From: Pierre-Emmanuel Viel
Date: Tue, 20 May 2014 20:52:11 +0000 (+0200)
Subject: Allows to choose orthogonal sub-vectors for LSH without using a static table among...
X-Git-Tag: accepted/tizen/6.0/unified/20201030.111113~1314^2~457^2~2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e63d7de87c3565555e4a73220a465ed39488160d;p=platform%2Fupstream%2Fopencv.git
Allows to choose orthogonal sub-vectors for LSH without using a static table among LshTable instances
---
diff --git a/modules/flann/include/opencv2/flann/lsh_index.h b/modules/flann/include/opencv2/flann/lsh_index.h
index 4d4670e..2530a01 100644
--- a/modules/flann/include/opencv2/flann/lsh_index.h
+++ b/modules/flann/include/opencv2/flann/lsh_index.h
@@ -109,10 +109,22 @@ public:
*/
void buildIndex()
{
+ std::vector indices(feature_size_ * CHAR_BIT);
+
tables_.resize(table_number_);
for (unsigned int i = 0; i < table_number_; ++i) {
+
+ //re-initialize the random indices table that the LshTable will use to pick its sub-dimensions
+ if( (indices.size() == feature_size_ * CHAR_BIT) || (indices.size() < key_size_) )
+ {
+ indices.resize( feature_size_ * CHAR_BIT );
+ for (size_t i = 0; i < feature_size_ * CHAR_BIT; ++i)
+ indices[i] = i;
+ std::random_shuffle(indices.begin(), indices.end());
+ }
+
lsh::LshTable& table = tables_[i];
- table = lsh::LshTable(feature_size_, key_size_);
+ table = lsh::LshTable(feature_size_, key_size_, indices);
// Add the features to the table
table.add(dataset_);
diff --git a/modules/flann/include/opencv2/flann/lsh_table.h b/modules/flann/include/opencv2/flann/lsh_table.h
index 18fb139..f6e68dc 100644
--- a/modules/flann/include/opencv2/flann/lsh_table.h
+++ b/modules/flann/include/opencv2/flann/lsh_table.h
@@ -153,7 +153,7 @@ public:
* @param feature_size is the size of the feature (considered as a ElementType[])
* @param key_size is the number of bits that are turned on in the feature
*/
- LshTable(unsigned int /*feature_size*/, unsigned int /*key_size*/)
+ LshTable(unsigned int /*feature_size*/, unsigned int /*key_size*/, std::vector & /*indices*/)
{
std::cerr << "LSH is not implemented for that type" << std::endl;
assert(0);
@@ -341,34 +341,20 @@ private:
// Specialization for unsigned char
template<>
-inline LshTable::LshTable(unsigned int feature_size, unsigned int subsignature_size)
+inline LshTable::LshTable( unsigned int feature_size,
+ unsigned int subsignature_size,
+ std::vector & indices )
{
initialize(subsignature_size);
// Allocate the mask
mask_ = std::vector((size_t)ceil((float)(feature_size * sizeof(char)) / (float)sizeof(size_t)), 0);
- // A bit brutal but fast to code
- static std::vector* indices = NULL;
-
- //Ensure the Nth bit will be selected only once among the different LshTables
- //to avoid having two different tables with signatures sharing many dimensions/many bits
- if( indices == NULL )
- {
- indices = new std::vector( feature_size * CHAR_BIT );
- }
- else if( indices->size() < key_size_ )
- {
- indices->resize( feature_size * CHAR_BIT );
- for (size_t i = 0; i < feature_size * CHAR_BIT; ++i) {
- (*indices)[i] = i;
- }
- std::random_shuffle(indices->begin(), indices->end());
- }
-
// Generate a random set of order of subsignature_size_ bits
for (unsigned int i = 0; i < key_size_; ++i) {
- size_t index = (*indices)[0];
- indices->erase( indices->begin() );
+ //Ensure the Nth bit will be selected only once among the different LshTables
+ //to avoid having two different tables with signatures sharing many dimensions/many bits
+ size_t index = indices[0];
+ indices.erase( indices.begin() );
// Set that bit in the mask
size_t divisor = CHAR_BIT * sizeof(size_t);