noisegenerator.h

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/***************************************************************************
 *   Copyright (C) 2005-2011 LpzRobots development team                    *
 *    Georg Martius  <georg dot martius at web dot de>                     *
 *    Frank Guettler <guettler at informatik dot uni-leipzig dot de        *
 *    Frank Hesse    <frank at nld dot ds dot mpg dot de>                  *
 *    Ralf Der       <ralfder at mis dot mpg dot de>                       *
 *                                                                         *
 *   This program 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 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program 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 this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 *                                                                         *
 ***************************************************************************/
#ifndef __NOISEGENERATOR_H
#define __NOISEGENERATOR_H

#include <stdlib.h>
#include <time.h>
#include <cmath>
#include <assert.h>

#include "randomgenerator.h"

/** Interface and basic class for noise generator.
    It is suitable for single noise channels but also multidimensional noise. 
 */
class NoiseGenerator{
public:
  NoiseGenerator()
  {
    dimension   = 0;
    randGen     = 0;
    ownRandGen  = false;
  };    

  virtual ~NoiseGenerator()
  {
    if (this->ownRandGen && this->randGen)
    {
      delete this->randGen;
      this->randGen     = 0;
      this->ownRandGen  = false;
    }
  }

  /** initialization with the the given dimension for multidimensional noise
      @param dimension dimensionality of vectors to be used by add
      @param randGen pointer to a random generator. If zero a new one generated internally
      @see add()
   */
  virtual void init(unsigned int dimension, RandGen* randGen=0)
  {
    this->dimension = dimension;
    if(randGen)
      this->randGen=randGen;

    else {
      this->randGen=new RandGen();
      this->randGen->init(rand());
      this->ownRandGen=true;
    }
  };

  /** generate somehow distributed random number parameterized with min and max.
      valid only for ONE random number, use \ref add() for 
      adding this kind of noise to several channels
   */
  virtual double generate() = 0; 

  /** adds multidimensional noise to the value field.
      Generic implementation calls generate for each channel.
      Overload this if you need different behavior.
      @param value field where noise is added. Must have length dimension (\ref init())
   */
  virtual void add(double *value, double noiseStrength){
    for (unsigned int i = 0; i < dimension; i++){
      value[i]+=generate()*noiseStrength;
    }    
  }

protected:
  //generates white (no averaging) uniformly distributed random number between "min" and "max"  
  double uniform(double min=-0.1, double max=0.1){
    assert(randGen);
    return( randGen->rand()*(max-min)+min);
  }
  //generates white uniformly distributed random number between in [0,1)
  double uniform01(){
    assert(randGen);
    return randGen->rand();
  }
  unsigned int dimension;
  RandGen* randGen;
  bool ownRandGen;
};

/// generates no noise
class NoNoise : public NoiseGenerator{
public:
  NoNoise() {}
  virtual ~NoNoise(){}
  virtual double generate() {
    return 0;
  }; 
};


/// generates white (no averaging) uniformly distributed random number between "min" and "max"  
class WhiteUniformNoise : public NoiseGenerator{
public:
  WhiteUniformNoise() {}
  virtual ~WhiteUniformNoise(){}
  virtual double generate() {
    return uniform(-1,1);
  }; 

};

/// generates white and normal distributed random numbers. p1: mean, p2: standard deviation
/// new parameter definition: p1: min, p2: max. the mean and standard deviation are calculated by this values
class WhiteNormalNoise : public NoiseGenerator{
public:
  WhiteNormalNoise(){}
  virtual ~WhiteNormalNoise(){}
  virtual double generate() {
    double x1=uniform01();
    double x2=uniform01();
    return( (sqrt(-2*log(x1)) *cos(2*M_PI*x2))); 
  };
  // original version
  //  virtual double generate(double mean, double stddev) {
  //    double x1=uniform(0, 1);
  //    double x2=uniform(0, 1);
  //    return( (sqrt(-2*log(x1)) *cos(2*M_PI*x2))  * stddev + mean) ; 
  //  }

};

/// generated colored noise. This is obtained by using time average of uniform distributed noise.
class ColorUniformNoise : public NoiseGenerator{
public:
  /** @param tau time averaging factor (1/window)
      (1: smoothing (white) 0.1: strong color, 0 no noise anymore
  */
  ColorUniformNoise(double tau=0.05)
    : tau(tau){
    sqrttau = sqrt(tau);
    mean1channel=0.0;
    mean=0;
  }
  virtual ~ColorUniformNoise(){ if(mean) free(mean);}
  virtual void init(unsigned int dimension, RandGen* randGen=0){
    NoiseGenerator::init(dimension, randGen);
    mean = (double*)malloc(sizeof(double) * dimension);    
    for (unsigned int i=0; i<dimension; i++){
        mean[i]=0.0;
    }   
  }

  virtual double generate() {    
    mean1channel+=  sqrttau *  uniform(-1,  +1) - tau *  mean1channel;
    return(mean1channel);
  } 

  /** adds multidimensional noise to the value field.
      @param value field where noise is added. Must have length dimension (\ref init())
      @param min lower bound of interval
      @param max upper bound of interval 
   */
  virtual void add(double *value, double noiseStrength){
    for (unsigned int i = 0; i < dimension; i++){     
      mean[i]+= sqrttau * uniform(-1,  +1)*noiseStrength - tau *  mean[i];
      value[i]+=mean[i];
    }    
  }   
  
  virtual double getTau(){ return tau;}
  virtual void setTau(double newTau){ 
    if(newTau >=0 && newTau <= 1){
      tau=newTau;
      sqrttau = sqrt(tau);
    }
  }

protected:
  double tau; // smoothing paramter
  double sqrttau; // square root of smoothing parameter 
  double* mean;  
  double mean1channel;
};

/// like ColorUniformNoise but averaging over normal distributed noise instead.
class ColorNormalNoise : public WhiteNormalNoise{
public:
  ColorNormalNoise(double tau=0.05)
    : tau(tau){
    sqrttau = sqrt(tau);
    mean = 0;
    mean1channel=0.0;
  }

  virtual ~ColorNormalNoise(){if(mean) free(mean);}

  virtual void init(unsigned int dimension, RandGen* randGen=0){
    WhiteNormalNoise::init(dimension, randGen);
    mean = (double*)malloc(sizeof(double) * dimension);    
    for (unsigned int i=0; i<dimension; i++){
        mean[i]=0.0;
    }   
  }

  virtual double generate() { //double stddev, double meanvalue) {
    mean1channel += sqrttau * WhiteNormalNoise::generate() - tau*mean1channel;
    return(mean1channel);
  } 

  virtual void add(double *value, double noiseStrength) { 
    for (unsigned int i = 0; i < dimension; i++){     
      mean[i]+=sqrttau * WhiteNormalNoise::generate()*noiseStrength - tau*mean[i];
      value[i]+=mean[i];
    }    
  }   

  virtual double getTau(){ return tau;}
  virtual void setTau(double newTau){ 
    if(newTau >=0 && newTau <= 1){
      tau=newTau;
      sqrttau = sqrt(tau);
    }
  }

protected:
  double tau; // smoothing paramter
  double sqrttau; // square root of smoothing parameter 
  double* mean;  
  double mean1channel;
  double factor;
};

/// Sine wave noise. Produces a 90 degree phase shifted sine wave or white noise
class SineWhiteNoise : public NoiseGenerator{
public:
  /** @param omega anglerate
      @param amplitude weighting of sine wave against noise strength
      @param phaseShift phase shift between channels in rad
      @param channels number of channel for sine noise (and the rest get white noise)
   */
  SineWhiteNoise(double omega, double amplitude, double phaseShift = M_PI/2, 
                 unsigned int channels = 0xFFFF)
    : omega(omega), amplitude(amplitude)
    , channels(channels), phaseShift(phaseShift){
    t=0;
  }

  virtual ~SineWhiteNoise(){}

  virtual double generate() {        
    t ++;
    return (1-amplitude)*uniform(-1,  1) + sin(t*omega)*amplitude;
  } 

  /** adds multidimensional noise to the value field.
      @param value field where noise is added. Must have length dimension (\ref init())
   */
  virtual void add(double *value, double noiseStrength) { // min, double max){

    for (unsigned int i = 0; i < dimension; i++){     
      if(i < channels){
        value[i]+=sin(t*omega+i*phaseShift)*amplitude*noiseStrength;
        value[i]+=(1-amplitude)*uniform(-1,  1)*noiseStrength;
      }else{
        value[i]+=uniform(-1,  1)*noiseStrength;
      }
    }    
    t ++;
  }   
  void setOmega(double omega){
    this->omega=omega;
  }
  void setPhaseShift(double phaseShift){
    this->phaseShift=phaseShift;
  }
  
protected:
  long int t;        // time
  double omega;     // angle velocity
  double amplitude; // factor for noise strength  
  unsigned int channels;     // number of channels with sine
  double phaseShift; // phase shift

};


#endif