1つめのsplotで渦度とベクトルを描画した図の上に円柱のマップを重ねて描画しています．2つめのsplotで背景は描画せずに円柱のみを描画することで下にある渦度とベクトルが見えます．($3 == 0 ? NaN : $3)のところで，$3が円柱と背景の値です．0が背景で1が円柱にしています．0でなければ表示しない(NaN)という設定になります．本来はグラフのデータ欠損表現で使います．
円柱は実験画像から二値化などして作成して下さい．時間ごとに変動する物体も応用が可能です．回転する円柱なら，円のフチ辺りに小さい白抜き円があるとわかりやすいです．
/******************************************************************************
AUTHER: Yohsuke Tanaka
DATE: 2018.07.27
******************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#ifdef __linux
#include <sys/stat.h>
#endif
#ifdef _WIN32
#include <direct.h>
#endif
const char* xxlabel = "x [pixel]";///color bar range min
const char* yylabel = "y [pixel]";///color bar range min
const int x_min = 0;///color bar range min
const int x_max = 1280;///color bar range min
const int y_min = 0;///color bar range min
const int y_max = 1024;///color bar range min
const double v_r = 6.0;///magnified ratio for vector length
const char* cb_label = "|U| [pixel]";///color bar range min
const int cb_min = 0;///color bar range min
const int cb_max = 8;///color bar range min
const char* read_file_object = "cylinder.dat";
const char* read_file_dir = "02_vec";
const char* read_file_header = "av-vec_v";
const char* write_file_dir = "03_splot_vec_contour_map";
const char* write_file_header = "splot_vec_contour_map";
//Graph parameters for GNU
#ifdef _WIN32
#define GNUPLOT_PATH "C:/PROGRA~2/gnuplot/bin/gnuplot.exe" // gnuplot.exe in your PC
#endif
char read_file[100];
void graph_GNU();//png & eps
FILE *gp; //gnuplot
FILE *infile;
/********************************* MAIN *********************************/
main(){
#ifdef __linux
mode_t mode= S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH;
mkdir(write_file_dir,mode);
#endif
#ifdef _WIN32
_mkdir(write_file_dir);//png directry
#endif
int i =0; int UP =0;
while(UP==0){
i++;
sprintf(read_file,"%s//%s%04d.dat",read_file_dir,read_file_header,i);
printf("%s//%s%04d.dat\n",read_file_dir,read_file_header,i);
infile=fopen(read_file,"rb");
fclose(infile);
if(infile==NULL)
{
printf("break!");
break;
}
#ifdef __linux
if ((gp = popen("gnuplot", "w")) == NULL) {
printf("gnuplot is not here!\n");
exit(0);
}
#endif
#ifdef _WIN32
if ((gp = _popen(GNUPLOT_PATH, "w")) == NULL) {
printf("gnuplot is not here!\n");
exit(0);
}
#endif
//PNG image
fprintf(gp,"set terminal pngcairo enhanced\n");
fprintf(gp,"set output '%s//%s%04d.png'\n",write_file_dir,write_file_header,i);
fprintf(gp,"set multiplot\n");// <steps in scan>,<steps between scans>
fprintf(gp,"unset key\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set lmargin screen 0.15\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set rmargin screen 0.85\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set tmargin screen 0.85\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set bmargin screen 0.15\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set xrange [%d:%d]\n",x_min,x_max);// <steps in scan>,<steps between scans>
fprintf(gp,"set xlabel '%s'offset 0.0,0.5\n",xxlabel);// <steps in scan>,<steps between scans>
fprintf(gp,"set yrange [%d:%d]\n",y_min,y_max);// <steps in scan>,<steps between scans>
fprintf(gp,"set ylabel '%s'offset 1.0,0.0\n",yylabel);// <steps in scan>,<steps between scans>
fprintf(gp,"set cblabel '%s'offset 0.0,0.0\n",cb_label);
fprintf(gp,"set cbrange['%d':'%d']\n",cb_min,cb_max);
fprintf(gp,"set colorbox vertical user origin 0.895, 0.2 size 0.025,0.6\n");
fprintf(gp,"set palette rgbformulae 22,13,-31\n");
fprintf(gp,"set pm3d map\n");// <steps in scan>,<steps between scans>
fprintf(gp,"splot '%s//%s%04d.dat' using 2:1:3 with pm3d, '%s//%s%04d.dat' using 2:1:($1*0.0):(%lf*$5):(%lf*$4)::($1*0.0) with vectors head filled lt 2 lc 'black' \n",read_file_dir,read_file_header,i,read_file_dir,read_file_header,i,v_r,v_r);
fprintf(gp,"set palette rgbformulae 0,0,0\n");
fprintf(gp,"unset colorbox\n");
fprintf(gp,"unset border\n");
fprintf(gp,"splot '%s' using 2:1:($3 == 0 ? NaN : $3) with pm3d\n",read_file_object);
fprintf(gp,"unset multiplot\n");// <steps in scan>,<steps between scans>
fflush(gp); //Clean up Data
fprintf(gp, "exit\n"); // Quit gnuplot
#ifdef __linux
pclose(gp);
#endif
#ifdef _WIN32
_pclose(gp);
#endif
}
return(0);
}
plot '%s' binary filetype=auto with rgbimage,'%s' with vector linecolor rgbcolor 'white'はmultiplotを使ってもかけます．ベクトルの大きさに合わせて色を付けたいのですが，スケールが上手く合わなかったり，グラデーションが出なかったりです．上手くいったら教えてください．（2015.12.28）下記のプログラムで可能です(2018.08.02)．
/******************************************************************************
AUTHER: Yohsuke Tanaka
DATE: 2018.08.02
******************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#ifdef __linux
#include <sys/stat.h>
#endif
#ifdef _WIN32
#include <direct.h>
#endif
const char* xxlabel = "x [pixel]";///color bar range min
const char* yylabel = "y [pixel]";///color bar range min
const int x_min = 0;///color bar range min
const int x_max = 1280;///color bar range min
const int y_min = 0;///color bar range min
const int y_max = 1024;///color bar range min
const double v_r = 5.0;///magnified ratio for vector length
const char* cb_label = "|U| [pixel/step]";///color bar range min
const int cb_min = 0;///color bar range min
const int cb_max = 15;///color bar range min
const char* read_file_dir = "02_vec";
const char* read_file_header = "av-vec";
const char* write_file_dir = "03_plot_vec";
const char* write_file_header = "plot";
const char* read_back_img = "lowest-intensity.png";
//Graph parameters for GNU
#ifdef _WIN32
#define GNUPLOT_PATH "C:/PROGRA~2/gnuplot/bin/gnuplot.exe" // gnuplot.exe in your PC
#endif
char read_file[100];
void graph_GNU();//png & eps
FILE *gp; //gnuplot
FILE *infile;
/********************************* MAIN *********************************/
main(){
#ifdef __linux
mode_t mode= S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH;
mkdir(write_file_dir,mode);
#endif
#ifdef _WIN32
_mkdir(write_file_dir);//png directry
#endif
int i =0; int UP =0;
while(UP==0){
i++;
sprintf(read_file,"%s//%s%04d.dat",read_file_dir,read_file_header,i);
printf("%s//%s%04d.dat\n",read_file_dir,read_file_header,i);
infile=fopen(read_file,"rb");
fclose(infile);
if(infile==NULL)
{
printf("break!");
break;
}
#ifdef __linux
if ((gp = popen("gnuplot", "w")) == NULL) {
printf("gnuplot is not here!\n");
exit(0);
}
#endif
#ifdef _WIN32
if ((gp = _popen(GNUPLOT_PATH, "w")) == NULL) {
printf("gnuplot is not here!\n");
exit(0);
}
#endif
//PNG image
fprintf(gp,"set terminal pngcairo enhanced\n");
fprintf(gp,"set output '%s//%s%04d.png'\n",write_file_dir,write_file_header,i);
fprintf(gp,"set multiplot\n");// <steps in scan>,<steps between scans>
fprintf(gp,"unset key\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set lmargin screen 0.125\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set rmargin screen 0.875\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set tmargin screen 0.875\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set bmargin screen 0.125\n");// <steps in scan>,<steps between scans>
fprintf(gp,"set xrange [%d:%d]\n",x_min,x_max);// <steps in scan>,<steps between scans>
fprintf(gp,"set xlabel '%s'offset 0.0,0.5\n",xxlabel);// <steps in scan>,<steps between scans>
fprintf(gp,"set yrange [%d:%d]\n",y_min,y_max);// <steps in scan>,<steps between scans>
fprintf(gp,"set ylabel '%s'offset 2.0,0.0\n",yylabel);// <steps in scan>,<steps between scans>
fprintf(gp,"plot '%s' binary filetype=png with rgbimage \n",read_back_img);
fprintf(gp,"set cblabel '%s'offset 0.0,0.0\n",cb_label);
fprintf(gp,"set cbrange['%d':'%d']\n",cb_min,cb_max);
fprintf(gp,"set colorbox vertical user origin 0.895, 0.2 size 0.025,0.6\n");
fprintf(gp,"set palette rgbformulae 22,13,-31\n");
fprintf(gp,"plot '%s//%s%04d.dat' u 2:1:(%lf*$5):(%lf*$4):(sqrt($4*$4+$5*$5)) with vectors head filled lt 2 lc palette \n",read_file_dir,read_file_header,i,v_r,v_r);
fprintf(gp,"unset multiplot\n");// <steps in scan>,<steps between scans>
fflush(gp); //Clean up Data
fprintf(gp, "exit\n"); // Quit gnuplot
#ifdef __linux
pclose(gp);
#endif
#ifdef _WIN32
_pclose(gp);
#endif
}
return(0);
}
/plot240.png)
/f_p.gif)
/2dvec_vortex_map000001.png)
/histogram.png)
/2d_flow.gif)
/lowest-intensity.png)
/2d_flow_with_backimg.gif)
/spectrum.png)
