TransformationEstimation.h

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// ----------------------------------------------------------------------------
// -                        Open3D: www.open3d.org                            -
// ----------------------------------------------------------------------------
// Copyright (c) 2018-2024 www.open3d.org
// SPDX-License-Identifier: MIT
// ----------------------------------------------------------------------------
 
#pragma once
 
#include <cmath>
#include <memory>
#include <string>
#include <utility>
#include <vector>
 
#include "open3d/core/Tensor.h"
#include "open3d/t/geometry/PointCloud.h"
#include "open3d/t/pipelines/kernel/TransformationConverter.h"
#include "open3d/t/pipelines/registration/RobustKernel.h"
#include "open3d/utility/Logging.h"
 
namespace open3d {
 
namespace t {
namespace geometry {
class PointCloud;
}
 
namespace pipelines {
namespace registration {
 
namespace {
 
// Minimum time period (sec) between two sequential scans for Doppler ICP.
constexpr double kMinTimePeriod{1e-3};
 
}  // namespace
 
enum class TransformationEstimationType {
    Unspecified = 0,
    PointToPoint = 1,
    PointToPlane = 2,
    ColoredICP = 3,
    DopplerICP = 4,
};

class TransformationEstimation {
public:
    TransformationEstimation() {}
    virtual ~TransformationEstimation() {}
 
public:
    virtual TransformationEstimationType GetTransformationEstimationType()
            const = 0;

    virtual double ComputeRMSE(const geometry::PointCloud &source,
                               const geometry::PointCloud &target,
                               const core::Tensor &correspondences) const = 0;
    virtual core::Tensor ComputeTransformation(
            const geometry::PointCloud &source,
            const geometry::PointCloud &target,
            const core::Tensor &correspondences,
            const core::Tensor &current_transform =
                    core::Tensor::Eye(4, core::Float64, core::Device("CPU:0")),
            const std::size_t iteration = 0) const = 0;
};

class TransformationEstimationPointToPoint : public TransformationEstimation {
public:
    // TODO: support with_scaling.
    TransformationEstimationPointToPoint() {}
    ~TransformationEstimationPointToPoint() override {}
 
public:
    TransformationEstimationType GetTransformationEstimationType()
            const override {
        return type_;
    };

    double ComputeRMSE(const geometry::PointCloud &source,
                       const geometry::PointCloud &target,
                       const core::Tensor &correspondences) const override;

    core::Tensor ComputeTransformation(
            const geometry::PointCloud &source,
            const geometry::PointCloud &target,
            const core::Tensor &correspondences,
            const core::Tensor &current_transform =
                    core::Tensor::Eye(4, core::Float64, core::Device("CPU:0")),
            const std::size_t iteration = 0) const override;
 
private:
    const TransformationEstimationType type_ =
            TransformationEstimationType::PointToPoint;
};

class TransformationEstimationPointToPlane : public TransformationEstimation {
public:
    TransformationEstimationPointToPlane() {}
    ~TransformationEstimationPointToPlane() override {}

    explicit TransformationEstimationPointToPlane(const RobustKernel &kernel)
        : kernel_(kernel) {}
 
public:
    TransformationEstimationType GetTransformationEstimationType()
            const override {
        return type_;
    };

    double ComputeRMSE(const geometry::PointCloud &source,
                       const geometry::PointCloud &target,
                       const core::Tensor &correspondences) const override;

    core::Tensor ComputeTransformation(
            const geometry::PointCloud &source,
            const geometry::PointCloud &target,
            const core::Tensor &correspondences,
            const core::Tensor &current_transform =
                    core::Tensor::Eye(4, core::Float64, core::Device("CPU:0")),
            const std::size_t iteration = 0) const override;
 
public:
    RobustKernel kernel_ = RobustKernel(RobustKernelMethod::L2Loss, 1.0, 1.0);
 
private:
    const TransformationEstimationType type_ =
            TransformationEstimationType::PointToPlane;
};

class TransformationEstimationForColoredICP : public TransformationEstimation {
public:
    ~TransformationEstimationForColoredICP() override{};

    explicit TransformationEstimationForColoredICP(
            double lambda_geometric = 0.968,
            const RobustKernel &kernel =
                    RobustKernel(RobustKernelMethod::L2Loss, 1.0, 1.0))
        : lambda_geometric_(lambda_geometric), kernel_(kernel) {
        if (lambda_geometric_ < 0 || lambda_geometric_ > 1.0) {
            lambda_geometric_ = 0.968;
        }
    }
 
    TransformationEstimationType GetTransformationEstimationType()
            const override {
        return type_;
    };
 
public:
    double ComputeRMSE(const geometry::PointCloud &source,
                       const geometry::PointCloud &target,
                       const core::Tensor &correspondences) const override;

    core::Tensor ComputeTransformation(
            const geometry::PointCloud &source,
            const geometry::PointCloud &target,
            const core::Tensor &correspondences,
            const core::Tensor &current_transform =
                    core::Tensor::Eye(4, core::Float64, core::Device("CPU:0")),
            const std::size_t iteration = 0) const override;
 
public:
    double lambda_geometric_ = 0.968;
    RobustKernel kernel_ = RobustKernel(RobustKernelMethod::L2Loss, 1.0, 1.0);
 
private:
    const TransformationEstimationType type_ =
            TransformationEstimationType::ColoredICP;
};

class TransformationEstimationForDopplerICP : public TransformationEstimation {
public:
    ~TransformationEstimationForDopplerICP() override{};

    explicit TransformationEstimationForDopplerICP(
            const double period = 0.1,
            const double lambda_doppler = 0.01,
            const bool reject_dynamic_outliers = false,
            const double doppler_outlier_threshold = 2.0,
            const std::size_t outlier_rejection_min_iteration = 2,
            const std::size_t geometric_robust_loss_min_iteration = 0,
            const std::size_t doppler_robust_loss_min_iteration = 2,
            const RobustKernel &geometric_kernel =
                    RobustKernel(RobustKernelMethod::L2Loss, 1.0, 1.0),
            const RobustKernel &doppler_kernel =
                    RobustKernel(RobustKernelMethod::L2Loss, 1.0, 1.0),
            const core::Tensor &transform_vehicle_to_sensor =
                    core::Tensor::Eye(4, core::Float64, core::Device("CPU:0")))
        : period_(period),
          lambda_doppler_(lambda_doppler),
          reject_dynamic_outliers_(reject_dynamic_outliers),
          doppler_outlier_threshold_(doppler_outlier_threshold),
          outlier_rejection_min_iteration_(outlier_rejection_min_iteration),
          geometric_robust_loss_min_iteration_(
                  geometric_robust_loss_min_iteration),
          doppler_robust_loss_min_iteration_(doppler_robust_loss_min_iteration),
          geometric_kernel_(geometric_kernel),
          doppler_kernel_(doppler_kernel),
          transform_vehicle_to_sensor_(transform_vehicle_to_sensor) {
        core::AssertTensorShape(transform_vehicle_to_sensor, {4, 4});
 
        if (std::abs(period) < kMinTimePeriod) {
            utility::LogError("Time period too small.");
        }
 
        if (lambda_doppler_ < 0 || lambda_doppler_ > 1.0) {
            lambda_doppler_ = 0.01;
        }
    }
 
    TransformationEstimationType GetTransformationEstimationType()
            const override {
        return type_;
    };
 
public:
    double ComputeRMSE(const geometry::PointCloud &source,
                       const geometry::PointCloud &target,
                       const core::Tensor &correspondences) const override;

    core::Tensor ComputeTransformation(
            const geometry::PointCloud &source,
            const geometry::PointCloud &target,
            const core::Tensor &correspondences,
            const core::Tensor &current_transform =
                    core::Tensor::Eye(4, core::Float64, core::Device("CPU:0")),
            const std::size_t iteration = 0) const override;
 
public:
    double period_{0.1};
    double lambda_doppler_{0.01};
    bool reject_dynamic_outliers_{false};
    double doppler_outlier_threshold_{2.0};
    std::size_t outlier_rejection_min_iteration_{2};
    std::size_t geometric_robust_loss_min_iteration_{0};
    std::size_t doppler_robust_loss_min_iteration_{2};
    RobustKernel geometric_kernel_ =
            RobustKernel(RobustKernelMethod::L2Loss, 1.0, 1.0);
    RobustKernel doppler_kernel_ =
            RobustKernel(RobustKernelMethod::L2Loss, 1.0, 1.0);
    core::Tensor transform_vehicle_to_sensor_ =
            core::Tensor::Eye(4, core::Float64, core::Device("CPU:0"));
 
private:
    const TransformationEstimationType type_ =
            TransformationEstimationType::DopplerICP;
};
 
}  // namespace registration
}  // namespace pipelines
}  // namespace t
}  // namespace open3d