Continued; Notes; Ambient Occlusions
Hey all,
Some notes I am gathering on making AO Maps.
* When you burn AO maps for interiors and interior parts, you will need to hide the Windows from the scene before rendering. If the glass is there, the parts might turn out very dark. Mental Ray has issues with light showing through transparent Materials, so you need to hide the windows to produce proper AO Maps of interior parts.
* You can mildly adjust AO Maps. If they are coming in a bit dark, you can lighten them up a bit in Photoshop as a layer, after you insert the layer as a Multiply and near the top of the Stack. To darken the layer you would of course use 'Contrast' in the Brightness and Contrast tool section. You do not want to make the background gray that was white, as white is 'transparent' in Multiply. Making it gray makes it visible all over.
Another way to 'adjusting' the AO Map is to use Opacity. This way, you do not mess up the settings of bright and dark. If you are worried you might mess up a Render that took a long time to make, this way is good. You can also 'save' (duplicate) a layer, then hide it and work on the other one, so you do not lose the original Render output.
* For those that might not know, your AO Maps are burned one at a time in Max. Thus you bring them also into Photoshop one at a time. You cannot make a 'cluster' Render unless you Attach the parts in Max. (You can Render several parts at a time in assembly line fashion. Picking several parts and then hitting the Render button will cause the process to start where the parts are Rendered, but still one at a time. I have found that Max started making mistakes, perhaps a Memory problem being its only 32 bit. The backgrounds turned black instead of White. Not good).
* Did you know you can 'Attach' (merge) Ambient Occlusion layers in Photoshop that are Multiply layers? Yes. Use Magic Wand set at 5 and select the white area in a part AO Map, then Delete. When you get several of these AO Map Layers, simply stack them, pick the highest one, and start using Control-E and Merge them, one at a time. They Merge nicely. Just make sure first in Max that they all look proper and arent out of adjustment. You want to adjust their brightness when they are separate, so dont get ahead of yourself.
* Duplicate 'Shared' sides using the same graphics. If you share sides on a graphics sheet, such as sides of a cabin, and you havent created the AO Map yet, you will need to attach a UV Unwrap Modifier and go in and move 'one side' of the UV mesh out of the way, 'then' burn a AO Rendering. Check the Render in Photoshop, save, then in Max to make sure its proper and blends with the rest. Once that is done, move the other side back and you are done. The reason is, double parts tend to 'darken' the AO map. Doing 'one' side doesnt.
You 'might' be able to hide the mesh of one side, then burn the Render. I havent tried that. It seems that AO Renderings only function with parts that are 'in the scene', so hiding sides in Polygon mode might get around this.
Fun with your AO Maps.
