advanced rendering for AutoCAD
6 passes in 40 minutes is not bad.
The more lights and reflective finishes the longer the render times. Materials with displacement have a big impact on render times. Do not use displacement unless necessary.
Chas has the right idea. There's obviously something bad happening on the ceiling-- I don't think your pendant light sources are working properly and they may be contributing to the problem. Tag surfaces as glossy whenever possible. Avoid Monte-Carlo reflection.
If you want to leave in all of the reflectivity and material effects-- I would strongly suggest using the Path Tracer engine. It won't be affected as much by displacement, reflectivity, etc..-- although it may take a while to remove all of the noise.
I'd be happy to take a look at the model if you wish-- I may be able to offer some more suggestions. It can be uploaded here.
Roy, I change the pendant light that i use from Ar4 and look better, I also send you the model for your revisions.
Rey, the model has a few big problems.
You're correct in your suspicion of the displacement maps. This is clearly not a good application for these. A simple bump map will suffice and will render much more quickly. Use displacements sparingly, and only when you can tell the difference.
There's also some nasty units problem going on here. The model is displayed in feet and inches by the INSUNITS are not set (0). This will cause nXt's units to default to meters. It's not very important to the appearance of your image, but it does mean that the lighting data is off by a factor of 39. This will make it difficult for you to do things like combine daylighting and artificial lighting. When I changed the INSUNITS to inches (1), the lighting data came out correct, but the texture maps were incorrectly scaled.
I'll take another crack at this tomorrow or later tonight if I have time.
Roy I make the correct changes and i think that every thing was fine now. I work in the final model and let you konow wen it is finish. All your points are correct...
Thanks a lot.
Another thing to try sould be to turn up the brightness in the render window dialog. You then may have to turn down some of the downlighting.