Shadow Terminator problem

[lacilaci]

So, I'm playing around with new build and it seems this terminator treatment introduces new problems to bump mapping!

some black spots on bump map and darkening of edges appear..

here's strong bump mapping with old behavior:

of course it looks wrong with the terminator but overal the bump is pretty much perfect (aside being overdone)

here's again strong bump mapping with newest luxcore and shadow terminator treatment:

now shading looks ok without terminator but bump mapping is all kind of wrong and it gets way too dark especially at glancing angles

This is pretty bad issue cause it's visible even with a very weak bump mapping:

this is without bump map:

[lacilaci]

for comparison, here's how strong bump map looks like in cycles:

sadly I don't know how they go about this issue.

[lacilaci]

And, of course here's a simplified scene:

bumpproblemscene.blend

(4.68 MiB) Downloaded 157 times

[lacilaci]

and here's also a comparison how bump mapping and this shadow terminator treatment is handled in cycles:

before fix


after


So I hope this can be fixed in luxcore

[Dade]

And, of course here's a simplified scene:
bumpproblemscene.blend

Are you sure to have posted the right scene ? I press F12 and I get a rendering without any bump mapping.

[lacilaci]

And, of course here's a simplified scene:
bumpproblemscene.blend

Are you sure to have posted the right scene ? I press F12 and I get a rendering without any bump mapping.

shit, It probably didn't package the texture... I'll check that out

[lacilaci]

Ok, here's a file with packed texture. I also had to change the texture cause the file was too big.

here's old bump map behavior:

The attachment bumpheavy_OLD.jpg is no longer available

here's latest build:

aand this hopefuly works now:

[Dade]

As far as I can see, the problem is in the old rendering, not in the new one. This is a rendering with old code (different scale and lighting just to show better the topic):

See how all bump image pixel are lighted ? This should ring a bell, with a such brutal bumps, something should be in shadow. This is the some rendering with the new code:

See how some bump image pixels is now totally in shadow ? Focus on the red circled area, the old code render all bright while the new one (correctly) cast shadows on the bump back sides.

Clearly, if you scale up the bump map the difference will be greater and greater.

and here's also a comparison how bump mapping and this shadow terminator treatment is handled in cycles:

[...]

So I hope this can be fixed in luxcore

It works really well in LuxCore, this is a rendering with the old code:

and this with the new one:

The rendering with the new code is clearly better and doesn't suffer of the shadow terminator (with bump map) problem.

Just switch between the 2 renderings and you will clearly have the feeling that old code was creating light from nowhere.

About Cycles, you are comparing 2 totally different test scenes, repeat the same tests with Cycles and you should get exactly the same results, as far as I know.

[lacilaci]

cycles full lighting:

luxcore full lighting:

cycles direct only:

luxcore direct only:

I cannot match skylight and sun white balance exactly but to me it seems pretty clear which surface looks more correct.

[provisory]

The light softness is very different. Try with a distant mesh light instead.