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Think of the Batman symbol, but reversed, i.e., the symbol would be brighter than the clouds.

How would one project light through a "stencil" (of any symbol/text) on clouds/fog/mist/or solid wall and have the remainder display?

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  • $\begingroup$ Can you provide a reference image of what you want it to look like? $\endgroup$ – Matt May 18 '16 at 20:45
  • $\begingroup$ Sorry, I don't have an image, it's in my head. $\endgroup$ – NeverGiveUp May 18 '16 at 21:00
  • $\begingroup$ Is there an image of something else that'a a little bit like what you want? I guess I'm not understanding why it's different from the Bat Signal. It sounds like you want the same thing as the Bat Signal, just with a different stencil. $\endgroup$ – Matt May 18 '16 at 21:05
  • $\begingroup$ From what I gathered it is different from the bat symbol in the sense that the bat itself is "shadow" with glow light around it, and the user wants the opposite, the bat shape to be "lit" with darkness around it. Either way it seems relatively straightforward to accomplish $\endgroup$ – Duarte Farrajota Ramos May 18 '16 at 22:58
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You could either model your batman logo or get one from the internet in SVG file format and use it as an actual "geometry stencil" in your scene to block out light coming from a projector line. If you prefer you may also use an image texture as alpha map for your stencil

Just make sure your spot light is strong enough to make a visible influence and the size of the lamp is small enough so the shadows don't become too blurry, otherwise it may be difficult to make out the symbol

Batman stencil

EDIT

For the materials simply use a Volume Scatter shader connected to the Volume socket of the Material Output. For the red volume use a very low density like 0.1 or less, for the blue volume receiving the symbol a higher density is acceptable like 1.0.

For a more physically accurate version mix a Volume Scatter and a Volume Absorption nodes using the Mix Shader node

Volume Materials

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  • $\begingroup$ Now place the camera in front of the stencil plane (not to block light) so I can render an image of the projected symbol. I'd sort of like God (crepuscular) rays "flowing" thru the stencil to the symbol as well. Maybe even a solid plane within the cloud to define it better. WIP. $\endgroup$ – NeverGiveUp May 18 '16 at 21:11
  • $\begingroup$ You can easily add the crepuscular rays by adding a second volume material from the stencil to the surface with a very low density $\endgroup$ – Duarte Farrajota Ramos May 18 '16 at 22:41
  • $\begingroup$ @DuarteFarrajotaRamos please expand on how to setup the materials for volumetrics to work. $\endgroup$ – cegaton May 19 '16 at 1:49
  • $\begingroup$ Volume material setup added $\endgroup$ – Duarte Farrajota Ramos May 19 '16 at 2:25
  • $\begingroup$ a. Can the volume material "box" be wider at the batman symbol end so the rays match the symbol? b. would it make sense to make a plane of the symbol and overlay it? Then adjust its transparency or gray level? $\endgroup$ – NeverGiveUp May 19 '16 at 2:44
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With Cycles this is actually pretty straightforward. You create a mesh that's the shape you want to project and you shine a really bright light through the gaps, just like you would in real life. The tricky part will be getting it focused so that the image converges where you want it to... again, just like real life.

Cycles is so realistic, that you can actually simulate a pinhole camera with Cycles. So really, just do it the way it's really done.

With the Blender Internal renderer, it's not so straightforward, but still pretty easy. The best way would be to set a b&w image as the texture for a spot lamp. Then, the lamp will just shine that image on whatever you point it at.

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  • $\begingroup$ Presume the stencil is a group of numbers projected against the cloud - so that the images would be seen throughout the cloud perhaps in different colors. Judging from the vg image above by Duarte extend the clouds forward to the stencil plane (to see the God rays). Maybe the cloud contains several invisible planes that catch the projected light? $\endgroup$ – NeverGiveUp May 18 '16 at 21:22

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