[popsift] configuration to ignore edge and peak thresholds

Author: Carsten Griwodz

src/application/main.cpp

@@ -74,13 +74,13 @@ static void parseargs(int argc, char** argv, popsift::Config& config, string& in
              "Initial sigma value")
             ("threshold",
              value<float>()->notifier([&](float f) { config.setThreshold(f); })->default_value(config.getThreshold()),
-             "Contrast threshold")
+             popsift::Config::getPeakThreshUsage().c_str() )
             ("edge-threshold",
              value<float>()->notifier([&](float f) { config.setEdgeLimit(f); })->default_value(config.getEdgeLimit()),
-             "On-edge threshold")
+             popsift::Config::getEdgeThreshUsage().c_str() )
             ("edge-limit",
              value<float>()->notifier([&](float f) { config.setEdgeLimit(f); }),
-             "On-edge threshold")
+             "synonym to --edge-threshold" )
             ("downsampling",
              value<float>()->notifier([&](float f) { config.setDownsampling(f); })->default_value(config.getDownsampling()),
              "Downscale width and height of input by 2^N")

src/popsift/s_extrema.cu

@@ -482,14 +482,21 @@ __device__ inline bool find_extrema_in_dog_sub(cudaTextureObject_t dog,
 
     /* accept-reject extremum */
     // if( fabsf(contr) < (d_consts.threshold*2.0f) )
-    if( fabsf(contr) < scalbnf( d_consts.threshold, 1 ) )
+    if( d_consts.threshold > 0.0f )
     {
-        return false;
+        if( fabsf(contr) < scalbnf( d_consts.threshold, 1 ) )
+        {
+            return false;
+        }
     }
 
-    /* reject condition: tr(H)^2/det(H) < (r+1)^2/r */
-    if( edgeval >= (d_consts.edge_limit+1.0f)*(d_consts.edge_limit+1.0f)/d_consts.edge_limit ) {
-        return false;
+    if( d_consts.edge_limit > 0.0f )
+    {
+        /* reject condition: tr(H)^2/det(H) < (r+1)^2/r */
+        if( edgeval >= (d_consts.edge_limit+1.0f)*(d_consts.edge_limit+1.0f)/d_consts.edge_limit )
+        {
+            return false;
+        }
     }
 
     ec.xpos      = xn;

src/popsift/sift_conf.cu

@@ -9,6 +9,7 @@
 #include "sift_conf.h"
 
 #include <iostream>
+#include <sstream>
 #include <algorithm>
 
 using namespace std;
@@ -28,8 +29,8 @@ Config::Config( )
     , octaves( -1 )
     , levels( 3 )
     , sigma( 1.6f )
-    , _edge_limit( 10.0f )
-    , _threshold( 0.04 ) // ( 10.0f / 256.0f )
+    , _edge_limit( getEdgeThreshDefault( ) )
+    , _threshold( getPeakThreshDefault() )
     , _gauss_mode( getGaussModeDefault() )
     , _sift_mode( Config::PopSift )
     , _log_mode( Config::None )
@@ -285,9 +286,38 @@ float Config::getSigma( ) const { return sigma; }
 
 void  Config::setEdgeLimit( float v ) { _edge_limit = v; }
 float Config::getEdgeLimit( ) const   { return _edge_limit; }
+float Config::getEdgeThreshDefault( )
+{
+    return 10.0f;
+}
+std::string Config::getEdgeThreshUsage( )
+{
+    std::ostringstream ostr;
+    ostr << "Edge Threshold: eliminates peaks of the DoG scale space whose curvature is too small." << endl
+         << "Default: " << getEdgeThreshDefault() << endl
+         << "Set to a value <= 0 to disable." << endl;
+    return ostr.str();
+}
 
 void  Config::setThreshold( float v ) { _threshold = v; }
 float Config::getThreshold( ) const   { return _threshold; }
+float Config::getPeakThreshold() const
+{
+    return ( _threshold * 0.5f * 255.0f / levels );
+}
+float Config::getPeakThreshDefault( )
+{
+    return 0.04f; // ( 10.0f / 256.0f )
+}
+std::string Config::getPeakThreshUsage( )
+{
+    std::ostringstream ostr;
+    ostr << "Peak Threshold: eliminates peaks of the DoG scale space that are too small" <<endl
+         << "(contrast too small in absolute value)." << endl
+         << "Default: " << getPeakThreshDefault() << endl
+         << "Set to a value <= 0 to disable." << endl;
+    return ostr.str();
+}
 
 void Config::setPrintGaussTables() { _print_gauss_tables = true; }
 void Config::setFilterMaxExtrema( int ext ) { _filter_max_extrema = ext; }
@@ -323,11 +353,6 @@ Config::SiftMode Config::getSiftMode() const
     return _sift_mode;
 }
 
-float Config::getPeakThreshold() const
-{
-    return ( _threshold * 0.5f * 255.0f / levels );
-}
-
 bool Config::ifPrintGaussTables() const
 {
     return _print_gauss_tables;

src/popsift/sift_conf.h

@@ -215,11 +215,25 @@ struct Config
     void  setSigma( float v );
     float getSigma( ) const;
 
-    void  setEdgeLimit( float v );
-    float getEdgeLimit( ) const;
+    /** Set the Edge threshold, which requires a minimum curviness in the
+     *  the extremum. Set to a value <= 0 to ignore.
+     */
+    void               setEdgeLimit( float v );
+    float              getEdgeLimit( ) const;
+    static std::string getEdgeThreshUsage( );
+    static float       getEdgeThreshDefault( );
 
+    /** Set the Peak threshold, which requires a minimum difference between
+     *  a peak and its surrounding pixels. Set to a value <= 0 to ignore.
+     */
     void  setThreshold( float v );
     float getThreshold( ) const;
+    /** computes the actual peak threshold depending on the threshold
+     *  parameter and the non-augmented number of levels
+     */
+    float getPeakThreshold() const;
+    static std::string getPeakThreshUsage( );
+    static float       getPeakThreshDefault( );
 
     void  setInitialBlur( float blur );
     bool  hasInitialBlur( ) const;
@@ -233,10 +247,6 @@ struct Config
     void setFilterSorting( const std::string& direction );
     void setFilterSorting( GridFilterMode m );
 
-    /// computes the actual peak threshold depending on the threshold
-    /// parameter and the non-augmented number of levels
-    float getPeakThreshold() const;
-
     /// print Gauss spans and tables?
     bool ifPrintGaussTables() const;