View Full Version : Rain Sheets

Ed Bittner
10 October 2003, 02:27 PM
I have an image rendered in another cg program of a subject looking out a window and would like to add the specularity, refraction, shadows, of rain on the window. Not water-drops so much, but the "sheeting" action and the distotion that accompanies it. It's a medium close-up shot so I want to establish the weather conditions via the rain effect. I know there may not be a simple solution, but if someone could point me in the right direction I would greatly apppreciate it. Thanks,

Ed Bittner
10 October 2003, 12:50 AM
Wow! 24 hits and no reply? Must be a tough one.

Ian Jones
10 October 2003, 01:42 AM
For the refraction, you'll need to investigate 'displacement maps'. Check the inbuilt help.

10 October 2003, 12:59 PM
Can you acquire an example photo for this? If so, post, and study it too.

The rain itself can be done with the Layer Styles, but in this case that may not be neccessary. Creating a "sheet" of water would not provide much detail to show the rain effect... except displacements within the moving water itself.

A sheet of rain on a window is not "deep" enough to actually show any visible refraction qualities. But it will displace and blur light and objects seen through it -- because it's moving.

In any event, Ian's advice on using the Displace filter still stands true to create a displacement effect for the running water. Although i believe the "DISTORT>Glass" filter with a custom dMap load will create a good effect, with a bit more control than Displace offers.
On the other hand... some sheets of water are so dense that no real displacement is seen. (see why i asked for a specific example?)

Try this for a start on the dMap:

New doc, and apply Clouds filter. Auto-Levels.
Motion Blur horizontally about 200.
Noise>Median filter. Turn up the amount until you only have a small amount of lines visible. Apply Auto-Levels. Then Gaussian Blur the image by about 2.5-3 pixels.

Save this doc somewhere... call it "rain" if you like.

Duplicate your photo layer and apply "DISTORT>Glass". Choose to laod a custom displacement map and browse to where you saved the "rain" document. Load it in and apply it. Don't try adjusting any settings yet until you see how strong the effect is using the defaults. Then, UNDO the filter and reapply it but alter the settings if need be. Repeat this until you have the look that works for you.

Bear in mind that without seeing an example of the specific effect you want... this is all just "a place to start". Not an end-all-be-all to create this effect. Details could help dial in the effect greatly.

If you want to help bring out the distortion lines more, simply paste a copy of the dMap into your document, right above the displaced duplicate photo layer. Set the blend mode to Color Dodge.

Hope that helps.

Ed Bittner
10 October 2003, 07:30 PM
Thanks guys. I'm on my way.

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