This routine helps you make 3D pictures from your data, using the public domain 3D rendering routine POVRay. See also:
POVRay is a standalone program that runs on a variety of operating systems. The mkpov routine generates a text file that is interpreted by POVRay to produce a picture. mkpov has a variety of options to help you make a nice picture. POVRay is a powerful program and can make beautiful and realistic pictures. Having it simply draw spheres is vast overkill, but it works. Furthermore, it makes it easy to change the color & size of each sphere individually.
Basic syntax:
IDL> pts=fltarr(3,1000) IDL> t=findgen(1000)/1000*3.14159*2*30 IDL> pts(0,*)=10*cos(t/3) IDL> pts(1,*)=10*sin(t/5) IDL> pts(2,*)=10*sin(t/2) IDL> mkpov,pts,'img01.pov' center of data at: 11.0000 11.0000 30.0000 camera at: 11.0000 11.0000 64.0000IDL> $xpovray +Iimg01.pov +D 2>err The mkpov command creates the file "img01.pov". The last command calls the linux routine xpovray which generates the picture. This is a threedimensional Lissajous figure. Larger values of x are at the left of the picture. Larger values of y are at the top of the picture. Larger values of z are closer to you. 
mkpov keywords: (Brief listing here, see examples below)
Using color:
Starting with the array pts defined in the first
example: Here I've made an array col which is in onetoone correspondence with the data array (pts). I've filled it with greyscale values between 0 and 1, or in this case, actually between 0.2 and 0.8. Also, I've used the /nobox keyword to turn off the bounding box. 

To be more colorful: IDL> col=bw2rgb(t) IDL> mkpov,pts,'img03.pov',color=col,/nobox IDL> $xpovray +Iimg03.pov +D 2>err Now I'm using the program bw2rgb which converts an array of greyscale values into red/green/blue values. (Here, my greyscale array is the original t array defined in the first example at the top of this page.) 

Different coloring: IDL> col=bw2rgb2(t) IDL> mkpov,pts,'img04.pov',color=col,/nobox IDL> $xpovray +Iimg04.pov +D 2>err bw2rgb2 has slightly more intense colors. 

Different coloring: IDL> col=bw2hotcold(t) IDL> mkpov,pts,'img05.pov',color=col,/nobox IDL> $xpovray +Iimg05.pov +D 2>err bw2hotcold maps 0 to blue, 1 to red. 

Changing particle size:
IDL> rad=(sin(t/6)+1.5)*0.4 Here I've defined the array rad which specifies the radius of each particle. The units for radius are the same as the input data.  
Changing camera angle:
IDL> col=bw2rgb2(t) I've moved the camera to a larger x value and slightly smaller z value. This is sort of like rotating the image to the right. See also the next example.  
Changing the box margin:
IDL> mkpov,pts,'img08.pov',color=col,camera=[34,11,70],margin=2 I've moved the camera again, further away and closer to the original angle; and also added a margin of 2 units to the box size.  
Slightly different camera angle:
IDL> mkpov,pts,'img09.pov',color=col,camera=[11,34,70],margin=2 I've moved the camera again. 
Programs:
POVRay input files from examples above: