Problem with semi-shadowing

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Problem with semi-shadowing

BRietzl
My objects designed with openSCAD use a bunch of colors. My problem is that
they are hardly distinguishable in the shadow zone. Is is possible to adjust
quasi-shadowing somehow? I searched the GUI for a setting and the manual,
but didn't find anything. This would also be a good candidate for another
special variable from 0 (no shadow) to 1 (dark shadow) for a scene.



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Re: Problem with semi-shadowing

nophead
I don't see any shadows in OpenSCAD. It doesn't do ray tracing, just a crude flat shading model with diffuse lighting.

On Fri, 27 Sep 2019 at 09:01, BRietzl <[hidden email]> wrote:
My objects designed with openSCAD use a bunch of colors. My problem is that
they are hardly distinguishable in the shadow zone. Is is possible to adjust
quasi-shadowing somehow? I searched the GUI for a setting and the manual,
but didn't find anything. This would also be a good candidate for another
special variable from 0 (no shadow) to 1 (dark shadow) for a scene.



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Re: Problem with semi-shadowing

MichaelAtOz
Administrator
I presume it is there areas

<http://forum.openscad.org/file/t359/Capture_shading.jpg>



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Admin - email* me if you need anything,
or if I've done something stupid...
* click on my MichaelAtOz label, there is a link to email me.

Unless specifically shown otherwise above, my contribution is in the Public Domain; to the extent possible under law, I have waived all copyright and related or neighbouring rights to this work.
Obviously inclusion of works of previous authors is not included in the above.


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Re: Problem with semi-shadowing

BRietzl
In reply to this post by nophead
nophead wrote
> I don't see any shadows in OpenSCAD. It doesn't do ray tracing, just a
> crude flat shading model with diffuse lighting.

Therefore I called it "SEMI-Shadowing". Surfaces pointing to the right are
darker (SEMI-shadow zones) than surfaces with the same color pointing to the
left. If you call it "crude flat shading model with diffuse lighting" then
it is ok, but the crucial thing is, that it does NOT seem to be adjustable,
therefore you probably call it "crude".



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Re: Problem with semi-shadowing

BRietzl
In reply to this post by MichaelAtOz
MichaelAtOz wrote
> I presume it is there areas
>
> &lt;http://forum.openscad.org/file/t359/Capture_shading.jpg&gt; 

Exactly these areas! I want to have them less dark to better distiguish
between the dark shaded colors. Shading should be softer, at best
adjustable.



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Re: Problem with semi-shadowing

nophead
Yes it would be a lot better with specular lighting and non diffuse lights so that flat faces at the same angle are not all the same colour and curved surfaces had highlights. I don't know if it is possible with OpenCSG.

There are two lights in the scene and I think they might be placed where they are to get around negative faces being back to front rather than giving a nicely lit scene. 

On Fri, 27 Sep 2019 at 10:10, BRietzl <[hidden email]> wrote:
MichaelAtOz wrote
> I presume it is there areas
>
> &lt;http://forum.openscad.org/file/t359/Capture_shading.jpg&gt;

Exactly these areas! I want to have them less dark to better distiguish
between the dark shaded colors. Shading should be softer, at best
adjustable.



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Re: Problem with semi-shadowing

alexgibson

I would be really interested to learn more about how OpenSCAD lighting rendering works currently.

 

More complex lighting, or really any level of more advanced scene rendering, feels to me like a whole new area of scope compare to our current expectations, which is just enough to better see the 3D structure.  One option might be to export your differently coloured parts as a series of separate models, and import them to another CAD software with more advanced control, such as Blender.

 

What I think would be nice in OpenSCAD is just to be able to better control what we have – IE could we specify placement of one, two or more lights.  This alone could solve the OP’s issue by allowing a light source to be targeted at the area the colours need to be seen better.

 

Alex Gibson

 

admg consulting

 

edumaker limited

 

·         Project management

·         Operations & Process improvement

·         3D Printing

 

From: Discuss [mailto:[hidden email]] On Behalf Of nop head
Sent: 27 September 2019 10:29
To: OpenSCAD general discussion
Subject: Re: [OpenSCAD] Problem with semi-shadowing

 

Yes it would be a lot better with specular lighting and non diffuse lights so that flat faces at the same angle are not all the same colour and curved surfaces had highlights. I don't know if it is possible with OpenCSG.

 

There are two lights in the scene and I think they might be placed where they are to get around negative faces being back to front rather than giving a nicely lit scene. 

 

On Fri, 27 Sep 2019 at 10:10, BRietzl <[hidden email]> wrote:

MichaelAtOz wrote
> I presume it is there areas
>
> &lt;http://forum.openscad.org/file/t359/Capture_shading.jpg&gt;

Exactly these areas! I want to have them less dark to better distiguish
between the dark shaded colors. Shading should be softer, at best
adjustable.



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Re: Problem with semi-shadowing

TLC123
In reply to this post by nophead
visibility sure is important but i don't know if  full control of all light
positions give the best for most.
everything is dark until you set up boiler plate light . that another
treshold for beginners.
for a quick increase in  shape visibility there a better option some
postprocesing.
If there is trivial access to the depth buffer after openCSG pass a thing
like
Screen space ambient occlusion (SSAO) could enhance shape perception a good
bit with not too much effort.



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