Cloud shadows

[mitthrawnuruodo]

Guys how you would go around doing a shot at an angle from the top, lets say like from a low flying balloon. I am using a vray sun with hdri, and what I need are the cloud shadows on the ground. Vray sun has no map slot for bitmap. What approach you would use.

[Ernest Burden III]

Get a sky photo with the sort of clouds you want to cast the shadows. In Photoshop, force the cyan/blue towards black and the clouds to white, but leave lots of soft variation in the clouds, very little in the clear-sky portion. Map this image as a transparency channel onto a polygon not visible to the camera, put it above your scene and let it cast shadows. If your light-casting sky object in vray is too soft you won't get much definition in your shadows, though.

 

Bonus - you can size/position the polygon by trial and error, or create a camera from the light and view the model through that so you see how the cloud mask hits the scene.

[mitthrawnuruodo]

Thanks Ernest, this works pretty well, and the shadows are nice, I forgot about opacity

[javierlopez]

Ernest, that's a really cool trick that I have never tried. And I think it has lot of applications!

 

For example for having faster trees shadows!

 

Have you used it this way?

[Ernest Burden III]

For example for having faster trees shadows! Have you used it this way?

 

Yes