Blender Foundation: Blender 2.x BF release: Detail: 25103 Weird artefacts in Normal

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[#25103] Weird artefacts in Normal

Date:
2010-12-08 20:53 Priority:
3

State:
Closed

Submitted by:
Moolah Nasreddin (moolah) Assigned to:
Brecht Van Lommel (blendix)

Category:
Rendering Status:
Fixed / Closed

Relates to: Duplicates:

Patches:

Summary:
Weird artefacts in Normal

Detailed description

win32, r33530

Some strange artefacts occurs in Normal rendering

Followup

Message

Date: 2010-12-08 23:04
Sender: Eugene Sanderson
This seem only to occur when u have anti-aliasing on

Date: 2010-12-09 00:59
Sender: Moolah Nasreddin
Yeah, and it's strange that it depends only on Anti-aliasing checked. I tried many settings with AA filters - no difference.
I found a possible clue - try to change the filter size in Image Sampling. Also this filter isn't working when AA is off.

Date: 2010-12-09 11:40
Sender: Ton Roosendaal
I'll ask Brecht to check on this.

However, there are many normal-rendering issues in this tracker. I'm losing a bit track of what the actual problem is here.
It would really help if you don't attach final projects, but try to create the simplest case that shows an error.

Date: 2010-12-09 15:14
Sender: Moolah Nasreddin
Now I did a test texture (white circle filled with a smooth gradient, without edges) and tried to apply it to this object also to a simple plane. Everything looks great when we don't use alpha. When use - it gives that oddness. I tried even 2000x2000 resolution and it's almost no matter.

Sorry, I tried to add another attachement yesterday but for some reason it's not working... So I described everything by words

Another detail - semi-transparent circle (the same) with "Use Alpha" and NO "Premultiply" checked gives the worst results.
"Use Alpha" and "Premultiply" checked - gives "better" results but the circle is still looks not like a nice pit. Edges are extremely "pressed" into.
The best results gives just black->white gradients without alpha usage. This possibly means that AA filter (or other?) interferres with alpha values and calculate normals to use in Geometry Normal wrong.
BTW - some strange artefacts occurs in that model of mine on places that were moved away from the texture in UV coords. This must not be happening at all because Image Mapping was set to Clip.
Then I made UV from view to the whole mesh... and I got that using Alpha with semi-trasparent texture gives very harsh edges and "moves" dark areas of a "bump" effect too far.
It's possible that these strange artefacts were produced because the first UV was made in this way:
1. Entered Edit Mode
2. Selected a place for my texture
3. Switched to UV
4. Unwrap View
5. Stretched main faces in UV to fit the texture
6. Ctrl-I in 3dView - invert select
7. Moved other faces in UV off the texture zone

Those UV faces were overlayed many times. Maybe that was a reason. But it looks like a bug anyway.

Date: 2010-12-10 14:32
Sender: Campbell Barton
Could this be a duplicate of 24591 ?, also normals with procedural textures and effected by anti-aliasing.

Date: 2011-01-07 15:47
Sender: Brecht Van Lommel
Fixed in revision #34155: improved bump mapping patch by M.G. Kishalmi (lmg) and M.S. Mikkelsen (sparky).

Attached Files:

Name	Date	Download

weird_bump_artefacts_repeated.png	2010-12-08 20:53	Download
weird_bump_artefacts.png	2010-12-08 20:53	Download
Weird_Bump.blend	2010-12-08 20:53	Download

Changes:

Field	Old Value	Date	By

status_id	Open	2011-01-07 15:47	blendix
close_date	None	2011-01-07 15:47	blendix
Status	Investigate	2011-01-07 15:47	blendix
assigned_to	none	2010-12-09 11:40	ton
Status	New	2010-12-09 11:40	ton
File Added	14026: Weird_Bump.blend	2010-12-08 20:53	moolah
File Added	14027: weird_bump_artefacts.png	2010-12-08 20:53	moolah
File Added	14028: weird_bump_artefacts_repeated.png	2010-12-08 20:53	moolah