X-Ray surface shader in Lightwave
This tutorial originally went up on the CGTalk Lightwave forum way back in 2003:
LINK
It then went on to be translated into spanish:
LINK
Then my tutorial wastranslated into Chinese for print in 3D User magazine.
It has certainly been around and I have had a great response. Since it has been translated into 3 languages I have always meant to go back and replicate the technique in multiple programs as well. When I get some time maybe I can do a write-up for Maya...
A little while ago I posted an image of an x-ray piston I made, like this one:
So how would you yourself go about making something with this texture and effect? it isn't so bad lets see here...
btw I am using LW v6.5
1. It is very important to model as clean as you can, stick to quads and smooth curves. Try to stay way from boolean operations and ultra smoothing your mesh, here is the rod for my piston:
It will help to break up the model with surface names based on metal density (we will discuss that later), bearings I guess would be very dense and let little x-rays through, but I am getting ahead of myself.
2. Rig up the model any way you want it to move, I used expressions to control mine. Since this isn't about making a piston but the x-ray material I will leave this up to you.
3. The fun stuff:
First you have to decide what style you want, I wanted an x-ray/mechanical drawing, so I turned on the outlins like this in the object properties panel:
This will give you nice white outlines, that are dependent on a few things in the surfaces panel. One of the primary ones is the smoothing threshold, this will be used to get creases to show up where you want them, just mess with it to get the results you want. I found 45 degrees was good for most things but sometimes smoother parts needed to be around 60 degrees, it depends on the part.
You will notice that the texture relies solely on the luminosity and bump channels. The bump channel gives that pitted look to the metal, I wanted something rough so I used this:
You will have to mess with this to give a proper scale to your model.
For the liuminosity the surface is ruled by an incidance gradient:
This sets up the general look of the x-ray material.
To get the see-through effect we must turn on the additive transparency check in the advanced tab on the surfaces panel, the amount it is additive will be determined by density.
4. Density and finishing touches
You are almost done, but this one surface alone won't be that interesting. I found it necessary to break up the pieces a little bit to give them more of an individuality. Here are a few ways to do this:
a. Vary the surface color, very small changes in this value can have a nice effect on the final image.
b. mess with the additive transparency. Less of a transparency will result in that object becomeing less transparent. The piston rod won't be nearly as dense as the bearings so I have additive transparency values of:
rod = 65%
bearings = 35 %
this gives the denser objects the impression that it is more dificult for the x-rays to penetrate that metal.
Problems with this method: The surface likes dark backgrounds! It is an additive affect so sometimes you can get completely white areas if you aren't careful. Also it can take a while to render.
-Aaron Berger