View Full Version : Odd artifacts

11-21-2010, 04:14 PM
Today I decided to work on improving my metal texturing skills and chose a gold ingot as my subject. This is my first try at a metal texture and as such, this still needs a lot of work.

In the scene, there are 2 objects. The gold bar (cloned) and a single poly floor element. The texture on the floor is the default felt preset. For the metal texture I used the gold preset and then tweaked it a little. Scene is lit with a single spotlight and then an HDR BG. Rendered with Monte Carlo radiosity with 3 bounces and the rest as default. This is the image:


Now in this version I have circled areas of concern for me. At the upper right is some odd looking artifact on the felt surface and in the center the edge of the bar has a strange rippling on it:


So two questions:

1. The artifact in the upper right - Any idea what that might be?
2. The strange zebra / rippling on the bar edge - is that correct?

And finally, any tips on improving this would be great.

Thanks all!

11-21-2010, 04:43 PM
It's not a rippling, it's a problem with aliasing that shows you need to up the Anti-aliasing passes. You can also turn on Adaptive Sampling to prevent doing unnecessary render passes. As for the mark in the upper right corner, it looks like a reflection to me - do you have anything above the floor in that area?

Other things to improve the image? You can start with a gold ingot imprint image map, rather than a silver one, or change the metal? ;) Also, the image needs to be higher resolution, the current one looks a little soft.


11-22-2010, 08:09 AM
Thanks. I upped the AA but it seemed to have little effect on that lower artifact. The upper one is caused by a hot spot in the HDRI probe. Not sure I can resolve that one...

11-22-2010, 08:36 AM
Maybe the ripple effect is the edge of a bump map or something.

11-22-2010, 03:09 PM
You can rotate the probe image to at least get the hot spot in a different, less obvious place?


11-23-2010, 12:06 AM
Don't forget references!

- turned up aa? for all we know you went from 2aa to 3. What are your settings?
- try as many different hdr's as you can until you find one that rocks
- 3 bounces GI is a waste of render time!
- model the grooves, or use a high-res map with displacement, bump looks cheap.