How can I plot a line in a volumetric (3D) image?

Hello, I need to plot lines in a 3D volumetric (i.e. voxel) image. Is there a function for this? I've looked around but unless i'm missing something obvious I can't find any.

To be more specific, I'd like to find an extension for the line or plot3 function that plots lines within a high resolution logical volume image.

Thanks! Todd

[Sean de Wolski]

How are you plotting the volume?

[Todd]

I view either using vol3d just for quick looks, and then I export and plot in my own external viewer. What i'm trying to do is represent polygon structures in volume images. If I could convert a 3D plot (created with say plot3) into a voxel image i guess that would work just as well. thx.