCoordinate(const Eigen::Vector3i &idx) const {
        auto it = voxels_.find(idx);
        if (it != voxels_.end()) {
            auto voxel = it->second;
            Eigen::Vector3d local = (voxel.grid_index_.cast<double>() +
                                     Eigen::Vector3d(0.5, 0.5, 0.5)) *
                                    voxel_size_;
            return origin_ + rotation_ * local;
        } else {
            return Eigen::Vector3d::Zero();
        }
    }
 
    void AddVoxel(const Voxel &voxel);
 
    void RemoveVoxel(const Eigen::Vector3i &idx);
 
    std::vector<Eigen::Vector3d> GetVoxelBoundingPoints(
            const Eigen::Vector3i &index) const;
 
    std::vector<bool> CheckIfIncluded(
            const std::vector<Eigen::Vector3d> &queries);
 
    VoxelGrid &CarveDepthMap(
            const Image &depth_map,
            const camera::PinholeCameraParameters &camera_parameter,
            bool keep_voxels_outside_image);
 
    VoxelGrid &CarveSilhouette(
            const Image &silhouette_mask,
            const camera::PinholeCameraParameters &camera_parameter,
            bool keep_voxels_outside_image);
 
    void CreateFromOctree(const Octree &octree);
 
    std::shared_ptr<geometry::Octree> ToOctree(const size_t &max_depth) const;
 
    static std::shared_ptr<VoxelGrid> CreateDense(const Eigen::Vector3d &origin,
                                                  const Eigen::Vector3d &color,
                                                  double voxel_size,
                                                  double width,
                                                  double height,
                                                  double depth);
 
    enum class VoxelPoolingMode { AVG, MIN, MAX, SUM };
 
    static std::shared_ptr<VoxelGrid> CreateFromPointCloud(
            const PointCloud &input,
            double voxel_size,
            VoxelPoolingMode color_mode = VoxelPoolingMode::AVG);
 
    static std::shared_ptr<VoxelGrid> CreateFromPointCloudWithinBounds(
            const PointCloud &input,
            double voxel_size,
            const Eigen::Vector3d &min_bound,
            const Eigen::Vector3d &max_bound,
            VoxelPoolingMode color_mode = VoxelPoolingMode::AVG);
 
    static std::shared_ptr<VoxelGrid> CreateFromTriangleMesh(
            const TriangleMesh &input, double voxel_size);
 
    static std::shared_ptr<VoxelGrid> CreateFromTriangleMeshWithinBounds(
            const TriangleMesh &input,
            double voxel_size,
            const Eigen::Vector3d &min_bound,
            const Eigen::Vector3d &max_bound);
 
    std::vector<Voxel> GetVoxels() const;
 
public:
    double voxel_size_ = 0.0;
    Eigen::Vector3d origin_ = Eigen::Vector3d::Zero();
    Eigen::Matrix3d rotation_ = Eigen::Matrix3d::Identity();
    std::unordered_map<Eigen::Vector3i,
                       Voxel,
                       utility::hash_eigen<Eigen::Vector3i>>
            voxels_;
};
 
class AvgColorVoxel {
public:
    AvgColorVoxel() : num_of_points_(0), color_(0.0, 0.0, 0.0) {}
 
public:
    void Add(const Eigen::Vector3i &voxel_index) {
        if (num_of_points_ > 0 && voxel_index != voxel_index_) {
            utility::LogWarning(
                    "Tried to aggregate ColorVoxel with different "
                    "voxel_index");
        }
        voxel_index_ = voxel_index;
    }
 
    void Add(const Eigen::Vector3i &voxel_index, const Eigen::Vector3d &color) {
        Add(voxel_index);
        color_ += color;
        num_of_points_++;
    }
 
    Eigen::Vector3i GetVoxelIndex() const { return voxel_index_; }
 
    Eigen::Vector3d GetAverageColor() const {
        if (num_of_points_ > 0) {
            return color_ / double(num_of_points_);
        } else {
            return color_;
        }
    }
 
public:
    int num_of_points_;
    Eigen::Vector3i voxel_index_;
    Eigen::Vector3d color_;
};
 
class AggColorVoxel {
public:
    AggColorVoxel()
        : num_of_points_(0),
          color_(0.0, 0.0, 0.0),
          min_color_(Eigen::Vector3d::Constant(
                  std::numeric_limits<double>::max())),
          max_color_(Eigen::Vector3d::Constant(
                  std::numeric_limits<double>::lowest())) {}
 
public:
    void Add(const Eigen::Vector3i &voxel_index) {
        if (num_of_points_ > 0 && voxel_index != voxel_index_) {
            utility::LogWarning(
                    "Tried to aggregate ColorVoxel with different "
                    "voxel_index");
        }
        voxel_index_ = voxel_index;
    }
 
    void Add(const Eigen::Vector3i &voxel_index, const Eigen::Vector3d &color) {
        Add(voxel_index);
        color_ += color;
        num_of_points_++;
        min_color_ = min_color_.cwiseMin(color);
        max_color_ = max_color_.cwiseMax(color);
    }
 
    Eigen::Vector3i GetVoxelIndex() const { return voxel_index_; }
 
    Eigen::Vector3d GetAverageColor() const {
        if (num_of_points_ > 0) {
            return color_ / double(num_of_points_);
        } else {
            return color_;
        }
    }
 
    Eigen::Vector3d GetMinColor() const { return min_color_; }
 
    Eigen::Vector3d GetMaxColor() const { return max_color_; }
 
    Eigen::Vector3d GetSumColor() const { return color_; }
 
public:
    int num_of_points_;
    Eigen::Vector3i voxel_index_;
    Eigen::Vector3d color_;
 
private:
    Eigen::Vector3d min_color_;
    Eigen::Vector3d max_color_;
};
 
}  // namespace geometry
}  // namespace open3d