VoxelGrid.h

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// The MIT License (MIT)
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#pragma once

#include <Eigen/Core>
#include <memory>
#include <unordered_map>
#include <vector>

#include "Open3D/Geometry/Geometry3D.h"
#include "Open3D/Utility/Console.h"

#include "Open3D/Utility/Helper.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;
    AxisAlignedBoundingBox GetAxisAlignedBoundingBox() const override;
    OrientedBoundingBox GetOrientedBoundingBox() const override;
    VoxelGrid &Transform(const Eigen::Matrix4d &transformation) override;
    VoxelGrid &Translate(const Eigen::Vector3d &translation,
                         bool relative = true) override;
    VoxelGrid &Scale(const double scale, bool center = true) override;
    VoxelGrid &Rotate(const Eigen::Matrix3d &R, bool center = true) 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;

    // Function that returns the 3d coordinates of the queried voxel center
    Eigen::Vector3d GetVoxelCenterCoordinate(const Eigen::Vector3i &idx) const {
        auto it = voxels_.find(idx);
        if (it != voxels_.end()) {
            auto voxel = it->second;
            return ((voxel.grid_index_.cast<double>() +
                     Eigen::Vector3d(0.5, 0.5, 0.5)) *
                    voxel_size_) +
                   origin_;
        } else {
            return Eigen::Vector3d::Zero();
        }
    }

    void AddVoxel(const Voxel &voxel);

    std::vector<Eigen::Vector3d> GetVoxelBoundingPoints(
            const Eigen::Vector3i &index) const;

    // Element-wise check if a query in the list is included in the VoxelGrid
    // Queries are double precision and are mapped to the closest voxel.
    std::vector<bool> CheckIfIncluded(
            const std::vector<Eigen::Vector3d> &queries);

    VoxelGrid &CarveDepthMap(
            const Image &depth_map,
            const camera::PinholeCameraParameters &camera_parameter);

    VoxelGrid &CarveSilhouette(
            const Image &silhouette_mask,
            const camera::PinholeCameraParameters &camera_parameter);

    void CreateFromOctree(const Octree &octree);

    std::shared_ptr<geometry::Octree> ToOctree(const size_t &max_depth) const;

    // Creates a voxel grid where every voxel is set (hence dense). This is a
    // useful starting point for voxel carving.
    static std::shared_ptr<VoxelGrid> CreateDense(const Eigen::Vector3d &origin,
                                                  double voxel_size,
                                                  double width,
                                                  double height,
                                                  double depth);

    // Creates a VoxelGrid from a given PointCloud. The color value of a given
    // voxel is the average color value of the points that fall into it (if the
    // PointCloud has colors).
    // The bounds of the created VoxelGrid are computed from the PointCloud.
    static std::shared_ptr<VoxelGrid> CreateFromPointCloud(
            const PointCloud &input, double voxel_size);

    // Creates a VoxelGrid from a given PointCloud. The color value of a given
    // voxel is the average color value of the points that fall into it (if the
    // PointCloud has colors).
    // The bounds of the created VoxelGrid are defined by the given parameters.
    static std::shared_ptr<VoxelGrid> CreateFromPointCloudWithinBounds(
            const PointCloud &input,
            double voxel_size,
            const Eigen::Vector3d &min_bound,
            const Eigen::Vector3d &max_bound);

    // Creates a VoxelGrid from a given TriangleMesh. No color information is
    // converted. The bounds of the created VoxelGrid are computed from the
    // TriangleMesh..
    static std::shared_ptr<VoxelGrid> CreateFromTriangleMesh(
            const TriangleMesh &input, double voxel_size);

    // Creates a VoxelGrid from a given TriangleMesh. No color information is
    // converted. The bounds of the created VoxelGrid are defined by the given
    // parameters..
    static std::shared_ptr<VoxelGrid> CreateFromTriangleMeshWithinBounds(
            const TriangleMesh &input,
            double voxel_size,
            const Eigen::Vector3d &min_bound,
            const Eigen::Vector3d &max_bound);

public:
    double voxel_size_ = 0.0;
    Eigen::Vector3d origin_ = Eigen::Vector3d::Zero();
    std::unordered_map<Eigen::Vector3i,
                       Voxel,
                       utility::hash_eigen::hash<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_;
};

}  // namespace geometry
}  // namespace open3d