Dark Hairline around objects against background

[Ugo Iglesias]

Hello all,

 

  I recently started using NXT and I'm getting an undesirable dark hairline surrounding the objects when rendered against a light image background. 

 

  Thanks in advance for your help and please let me know if more information is needed.

 

Ugo

INCUBOX

[Ros. Riha]

you must have messed up with background settings - try to change it. Generally speaking: the less you change in the setup, the better

[Roy Hirshkowitz]

It's a known problem.  Two choices here-- use the Path Tracer to render -- OR-- use the default sky background and save the image w/ alpha channel and then composite into a background image using Photoshop or eq.

[Ugo Iglesias]

 

Thank you for such quick response. 

 

I didn't know it was an issue and tried looking into the forums but didn't find alike topic. I'll try on the Path Tracer as suggested. The Alpha Channel seems to be a good choice because most of times, a rendered image that includes a background in the rendering process may end up having mismatch appearance between objects and the background. It just guarantees a chance to tweak the background to achieve overall uniformity. Also, I've noticed that when I try to include a high resolution background image, it tends to slow things down a bit. 

 

Ugo

INCUBOX

[Roy Hirshkowitz]

Just so you know-- when you're compositing onto a very light background (white, for example) all of the approaches may require a little post-processing.  The two suggestions I had will help mitigate the problem.

Another possible solution is to turn the background into a planar HDRI by using the tools provided in the Widget pulldown.  This sometimes works nicely and does allow you to manipulate "Channel 8" to change the brightness of the background.

 

[Rich Rosemann]

This is another good example of the miss-match of model and background.  The sun appears to be almost at noon, from the left, and the background is at near sunset, from the right.  The background makes a very dramatic sky, but at the cost of the realism.  Assuming we are all shooting for photo-realism in our images.

 

Rich Rosemann