Please someone remind me why I get jagged edges on lights?

[rfollett]

can someone please remind me why I get jagged edges on the lumens areas..? samples set to 18 on green light, this render I took to 512 samples

http://prntscr.com/iiv59m

[mattjgerard]

Looks like anti-aliasing to me, shallow angles off of 90 deg tend to exhibit that. The only place I've seen to correct it is in the advanced controls of the render settings. The reason its so apparent on those areas is due to the high contrast between the materials.  I think I fixed the issue I was having by rendering a region of the troubled area at a super high anti-aliasing setting and letting it bake for a longer time, then photoshopping it in.

[INNEO_MWo]

I can rebuild this effect. You'll see this in the attached scene.
On the first look this will appear if the area light has a very high lumen value applied.

And max samples mode as well the advanced control (with anti aliasing set to max) will render this way. I also tried max samples with a value of 1000 and advanced control with different setups (turn most options of, use the local lighting cache, increase the global illumination (even it makes no sense))

The only thing that works is the bloom effect to reduce the steps (aliasing).

Hope that helps

Cheers
Marco

[rfollett]

Hello Marco & Matt,
thank you for your help
switching bloom on is the only thing that seems to help ...

cheers

[rfollett]

actually the bloom does not work when you run a render..

it works in realtime when you let the scene res up..

But when I run a render (and this happens on your test scene) it goes back to jagged edges...

This is very frustrating, can anyone help??

[INNEO_MWo]

I attached two quick renders.
1. render in max samples mode with 20 samples and interior mode
2. render with advanced control (samples 20, GI 1, Rays 14, anti-aliasing 3, shadow 3) in experimental product mode (cause interior don't work with advanced control)

[rfollett]

ok thank you... seems a little confusing, as what you see rendering is not what you end up with.. thank you for your help

[Will Gibbons]

I would advise using Custom Control as it'll help you cut down on render time while improving image quality if your settings are optimized. Matt's right in that Anti-Aliasing (or lack thereof) is the issue seeing here.

As stated though, interior mode isn't compatible with Custom Control, but the experimental product mode is if that's enabled in the .xml file.

If your machine can handle it, I think you'll get better results with Custom Control, no interior mode.

If you use max samples, bloom should work and be applied to the final rendering after it finishes rendering. Does it not?

[rfollett]

Hi Will
thanks..yes the bloom is applied to the final render. That was confusing me as  I could not see it as it was resing up.
not familier with Customer control or the experimental mode but will take a look

thank you

[andy.engelkemier]

Here's a probably oversimplified explanation of why.
Anti-aliasing works by taking samples of your pixel and creating an average. So if you're pixel is at the edge of a black object and a white object, you'll get a grey color. This smooths things out for sure. BUT, colors aren't limited to 0-255. They are actually stored in floating point before they are displayed to you, so the average may be quite ugly, as you are noticing. You're averaging something like .2 with lets say 7.1. And what do you get? Well, 3.65? Shoot. That green color will overpower nearly Any value. So as soon as a portion of your light hits a pixel, it's above 1. That's why you get a stair step.

Some renderers let you do anti-aliasing on clamped values. That's Really what you likely want, but I don't believe keyshot allows that. I requested that feature years ago, but I think it fell on deaf ears. I think most keyshot users would want clamped antialiasing. But that does mess up your 32 bit renders. So it needs to be an option. They Could just hide it. There's no reason Not to clamp 8-16bit renders. Just just clamp those, and don't clamp the 32bit ones.

My suggestion anyway is to render twice. Render once where you get enough light, as you see it. Lower the value so none of the values are blown out, and composite the results together.