Reducing Bitmap Blurring To Get Cleaner Results
By Neil Blevins
Created On: Nov 21st 2013

Sometimes you'll have a model that has a texture map on it



and when you get at a glancing angle, the texture map gets super blurry...



Sometimes changing the bitmap filtering from Pyramidal to Summed Area helps, but when it doesn't, one other solution is to reduce the bitmap blur from the default of 1.0 to a small number like 0.1-0.2, or turn it off entirely. Or another things to try is turn down the bitmap blur to 0.1 and then increase the blur offset to a really low value like 0.005 (thanks Aaron for the suggestion).



For the image below, I turned Blur down from 1.0 to 0.4 and rendered in vray.



What's happening is this. All renders do some form of filtering. This filtering can happen at the bitmap level, or to the entire image, or both.

Below is a high contrast image, a black dot on a white background. When you filter it, you get a "blurrier" image, where it averages out the colors creating grey around the black dot. Filtering even further (or using a larger filter) gives you an even blurrier image.



So turning down the blur in your bitmap will frequently give you a much crisper result (closer to your original image). There are a number of considerations though before you decide to turn down filtering on all your bitmaps.

Advantages of turning blur off:
Disadvantages of turning blur off:


So there isn't a perfect one fits all solution, but try turning blur down or off the next time you see problems and find that good middle ground between too blurry and too crisp.


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