View Full Version : Falloff maps

05-23-2005, 08:16 PM
Greetings, I'm working my way through a max tutorial trying to figure out how to do it in LW

Its creating a planet, what I want to do is animate it and use it as a background image, anyway....


It says:

"The third element will describe the self-illumination of the globe when it is not under direct light, resulting from artificial lighting of the cities or the oil wells in the Persian Gulf. The very powerful Falloff map is used here with the "shadow/light" parameter selected. Falloff generates a map based on the illumination of the scene.
I set it up to do nothing in the lit areas and to display Earth-night4096.jpg in the shadow areas."

I would really like to do this, since the backside of my planet is very hard to see.
(No culling jokes please)
Have a texture show through only in the places where there is little or no light.
Falloff or something. THANKS SO MUCH IF YOU CAN HELP!

Also regarding the animation, in the future when I'm better at LW I would like to create somekind of procedural texture that would simulate the clouds actualy changing and moving. instead of a texture that just rotates with the planet.
If you have any suggestions... :D


05-25-2005, 09:31 AM
Man, I figured is max could do it LW sure could do it...

05-25-2005, 10:23 AM
Hi Macarthur,

I think the best approach to this would be a light incidence gradient alpha type thing- set up so that the gradient alpha only allows the shadow side map to leak through where the light isn't.

05-26-2005, 06:06 AM
Looks like it could work, Ive set up a gradient but how do I tie that gradient into the other texture so that its only visible for that area?

Currently the object has 3 textures

the globe shot
the night globe shot
and the gradient

05-26-2005, 09:34 AM
Hi Macarthur,

The way to do this is by placing the gradient in the layer directly above the night shot and setting its blending mode to alpha, which causes it to mask the layer below. Lightwave allows you to add layers within a channel, sort of like photoshop layers. Then if your globe shot was underneath the night shot, it would show through where the night shot is masked by the gradient. You'd need to duplicate this set up for each channel the images are applied to ( say luminosity for example.)

05-26-2005, 07:33 PM
Sorry to be annoying but how do I set this up?
My meager skills are weak...

This is how my Textures are layed out

Gradient: Light incidence: with a white to black gradient Opacity 100
Earth-Night : My earth texture opacity 100
Gradient: Light incidence: with a black to white gradient Opacity 100
Earth-day : My earth day texture opacity 100

What Am I missing?

05-28-2005, 12:06 PM
the light incidence seems to affect the fuzzy area between light and shadow, and not just shadow or light... :confused:

05-31-2005, 05:47 AM
Hi Macarthur,

You can use the gradients to control the blending here- basicly the sharper the contrast between your gradient keys, the sharper the falloff on the light incidence will be. Actualy, for a planet this can also be used to create the rather sharper falloff from light to shadow that planets, (being so big) tend to show.

05-31-2005, 10:30 PM
Hi Mac :)

You only need one of those gradients, the one on the top. It will make the layer beneath it partially transparent, and the other layer will show through. With the gradient set to alpha you will want the top key of the gradient to be white, and one more key, black. The area between the two keys represents the falloff area, so for a short falloff area put the black key closer to the top.