best way to make emissive maps

[Sharky85]

im interested in how to make emission maps but ive never attempted them before and not really sure where to start. I was checking out this thread the other day (*http://www.polycount.com/forum/showthread.php?t=88996) and thought the effect looked really cool on the 'spider food' model.

Also, where do these maps go in regards to Max and UDK, im assuming in max it would go in the 'self-illumination' map slot?

[dustinbrown]

The value of the pixels on the glow map will dictate how bright each pixel glows, relative to any other input values you include, like a Multiply node. So black equals a value of zero (no glow), and white equals uber glow. The hues you use in the map are the hues you'll see glow - that's straight forward enough. If you just need one glow color, you could choose your hue via your shader network and control the per pixel output of the glow in one channel of a texture map. Call it a "glow mask" if you like. That way you have two or three other channels to utilize however you see fit.

In Max, yep, you put it in the self-illumination slot. In UDK there's a slot called emissive.

You can approximate your per-channel texture set up for the engine in Max. Use Color Correction nodes to isolate each channel, then plug your texture map into that :)

http://www.dustinbrown.com/wip/perm/colorCorrection.jpg

[Computron]

You can also click on your texture sample and turn off color channels in the outputs.

[dustinbrown]

You can also click on your texture sample and turn off color channels in the outputs.

That's absolutely true, great point. The only downside to that is that the Output panel doesn't give you access to the alpha channel. The color correction maps also give you some other control features that may be useful, depending on what you're trying to achieve.

[Sharky85]

awesome thanks guys,

what about techniques for the actual emmisive texture map

[bb0x]

Think about it like this. A world completely stripped of light. Everything is black.

Whatever you paint on the emissive texture is the only thing that you will see.
Basically emissive is like a mask. Black will not show up anytyhing birghter than black will.

[Sharky85]

perfect direction! thanks =D

[dustinbrown]

An example of a really simple emissive map HERE (http://www.dustinbrown.com/wp-content/gallery/galleryportfolio/bobodemoskd.jpg)