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black pixels

Unread postPosted: Wed Jan 15, 2020 1:18 am
by jactahiti
Iaorana ,
I am calculating a small sequence.
Black pixels appear which are placed differently on each image, but remain located in the parking lot at the back. If I disable the cars there is no problem. I think it is related to one or more materials of the cars.
When I convert the images to (.jpg) the black pixels become white.
An idea would be welcome
Thank's a lot
Regards
Jacques

Re: black pixels

Unread postPosted: Wed Jan 15, 2020 9:56 am
by dboude
Hi,

Those are NaNs. With version are you using? Can you give us more info?

Thank you

Re: black pixels

Unread postPosted: Wed Jan 15, 2020 12:54 pm
by jactahiti
Iaorana Demian,
I am using version SP4 5b
new Path tracer system
clamping: 1
One distance light
HDR
Anti aliasing 64
no Fireflies Filtering
 
Thank's
jacques

Re: black pixels

Unread postPosted: Wed Jan 15, 2020 3:51 pm
by dboude
4.0 SP5b that's right?

If yes, you have maybe material with negative texturing. It can lead to NaNs

Could you check if you have some kind of shading network ? (Like subtract nodes or any other nodes that can output negative values)

Cheers

Re: black pixels

Unread postPosted: Wed Jan 15, 2020 10:32 pm
by jactahiti
4.0 SP5b that's right
I don't have a "substract" node
Could this be caused by overlapped inverted normals of polygons ?
Thank's

Re: black pixels

Unread postPosted: Thu Jan 16, 2020 6:36 am
by Refik
jactahiti wrote:Could this be caused by overlapped inverted normals of polygons ?

Yes, this may be due to your problem. Try setting "Sidedness = Double" in the properties of this material..
it is in the "Geometry" tab .
Maybe it will help

Re: black pixels

Unread postPosted: Thu Jan 16, 2020 9:27 pm
by jactahiti
Iaorana Refik ,
Thank you for your answer, suddenly I converted all the materials of the cars to "double side", but that did not change anything...
A big Photoshop session seems to be coming
Regards
jacques

Re: black pixels

Unread postPosted: Fri Jan 17, 2020 9:55 am
by dboude
Hi,

If you can provide us the scene we could have a look into it.

Cheers

Re: black pixels

Unread postPosted: Sat Jan 18, 2020 12:43 am
by jactahiti
Iaorana Démian , Refik
I think I found something ...

Re: black pixels

Unread postPosted: Mon Jan 20, 2020 9:29 am
by dboude
One thing,

What did you set on the "Specular 1 Index of refraction" attribute? (In the "Specular 1 Fresnel" submenu). We can't see it on your snapshot.

Cheers