geo/tcLambertianShading.cpp

   1 /***************************************************************************
   2  *   This file is part of Tecorrec.                                        *
   3  *   Copyright 2008 James Hogan <james@albanarts.com>                      *
   4  *                                                                         *
   5  *   Tecorrec is free software: you can redistribute it and/or modify      *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation, either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   Tecorrec is distributed in the hope that it will be useful,           *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  *   You should have received a copy of the GNU General Public License     *
  16  *   along with Tecorrec.  If not, write to the Free Software Foundation,  *
  17  *   Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.   *
  18  ***************************************************************************/
  19
  20 /**
  21  * @file tcLambertianShading.cpp
  22  * @brief Shading channel using lambertian reflectance.
  23  */
  24
  25 #include "tcLambertianShading.h"
  26
  27 #include <QObject>
  28
  29 /*
  30  * Constructors + destructor
  31  */
  32
  33 /// Primary constructor.
  34 tcLambertianShading::tcLambertianShading(tcChannel* reference, tcSrtmModel* dem, tcGeoImageData* imagery)
  35 : tcChannelDem(dem, imagery,
  36                QObject::tr("Lambertian Shading"),
  37                QObject::tr("Uses lambertian shading and elevation data to shade pixels. "
  38                            "Cast shadows are not taken into account. "
  39                            "Self shadows are set to zero."))
  40 , m_referenceChannel(reference)
  41 {
  42 }
  43
  44 /// Destructor.
  45 tcLambertianShading::~tcLambertianShading()
  46 {
  47 }
  48
  49 /*
  50  * Interface for derived class to implement
  51  */
  52
  53 void tcLambertianShading::roundPortion(double* x1, double* y1, double* x2, double* y2)
  54 {
  55   m_referenceChannel->roundPortion(x1,y1,x2,y2);
  56 }
  57
  58 tcAbstractPixelData* tcLambertianShading::loadPortion(double x1, double y1, double x2, double y2)
  59 {
  60   Reference<tcAbstractPixelData> channelData = m_referenceChannel->loadPortion(x1, y1, x2, y2);
  61   int width = channelData->width();
  62   int height = channelData->height();
  63
  64   // Create a new pixel buffer
  65   tcPixelData<float>* data = new tcPixelData<float>(width, height);
  66   for (int j = 0; j < height; ++j)
  67   {
  68     for (int i = 0; i < width; ++i)
  69     {
  70       int index = j*width + i;
  71       // Transform coordinates
  72       maths::Vector<2,float> coord      (       x1 + (x2-x1)*i / (width  - 1),
  73                                          1.0f - y1 - (y2-y1)*j / (height - 1));
  74       tcGeo                  geoCoord = geoAt(coord);
  75
  76       // Get some elevation data
  77       maths::Vector<3,float> normal   = normalAt(geoCoord);
  78       maths::Vector<3,float> light    = lightDirectionAt(geoCoord);
  79       // Find dot product between normal and light vectors and limit it to 0.0
  80       float                  lambert  = normal * light;
  81       data->buffer()[index]           = (lambert >= 0.0f ? lambert : 0.0f);
  82     }
  83   }
  84   return data;
  85 }