CloudCompare——统计滤波

1.统计滤波

算法原理见：PCL 统计滤波器。

2.软件实现

参数设置
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3.完整操作

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4.算法源码

ReferenceCloud* CloudSamplingTools::sorFilter(	GenericIndexedCloudPersist* inputCloud,int knn/*=6*/,double nSigma/*=1.0*/,DgmOctree* inputOctree/*=0*/,GenericProgressCallback* progressCb/*=0*/)
{if (!inputCloud || knn <= 0 || inputCloud->size() <= static_cast<unsigned>(knn)){//invalid inputassert(false);return nullptr;}DgmOctree* octree = inputOctree;if (!octree){//compute the octree if necessaryoctree = new DgmOctree(inputCloud);if (octree->build(progressCb) < 1){delete octree;return nullptr;}}//outputReferenceCloud* filteredCloud = nullptr;for (unsigned step = 0; step < 1; ++step) //fake loop for easy break{unsigned pointCount = inputCloud->size();std::vector<PointCoordinateType> meanDistances;try{meanDistances.resize(pointCount, 0);}catch (const std::bad_alloc&){//not enough memorybreak;}double avgDist = 0;double stdDev = 0;//1st step: compute the average distance to the neighbors{//additional parametersvoid* additionalParameters[] = {reinterpret_cast<void*>(&knn),reinterpret_cast<void*>(&meanDistances)};unsigned char octreeLevel = octree->findBestLevelForAGivenPopulationPerCell(knn);if (octree->executeFunctionForAllCellsAtLevel(	octreeLevel,&applySORFilterAtLevel,additionalParameters,true,progressCb,"SOR filter") == 0){//something went wrongbreak;}//deduce the average distance and std. dev.double sumDist = 0;double sumSquareDist = 0;for (unsigned i = 0; i < pointCount; ++i){sumDist += meanDistances[i];sumSquareDist += meanDistances[i] * meanDistances[i];}avgDist = sumDist / pointCount;stdDev = sqrt(std::abs(sumSquareDist / pointCount - avgDist*avgDist));}//2nd step: remove the farthest points {//deduce the max distancedouble maxDist = avgDist + nSigma * stdDev;filteredCloud = new ReferenceCloud(inputCloud);if (!filteredCloud->reserve(pointCount)){//not enough memorydelete filteredCloud;filteredCloud = nullptr;break;}for (unsigned i = 0; i < pointCount; ++i){if (meanDistances[i] <= maxDist){filteredCloud->addPointIndex(i);}}filteredCloud->resize(filteredCloud->size());}}if (!inputOctree){delete octree;octree = nullptr;}return filteredCloud;
}