No tone mapping for backrounds?

[Duron]

Hey Folks,

i work a lot with cars onto backdrops and i just want to know if there is a workflow or trick just to get rid of tone mapping for directly visible maps as backdrops. I do not want to fake HDR effect by boosting highlights with output maps or similar. I just want the map being untouched and want that tone mapping only affecting the rendered objects in scene.

When i change the exposure settings or increase the filmic highlights, to get proper looking exposure on the rendered objects the backdrop is getting affected too.

The typical workflow is that you make a proper looking backdrop before you do any rendering and then try to match the rendered car as close as possible to the backdrop (highlights shadows etc.).

I already using the backdrop on a CoronaOutput map while the "Affected by Corona VFB tone mapping" is unchecked.

Thanks for any Help.

[Ludvik Koutny]

There's your problem:



As far as I understand, Fimic does some kind of math that can't be easily countered in CoronaOutput. So just ditch filmic highlights and use HL compression instead. Filmic highlights do not work very well anyway ;)

[Duron]

You're totally right, but this isn't my trouble. HC also affecting the backdrop as well and is killing my whitepoints. I'm looking for a way where my backdrop is not getting tone mapped by corona vfb at all. Something like "do not affect backround" on camera/tone mapping settings.

[Ludvik Koutny]

You're totally right, but this isn't my case. HC also affecting the backdrop as well and is killing my whitepoints. I'm looking for a way where my backdrop is not getting tone mapped by corona vfb at all.

That's strange... In that case it's a bug. Just to make sure, could you try to set all the other post settings to defaults, and try HC on it's own? If it really happens even with HC only? (In case you did not try that yet). Just set filmic highlights to 0, Vignette to 0, saturation to 0, and white balance back to 6500k. Then check if HC is really the culprit here.

I am suspecting that you mistakenly assumed Filmic highlights default to be 1 instead of 0. :)

[Duron]

See Attachement. HC is affecting backround as well. So this is a bug you say?

[Ludvik Koutny]

Yes, if it does not work under these conditions, then it indeed may be a bug. I've checked it here, on my Corona 1.5 RC4, and it seems to work fine.

Just to make sure, do you re-render between changes? Because CoronaOutput does not work in realtime in VFB. It requires re-render everytime you change settings, because all the tone mapping settings have to be established prior to rendering, so corona can invert those changes for backplate picture during render.

[Duron]

Alright, i got it. Re-Render is the key. As you said all changes being calculated backwards again so everytime i hit render, the backround is getting his original exposure.

I hope there can be a more decent solution for this! As i said something like "do not affect backround" on tone mapper. This way i could play with exposure settings in real time.

Thanks for helping!

[Ludvik Koutny]

Yeah, it's without a doubt bit confusing, but I am afraid it's not easily possible to have it realtime. As long as you use backplate for shadowcatcher or even just reflections or refractions, you have to re-render. Those exact color values at given time on the backplate are used by corona to calculate how much reflection, GI, etc... shadowcatcher reflects.

Changing any color value of backplate that's mapped on shadowcatcher geo or used as reflection/refraction environment is as much of a change as changing diffuse color of a material... it can't be done without rendering. :) Simply put, corona needs to know these values prior to rendering to know what exact color the "material" of the shadowcatcher is.

There's a little bit of a workaround, that could make your life at least little bit easier. Just run Interactive renderer, and anytime you change color mapping stuff around, just move timeline slider to different keyframe. That will force IR to reload scene and backplate will update. It's still not optimal, but should be a bit more comfortable than mashing F9 key all the time :)

[pokoy]

...
There's a little bit of a workaround, that could make your life at least little bit easier. Just run Interactive renderer, and anytime you change color mapping stuff around, just move timeline slider to different keyframe. That will force IR to reload scene and backplate will update. It's still not optimal, but should be a bit more comfortable than mashing F9 key all the time :)

I thought that's what the 'Refresh' button is for... it doesn't do anything in IR as far as I can see but this here is a case where it should restart rendering in IR.

[Ludvik Koutny]

...
There's a little bit of a workaround, that could make your life at least little bit easier. Just run Interactive renderer, and anytime you change color mapping stuff around, just move timeline slider to different keyframe. That will force IR to reload scene and backplate will update. It's still not optimal, but should be a bit more comfortable than mashing F9 key all the time :)

I thought that's what the 'Refresh' button is for... it doesn't do anything in IR as far as I can see but this here is a case where it should restart rendering in IR.

Yep, I suggested timeline because it's simply faster to reach than that button.

That being said, this could be solved in a lot more elegant way. A simple checkbox in CoronaOutput map which if enabled, would force IR to refresh with every tone mapping change as long as that CoronaOutput map is used somewhere in the scene. And it would be just refresh, not re-parse, so it would be quick as the geometry would not have to be re-translated again :) Similar to just changing material diffuse color for example :)

[pokoy]

The Refresh button doesn't do anything so a parameter change is needed anyways. But it *should* refresh.

What you suggest sounds good to me, this could be made a general checkbox in the renderer settings.

[Ludvik Koutny]

The Refresh button doesn't do anything so a parameter change is needed anyways. But it *should* refresh.

What you suggest sounds good to me, this could be made a general checkbox in the renderer settings.

Actually, it should stay in output map in this case. OutputMap has also brightness/contrast/saturation controls and LUT application capability. So if someone used output map for that, then refreshing IR with each color mapping change would be problematic. What we need is to tell Corona that only if this particular map is present in the scene, should color mapping IR refreshes happen.