Shadow Catcher plus Lighting

[fixeighted]

Not quite sure exactly what you want but here is a simple scene with the above result.
Hope it does all or part of what you're after https://www.dropbox.com/s/386f28goth...20TEX.zip?dl=0

[JuhaHo]

Thanks,

Now I got it working and was able to fine tune it quite a lot. I even created special geometry to be the ground shadow generator. However the customer rejected the results. I need to find another way for generating decent ground shadows.

[fixeighted]

Sorry but I don't understand your wording...it's a language thing I think, so no probs
Give me an example of what you want to achieve and maybe there is a more ideal solution.
The distance texture is very simple but you'd need to experiment with its parameters to work out how it's used.

[JuhaHo]

What I was trying to say, is that I opened and analyzed the scene You kindly shared. Then I transferred the solution into my scene. I noticed immediately, that it doesn't provide desired effect. It works perfectly in Your scene, but didn't look that good in mine. The difference between the two scenes was, that in Your scene, one cannot see the ground under the object to be visualized. In my scene the ground is clearly visible under object, except of course the "feet" that are supporting the structure. The ground shadows were OK near the feet, but the ground was overall unnaturally bright. Then I created geometry only for the DistanceTex use near the ground surface, which made the ground shadow dark enough. However the shape of the shadow was all wrong.

What I want, is to fade the shape near the object. I Thought, I could do this with light for shadow only. But then again the shadow had wrong shape, because the distance between each object in shadow and ground cannot be seen in shadow.

[JuhaHo]

Would it be possible to achieve some results by using Render elements? I normally do everything in one pass. And if so, what channel would be the one? I just received yet another reproof on my ground shadows.

[fixeighted]

Any way you can post a simplified version of the model, so just the blocked in main shapes?
It would be easier to assess it that way. A sketch would do

[JuhaHo]

I was thinking earlier to create a similar scene, but at the moment it' seems to be impossible. I have V-Ray licensing issues and don't have access V-Ray at the moment.

[fixeighted]

Oh that's annoying....hope you get it fixed soon.
I'm mid big project but could do with a little break to look at this....it's intriguing me

[ttdww]

I may not be understanding the issue, however what about rendering a separate shadow-only element and in post using a gamma curve to bend the shadow falloff gradient inward toward the object? It's sort of the equivalent of how you control the Vray Dirt shader to expand or contract, but in post so it's interactively controllable and based on the lighting. It's not an all-in-one render, however it saves a boatload of time and the comp is simple.

[JuhaHo]

Thanks ttdww,

Is there a best practices tutorial for us, one pass dummies, to use multi pass workflow?

For one pass, I was thinking to render a top view and save alpha channel which would be used blurred as opacity map for shadow catcher object. I have not tested yet, but it would be on my list to do.

[fixeighted]

Yes, in the past I used to create the shadow as a map in P'shop...works great for a lot of things...just used it for a car actually...forgot about that

[JuhaHo]

Actually this would have been kind of a car.

[fixeighted]

Hehe, that'll work then.
Used to do it decades ago, when useable GI was just a concept and soft shadows were a mere dream
We were very inventive back then.