This is a copy of a posting to the AccuRender Newsgroup.
This is such a difficult subject that it's hard to know where to start.Several things will massively increase your rendering times - some I mentioned in the previous mail. Don't fool yourself into thinking that you need detail where you really don't. I have entire buildings, with hundreds of lights, hundreds of chairs, plants, landscaping rendering on a machine with 256Mb of RAM, without overloading it. The trick is to only make what you really need, and simply that as much as you can. I will repeat - this doesn't mean compromising your image, it means discarding what can't be seen, or using a bitmap for detail rather than modelling.
One of the most important jobs of the 3D modeller is to keep the face count down to an absolute minimum. In most cases, a 16 sided polygon will look exactly like a circle - and in some cases 8 will be enough. If the circle is tiny, use a square ! In any case, unless you really know how to control the faceting of round objects, don't let AutoCAD and AccuRender do it for you - use lines instead of curves. Think about how many faces you are creating for every object you make. If you make a sheet of glass from an extruded solid, you are creating 12 triangular faces. If you make it from a 3dface, you create only 2 triangular faces. Over a whole building, this can be a massive saving in memory.
Keep your use of raytracing effects to a minimum. By this I mean reflectance, transparency, refraction, depth of field. Only use them if you need them - don't just add 30% reflectance to a material if you feel like it - make sure you will need it - if you can't see the effect in the final rendering, you don't need it.
Procedural materials can get heavy. If you have a granite procedure on top of a blend on top of a mask, and all made into a tile with a granite joint material, the stuff will take ages to render. Use a bitmap instead.
Too many lights in a raytrace-only rendering will cause quite a big slow down. If you have loads of lights, consider radiosity.
Finally, the most obvious one: Don't set your anti-aliasing higher than you need. We have discussed this before on the NG at length, but I believe the consensus is that you will rarely need any higher than the "high" setting. You many find that certain tiled materials look better at higher settings, but in most cases rendering at a higher resolution is a better option. In general you should use "medium" for test runs, and "high" for finals - unless you have a specific reason for the "very high" and "highest" settings.
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