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Topic: Dithering Shadows in Blender/Gimp (Read 7729 times) previous topic - next topic

Dithering Shadows in Blender/Gimp

Hi,
it seems that i'll need to dither the Shadows outside the ground-plates in my current Blender project.
I guess that most people do it in some sort of Imaging programm. I was planning to do it in gimp also.
The questions are:

1. how exactly do you do it? Just painting single transparent pixels into rendered image or with some sort of alpha-mask or something like that? I'm really no expert, usually just cutting/pasting and doing other pretty basic stuff.

2. Is there a way to dither those Shadows directly in Blender? It seems to be doable with Composite Nodes(shadow p****?), but I couldn't get it to work yet.

Was planning to ask about Implementation of Alpha-Channel into Makeobj/Simutrans, but already found an old thread about it.

Re: Dithering Shadows in Blender/Gimp

Reply #1 –
Since there is no alpha in Simutrans, shadows are effectively "Emental" black - pattern of black and transparent pixels. With Gimp you could create a pattern, select the area you want and fill it...

My projects... Tools for messing with Simutrans graphics. Graphic archive - templates and some other stuff for painters. Development logs for most recent information on what is going on. And of course pak128!

Re: Dithering Shadows in Blender/Gimp

Reply #2 –
I haven't it test it but seems that using ColorRamp in Composite mode you should be able to extract the shadow.  I got the info from this tutorial. The resulting shadow seems to be plain with no alpha, so you just have to cut and paste.



Re: Dithering Shadows in Blender/Gimp

Reply #3 –
I've been trying to follow the advices of the tutorial mentioned above, and I must conclude it's possible to "render" the shadow in another image/layer and get a good result.

In fact, it's really simple. You need to use composite nodes with this config (all the details are in the tutorial)
us (site down, do not visit) ]/image/show/pmCDEBCS3k/shadow.png]
Note: I used an extra node to output the result into a file. the Add node is a Math type node.

and from this scene..
us (site down, do not visit) ]/image/show/g92xq3Gsll/original.png]

you should get these shadows....
us (site down, do not visit) ]/image/show/XsxHvUKUvh/prueba-sombra0010.png]

There's no possible overlaping between the original and shadow images, thus it's just a matter of copy and paste..   :)

us (site down, do not visit) ]/image/show/oUmwmIY4wf/result-shadow.png]
Note: I've modified the shadow's color using GIMP to make it more visible.