[Paraview] CSV Files and Volumetric Data

[Moreland, Kenneth]

In order for this to work, your CSV file has to contain columns for both the spatial position AND the vectors you want to visualize. It looks like the csv file you are creating is actually only writing out the vector field. To get this to work, your gen_sally function should fill a second array that simply contains the x, y, and z variables on the inner loop. Then your create_csv function should write a csv file with 6 columns. Three of them are for the position coordinate I just described, and the other 3 are the vector that you are currently writing.

-Ken

From: ParaView [mailto:paraview-bounces at public.kitware.com] On Behalf Of GILLILAND G. (929919)
Sent: Wednesday, April 4, 2018 3:16 PM
To: paraview at public.kitware.com
Subject: [EXTERNAL] [Paraview] CSV Files and Volumetric Data

Hi there,

I have assignment where data is produced in C, and i have to export it to a relevant file format that works with a visualisation software of my choice.

I've chosen Paraview, because i know that CSV files work with this software.

Rather than table to points, i want to be able to convert the points to a volumetric dataset... So i can have greater control over colour mapping. But i was told that the code that generates the dataset is missing some data, or i may have missed something in the way i export the file.

I've included the code below; i would love some help with this. I'm only decent with coding in Java and my lecturer has really given the class a lot of support.

Cheers

#include<stdio.h>
#include<math.h>
#include<string.h>
#include<stdlib.h>

void gen_sally( int xs, int ys, int zs, int time, float *sally )
/*
 *  Gen_Sally creates a vector field of dimension [xs,ys,zs,3] from
 *  a proceedural function. By passing in different time arguements,
 *  a slightly different and rotating field is created.
 *
 *  The magnitude of the vector field is highest at some funnel shape
 *  and values range from 0.0 to around 0.4 (I think).
 *
 *  I just wrote these comments, 8 years after I wrote the function.
 *
 *  Developed by Sally of Sally University
 *
 */
{
  float x, y, z;
  int ix, iy, iz;
  float r, xc, yc, scale, temp, z0;
  float r2 = 8;
  float SMALL = 0.00000000001;
  float xdelta = 1.0 / (xs-1.0);
  float ydelta = 1.0 / (ys-1.0);
  float zdelta = 1.0 / (zs-1.0);

  for( iz = 0; iz < zs; iz++ )
  {
z = iz * zdelta;                        // map z to 0->1
xc = 0.5 + 0.1*sin(0.04*time+10.0*z);   // For each z-slice, determine the spiral circle.
yc = 0.5 + 0.1*cos(0.03*time+3.0*z);    //    (xc,yc) determine the center of the circle.
r = 0.1 + 0.4 * z*z + 0.1 * z * sin(8.0*z); //  The radius also changes at each z-slice.
r2 = 0.2 + 0.1*z;                           //    r is the center radius, r2 is for damping
for( iy = 0; iy < ys; iy++ )
{
y = iy * ydelta;
for( ix = 0; ix < xs; ix++ )
{
x = ix * xdelta;
temp = sqrt( (y-yc)*(y-yc) + (x-xc)*(x-xc) );
scale = fabs( r - temp );
/*
 *  I do not like this next line. It produces a discontinuity
 *  in the magnitude. Fix it later.
 *
 */
   if ( scale > r2 )
  scale = 0.8 - scale;
   else
  scale = 1.0;
z0 = 0.1 * (0.1 - temp*z );
   if ( z0 < 0.0 )  z0 = 0.0;
   temp = sqrt( temp*temp + z0*z0 );
scale = (r + r2 - temp) * scale / (temp + SMALL);
scale = scale / (1+z);
   *sally++ = scale * (y-yc) + 0.1*(x-xc);
   *sally++ = scale * -(x-xc) + 0.1*(y-yc);
   *sally++ = scale * z0;
}
}
  }
}


void create_csv(char* filename,float *sally, int size){
printf("1");
printf("\n Creating %s.csv file",filename);
FILE *fp;
fp=fopen(filename,"w");
fprintf(fp,"X,Y,Z\n");
int i;
int counter = 0;
for(i = 0; i< size; i++){
if(sally[i] == 0){
fprintf(fp,"0");
}
else{
fprintf(fp,"%f",sally[i]);
}
counter++;
if(counter == 3){
fprintf(fp, "\n");
counter = 0;
}
else{
fprintf(fp,",");
}
}
fclose(fp);
printf("\n %sfile created",filename);
}
int main(int argc, char *argv[]){
printf("1\n");
//read from args
int xs;
int ys;
int zs;
int time;
sscanf(argv[1],"%d",&xs);
sscanf(argv[2],"%d",&ys);
sscanf(argv[3],"%d",&zs);
sscanf(argv[4],"%d",&time);


int arraySize = xs*ys*zs*3;
//allocate memeory for array. This is done so that stack memory doesn't run out.'
float* sally;
sally = (float*)malloc((arraySize) * sizeof(float));

//runs the code. One of the args is a pointer so no return type is needed.
gen_sally(xs,ys,zs,time,sally);
//create varibles for file generation
char filename[20] = "results.csv";
create_csv(filename, sally, arraySize);

free(sally);
return 0;
}

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://public.kitware.com/pipermail/paraview/attachments/20180404/a4ae3548/attachment.html>