Potpourri March 2018 challenge WIP

[Finis]

Blah! Too much trouble. But it looks like that is the only way. People are having trouble with it appearing in reflections too. They have to give the catcher a material, which has to match the background image, and move and scale it to fit so the reflection looks right. That is ridiculous. It should have remained experimental in 2.79 because it is not ready.

Hopefully it will be fixed so it always invisible everywhere except the shadows. For now though it is like you, Draise, said unless someone knows of something else.

[Draise]

Render pass workflow is.... really an industry standard. Only in game engines have they really tackled this due to the nature of not being a raytracer. I don't know of a raytrace renderer who has solved this issue.

I have attached the basic passes of how I would render them out to save you some discovering how.

Then in the compositor I'd just use Alpha Over or Mix nodes for the two lanes and composite.

A good thing about passes is each can have different render settings, so something like AO only would have a quarter quality than the beauty image (and the beauty wouldn't have AO) so you save time rendering by dropping the AO quality. (and you get control of tuning the AO after you've rendered in the compositing nodes)

[Finis]

Render passes/compositing standard for pros, of course. Useful for some things, of course. Must use that to fix shadow catcher bugs, ludicrous. The blender shadow catcher is not finished enough to be released other than as experimental or in a beta. No big deal ... passes/compositing shouldn't be needed but they can work around the problem ... or is the problem bigger than shadow catchers? See below.

Here is a shadow catcher test with Iray in Daz. No problems with reflecting the catcher or it appearing through glass. The ground is HDRI which is also the only light. There is a glass plane in front of the ball. No passes needed. No layers needed. No compositing needed. Rendered in seconds so passes/compositing equals effort wasted.

I put the two trees and the shadow catcher, which are beyond the wall, on another layer. I set Transparent on in Render->Film so the hdri would give light but not appear in the render. That creates a transparency where it would have been. Problem if I needed reflection of it in the glass. Then I would render the "beyond the wall" layer with hdri visible and put them together in Paint Shop. Except the hdri still shows through the glass! So the glass bsdf shader shows whatever is behind it whether it should or not. I tried mixing a transparency shader node and using the principled bsdf. Didn't work either.

I need the view through the glass to be a transparent background to see the other layer.

(The black part is transparent in a png.)

I'll try the more complicated layering scheme you described. Looks like good stuff to learn anyway. I think the problem now is that things show through the glass when they shouldn't. Since this is a hobby picture I should wait for the bugs to be fixed or rearrange it so the catcher isn't needed but I don't want to.

[Finis]

EDIT: Nope, didn't get it. The shadows are also not present with the action below. Re-thinking it that makes sense.

Got it!

Select the shadow catcher object. Go to its Object panel. In Cycles Settings->Ray Visibility uncheck Transmission. Then it looks right through the glass!

[Finis]

OK. The problem is not with the shadow catcher. Blender has a problem with glass. Looking through glass to a transparent background won't work. That is why Render->Film->transparent shows the hdri through the glass. The catcher's transparent parts show white through glass so again it is transparency.

Current solution: coming soon.

Future solution: The cutting edge 2.79 available from the "Blender Bot" (I don't know what that is) has a new feature Transparent Glass. It is a checkbox near the Film->transparent box. That might fix this. Better if they would fix glass and reflections so they don't show invisible things.

Draise: Thanks for the info. about layers, masks, passes, and so forth. It is good stuff to know, introduced me to features I hadn't explored, and will be useful in future projects.

I'll post an April challenge soon.

[RAYMAN]

Much easier! Just copy in the shadow in post pro!
Blender isnt production quality Im afraid!
On paper its not bad and it has good functions!
But it simply lacks...quality!
Cinema 4d costs money ... but you import fbx and it works! Import it in Blender and its always hit and miss! Sometimes it works ..but sometimes not!
Dont know..its a well known issue..and even the boss of Blender admits....the industry doesnt make it easy for Blender! They always slightly change specs ie in formats.. against compatability!

[Finis]

@Rayman. Agreed, Blender isn't production level but I'd qualify that as dependent on what you want to produce. I think many Blender users are hobbyists like me where the main factor is price but people do use it for professional work.

The problem with shadow catcher's invisible part showing through the glass prevented doing it in a single render like would be possible in Iray/Daz. Working around that with compositing as recommend require transparency behind the glass but like the shadow catcher the hdri background also appeared through the glass when it shouldn't. Counter measures for that didn't work. There are probably things I didn't find to try. So making appropriate layers or masks wouldn't work due to glass transparency trouble.

Ordinary objects appear without trouble through the glass. I made an image of the background trees and the hdri. With no glass the shadow catcher worked. Then I applied that image to a plane behind the foreground objects as shown below. The hdri is not visible in the finished picture but does provide the light.

[Dragneye]

Very nice work Finis.
I'm working on a scene with glass so all this effort may be useful. Have to look into these details.

Draise, thanks for sharing.

[Draise]

Final images are great. Glad you got it sorted. Good work.

Lately I've ditched all raytracing software due to the annoying headaches and times and only render realtime in Unreal Engine or others. I prefer seeing what you'll get...

Keep them coming!

[Finis]

Yeah, I'm looking at eevee or similar for a larger project later on. Mostly it is the speed to render lots of frames.

Thanks y'all. Dragneye, I used the glass bsdf shader to make it easy. It worked ok for regular stuff. Just things that should be transparent or invisible cause trouble when seen through glass. I think there are node recipes for better glass.

The final renders have many samples and no denoise since the water looks better. Still mysterious darkness in the water at the bottom.

April challenge coming probably tonight.