What are normal maps actually used for

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Old 01 January 2013   #1
What are normal maps actually used for

Hello there,
I had a thread here
And basically it was showing my AK-47 Models and the model had 53K polygons, now obviously this is very high (for games) and would like to know exactly how to reduce this to <20K and preferably <10K, if possible. By using Normals maps can I retain the model to something close to identical to the images posted, if not how is there a way to do this...
Thanks,
 
Old 01 January 2013   #2
Normal maps are images that can change the direction a surface is facing. The colors represent directions for the surface. What it is used for is that details on a high-detail model can be transferred onto a low-poly mesh to make it look like the high-poly mesh. so things like small screws/bolts or panel seams, scratches, wrinkles, all kinds of small details can be captured. And unlike a bump map, it doesn't make things look like they are sticking out, but rather only changes what direction it appears the surface is facing.
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Old 01 January 2013   #3
Like darthviper107 says normal maps give the illusion of depth. Normal maps give light information along the x,y and z axis. The maps are usually derived from high resolution surfaces but are sometimes painted directly in an image editing application and sometimes a combination of 'baking' and painting is used. The plugin nDo is a good example of a tool used to paint normal maps. Here is a game character I am busy with and I thought it would be easier to show what effect normal maps have. What they are used for is to give the impression of high detail in a realtime environment like a game engine. Normal maps are also used in combination with displacement maps to give ultra high detail to high resolution computer models in various situations as well.

Normal maps do not alter the geometry of models so in the example below you will see that the profile or silhouette of the model stays the same for each shot so normal maps will provide all the detail you need up to a certain point. The zbrush model for this character is 7.5 million polygons or 15 million triangles. The low poly representation of the model is 10,288 triangles which is a pretty big reduction. Not only that but there are two other versions of this character which are 4000 and 2000 triangles for Level of Detail models that can be used for distance shots. The absolute best software at this moment for extracting various maps is a free application called xnormal : http://www.xnormal.net/1.aspx by Santiago Orgaz. If you download xnormal the support documents that come with it will give you the best explanation of how normal maps work and hints on how to best extract them. The images below are realtime viewport screen captures so they are not rendered and this is the whole point.

Hope this helps
Cheerio
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Last edited by Kanga : 01 January 2013 at 06:27 AM.
 
Old 01 January 2013   #4
From my knowledge their used on low poly models to convey detail. Video games rely on this heavily since they render on real-time and therefore need low poly models.

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Old 01 January 2013   #5
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