HOW TO REDUCE THE POLYGON COUNT
Even modern video cards are constrained in terms of the number of polygons that they can draw at an interactive frame rate (10 to 60 frames per second). This article describes a few tips for reducing the number of polygons in your 3D models, which will result in models that run more smoothly and download more quickly.
Step 1: Identify any curved objects with excessively high tessellation
At the current time, a computer's video card is only capable of drawing flat surfaces called "polygons". When you create a curved or rounded surface such as a cylinder or sphere, the surface is approximated by a large number of small polygons. This approximation process is called "tessellation". It's common to find objects with much higher tessellation than they need for real-time interactive use where usability is more important than visual perfection.
Once you have identified these objects, reduce the number of polygons used until you find a reasonable compromise between visual quality and performance.
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| Wrong! Chair legs have excessively high tessellation. |
Right! Chair legs have an appropriate level of tessellation. |
Step 2: Identify objects that can be drawn as textures
Creating 3D models is a bit like stagecraft - the only thing that matters is what the audience sees. Often, if an object is normally viewed only from a few sides or if the object is mostly flat, then it can be approximated by a textured polygon rather than by a full geometrical model.
Examples:
- Trees, bushes, foliage
- Lettering and signage
- Building facades
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| Wrong! Tree modeled using hundreds or thousands of discrete polygons for the leaves |
Right! Tree modeled using only 2 textured polygons for the leaves |
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| Wrong! Stop sign using polygon text requires several dozen edges and faces for face of the sign |
Right! Stop sign using texture text requires only a single textured polygon for the face of the sign. |
Step 3: Identify objects that can be eliminated from the scene
The most drastic way to reduce the number of polygons in an object is to eliminate the object entirely. To learn more about how to identify hidden objects and objects that make a minimal contribution to the scene, read the article How to Reduce the Object Count.