miniflann.cpp

#include "precomp.hpp"

#define MINIFLANN_SUPPORT_EXOTIC_DISTANCE_TYPES 0

static cvflann::IndexParams& get_params(const cv::flann::IndexParams& p)
{
    return *(cvflann::IndexParams*)(p.params);
}

cv::flann::IndexParams::~IndexParams()
{
    delete &get_params(*this);
}

namespace cv
{
    
namespace flann
{

using namespace cvflann;
    
IndexParams::IndexParams()
{
    params = new ::cvflann::IndexParams();
}

template<typename T>
T getParam(const IndexParams& _p, const std::string& key, const T& defaultVal=T())
{
    ::cvflann::IndexParams& p = get_params(_p);
    ::cvflann::IndexParams::const_iterator it = p.find(key);
    if( it == p.end() )
        return defaultVal;
    return it->second.cast<T>();
}

template<typename T>
void setParam(IndexParams& _p, const std::string& key, const T& value)
{
    ::cvflann::IndexParams& p = get_params(_p);
    p[key] = value;
}    
    
std::string IndexParams::getString(const std::string& key, const std::string& defaultVal) const
{
    return getParam(*this, key, defaultVal);
}
    
int IndexParams::getInt(const std::string& key, int defaultVal) const
{
    return getParam(*this, key, defaultVal);
}
    
double IndexParams::getDouble(const std::string& key, double defaultVal) const
{
    return getParam(*this, key, defaultVal);
}

    
void IndexParams::setString(const std::string& key, const std::string& value)
{
    setParam(*this, key, value);
}

void IndexParams::setInt(const std::string& key, int value)
{
    setParam(*this, key, value);
}

void IndexParams::setDouble(const std::string& key, double value)
{
    setParam(*this, key, value);
}

void IndexParams::setFloat(const std::string& key, float value)
{
    setParam(*this, key, value);
}

void IndexParams::setBool(const std::string& key, bool value)
{
    setParam(*this, key, value);
}

void IndexParams::setAlgorithm(int value)
{
    setParam(*this, "algorithm", (cvflann::flann_algorithm_t)value);
}
    
void IndexParams::getAll(std::vector<std::string>& names,
            std::vector<int>& types,
            std::vector<std::string>& strValues,
            std::vector<double>& numValues) const
{
    names.clear();
    types.clear();
    strValues.clear();
    numValues.clear();
    
    ::cvflann::IndexParams& p = get_params(*this);
    ::cvflann::IndexParams::const_iterator it = p.begin(), it_end = p.end();
    
    for( ; it != it_end; ++it )
    {
        names.push_back(it->first);
        try
        {
            std::string val = it->second.cast<std::string>();
            types.push_back(CV_USRTYPE1);
            strValues.push_back(val);
            numValues.push_back(-1);
	    continue;
        }
        catch (...) {}
        
        strValues.push_back(it->second.type().name());
        
        try
        {
            double val = it->second.cast<double>();
            types.push_back( CV_64F );
            numValues.push_back(val);
	    continue;
        }
        catch (...) {}
        try
        {
            float val = it->second.cast<float>();
            types.push_back( CV_32F );
            numValues.push_back(val);
	    continue;
        }
        catch (...) {}
        try
        {
            int val = it->second.cast<int>();
            types.push_back( CV_32S );
            numValues.push_back(val);
	    continue;
        }
        catch (...) {}
        try
        {
            short val = it->second.cast<short>();
            types.push_back( CV_16S );
            numValues.push_back(val);
	    continue;
        }
        catch (...) {}
        try
        {
            ushort val = it->second.cast<ushort>();
            types.push_back( CV_16U );
            numValues.push_back(val);
	    continue;
        }
        catch (...) {}
        try
        {
            char val = it->second.cast<char>();
            types.push_back( CV_8S );
            numValues.push_back(val);
	    continue;
        }
        catch (...) {}
        try
        {
            uchar val = it->second.cast<uchar>();
            types.push_back( CV_8U );
            numValues.push_back(val);
	    continue;
        }
        catch (...) {}
        try
        {
            bool val = it->second.cast<bool>();
            types.push_back( CV_MAKETYPE(CV_USRTYPE1,2) );
            numValues.push_back(val);
	    continue;
        }
        catch (...) {}
        try
        {
            cvflann::flann_algorithm_t val = it->second.cast<cvflann::flann_algorithm_t>();
            types.push_back( CV_MAKETYPE(CV_USRTYPE1,3) );
            numValues.push_back(val);
	    continue;
        }
        catch (...) {}


        types.push_back(-1); // unknown type
        numValues.push_back(-1);
    }
}
    
    
KDTreeIndexParams::KDTreeIndexParams(int trees)
{
    ::cvflann::IndexParams& p = get_params(*this);
    p["algorithm"] = FLANN_INDEX_KDTREE;
    p["trees"] = trees;
}

LinearIndexParams::LinearIndexParams()
{
    ::cvflann::IndexParams& p = get_params(*this);
    p["algorithm"] = FLANN_INDEX_LINEAR;
}

CompositeIndexParams::CompositeIndexParams(int trees, int branching, int iterations,
                             flann_centers_init_t centers_init, float cb_index )
{
    ::cvflann::IndexParams& p = get_params(*this);
    p["algorithm"] = FLANN_INDEX_KMEANS;
    // number of randomized trees to use (for kdtree)
    p["trees"] = trees;
    // branching factor
    p["branching"] = branching;
    // max iterations to perform in one kmeans clustering (kmeans tree)
    p["iterations"] = iterations;
    // algorithm used for picking the initial cluster centers for kmeans tree
    p["centers_init"] = centers_init;
    // cluster boundary index. Used when searching the kmeans tree
    p["cb_index"] = cb_index;
}
    
AutotunedIndexParams::AutotunedIndexParams(float target_precision, float build_weight,
                                           float memory_weight, float sample_fraction)
{
    ::cvflann::IndexParams& p = get_params(*this);
    p["algorithm"] = FLANN_INDEX_AUTOTUNED;
    // precision desired (used for autotuning, -1 otherwise)
    p["target_precision"] = target_precision;
    // build tree time weighting factor
    p["build_weight"] = build_weight;
    // index memory weighting factor
    p["memory_weight"] = memory_weight;
    // what fraction of the dataset to use for autotuning
    p["sample_fraction"] = sample_fraction;
}
    

KMeansIndexParams::KMeansIndexParams(int branching, int iterations,
                  flann_centers_init_t centers_init, float cb_index )
{
    ::cvflann::IndexParams& p = get_params(*this);
    p["algorithm"] = FLANN_INDEX_KMEANS;
    // branching factor
    p["branching"] = branching;
    // max iterations to perform in one kmeans clustering (kmeans tree)
    p["iterations"] = iterations;
    // algorithm used for picking the initial cluster centers for kmeans tree
    p["centers_init"] = centers_init;
    // cluster boundary index. Used when searching the kmeans tree
    p["cb_index"] = cb_index;
}
    
LshIndexParams::LshIndexParams(int table_number, int key_size, int multi_probe_level)
{
    ::cvflann::IndexParams& p = get_params(*this);
    p["algorithm"] = FLANN_INDEX_LSH;
    // The number of hash tables to use
    p["table_number"] = (unsigned)table_number;
    // The length of the key in the hash tables
    p["key_size"] = (unsigned)key_size;
    // Number of levels to use in multi-probe (0 for standard LSH)
    p["multi_probe_level"] = (unsigned)multi_probe_level;
}    
    
SavedIndexParams::SavedIndexParams(const std::string& _filename)
{
    std::string filename = _filename;
    ::cvflann::IndexParams& p = get_params(*this);
    
    p["algorithm"] = FLANN_INDEX_SAVED;
    p["filename"] = filename;
}
    
SearchParams::SearchParams( int checks, float eps, bool sorted )
{
    ::cvflann::IndexParams& p = get_params(*this);
    
    // how many leafs to visit when searching for neighbours (-1 for unlimited)
    p["checks"] = checks;
    // search for eps-approximate neighbours (default: 0)
    p["eps"] = eps;
    // only for radius search, require neighbours sorted by distance (default: true)
    p["sorted"] = sorted;
}    

    
template<typename Distance, typename IndexType> void
buildIndex_(void*& index, const Mat& data, const IndexParams& params, const Distance& dist = Distance())
{
    typedef typename Distance::ElementType ElementType;
    if(DataType<ElementType>::type != data.type())
        CV_Error_(CV_StsUnsupportedFormat, ("type=%d\n", data.type()));
    if(!data.isContinuous())
        CV_Error(CV_StsBadArg, "Only continuous arrays are supported");
    
    ::cvflann::Matrix<ElementType> dataset((ElementType*)data.data, data.rows, data.cols);
    IndexType* _index = new IndexType(dataset, get_params(params), dist);
    _index->buildIndex();
    index = _index;
}

template<typename Distance> void
buildIndex(void*& index, const Mat& data, const IndexParams& params, const Distance& dist = Distance())
{
    buildIndex_<Distance, ::cvflann::Index<Distance> >(index, data, params, dist);
}

#if CV_NEON
typedef ::cvflann::Hamming<uchar> HammingDistance;
#else
typedef ::cvflann::HammingLUT HammingDistance;
#endif
typedef ::cvflann::LshIndex<HammingDistance> LshIndex;

Index::Index()
{
    index = 0;
    featureType = CV_32F;
    algo = FLANN_INDEX_LINEAR;
    distType = FLANN_DIST_L2;
}
    
Index::Index(InputArray _data, const IndexParams& params, flann_distance_t _distType)
{
    index = 0;
    featureType = CV_32F;
    algo = FLANN_INDEX_LINEAR;
    distType = FLANN_DIST_L2;
    build(_data, params, _distType);
}
    
void Index::build(InputArray _data, const IndexParams& params, flann_distance_t _distType)
{
    release();
    algo = getParam<flann_algorithm_t>(params, "algorithm", FLANN_INDEX_LINEAR);
    if( algo == FLANN_INDEX_SAVED )
    {
        load(_data, getParam<std::string>(params, "filename", std::string()));
        return;
    }
    
    Mat data = _data.getMat();
    index = 0;
    featureType = data.type();
    distType = _distType;

    if( algo == FLANN_INDEX_LSH )
    {
        buildIndex_<HammingDistance, LshIndex>(index, data, params);
        return;
    }
    
    switch( distType )
    {
    case FLANN_DIST_L2:
        buildIndex< ::cvflann::L2<float> >(index, data, params);
        break;
    case FLANN_DIST_L1:
        buildIndex< ::cvflann::L1<float> >(index, data, params);
        break;
#if MINIFLANN_SUPPORT_EXOTIC_DISTANCE_TYPES
    case FLANN_DIST_MAX:
        buildIndex< ::cvflann::MaxDistance<float> >(index, data, params);
        break;
    case FLANN_DIST_HIST_INTERSECT:
        buildIndex< ::cvflann::HistIntersectionDistance<float> >(index, data, params);
        break;
    case FLANN_DIST_HELLINGER:
        buildIndex< ::cvflann::HellingerDistance<float> >(index, data, params);
        break;
    case FLANN_DIST_CHI_SQUARE:
        buildIndex< ::cvflann::ChiSquareDistance<float> >(index, data, params);
        break;
    case FLANN_DIST_KL:
        buildIndex< ::cvflann::KL_Divergence<float> >(index, data, params);
        break;
#endif
    default:
        CV_Error(CV_StsBadArg, "Unknown/unsupported distance type");
    }
}

template<typename IndexType> void deleteIndex_(void* index)
{
    delete (IndexType*)index;
}

template<typename Distance> void deleteIndex(void* index)
{
    deleteIndex_< ::cvflann::Index<Distance> >(index);
}
    
Index::~Index()
{
    release();
}
    
void Index::release()
{
    if( !index )
        return;
    if( algo == FLANN_INDEX_LSH )
    {
        deleteIndex_<LshIndex>(index);
    }
    else
    {
        CV_Assert( featureType == CV_32F );
        switch( distType )
        {
        case FLANN_DIST_L2:
            deleteIndex< ::cvflann::L2<float> >(index);
            break;
        case FLANN_DIST_L1:
            deleteIndex< ::cvflann::L1<float> >(index);
            break;
#if MINIFLANN_SUPPORT_EXOTIC_DISTANCE_TYPES
        case FLANN_DIST_MAX:
            deleteIndex< ::cvflann::MaxDistance<float> >(index);
            break;
        case FLANN_DIST_HIST_INTERSECT:
            deleteIndex< ::cvflann::HistIntersectionDistance<float> >(index);
            break;
        case FLANN_DIST_HELLINGER:
            deleteIndex< ::cvflann::HellingerDistance<float> >(index);
            break;
        case FLANN_DIST_CHI_SQUARE:
            deleteIndex< ::cvflann::ChiSquareDistance<float> >(index);
            break;
        case FLANN_DIST_KL:
            deleteIndex< ::cvflann::KL_Divergence<float> >(index);
            break;
#endif
        default:
            CV_Error(CV_StsBadArg, "Unknown/unsupported distance type");
        }
    }
    index = 0;
}

template<typename Distance, typename IndexType>
void runKnnSearch_(void* index, const Mat& query, Mat& indices, Mat& dists,
                  int knn, const SearchParams& params)
{
    typedef typename Distance::ElementType ElementType;
    typedef typename Distance::ResultType DistanceType;
    int type = DataType<ElementType>::type;
    int dtype = DataType<DistanceType>::type;
    CV_Assert(query.type() == type && indices.type() == CV_32S && dists.type() == dtype);
    CV_Assert(query.isContinuous() && indices.isContinuous() && dists.isContinuous());
    
    ::cvflann::Matrix<ElementType> _query((ElementType*)query.data, query.rows, query.cols);
    ::cvflann::Matrix<int> _indices((int*)indices.data, indices.rows, indices.cols);
    ::cvflann::Matrix<DistanceType> _dists((DistanceType*)dists.data, dists.rows, dists.cols);
    
    ((IndexType*)index)->knnSearch(_query, _indices, _dists, knn,
                                   (const ::cvflann::SearchParams&)get_params(params));
}
    
template<typename Distance>
void runKnnSearch(void* index, const Mat& query, Mat& indices, Mat& dists,
                  int knn, const SearchParams& params)
{
    runKnnSearch_<Distance, ::cvflann::Index<Distance> >(index, query, indices, dists, knn, params);
}

template<typename Distance, typename IndexType>
int runRadiusSearch_(void* index, const Mat& query, Mat& indices, Mat& dists,
                    double radius, const SearchParams& params)
{
    typedef typename Distance::ElementType ElementType;
    typedef typename Distance::ResultType DistanceType;
    int type = DataType<ElementType>::type;
    int dtype = DataType<DistanceType>::type;
    CV_Assert(query.type() == type && indices.type() == CV_32S && dists.type() == dtype);
    CV_Assert(query.isContinuous() && indices.isContinuous() && dists.isContinuous());
    
    ::cvflann::Matrix<ElementType> _query((ElementType*)query.data, query.rows, query.cols);
    ::cvflann::Matrix<int> _indices((int*)indices.data, indices.rows, indices.cols);
    ::cvflann::Matrix<DistanceType> _dists((DistanceType*)dists.data, dists.rows, dists.cols);
    
    return ((IndexType*)index)->radiusSearch(_query, _indices, _dists,
                                            saturate_cast<DistanceType>(radius),
                                            (const ::cvflann::SearchParams&)get_params(params));
}

template<typename Distance>
int runRadiusSearch(void* index, const Mat& query, Mat& indices, Mat& dists,
                     double radius, const SearchParams& params)
{
    return runRadiusSearch_<Distance, ::cvflann::Index<Distance> >(index, query, indices, dists, radius, params);
}
        
    
static void createIndicesDists(OutputArray _indices, OutputArray _dists,
                               Mat& indices, Mat& dists, int rows,
                               int minCols, int maxCols, int dtype)
{
    if( _indices.needed() )
    {
        indices = _indices.getMat();
        if( !indices.isContinuous() || indices.type() != CV_32S ||
            indices.rows != rows || indices.cols < minCols || indices.cols > maxCols )
        {
            if( !indices.isContinuous() )
               _indices.release();
            _indices.create( rows, minCols, CV_32S );
            indices = _indices.getMat();
        }
    }
    else
        indices.create( rows, minCols, CV_32S );
    
    if( _dists.needed() )
    {
        dists = _dists.getMat();
        if( !dists.isContinuous() || dists.type() != dtype ||
           dists.rows != rows || dists.cols < minCols || dists.cols > maxCols )
        {
            if( !indices.isContinuous() )
                _dists.release();
            _dists.create( rows, minCols, dtype );
            dists = _dists.getMat();
        }
    }
    else
        dists.create( rows, minCols, dtype );
}

    
void Index::knnSearch(InputArray _query, OutputArray _indices, 
               OutputArray _dists, int knn, const SearchParams& params)
{
    Mat query = _query.getMat(), indices, dists;
    int dtype = algo == FLANN_INDEX_LSH ? CV_32S : CV_32F;
    
    createIndicesDists( _indices, _dists, indices, dists, query.rows, knn, knn, dtype );
    
    if( algo == FLANN_INDEX_LSH )
    {
        runKnnSearch_<HammingDistance, LshIndex>(index, query, indices, dists, knn, params);
        return;
    }
    
    switch( distType )
    {
    case FLANN_DIST_L2:
        runKnnSearch< ::cvflann::L2<float> >(index, query, indices, dists, knn, params);
        break;
    case FLANN_DIST_L1:
        runKnnSearch< ::cvflann::L1<float> >(index, query, indices, dists, knn, params);
        break;
#if MINIFLANN_SUPPORT_EXOTIC_DISTANCE_TYPES
    case FLANN_DIST_MAX:
        runKnnSearch< ::cvflann::MaxDistance<float> >(index, query, indices, dists, knn, params);
        break;
    case FLANN_DIST_HIST_INTERSECT:
        runKnnSearch< ::cvflann::HistIntersectionDistance<float> >(index, query, indices, dists, knn, params);
        break;
    case FLANN_DIST_HELLINGER:
        runKnnSearch< ::cvflann::HellingerDistance<float> >(index, query, indices, dists, knn, params);
        break;
    case FLANN_DIST_CHI_SQUARE:
        runKnnSearch< ::cvflann::ChiSquareDistance<float> >(index, query, indices, dists, knn, params);
        break;
    case FLANN_DIST_KL:
        runKnnSearch< ::cvflann::KL_Divergence<float> >(index, query, indices, dists, knn, params);
        break;
#endif
    default:
        CV_Error(CV_StsBadArg, "Unknown/unsupported distance type");
    }
}
        
int Index::radiusSearch(InputArray _query, OutputArray _indices,
                        OutputArray _dists, double radius, int maxResults,
                        const SearchParams& params)
{
    Mat query = _query.getMat(), indices, dists;
    int dtype = algo == FLANN_INDEX_LSH ? CV_32S : CV_32F;
    CV_Assert( maxResults > 0 );
    createIndicesDists( _indices, _dists, indices, dists, query.rows, maxResults, INT_MAX, dtype );
    
    if( algo == FLANN_INDEX_LSH )
        CV_Error( CV_StsNotImplemented, "LSH index does not support radiusSearch operation" );
    
    switch( distType )
    {
    case FLANN_DIST_L2:
        return runRadiusSearch< ::cvflann::L2<float> >(index, query, indices, dists, radius, params);
    case FLANN_DIST_L1:
        return runRadiusSearch< ::cvflann::L1<float> >(index, query, indices, dists, radius, params);
#if MINIFLANN_SUPPORT_EXOTIC_DISTANCE_TYPES
    case FLANN_DIST_MAX:
        return runRadiusSearch< ::cvflann::MaxDistance<float> >(index, query, indices, dists, radius, params);
    case FLANN_DIST_HIST_INTERSECT:
        return runRadiusSearch< ::cvflann::HistIntersectionDistance<float> >(index, query, indices, dists, radius, params);
    case FLANN_DIST_HELLINGER:
        return runRadiusSearch< ::cvflann::HellingerDistance<float> >(index, query, indices, dists, radius, params);
    case FLANN_DIST_CHI_SQUARE:
        return runRadiusSearch< ::cvflann::ChiSquareDistance<float> >(index, query, indices, dists, radius, params);
    case FLANN_DIST_KL:
        return runRadiusSearch< ::cvflann::KL_Divergence<float> >(index, query, indices, dists, radius, params);
#endif
    default:
        CV_Error(CV_StsBadArg, "Unknown/unsupported distance type");
    }
    return -1;
}

flann_distance_t Index::getDistance() const
{
    return distType;
}
    
flann_algorithm_t Index::getAlgorithm() const
{
    return algo;
}

template<typename IndexType> void saveIndex_(const Index* index0, const void* index, FILE* fout)
{
    IndexType* _index = (IndexType*)index;
    ::cvflann::save_header(fout, *_index);
    // some compilers may store short enumerations as bytes,
    // so make sure we always write integers (which are 4-byte values in any modern C compiler)
    int idistType = (int)index0->getDistance();
    ::cvflann::save_value<int>(fout, idistType);
    _index->saveIndex(fout);
}

template<typename Distance> void saveIndex(const Index* index0, const void* index, FILE* fout)
{
    saveIndex_< ::cvflann::Index<Distance> >(index0, index, fout);
}   
    
void Index::save(const std::string& filename) const
{
    FILE* fout = fopen(filename.c_str(), "wb");
    if (fout == NULL)
        CV_Error_( CV_StsError, ("Can not open file %s for writing FLANN index\n", filename.c_str()) );
    
    if( algo == FLANN_INDEX_LSH )
    {
        saveIndex_<LshIndex>(this, index, fout);
        fclose(fout);
        return;
    }
    
    switch( distType )
    {
    case FLANN_DIST_L2:
        saveIndex< ::cvflann::L2<float> >(this, index, fout);
        break;
    case FLANN_DIST_L1:
        saveIndex< ::cvflann::L1<float> >(this, index, fout);
        break;
#if MINIFLANN_SUPPORT_EXOTIC_DISTANCE_TYPES
    case FLANN_DIST_MAX:
        saveIndex< ::cvflann::MaxDistance<float> >(this, index, fout);
        break;
    case FLANN_DIST_HIST_INTERSECT:
        saveIndex< ::cvflann::HistIntersectionDistance<float> >(this, index, fout);
        break;
    case FLANN_DIST_HELLINGER:
        saveIndex< ::cvflann::HellingerDistance<float> >(this, index, fout);
        break;
    case FLANN_DIST_CHI_SQUARE:
        saveIndex< ::cvflann::ChiSquareDistance<float> >(this, index, fout);
        break;
    case FLANN_DIST_KL:
        saveIndex< ::cvflann::KL_Divergence<float> >(this, index, fout);
        break;
#endif
    default:
        fclose(fout);
        fout = 0;
        CV_Error(CV_StsBadArg, "Unknown/unsupported distance type");
    }
    if( fout )
        fclose(fout);
}


template<typename Distance, typename IndexType>
bool loadIndex_(Index* index0, void*& index, const Mat& data, FILE* fin, const Distance& dist=Distance())
{
    typedef typename Distance::ElementType ElementType;
    CV_Assert(DataType<ElementType>::type == data.type() && data.isContinuous());
    
    ::cvflann::Matrix<ElementType> dataset((ElementType*)data.data, data.rows, data.cols);
    
    ::cvflann::IndexParams params;
    params["algorithm"] = index0->getAlgorithm();
    IndexType* _index = new IndexType(dataset, params, dist);
    _index->loadIndex(fin);
    index = _index;
    return true;
}

template<typename Distance>
bool loadIndex(Index* index0, void*& index, const Mat& data, FILE* fin, const Distance& dist=Distance())
{
    return loadIndex_<Distance, ::cvflann::Index<Distance> >(index0, index, data, fin, dist);
}    
    
bool Index::load(InputArray _data, const std::string& filename)
{
    Mat data = _data.getMat();
    bool ok = true;
    release();
    FILE* fin = fopen(filename.c_str(), "rb");
    if (fin == NULL)
        return false;
    
    ::cvflann::IndexHeader header = ::cvflann::load_header(fin);
    algo = header.index_type;
    featureType = header.data_type == FLANN_UINT8 ? CV_8U :
                  header.data_type == FLANN_INT8 ? CV_8S :
                  header.data_type == FLANN_UINT16 ? CV_16U :
                  header.data_type == FLANN_INT16 ? CV_16S :
                  header.data_type == FLANN_INT32 ? CV_32S :
                  header.data_type == FLANN_FLOAT32 ? CV_32F :
                  header.data_type == FLANN_FLOAT64 ? CV_64F : -1;
    
    if( (int)header.rows != data.rows || (int)header.cols != data.cols ||
        featureType != data.type() )
    {
        fprintf(stderr, "Reading FLANN index error: the saved data size (%d, %d) or type (%d) is different from the passed one (%d, %d), %d\n",
                (int)header.rows, (int)header.cols, featureType, data.rows, data.cols, data.type());
        fclose(fin);
        return false;
    }
    
    if( !((algo == FLANN_INDEX_LSH && featureType == CV_8U) ||
          (algo != FLANN_INDEX_LSH && featureType == CV_32F)) )
    {
        fprintf(stderr, "Reading FLANN index error: unsupported feature type %d for the index type %d\n", featureType, algo);
        fclose(fin);
        return false;
    }
    int idistType = 0;
    ::cvflann::load_value(fin, idistType);
    distType = (flann_distance_t)idistType;
    
    if( algo == FLANN_INDEX_LSH )
    {
        loadIndex_<HammingDistance, LshIndex>(this, index, data, fin);
    }
    else
    {
        switch( distType )
        {
        case FLANN_DIST_L2:
            loadIndex< ::cvflann::L2<float> >(this, index, data, fin);
            break;
        case FLANN_DIST_L1:
            loadIndex< ::cvflann::L1<float> >(this, index, data, fin);
            break;
    #if MINIFLANN_SUPPORT_EXOTIC_DISTANCE_TYPES
        case FLANN_DIST_MAX:
            loadIndex< ::cvflann::MaxDistance<float> >(this, index, data, fin);
            break;
        case FLANN_DIST_HIST_INTERSECT:
            loadIndex< ::cvflann::HistIntersectionDistance<float> >(index, data, fin);
            break;
        case FLANN_DIST_HELLINGER:
            loadIndex< ::cvflann::HellingerDistance<float> >(this, index, data, fin);
            break;
        case FLANN_DIST_CHI_SQUARE:
            loadIndex< ::cvflann::ChiSquareDistance<float> >(this, index, data, fin);
            break;
        case FLANN_DIST_KL:
            loadIndex< ::cvflann::KL_Divergence<float> >(this, index, data, fin);
            break;
    #endif
        default:
            fprintf(stderr, "Reading FLANN index error: unsupported distance type %d\n", distType);
            ok = false;
        }
    }
    
    if( fin )
        fclose(fin);
    return ok;
}
    
}
    
}