Pixels, pixels, pixels.

[Rich Rosemann]

Good morning,

 

I'm having a problem with (pixilation?) on some drawings I'm rendering. As you can see from the image, there is a heavy concentration in the shadow area.  This image is after 2,300 passes using Path Tracer.  The concrete material has Intensity & Sharpness set to 0.  Using the latest nXt.  The drawing is 105 Mb in size, but I've rendered drawings twice that size without the problem.  So I'm assuming size does not matter (in this case).  Any suggestions on how to avoid this condition?

 

Rich Rosemann

 

[Roy Hirshkowitz]

Not pixellation, no (and not size). I can't really tell without having the drawing-- but I would start by checking that caustics aren't on for some of the reflective objects-- like the tank.

[Rich Rosemann]

Hi Roy & Ros

Yes, Roy, the tanks have caustics attached. This to try to break up the reflections as uneven insulaton sheathing would do. Apparently this is not a good idea, huh? The attached .jpg image shows the current lighting setup. I'm testing different setups. As you might assume, the drawing is 90 percent metal and separating the surfaces visually is a challenge. Using the standard exterior setup with HDRI gives a flat (no shadows) image, even if I have the sun turned on.
Interesting that you pick the one setup (caustics) that I have. Is coustics not a good choice for solid surfaces, or cylinders?

Rich Rosemann

[Roy Hirshkowitz]

Caustics don't affect shiny surfaces per se-- they affect the matte surfaces surrounding the shiny surface as light reflects off of the shiny surfaces-- think of a disco ball casting light on the dark walls. A more common use for caustics is refractive-- the concentration of light passing through a clear object.

Your rendering looks pretty good without this effect-- I'd take it out. Use the path tracer.

[Rich Rosemann]

Got it, Roy.
So, if I set the Shader for the concrete texture to one of the settings controlling the Reflections or Highlights, will that have any effect on the concrete from the caustics surface? Or would the results be the same? I would run these test myself, but I know you already know the answer.
Thanks

Rich Rosemann

[Roy Hirshkowitz]

Those Shaders don't do anything at all in the Path Tracer.

[Ros. Riha]

In order to separate, I would:
- turn Indirect ON
- use a HDRI (from image you posted it seems you are not using it) - I would go for BeachProbe or similar...
- if the above would fail, I would try studio preset and set couple of strong light sources from various direction
- to my knowledge, use of caustics makes sense ONLY on (semi)transparent surfaces ... am I right assuming this?

[Rich Rosemann]

I'll run a test using the beachProbe first chance I get. Thanks Ros.
How effective are Studio presets for Exterior models? I assumed nada.

Rich Rosemann

[Roy Hirshkowitz]

Nope-- reflective caustics are sometimes useful too (like the disco ball.)

[Ros. Riha]

If I recall correctly, there was something related to setting the Sun Highlight to 0...how is your lighting set up?