How to render shadows during solar eclipse ?

bc547 · March 27, 2015, 2:41pm

hi,
I’d like to render shadows that appear during a solar eclipse when the light rays pass through tiny gaps.
Just to explay the phenomenon, each gap acts as a “pinhole camera” projecting the shape of the eclipsed sun.

Here an example

I think that it is feasible to get this effect in cycles renderer.

I’m trying to use the sun lamp and I noticed that cycles correcty casts the shadow through a pair of slits.

Here is my result

Now I need a custom lamp that simulates the occlusion of the moon on the sun.
I think that this special light source should be exactly like the sun lamp (that is, the intensity depends only from the direction) but from some directions the emission should be zero.

Do you think that a such kind of anisotropic light can be implemented in cycles ?
any ideas ?

anon65932258 · March 30, 2015, 11:11am

Hi bc547,

don`t think so. If you realy need it it needs to be faked…

goldomega · March 30, 2015, 1:17pm

Try applying this image texture to the color input of your sun lamp’s emission node:

Then, set up your node tree with a Geometry input node like this:

You may need to increase your emission strength settings and play with the sun lamp’s size settings, but hopefully this will get you going. Also, because sun lamps’ rays are parallel, you may need to rotate the lamp or adjust the position of the image texture for it to have an effect.

bc547 · April 3, 2015, 9:49am

thank you all
@goldmeda I tried your approach with little success. Both the sun lamp and the area lamp were not working. However the idea of modifying the emission of the source was the key. I created two large filled circles, one behind the other. One is the sun which has a material with a strong emission. The other one is the moon. These two objects are very far away from the center of the scene .

Moving the moon I got this

This was exactly what I saw on March 20, 2015 during the eclipse on my desk because of the window blinds.