MaxPointCount.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:
    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of the <organization> nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL ETH-ASL BE LIABLE FOR ANY
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*/
#include "MaxPointCount.h"

// MaxPointCountDataPointsFilter
// Constructor
template<typename T>
MaxPointCountDataPointsFilter<T>::MaxPointCountDataPointsFilter(const Parameters& params):
        PointMatcher<T>::DataPointsFilter("MaxPointCountDataPointsFilter", 
                MaxPointCountDataPointsFilter::availableParameters(), params),
        maxCount(Parametrizable::get<size_t>("maxCount"))
{
        try 
        {
                seed = this->template get<size_t>("seed");
        } 
        catch (const InvalidParameter& e) 
        {
                seed = static_cast<size_t>(1); // rand default seed number
        }
}

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

// In-place filter
template<typename T>
void MaxPointCountDataPointsFilter<T>::inPlaceFilter(DataPoints& cloud)
{
        const size_t N = static_cast<size_t> (cloud.features.cols() - 1);
        
        if (maxCount <= N) 
        {
                //Re-init seed at each call, to ensure same results
                std::srand(seed);
                
                for(size_t j=0; j<maxCount; ++j)
                {
                        //Get a random index in [j; N]
                        const size_t idx = j + static_cast<size_t>((N-j)*(static_cast<float>(std::rand()/static_cast<float>(RAND_MAX))));
                        
                        //Switch columns j and idx
                        const auto feat = cloud.features.col(j);
                        cloud.features.col(j) = cloud.features.col(idx);
                        cloud.features.col(idx) = feat;
                        
                        if (cloud.descriptors.cols() > 0)
                        {
                                const auto desc = cloud.descriptors.col(j);
                                cloud.descriptors.col(j) = cloud.descriptors.col(idx);
                                cloud.descriptors.col(idx) = desc;
                        }
                        if (cloud.times.cols() > 0)
                        {
                                const auto time = cloud.times.col(j);
                                cloud.times.col(j) = cloud.times.col(idx);
                                cloud.times.col(idx) = time;
                        }       
                }
                //Resize the cloud
                cloud.conservativeResize(maxCount);
        }
}

template struct MaxPointCountDataPointsFilter<float>;
template struct MaxPointCountDataPointsFilter<double>;