Hannes' Cliff WIPs

[bobbystahr]

Cool!!!

But that was a tough one. I rendered out the silhouette of the arch, put it as an opacity map onto a sphere, and no matter what I did, I got a strange shadow gap even where there was shadow without the plane.
So I used this shadow map and created a spline object out of that in Max, converted it into a mesh and used this one as shadow object. I hope this is OK with the rules as well, since I'm rendering something quite similar to the previous invisible card in TG.

As it's overcoming an obvious bug in TG I'd have to vote to allow this and WOW...

[Dune]

Yeah, this is too great to be dismissed as fraudulent. But there should be (must be) another way!

[cyphyr]

Well "if it works" has always been my motto. I would have thought this was within the rules but Danny will have to say obviously.
Could you not just use a card object with the silhouette uv projected onto it?
Cool image, it looks a very hot day

[Hannes]

Could you not just use a card object with the silhouette uv projected onto it?

That's what I did and what Danny allowed, but as I said, there was this strange small stripe of "shadowlessness", I couldn't get rid off (see image below).

However, I wouldn't use this sort of "dirty trick"  , if there wasn't this (displaced sphere/shadow)-bug in TG.
But I will of course follow the rules. So, if there's any concern, I'll think about something else.

[bobbystahr]

Could you not just use a card object with the silhouette uv projected onto it?

That's what I did and what Danny allowed, but as I said, there was this strange small stripe of "shadowlessness", I couldn't get rid off (see image below).

However, I wouldn't use this sort of "dirty trick"  , if there wasn't this (displaced sphere/shadow)-bug in TG.
But I will of course follow the rules. So, if there's any concern, I'll think about something else.

we could all vote to allow it...it's a great image you got going...I'm on my 5th start on this massively snow day here in the frozen north....

[Dune]

I did a quick test with a vector displaced arch (by simple shape and distribution shader), and with displacement tolerance upped to 1.4 got the shadows right. So you could try something like that...

[Hannes]

Thanks, Ulco. That looks cool. I even tried a displacement tolerance of 3, and didn't succeed 
And I like the shape of my actual arch very much and would love to keep it (if Danny is OK with that). In my opinion it doesn't make much of a difference, if I use a plane with an image mask or a flat shape with exactly the same contours to get the shadow right. It's a trick, OK, but it's not to create fancy things in the image, that otherwise wouldn't be there.

And I'd like to carry on with this image without caring about incorrect shadows...

[Hannes]

I made a little test with the arch animating the displacement multiplier, that is responsable for the bending, from 0 to 100. It seems the displacement produces a correct shadow until it reaches a value of around 40, and then it's sort of cut off at the top.

[Dune]

Displacement tolerance needed seems indeed dependent upon the amount of displacement. Maybe I was lucky with my setup, and a tolerance of only 1,4. And mine was not a cube or sphere, maybe that's different too.

[Hannes]

OK, I found a way!!!!!!

Since I saw, that from a certain displacement amount on, the shadow is cut off, I decreased the value, which made the arch of course a little straighter and positioned too low.
So I moved it up slightly and got what you see on image one. An amputee.

Now I thought, the best way to continue would be to stay calm, sit back, analyze the problem, think logically and eliminate everything that could possibly cause the problem.

Instead I called my computer names, screamed all naughty (four letters-) words, that came into my mind (we germans like to use words with more letters!), hit any button I could find, and moved desperately sliders up and down. Or right and left. And I threw some things around.

I can't really remember, but I must have accidentally fumbled around in the "sorting bias" area... Typing in another value fixed the problem, and my arch regrew again. With a proper shadow. Looking good.

Well, I'm happy, that it worked, but this doesn't make any sense, does it?
So, I have a distorted and crippled arch, and "sorting bias" fixes it?

However, I'm happy with it now. No dirty tricks.

[Dune]

Sorting bias? I would never have thought of that one  I only use it in water to save render time. Never thought it would influence shadows. That needs more experimentation! What number did you use, something in the 1000000? Or minus?

[SILENCER]

Looks fabulous.

Add a Pterosaur, and you're in the era.

[j meyer]

Strange, but interesting find.
Glad to see you got it solved.

[Hannes]

Thanks, guys!!

Sorting bias? I would never have thought of that one  I only use it in water to save render time. Never thought it would influence shadows. That needs more experimentation! What number did you use, something in the 1000000? Or minus?

No, it didn't affect the shadows. It affected the arch itself (lowering the displacement value affected the shadows).
After I moved the arch up, it was cut off (amputee), then I entered another value (no matter which one!) in "sorting bias", and it was back again and healthy. It didn't depend on the bias's value, just changing it did the trick. TG is mysterious sometimes...

[Oshyan]

Fascinating! Looks great though, at least it worked.

- Oshyan