Jeff Myler Posted August 5, 2014 Share Posted August 5, 2014 Can someone explain what deselecting "Ignore Bump Normals" in Global Illumination dialog box does? I believe by default it is selected. I deselected it and it seems my rendering increased several hours in render time. I have a metal display frame that has a noise bump shader to give the effect of textured powder coat. Quote Link to comment Share on other sites More sharing options...
Cary OConnor Posted August 5, 2014 Share Posted August 5, 2014 "This option by default will ignore bump normals which may yield undesireable result when GI is the only source of illumination. Un-check this option for better result. Note: Un-checking this option will can decrease performance with GI." Since you are using a Bump Map/Shader, it may be best to have this option off as long as you have light source other than GI. If you are only using GI to light the scene, the performance will be affected. Are you using multiple light sources and what are your settings on the GI tabs? Cary Quote Link to comment Share on other sites More sharing options...
Jeff Myler Posted August 8, 2014 Author Share Posted August 8, 2014 I have been using hdri background, with 1 direct light on in scene (shadow OFF) set to .5 and GI set to full illumination & high quality. I like the render results with these settings. Sometimes I set it to Medium quality and GI to just background illumination seems to speed up render times. I guess I still don't really grasp the term "bump Normal". If it is deselected you will not see bump effect? If it is selected you will see bumps? Quote Link to comment Share on other sites More sharing options...
Cary OConnor Posted August 8, 2014 Share Posted August 8, 2014 You will still see the bump effect in some cases. What it really means is that does the GI pixel calculations account for the bump normals (meaning how the light will reflect off the bumps). So if you have only GI lighting, you may not see the bumps if the option is checked. Easy test to see what is happening is drop a block and apply a Circle or Dimple bump to a face. Use GI rendering (turn off all the lights in the scene). When you render, look at the pixels that are calculate in the processing. You will see a big difference when the setting it on and off. The results will show you the difference as well. So if you have other light sources that will hit the bumps, then you can leave that option checked since you will still see the effects of the bump. If you don't have other light source or you want to get more realistic results with lighting and shadows on the bumps, turn the option off but be prepared to wait especially if you have a small bump map that is repeated in large areas (like noise). Hope that helps, Cary Quote Link to comment Share on other sites More sharing options...
Jeff Myler Posted August 8, 2014 Author Share Posted August 8, 2014 That explanation helps, thank you. I will give the test a try. Quote Link to comment Share on other sites More sharing options...
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