MaxDensity.cpp

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// kate: replace-tabs off; indent-width 4; indent-mode normal
// vim: ts=4:sw=4:noexpandtab
/*

Copyright (c) 2010--2018,
François Pomerleau and Stephane Magnenat, ASL, ETHZ, Switzerland
You can contact the authors at <f dot pomerleau at gmail dot com> and
<stephane at magnenat dot net>

All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
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      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

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*/
#include "MaxDensity.h"

// MaxDensityDataPointsFilter
// Constructor
template<typename T>
MaxDensityDataPointsFilter<T>::MaxDensityDataPointsFilter(const Parameters& params):
        PointMatcher<T>::DataPointsFilter("MaxDensityDataPointsFilter", 
                MaxDensityDataPointsFilter::availableParameters(), params),
        maxDensity(Parametrizable::get<T>("maxDensity"))
{
}

// Compute
template<typename T>
typename PointMatcher<T>::DataPoints MaxDensityDataPointsFilter<T>::filter(
        const DataPoints& input)
{
        DataPoints output(input);
        inPlaceFilter(output);
        return output;
}

// In-place filter
template<typename T>
void MaxDensityDataPointsFilter<T>::inPlaceFilter(
        DataPoints& cloud)
{
        typedef typename DataPoints::View View;

        // Force densities to be computed
        if (!cloud.descriptorExists("densities"))
        {
                throw InvalidField("MaxDensityDataPointsFilter: Error, no densities found in descriptors.");
        }

        const int nbPointsIn = cloud.features.cols();
        View densities = cloud.getDescriptorViewByName("densities");
        const T lastDensity = densities.maxCoeff();
        const int nbSaturatedPts = (densities.array() == lastDensity).count();

        // fill cloud values
        int j = 0;
        for (int i = 0; i < nbPointsIn; ++i)
        {
                const T density(densities(0,i));
                if (density > maxDensity)
                {
                        const float r = (float)std::rand()/(float)RAND_MAX;
                        float acceptRatio = maxDensity/density;

                        // Handle saturation value of density
                        if (density == lastDensity)
                        {
                                acceptRatio = acceptRatio * (1-nbSaturatedPts/nbPointsIn);
                        }

                        if (r < acceptRatio)
                        {
                                cloud.setColFrom(j, cloud, i);
                                ++j;
                        }
                }
                else
                {
                        cloud.setColFrom(j, cloud, i);
                        ++j;
                }
        }

        cloud.conservativeResize(j);
}

template struct MaxDensityDataPointsFilter<float>;
template struct MaxDensityDataPointsFilter<double>;