Black spots on Interior

[Behnam_cg]

hi all,
I have a little but famous problem, i searched all over the forum for the solution but still no clue.
1.it's simple: What are those Black spots on the surfaces ( on columns on this example ) and how to remove them.
2.how can i improve the pixelated edges indicated into the red circles?

Here is my IR settings:


waiting for u're help!

[fpedrogo]

Re: Black spots on Interior

Those black dot seem the be a duplicate surface. If you have two surface occupying the same area you will get that kind of effect.

[fpedrogo]

Re: Black spots on Interior

To resolve the pixelated issue enable the sub-pixel option on the color mapping rollout.

[Behnam_cg]

Re: Black spots on Interior

Thanks for the quick response.
BTW i checked the sub-pixel option but still no change.
but my real question was about this Black spots on thin test render. What causes that? what's the cure? ???

[Jackson_cg]

Re: Black spots on Interior

On the Irradiance Map roll-out set your min rate to -3 max rate to 0. Set HSph. subdivs to 50+ and samples to 20.

On the DMC Sampler roll-out set your Adaptive Amount to 0.85.

If this doesn't work, post another screenshot with the new settings.

[dcauldwell_cg]

Re: Black spots on Interior

I would up the HSph Subdivs to 100, set the Min rate to -4 and max rate to -2
I use 'Reinhard' for the colour mapping.

[Behnam_cg]

Re: Black spots on Interior

With the best consideration of U guys the Black spots are now history. but still some Saw-shaped edges.

>>here's the result with you're tips dear jackson:


>>and yours dear dcauldwell:


With Best Regards!

[dcauldwell_cg]

Re: Black spots on Interior

Have you checked the AA box in the image sampler?
I think that will get rid of the jaggies.

(I hope those aren't emissive materials being use to light the scene - not good practice. Use invisible rect lights instead.

D

[Behnam_cg]

Re: Black spots on Interior

Yeap those are rec lights, and the AA did well

what about the noisy shadows ? how to smooth them up without any PS work? Does it worth the added rendering time?

Sincerely.

[aufifillah alwi]

Re: Black spots on Interior

wow ive never have ever done any extensive test on lighting..... i hope this thread turn out very well

[dcauldwell_cg]

Re: Black spots on Interior

In the image sampler, try a lower noise threshold - I use 0.01

D

[Behnam_cg]

Re: Black spots on Interior

Oh man really quick answers, really! and wit your help it's exactly like i wanted.

Most Appreciated dear dcauldwell

if you or any one could show me some good threats about interior basic and advance renderings, that would be great!

and aufi, i'm looking forward for that tut that you promised on your blog!

[Jackson_cg]

Re: Black spots on Interior

At first glance it may seem like dcauldwell's 100 HSph. subdivs "fixed" the blotchiness, but you shoud be aware that reducing the IM min and max rates to -4 and -2 is actually simply reducing the quality of the GI calculations, which, paradoxically can reduce the blotchy effect, but also results in so-called "light leaks" at junctions between surfaces. It's not obvious at the low resolution of your attachments, but if you look carefully you'll notice that the bases and heads of the columns appear to "float" above and below the floor and ceiling due to the low GI quality. Not sour grapes (sorry David! ), just think that anyone following this thread should be aware of the whole picture.

Note the attachments and their parameters below- the results vary considerably. The relative blotchiness is obvious, but look carefully at the bottom corners of the red and blue forms and note whether they appear to sit on the ground plane or float slightly above it. Frustrating as it is, there is rarely a quick fix in biased renderers, but rather a combination and balance of parameters which produces the desired results.

[Behnam_cg]

Re: Black spots on Interior

but rather a combination and balance of parameters which produces the desired results.

Totally agree.
and the renders of yours are Christal clear about what you're talking about. It seems to me like the floor kind of stretched and not really holding the volumes on it self.

but what about the render time?
which of the parameters are more time eater?

thx for the demonstration though.

cheers.

[dcauldwell_cg]

Re: Black spots on Interior

Jackson

I agree with you. However (!), it is a matter of striking a balance, quality / effect / time.
The whole thing is about perception.
Your examples are interesting, and I see what you mean about the 'floating' effect, which from time to time I have noticed in my own renders. However, it is no good getting rid of the floating effect if the rest of the model is covered in black spots, and at the moment, other than throwing loads of time at the render, I am not sure what gives the 'best' results. I think maybe I am too impatient and am prepared to sacrifice some of the quality to get the right effect in as short a time as possible. I guess we each have our own favourite settings to suit our priorities.

David