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121 lines
4.9 KiB
C++
121 lines
4.9 KiB
C++
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/*
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#
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# File : mcf_levelsets2d.cpp
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# ( C++ source file )
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#
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# Description : Implementation of the Mean Curvature Flow on a 2D curve,
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# using the framework of Level Sets.
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# This file is a part of the CImg Library project.
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# ( http://cimg.eu )
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#
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# Copyright : David Tschumperlé
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# ( http://tschumperle.users.greyc.fr/ )
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#
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# License : CeCILL v2.0
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# ( http://www.cecill.info/licences/Licence_CeCILL_V2-en.html )
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#
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# This software is governed by the CeCILL license under French law and
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# abiding by the rules of distribution of free software. You can use,
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# modify and/ or redistribute the software under the terms of the CeCILL
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# license as circulated by CEA, CNRS and INRIA at the following URL
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# "http://www.cecill.info".
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#
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# As a counterpart to the access to the source code and rights to copy,
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# modify and redistribute granted by the license, users are provided only
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# with a limited warranty and the software's author, the holder of the
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# economic rights, and the successive licensors have only limited
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# liability.
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#
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# In this respect, the user's attention is drawn to the risks associated
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# with loading, using, modifying and/or developing or reproducing the
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# software by the user in light of its specific status of free software,
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# that may mean that it is complicated to manipulate, and that also
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# therefore means that it is reserved for developers and experienced
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# professionals having in-depth computer knowledge. Users are therefore
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# encouraged to load and test the software's suitability as regards their
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# requirements in conditions enabling the security of their systems and/or
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# data to be ensured and, more generally, to use and operate it in the
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# same conditions as regards security.
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#
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# The fact that you are presently reading this means that you have had
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# knowledge of the CeCILL license and that you accept its terms.
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#
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*/
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#include "CImg.h"
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using namespace cimg_library;
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#undef min
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#undef max
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// Retrieve the curve corresponding to the zero level set of the distance function.
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template<typename T>
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CImg<unsigned char> get_level0(const CImg<T>& img) {
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CImg<unsigned char> dest(img);
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CImg_2x2(I,T); Inn = 0;
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cimg_for2x2(img,x,y,0,0,I,T) if (Icc*Inc<0 || Icc*Icn<0) dest(x,y) = 255; else dest(x,y) = Icc<0?100:0;
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return dest;
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}
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/*--------------------
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Main procedure
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----------------------*/
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int main(int argc,char **argv) {
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cimg_usage("Perform a Mean Curvature Flow on closed curves, using Level Sets");
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const float dt = cimg_option("-dt",0.8f,"PDE time step");
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const unsigned int nb_iterations = cimg_option("-iter",10000,"Number of iterations");
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// Create a user-defined closed curve.
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CImg<unsigned char> curve(256,256,1,2,0);
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unsigned char col1[] = {0,255}, col2[] = {200,255}, col3[] = {255,255};
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curve.draw_grid(20,20,0,0,false,false,col1,0.4f,0xCCCCCCCC,0xCCCCCCCC).
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draw_text(5,5,"Please draw your curve\nin this window\n(Use your mouse)",col1);
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CImgDisplay disp(curve,"Mean curvature flow",0);
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int xo = -1, yo = -1, x0 = -1, y0 = -1, x1 = -1, y1 = -1;
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while (!disp.is_closed() && (x0<0 || disp.button())) {
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if (disp.button() && disp.mouse_x()>=0 && disp.mouse_y()>=0) {
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if (x0<0) { xo = x0 = disp.mouse_x(); yo = y0 = disp.mouse_y(); } else {
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x1 = disp.mouse_x(); y1 = disp.mouse_y();
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curve.draw_line(x0,y0,x1,y1,col2).display(disp);
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x0 = x1; y0 = y1;
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}
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}
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disp.wait();
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if (disp.is_resized()) disp.resize(disp);
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}
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curve.draw_line(x1,y1,xo,yo,col2).channel(0).draw_fill(0,0,col3);
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CImg<> img = CImg<>(curve.get_shared_channel(0)).normalize(-1,1);
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// Perform the "Mean Curvature Flow".
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img.distance_eikonal(10);
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CImg_3x3(I,float);
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for (unsigned int iteration = 0; iteration<nb_iterations && !disp.is_closed() &&
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!disp.is_keyQ() && !disp.is_keyESC(); ++iteration) {
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CImg<float> velocity(img.width(),img.height(),img.depth(),img.spectrum());
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float *ptrd = velocity.data(), veloc_max = 0;
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cimg_for3x3(img,x,y,0,0,I,float) {
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const float
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ix = (Inc - Ipc)/2,
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iy = (Icn - Icp)/2,
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ixx = Inc + Ipc - 2*Icc,
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iyy = Icn + Icp - 2*Icc,
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ixy = (Ipp + Inn - Inp - Ipn)/4,
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ngrad = ix*ix + iy*iy,
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iee = (ngrad>1e-5)?((iy*iy*ixx - 2*ix*iy*ixy + ix*ix*iyy)/ngrad):0;
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*(ptrd++) = iee;
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if (iee>veloc_max) veloc_max = iee; else if (-iee>veloc_max) veloc_max = -iee;
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}
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if (veloc_max>0) img+=(velocity*=dt/veloc_max);
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if (!(iteration%10)) {
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get_level0(img).resize(disp.width(),disp.height()).
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draw_grid(20,20,0,0,false,false,col3,0.4f,0xCCCCCCCC,0xCCCCCCCC).
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draw_text(5,5,"Iteration %d",col3,0,1,13,iteration).display(disp);
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}
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if (!(iteration%60)) img.distance_eikonal(1,3);
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if (disp.is_resized()) disp.resize();
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}
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return 0;
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}
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