~bertrand-nouvel/pycvf-keypoints/trunk

# -*- coding: utf-8 -*-

import numpy

import scipy.spatial

import pyfastemd

 

class SiftEMDDistanceComputer:

  def __init__(self,XNBP= 4 ,YNBP= 4, NBO= 8,thresh= 5,extra_mass_penalty= -1,flowType=1,dt=None):

      self.XNBP= XNBP # SIFT's X-dimension

      self.YNBP= YNBP # SIFT's Y-dimension

      self.NBO=  NBO # SIFT's Orientation-dimension

      self.N= XNBP*YNBP*NBO 

      self.thresh= thresh

      self.extra_mass_penalty= extra_mass_penalty # Default of maximum distance

      self.flowType= flowType # Regular flows

      #self.D= numpy.zeros((self.N,self.N)); 

      print "computing siftdistance mat"     

      siftenum=numpy.vstack(map(numpy.array,numpy.ndindex((YNBP,XNBP,NBO))))

      self.D=scipy.spatial.distance.cdist(siftenum,siftenum,lambda x,y: (x[0]-y[0])**2 + (x[1]-y[1])**2 + min(abs(x[2]-y[2]),NBO-abs(x[2]-y[2])))

      assert((self.D>=0).all())

      assert((self.D==self.D.T).all())

      print "/computing siftdistance mat"

      #maxDist= D.max();

      self.D[self.D>self.thresh]=self.thresh

      if (dt!=None):

        self.D=self.D.astype(dt)

      print self.D.shape

      self.dt=dt

  def distance(self,P,Q):

      if (self.dt==None):

          dt=P.dtype

      else:

          dt=self.dt

      if (self.flowType==1):

         return pyfastemd.emd_hat(P.astype(dt),Q.astype(dt),self.D.astype(dt),self.extra_mass_penalty,self.flowType)

      else:

         flow=numpy.zeros((self.N,self.N),dtype=dt)

         r=pyfastemd.emd_hat(P.astype(dt),Q.astype(dt),self.D.astype(dt),self.extra_mass_penalty,self.flowType,flow)

         return r,flow

 

 

shared_sift_emd_dist_computer=None     

     

def siftemd_distance(P,Q):

   global shared_sift_emd_dist_computer

   if shared_sift_emd_dist_computer==None:

       shared_sift_emd_dist_computer=SiftEMDDistanceComputer(dt=numpy.float64)

   return shared_sift_emd_dist_computer.distance(P,Q)