Print at Dec 19, 2025, 10:42:00 PM
Posted by tapia at Jan 15, 2018, 10:53:23 PM
Strange rectangular shadow artifact in rendering
Hi! Firstly I wanted to thank the developers of this software! It is really great! :)

I am using it to model my small apartment and have been having a slightly annoying problem with the render.
I am trying to create a "paper lantern", which is one of those typical balls made of papers that you can hang so you can have a nice light.
So I defined a material, like this:


newmtl lamp
Ns 1.0
Ka 0.3 0.3 0.3
Kd 0.5 0.5 0.5
Ks 0.2 0.2 0.2
Tf 1 1 1
Ni 1.100000
d 0.8
illum 9
sharpness 10

map_Ka lamp_globe_white.png
map_Ks lamp_globe.png
map_Ns lamp_globe.png
map_Kd lamp_globe.png


I am no expert in wavefront, but after playing with the values for a while I think that I got the effect I was looking for:



The problem is that strange artefact (the rectangular shadow) that appears when I make the rendering. If, instead of the defined texture, I apply a color (from within sweethome3d), then I get this result:



There is no artefact anymore. That means that there must be some problem with the definition of my material. But what? Can anybody help me, please?

Posted by bdfd at Jan 16, 2018, 9:15:22 AM
Re: Strange rectangular shadow artifact in rendering
Hi,

Have you verify that you have not a very thin transparant object over the bed ?

wink
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Evil progresses when good people do nothing!
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SH3D 7.1 and nothing else - W11 64b in 4K

Posted by tapia at Jan 16, 2018, 10:15:54 PM
Re: Strange rectangular shadow artifact in rendering
I am sure that there is nothing in-between there. I have even taken all the furniture out and the problem is still there:



From another perspective, exactly the same can be observed:



The shadow region always fits exactly some number of the square regions that take care of the rendering (the regions that get computed by each core). So that is why i looks like some problem with the rendering process.

Posted by Puybaret at Jan 17, 2018, 5:28:04 PM
Re: Strange rectangular shadow artifact in rendering
Could you share your simplified project or send it to me?
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Emmanuel Puybaret, Sweet Home 3D creator

Posted by tapia at Jan 17, 2018, 9:00:14 PM
Re: Strange rectangular shadow artifact in rendering
Could you share your simplified project or send it to me?


Hi! I have just e-mailed it to you ;)

Thanks for the help.