Vray renderings - rings problem!

[mohsinraza1]

Hi,

 

Could someone please recommend a solution to this problem:

 

Rendered with Vray physical camera (shutter 30 - ISO 200).

 

Many thanks,

[salvador]

You got this out of the frame buffer?

 

If this is the saved image I'm looking at a lot of compression. Try saving to a different format.

 

Ahh, yes, you need to post more settings.

[renderingdesigner]

Review your antialiaser filter. could you post the vray parameters?

[cg_Butler]

Never seen that before! I agree it looks like anti-aliasing. It also looks like my Amiga 500's graphics in the early 90's.

[Ricardo Eloy]

I can think of a few things:

- This looks like a low-depth image. Saving your renderings as PNG or EXR with 32-bits helps avoiding this

- Working with LWF definetly will also give you a more correct rendering.

[karthiksn]

i think subpixel mapping is on just off it and make a try

[mohsinraza1]

Thanks all for replying.

 

It happens with low level lighting scenes where as brightly lit interiors are fine. Here is another view(straight out of V-frame buffer, PNG), you can see it around dark corners:

 

Vray standard material with default settings, lit by HDRI.

Settings are:

 

Many thanks for your help, another ideas please?

 

Thanks,

[Ismael]

Study this: http://renderstuff.com/irradiance-map-vray-best-settings-cg-tutorial/

[Scott Schroeder]

This is not an imap, vray or render problem. This is a image quality problem. You are seeing image banding. Either you are saving too low of a bit-rate, you are using improper gamma, or both. Did you use a higher bit PNG or just default? You have a gradient from light to dark, yet your bit depth is not sufficient enough to produce all of the colors needed in that gradient, thus the banding effect.

 

You also have to ask yourself, are you ever going to render a solid gray scene? Does this effect happen when you use materials? Most of the time, our materials hide this banding effect, where a solid gray scene shows it off quite well.

 

http://en.wikipedia.org/wiki/Color_banding

 

http://en.wikipedia.org/wiki/Posterization

 

http://www.davidfleet.com/tutorials/linear-workflow

"FILE FORMATS AND RENDERING:

 

Compositing in 32-bit has been used in feature films for years. Color correction is much more flexible especially when controlling highlights. The ideal solution is to export a linear image like EXR or DPX for example. With Linear images all of the pixel data is mathematically correct as opposed to ‘looking’ correct, resulting in accurate and predictable results when adding or multiplying in post. After effects and Nuke can be setup to view Linear images in sRGB colourspace, composited in 32bit and then exported at 8bit for broadcast.

 

When saving linear images, 8bit formats will most likely result in some colour banding. There often isn’t enough range in 8bit colourspace to represent a complete tonal range when working with linear images. So whenever possible always render out to either 16bit (TIFs or SGIs) or 32bit (EXRs, DPX).

 

Never use JPEGs for rendering as JPEG compression is optimised for nonlinear images and will throw away much of the data required for gamma translations to and from Linear space."

[mohsinraza1]

Thanks guys, really helpful.