Glow and screen AO

[detbear]

I was rendering a shot with a glowing object and I noticed that Screen based AO causes a 'banding' in the glow/ halow/ orb is present at the end of the last render pass.

 

I wonder if this has to do with a setting or just a casualty of using screen based AO.... The glow is looking great until that last pass finishes and the AO is added in.

 

I'm in V18.

 

I increased the multipasses but that didn't help. Both with and without motion blurr carries the same results.

[Rodney]

The glow is looking great until that last pass finishes and the AO is added in.

 

Assumption: The same thing happens wihen the SSAO is rendered out to diffrent images (rather than with the 'Add to Image' option on?

[NancyGormezano]

Your settings for glow? SSAO are? Pics before and after?

[detbear]

Hmmmm....Rodney could be right. I'll have to check it out.

 

Nancy.....If the problem persists, I'll post something. I'm about to post a new version of one of my short films. This glow thingy may

not be a huge issue......Yet

[Rodney]

As I recall something that will kill glow around the edges of objects is rendering the object with glow with alpha channel with nothing behind the object.

This is generally something people don't like... they want to see the glow emanate out past the object but in your case you may want it to stop at the object edge threshold.

The workaround to fix to get the glow is to put a solid shape (a plane perhaps) behind the object to prevent the loss of the glow so refraining from placing that mask behind the object should remove it all.

If the mask is of a specific color then a chroma keyer can be used to remove everything but the object and it's radiated glow.

None of this particularly relates to the banding issue but I'm including it for discussions sake as I try to understand what actually is going on with SSAO.

 

Regarding the banding, perhaps if you crank up the number of passes with multipass that will blend out the banding more.

There is much about SSAO I am unfamiliar with (I thought SSAO could apply it's settings to every pass of the multipass render but at present I don't see that option).

There is an option to blur the SSAO effect which when combined with higher levels of multipass should soften out any banding considerably.

[detbear]

Hey Rodney,

 

I'm also not as familiar yet with the SSAO as it exists in the new versions. I used Jenpy's "Fake AO" plugin quite a bit in previous versions. They don't seem

to operate exactly the same.

 

Overall....I've found some strange banding with the SSAO when combining it with motion blur and things like glow. I guess discovering that "Sweet Spot" setting is

key.

 

I am rendering with an alpha channel.....so that could be contributing to the banding. I did increase the multi-pass count quite a bit because I too suspected that this might

blend the bands a bit better. But that did not seem to make much difference.

 

I'll figure it out. It will take some more experimentation with the SSAO.

[robcat2075]

My suggestion would be to render with SSAO, then turn out all the lights and render the glow as a separate pass and composite the two with either "lighten" or "add".

 

I dimly recall a similar problem with glow in my "painting with light" series and I found that compositing the glow an easy fix.

[detbear]

I've got several projects pending but I'm really glad to be finishing this 1 minute short(or about that length).

 

It's crazy the amount of mental planning, problem solving, artistic choices, and R&D that goes into producing a short

clip. Then there are the things I often have to just "go with."

 

The only budget for this is whatever time I have. So the budget is whatever motivation and time that's available.

 

Then there is that artist part of me that is never satisfied and is often forced to abandon things while calling them finished. Simply because

being a perfectionist rarely sees anyhing as finished or completed.

 

I had to come up with several effects and "looks" that I wasn't sure originally how they should be.

 

But the completion is nevertheless close for this short. Then it will be on to several others in the works.

[John Bigboote]

Cogratulations William... would be great to see what you are up to. Sounds like you found 2 features that counteract each other in the renderer, I just discovered one that has me scratchin my head... use SSS and DOF together and you get a 'un-additive' unwanted darkened effect . (Sub Surface Scattering and Depth-of-Field.)

[detbear]

Yeah..it seems like the relationships between certain blends doesn't always work. I guess that's when your favorite compositing AP

becomes move handy.

 

Hey.....whatever happened to the "All the best" guy? Ever hear back from all that?