Author Topic: stairs in gradient reflection  (Read 3194 times)

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Offline fonzibear

stairs in gradient reflection
« on: April 02, 2015, 05:00:29 am »
Hi guys
I wonder if there is a solution to this:
When rendering plane reflective surfaces with no roughness, iI always get these different shades of gray in my reflections. And there are more than 50!
As soon as i turn the roughness of the material up, of course it disappears. Is there something i can tweek in the hdr editor?

Hope someone can answer this.
Thanks guys

« Last Edit: April 02, 2015, 06:45:04 am by fonzibear »

Offline richardfunnell

Re: stairs in gradient reflection
« Reply #1 on: April 05, 2015, 03:25:15 am »
A limitation may be in the image format you choose, not the scene or materials themselves. 8-bit images (JPG, PNG, TIFF, PSD) only support 256 shades of grey which may explain the banding that you're getting.

If you render out a 32 bit image (EXR, TIFF 32, PSD 32) you now have tens of thousands of levels of grey and should get smooth gradients. Also, I don't recommend working with JPG images for high quality purposes since the format tends to be somewhat lossy.

Offline fonzibear

Re: stairs in gradient reflection
« Reply #2 on: April 05, 2015, 02:25:18 pm »
Thanks very much for the input, it worked with 32bit tiffs!
Since i'm working on an animation, i was only allowed to outrender the single frames because 32bit is not suported in avi or mov. When imported in After Effects, the banding in the gradient was still there, but by adding 0.05% of noise, the whole surface just turned out perfectly smooth!
It also worked in 16bit mode. In the beginning, i tried the "adding grain trick" on my 8bit png's, but the surface turned out very bad since i had to add a lot more noise to make the steps to disappear. So then the result was more of a speckled mess instead of a smooth glassy surface.