sparel.cc

/*Copyright 2014 Francisco Alvaro

 This file is part of SESHAT.

    SESHAT is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    SESHAT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with SESHAT.  If not, see <http://www.gnu.org/licenses/>.
*/
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cfloat>
#include "sparel.h"

using namespace std;

//Aux functions

Hypothesis *leftmost(Hypothesis *h) {
  if( h->pt )
    return h;

  Hypothesis *izq = leftmost(h->hi);
  Hypothesis *der = leftmost(h->hd);

  return izq->parent->x < der->parent->x ? izq : der;
}

Hypothesis *rightmost(Hypothesis *h) {
  if( h->pt )
    return h;

  Hypothesis *izq = rightmost(h->hi);
  Hypothesis *der = rightmost(h->hd);

  return izq->parent->s > der->parent->s ? izq : der;
}

//Percentage of the area of region A that overlaps with region B
float solape(CellCYK *a, CellCYK *b) {
  int x = max(a->x, b->x);
  int y = max(a->y, b->y);
  int s = min(a->s, b->s);
  int t = min(a->t, b->t);

  if( s >= x && t >= y ) {
    float aSolap = (s-x+1.0)*(t-y+1.0);
    float aTotal = (a->s - a->x+1.0)*(a->t - a->y+1.0);

    return aSolap/aTotal;
  }

  return 0.0;
}


//
//SpaRel methods
//

SpaRel::SpaRel(GMM *gmm, Sample *m) {
  model = gmm;
  mue = m;
}

void SpaRel::smooth(float *post){
  for(int i=0; i<NRELS;i++)
    post[i] = (post[i]+0.02)/(1.00 + NRELS*0.02);
}

void SpaRel::getFeas(Hypothesis *a, Hypothesis *b, float *sample, int ry) {
  //Normalization factor: combined height
  float F = max(a->parent->t, b->parent->t) - min(a->parent->y, b->parent->y) + 1;

  sample[0] = (b->parent->t-b->parent->y+1)/F;
  sample[1] = (a->rcen - b->lcen)/F;
  sample[2] = ((a->parent->s+a->parent->x)/2.0 - (b->parent->s+b->parent->x)/2.0)/F;
  sample[3] = (b->parent->x-a->parent->s)/F;
  sample[4] = (b->parent->x-a->parent->x)/F;
  sample[5] = (b->parent->s-a->parent->s)/F;
  sample[6] = (b->parent->y-a->parent->t)/F;
  sample[7] = (b->parent->y-a->parent->y)/F;
  sample[8] = (b->parent->t-a->parent->t)/F;
}

double SpaRel::compute_prob(Hypothesis *h1, Hypothesis *h2, int k) {

  //Set probabilities according to spatial constraints  

  if( k<=2 ) {
    //Check left-to-right order constraint in Hor/Sub/Sup relationships
    Hypothesis *rma = rightmost(h1);
    Hypothesis *lmb =  leftmost(h2);
    
    if( lmb->parent->x < rma->parent->x || lmb->parent->s <= rma->parent->s )
      return 0.0;
  }

  //Compute probabilities
  float sample[NFEAT];

  getFeas(h1,h2,sample,mue->RY);

  //Get spatial relationships probability from the model
  model->posterior(sample, probs);

  //Slightly smooth probabilities because GMM classifier can provide
  //to biased probabilities. Thsi way we give some room to the
  //language model (the 2D-SCFG grammar)
  smooth(probs);

  return probs[k];
}


SpaRel::~SpaRel() {
}


double SpaRel::getHorProb(Hypothesis *ha, Hypothesis *hb) {
  return compute_prob(ha,hb,0);
}
double SpaRel::getSubProb(Hypothesis *ha, Hypothesis *hb) {
  return compute_prob(ha,hb,1);
}
double SpaRel::getSupProb(Hypothesis *ha, Hypothesis *hb) {
  return compute_prob(ha,hb,2);
}
double SpaRel::getVerProb(Hypothesis *ha, Hypothesis *hb, bool strict) {
  //Pruning
  if( hb->parent->y < (ha->parent->y + ha->parent->t)/2
      || abs((ha->parent->x+ha->parent->s)/2 - (hb->parent->x+hb->parent->s)/2) > 2.5*mue->RX 
      || (hb->parent->x > ha->parent->s || hb->parent->s < ha->parent->x) )
    return 0.0;

  if( !strict )
    return compute_prob(ha,hb,3);

  //Penalty for strict relationships
  float penalty = abs(ha->parent->x - hb->parent->x)/(3.0*mue->RX)
    + abs(ha->parent->s - hb->parent->s)/(3.0*mue->RX);

  if( penalty > 0.95 ) penalty = 0.95;

  return (1.0 - penalty) * compute_prob(ha,hb,3);
}

double SpaRel::getInsProb(Hypothesis *ha, Hypothesis *hb) {
  if( solape(hb->parent,ha->parent) < 0.5 || 
      hb->parent->x < ha->parent->x || hb->parent->y < ha->parent->y )
    return 0.0;

  return compute_prob(ha,hb,4);
}
double SpaRel::getMrtProb(Hypothesis *ha, Hypothesis *hb) {
  return compute_prob(ha,hb,5);
}