util3d_registration.cpp

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/*
Copyright (c) 2010-2016, Mathieu Labbe - IntRoLab - Universite de Sherbrooke
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#include "rtabmap/core/util3d_registration.h"

#include "rtabmap/core/util3d_transforms.h"
#include "rtabmap/core/util3d_filtering.h"
#include "rtabmap/core/util3d.h"

#include <pcl/registration/icp.h>
#include <pcl/registration/transformation_estimation_2D.h>
#include <pcl/registration/transformation_estimation_svd.h>
#include <pcl/sample_consensus/sac_model_registration.h>
#include <pcl/sample_consensus/ransac.h>
#include <pcl/common/common.h>
#include <rtabmap/utilite/ULogger.h>
#include <rtabmap/utilite/UMath.h>

namespace rtabmap
{

namespace util3d
{

// Get transform from cloud2 to cloud1
Transform transformFromXYZCorrespondencesSVD(
        const pcl::PointCloud<pcl::PointXYZ> & cloud1,
        const pcl::PointCloud<pcl::PointXYZ> & cloud2)
{
        pcl::registration::TransformationEstimationSVD<pcl::PointXYZ, pcl::PointXYZ> svd;

        // Perform the alignment
        Eigen::Matrix4f matrix;
        svd.estimateRigidTransformation(cloud1, cloud2, matrix);
        return Transform::fromEigen4f(matrix);
}

// Get transform from cloud2 to cloud1
Transform transformFromXYZCorrespondences(
                const pcl::PointCloud<pcl::PointXYZ>::ConstPtr & cloud1,
                const pcl::PointCloud<pcl::PointXYZ>::ConstPtr & cloud2,
                double inlierThreshold,
                int iterations,
                int refineIterations,
                double refineSigma,
                std::vector<int> * inliersOut,
                cv::Mat * covariance)
{
        //NOTE: this method is a mix of two methods:
        //  - getRemainingCorrespondences() in pcl/registration/impl/correspondence_rejection_sample_consensus.hpp
        //  - refineModel() in pcl/sample_consensus/sac.h

        if(covariance)
        {
                *covariance = cv::Mat::eye(6,6,CV_64FC1);
        }
        Transform transform;
        if(cloud1->size() >=3 && cloud1->size() == cloud2->size())
        {
                // RANSAC
                UDEBUG("iterations=%d inlierThreshold=%f", iterations, inlierThreshold);
                std::vector<int> source_indices (cloud2->size());
                std::vector<int> target_indices (cloud1->size());

                // Copy the query-match indices
                for (int i = 0; i < (int)cloud1->size(); ++i)
                {
                        source_indices[i] = i;
                        target_indices[i] = i;
                }

                // From the set of correspondences found, attempt to remove outliers
                // Create the registration model
                pcl::SampleConsensusModelRegistration<pcl::PointXYZ>::Ptr model;
                model.reset(new pcl::SampleConsensusModelRegistration<pcl::PointXYZ>(cloud2, source_indices));
                // Pass the target_indices
                model->setInputTarget (cloud1, target_indices);
                // Create a RANSAC model
                pcl::RandomSampleConsensus<pcl::PointXYZ> sac (model, inlierThreshold);
                sac.setMaxIterations(iterations);

                // Compute the set of inliers
                if(sac.computeModel())
                {
                        std::vector<int> inliers;
                        Eigen::VectorXf model_coefficients;

                        sac.getInliers(inliers);
                        sac.getModelCoefficients (model_coefficients);

                        if (refineIterations>0)
                        {
                                double error_threshold = inlierThreshold;
                                int refine_iterations = 0;
                                bool inlier_changed = false, oscillating = false;
                                std::vector<int> new_inliers, prev_inliers = inliers;
                                std::vector<size_t> inliers_sizes;
                                Eigen::VectorXf new_model_coefficients = model_coefficients;
                                do
                                {
                                        // Optimize the model coefficients
                                        model->optimizeModelCoefficients (prev_inliers, new_model_coefficients, new_model_coefficients);
                                        inliers_sizes.push_back (prev_inliers.size ());

                                        // Select the new inliers based on the optimized coefficients and new threshold
                                        model->selectWithinDistance (new_model_coefficients, error_threshold, new_inliers);
                                        UDEBUG("RANSAC refineModel: Number of inliers found (before/after): %d/%d, with an error threshold of %f.",
                                                        (int)prev_inliers.size (), (int)new_inliers.size (), error_threshold);

                                        if (new_inliers.empty ())
                                        {
                                                ++refine_iterations;
                                                if (refine_iterations >= refineIterations)
                                                {
                                                        break;
                                                }
                                                continue;
                                        }

                                        // Estimate the variance and the new threshold
                                        double variance = model->computeVariance ();
                                        error_threshold = std::min (inlierThreshold, refineSigma * sqrt(variance));

                                        UDEBUG ("RANSAC refineModel: New estimated error threshold: %f (variance=%f) on iteration %d out of %d.",
                                                  error_threshold, variance, refine_iterations, refineIterations);
                                        inlier_changed = false;
                                        std::swap (prev_inliers, new_inliers);

                                        // If the number of inliers changed, then we are still optimizing
                                        if (new_inliers.size () != prev_inliers.size ())
                                        {
                                                // Check if the number of inliers is oscillating in between two values
                                                if (inliers_sizes.size () >= 4)
                                                {
                                                        if (inliers_sizes[inliers_sizes.size () - 1] == inliers_sizes[inliers_sizes.size () - 3] &&
                                                        inliers_sizes[inliers_sizes.size () - 2] == inliers_sizes[inliers_sizes.size () - 4])
                                                        {
                                                                oscillating = true;
                                                                break;
                                                        }
                                                }
                                                inlier_changed = true;
                                                continue;
                                        }

                                        // Check the values of the inlier set
                                        for (size_t i = 0; i < prev_inliers.size (); ++i)
                                        {
                                                // If the value of the inliers changed, then we are still optimizing
                                                if (prev_inliers[i] != new_inliers[i])
                                                {
                                                        inlier_changed = true;
                                                        break;
                                                }
                                        }
                                }
                                while (inlier_changed && ++refine_iterations < refineIterations);

                                // If the new set of inliers is empty, we didn't do a good job refining
                                if (new_inliers.empty ())
                                {
                                        UWARN ("RANSAC refineModel: Refinement failed: got an empty set of inliers!");
                                }

                                if (oscillating)
                                {
                                        UDEBUG("RANSAC refineModel: Detected oscillations in the model refinement.");
                                }

                                std::swap (inliers, new_inliers);
                                model_coefficients = new_model_coefficients;
                        }

                        if (inliers.size() >= 3)
                        {
                                if(inliersOut)
                                {
                                        *inliersOut = inliers;
                                }
                                if(covariance)
                                {
                                        double variance =  model->computeVariance();
                                        UASSERT(uIsFinite(variance));
                                        *covariance *= variance;
                                }

                                // get best transformation
                                Eigen::Matrix4f bestTransformation;
                                bestTransformation.row (0) = model_coefficients.segment<4>(0);
                                bestTransformation.row (1) = model_coefficients.segment<4>(4);
                                bestTransformation.row (2) = model_coefficients.segment<4>(8);
                                bestTransformation.row (3) = model_coefficients.segment<4>(12);

                                transform = Transform::fromEigen4f(bestTransformation);
                                UDEBUG("RANSAC inliers=%d/%d tf=%s", (int)inliers.size(), (int)cloud1->size(), transform.prettyPrint().c_str());

                                return transform.inverse(); // inverse to get actual pose transform (not correspondences transform)
                        }
                        else
                        {
                                UDEBUG("RANSAC: Model with inliers < 3");
                        }
                }
                else
                {
                        UDEBUG("RANSAC: Failed to find model");
                }
        }
        else
        {
                UDEBUG("Not enough points to compute the transform");
        }
        return Transform();
}

void computeVarianceAndCorrespondences(
                const pcl::PointCloud<pcl::PointNormal>::ConstPtr & cloudA,
                const pcl::PointCloud<pcl::PointNormal>::ConstPtr & cloudB,
                double maxCorrespondenceDistance,
                double maxCorrespondenceAngle,
                double & variance,
                int & correspondencesOut)
{
        variance = 1;
        correspondencesOut = 0;
        pcl::registration::CorrespondenceEstimation<pcl::PointNormal, pcl::PointNormal>::Ptr est;
        est.reset(new pcl::registration::CorrespondenceEstimation<pcl::PointNormal, pcl::PointNormal>);
        const pcl::PointCloud<pcl::PointNormal>::ConstPtr & target = cloudA->size()>cloudB->size()?cloudA:cloudB;
        const pcl::PointCloud<pcl::PointNormal>::ConstPtr & source = cloudA->size()>cloudB->size()?cloudB:cloudA;
        est->setInputTarget(target);
        est->setInputSource(source);
        pcl::Correspondences correspondences;
        est->determineCorrespondences(correspondences, maxCorrespondenceDistance);

        if(correspondences.size())
        {
                std::vector<double> distances(correspondences.size());
                correspondencesOut = 0;
                for(unsigned int i=0; i<correspondences.size(); ++i)
                {
                        distances[i] = correspondences[i].distance;
                        if(maxCorrespondenceAngle <= 0.0)
                        {
                                ++correspondencesOut;
                        }
                        else
                        {
                                Eigen::Vector4f v1(
                                                target->at(correspondences[i].index_match).normal_x,
                                                target->at(correspondences[i].index_match).normal_y,
                                                target->at(correspondences[i].index_match).normal_z,
                                                0);
                                Eigen::Vector4f v2(
                                                source->at(correspondences[i].index_query).normal_x,
                                                source->at(correspondences[i].index_query).normal_y,
                                                source->at(correspondences[i].index_query).normal_z,
                                                0);
                                float angle = pcl::getAngle3D(v1, v2);
                                if(angle < maxCorrespondenceAngle)
                                {
                                        ++correspondencesOut;
                                }
                        }
                }
                if(correspondencesOut)
                {
                        distances.resize(correspondencesOut);

                        //variance
                        std::sort(distances.begin (), distances.end ());
                        double median_error_sqr = distances[distances.size () >> 1];
                        variance = (2.1981 * median_error_sqr);
                }
        }
}

void computeVarianceAndCorrespondences(
                const pcl::PointCloud<pcl::PointXYZ>::ConstPtr & cloudA,
                const pcl::PointCloud<pcl::PointXYZ>::ConstPtr & cloudB,
                double maxCorrespondenceDistance,
                double & variance,
                int & correspondencesOut)
{
        variance = 1;
        correspondencesOut = 0;
        pcl::registration::CorrespondenceEstimation<pcl::PointXYZ, pcl::PointXYZ>::Ptr est;
        est.reset(new pcl::registration::CorrespondenceEstimation<pcl::PointXYZ, pcl::PointXYZ>);
        est->setInputTarget(cloudA->size()>cloudB->size()?cloudA:cloudB);
        est->setInputSource(cloudA->size()>cloudB->size()?cloudB:cloudA);
        pcl::Correspondences correspondences;
        est->determineCorrespondences(correspondences, maxCorrespondenceDistance);

        if(correspondences.size()>=3)
        {
                std::vector<double> distances(correspondences.size());
                for(unsigned int i=0; i<correspondences.size(); ++i)
                {
                        distances[i] = correspondences[i].distance;
                }

                //variance
                std::sort(distances.begin (), distances.end ());
                double median_error_sqr = distances[distances.size () >> 1];
                variance = (2.1981 * median_error_sqr);
        }

        correspondencesOut = (int)correspondences.size();
}

// return transform from source to target (All points must be finite!!!)
Transform icp(const pcl::PointCloud<pcl::PointXYZ>::ConstPtr & cloud_source,
                          const pcl::PointCloud<pcl::PointXYZ>::ConstPtr & cloud_target,
                          double maxCorrespondenceDistance,
                          int maximumIterations,
                          bool & hasConverged,
                          pcl::PointCloud<pcl::PointXYZ> & cloud_source_registered,
                          float epsilon,
                          bool icp2D)
{
        pcl::IterativeClosestPoint<pcl::PointXYZ, pcl::PointXYZ> icp;
        // Set the input source and target
        icp.setInputTarget (cloud_target);
        icp.setInputSource (cloud_source);

        if(icp2D)
        {
                pcl::registration::TransformationEstimation2D<pcl::PointXYZ, pcl::PointXYZ>::Ptr est;
                est.reset(new pcl::registration::TransformationEstimation2D<pcl::PointXYZ, pcl::PointXYZ>);
                icp.setTransformationEstimation(est);
        }

        // Set the max correspondence distance to 5cm (e.g., correspondences with higher distances will be ignored)
        icp.setMaxCorrespondenceDistance (maxCorrespondenceDistance);
        // Set the maximum number of iterations (criterion 1)
        icp.setMaximumIterations (maximumIterations);
        // Set the transformation epsilon (criterion 2)
        icp.setTransformationEpsilon (epsilon*epsilon);
        // Set the euclidean distance difference epsilon (criterion 3)
        //icp.setEuclideanFitnessEpsilon (1);
        //icp.setRANSACOutlierRejectionThreshold(maxCorrespondenceDistance);

        // Perform the alignment
        icp.align (cloud_source_registered);
        hasConverged = icp.hasConverged();
        return Transform::fromEigen4f(icp.getFinalTransformation());
}

// return transform from source to target (All points/normals must be finite!!!)
Transform icpPointToPlane(
                const pcl::PointCloud<pcl::PointNormal>::ConstPtr & cloud_source,
                const pcl::PointCloud<pcl::PointNormal>::ConstPtr & cloud_target,
                double maxCorrespondenceDistance,
                int maximumIterations,
                bool & hasConverged,
                pcl::PointCloud<pcl::PointNormal> & cloud_source_registered,
                float epsilon,
                bool icp2D)
{
        pcl::IterativeClosestPoint<pcl::PointNormal, pcl::PointNormal> icp;
        // Set the input source and target
        icp.setInputTarget (cloud_target);
        icp.setInputSource (cloud_source);

        pcl::registration::TransformationEstimationPointToPlaneLLS<pcl::PointNormal, pcl::PointNormal>::Ptr est;
        est.reset(new pcl::registration::TransformationEstimationPointToPlaneLLS<pcl::PointNormal, pcl::PointNormal>);
        icp.setTransformationEstimation(est);

        // Set the max correspondence distance to 5cm (e.g., correspondences with higher distances will be ignored)
        icp.setMaxCorrespondenceDistance (maxCorrespondenceDistance);
        // Set the maximum number of iterations (criterion 1)
        icp.setMaximumIterations (maximumIterations);
        // Set the transformation epsilon (criterion 2)
        icp.setTransformationEpsilon (epsilon*epsilon);
        // Set the euclidean distance difference epsilon (criterion 3)
        //icp.setEuclideanFitnessEpsilon (1);
        //icp.setRANSACOutlierRejectionThreshold(maxCorrespondenceDistance);

        // Perform the alignment
        icp.align (cloud_source_registered);
        hasConverged = icp.hasConverged();
        Transform t = Transform::fromEigen4f(icp.getFinalTransformation());

        if(icp2D)
        {
                // FIXME probably an estimation approach already 2D like in icp() version above exists.
                t = t.to3DoF();
        }

        return t;
}

}

}