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Help needed modelling raindrops

May 9, 2012, 19:59
Post: #1
Help needed modelling raindrops
Im trying to model raindrops hitting water.
Can anyone suggest how I can have simultaneous wave generators,rather that the central based tool in Gimp.I need to be able to adjust the parameters in the same way as the distortion tool allows...any help would be appreciated.
Thanks in advance.

Win vista (for now)
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May 9, 2012, 21:58
Post: #2
RE: Help needed modelling raindrops
(May 9, 2012 19:59)nature studies Wrote:  Im trying to model raindrops hitting water.
Can anyone suggest how I can have simultaneous wave generators,rather that the central based tool in Gimp.I need to be able to adjust the parameters in the same way as the distortion tool allows...any help would be appreciated.
Thanks in advance.

Win vista (for now)
Something like this?
[attachment=1135]

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May 9, 2012, 22:30
Post: #3
RE: Help needed modelling raindrops
Yes,thats great.can I add as many drops as i wish ?
Either way,this looks like just the job.
Many thanks Ofnuts ,for your speedy reply too :-)
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May 9, 2012, 23:50
Post: #4
RE: Help needed modelling raindrops
(May 9, 2012 22:30)nature studies Wrote:  Yes,thats great.can I add as many drops as i wish ?
Either way,this looks like just the job.
Many thanks Ofnuts ,for your speedy reply too :-)

Yes, you have more drops...

[attachment=1136]

Process is not very hard to do, but a bit complex to describe and it's a bit late here, so I'll post tomorrow.

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May 10, 2012, 01:39
Post: #5
RE: Help needed modelling raindrops
Greatly appreciated Ofnuts..thanks again :-)
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May 10, 2012, 23:08
Post: #6
RE: Help needed modelling raindrops
OK, here we go....

Create a background layer and fill with gray 50% (#808080)

Add a square layer the size of a ripple circle. Fill it with a radial white to black gradient.

[attachment=1143]

Start the Curves tool. Draw the profile of the ripples (the left side should end smoothly at mid-scale, i.e. #808080). This is clever spot #1. We are actually using the black-to-white values created by the radial gradient above as measure of the distance from the center. And the new values will be used as the height of the water...

[attachment=1144]

Create a couple more of such layers, with varying sizes (I only did two). The wavelength should normally always be more or less the same (less ripples in a small circle). You can also start with a low in the center. Set the layer mode of all the ripple layers created to "grain merge". Why grain merge? This is clever spot #2. In grain merge, the composition of two layers is "V1+V2-128" (which is also (V1-128)+(V2-128)+128, in other words, it exactly does the algebraic addition of the height of the waves, if we consider that the "0" of the height is value 128, which is exactly how bump maps are used...).

Duplicate each layer several times and artistically spread the ripple layers around. The "grain merge" setting will compute the resulting waves for us...

[attachment=1141]

Create a single layer from all the ripples: "Layer/New from visible". This will be our bump map. Create a new layer and fill it with blueish gray. This will be the water.

Select the water layer and run "Filter/Map/Bump map". Use the ripples as the bump map. Adjust the height of the ripples to your liking, Increase the light source elevation, and possibly add some ambient light. See my values in the screenshot

[attachment=1142]

Apply the filter. Apply a slight Gaussian blur (2 to 5 px) on the result to smooth irregularities.

Enjoy.

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May 11, 2012, 13:26
Post: #7
RE: Help needed modelling raindrops
Many thanks Ofnuts :-) very well explained,and very helpful indeed.
Im particularly interested in the reflective feedback patterns,and im sure this is the way to go about it.
Thanks again,for this; and for your time taken to explain it to me.
Cheers - Steve
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May 12, 2012, 05:15
Post: #8
RE: Help needed modelling raindrops
Cheers Ofnuts - got this far tonight :-) got an extra layer somehow,but no problem i guess.
   
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May 12, 2012, 09:07
Post: #9
RE: Help needed modelling raindrops
(May 12, 2012 05:15)nature studies Wrote:  Cheers Ofnuts - got this far tonight :-) got an extra layer somehow,but no problem i guess.
Yes, the original "background" layer can be discarded. Otherwise, you got it Smile

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May 12, 2012, 12:33
Post: #10
RE: Help needed modelling raindrops
Many thanks for your clear description :-) what i am looking to do though,is animate the ripples...using the image created, as a frame..
The technique i really need to develop,is to allow the ripples to feedback,and create an interference pattern..
this would involve a control to adjust the individual wavelength,and frequency of each droplet,as per the wave tool (which only allows the center as a point source)

Perhaps,i can create individual frames using the conventional wave tool,then align the layers in an offset way,and using the grain merge you described get the results i require...hmmm...sounds feasable...will test an let you know..
You have really been a great help,and i am most grateful :-)
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May 14, 2012, 00:34
Post: #11
RE: Help needed modelling raindrops
Just wanted to update you Ofnuts,thanks to your excellent info,and smart tips :-) I have found a succesful way to create the effect i was looking for - using these and combined techniques from them..This will keep me busy for months now :-)
Best regards - NatureStudies
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May 14, 2012, 06:33
Post: #12
RE: Help needed modelling raindrops
Good. Have fun Smile

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May 21, 2012, 21:52
Post: #13
RE: Help needed modelling raindrops
(May 14, 2012 00:34)nature studies Wrote:  Just wanted to update you Ofnuts,thanks to your excellent info,and smart tips :-) I have found a succesful way to create the effect i was looking for - using these and combined techniques from them..This will keep me busy for months now :-)
Best regards - NatureStudies

I don't suppose you'd care to share this revolutionary new information with the rest of the world, would you, please? It would seem I was on a quest today for this very same procedure, & I just had to join the forum just to ask -- only days after you first joined and posted. Weird.

btw thanks ofnuts for getting me started on the bumpmap. I got lost at "Set the layer mode of all the ripple layers created to "grain merge" ; I've seen it before but I'm one of those who can't find a simple "burger, fries and a coke" anywhere on a McDonald's menu.
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May 21, 2012, 22:13
Post: #14
RE: Help needed modelling raindrops
(May 21, 2012 21:52)scorpivs Wrote:  
(May 14, 2012 00:34)nature studies Wrote:  Just wanted to update you Ofnuts,thanks to your excellent info,and smart tips :-) I have found a succesful way to create the effect i was looking for - using these and combined techniques from them..This will keep me busy for months now :-)
Best regards - NatureStudies

I don't suppose you'd care to share this revolutionary new information with the rest of the world, would you, please? It would seem I was on a quest today for this very same procedure, & I just had to join the forum just to ask -- only days after you first joined and posted. Weird.

btw thanks ofnuts for getting me started on the bumpmap. I got lost at "Set the layer mode of all the ripple layers created to "grain merge" ; I've seen it before but I'm one of those who can't find a simple "burger, fries and a coke" anywhere on a McDonald's menu.
Here:
[attachment=1178]
(applies to the selected layer)

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May 21, 2012, 23:47
Post: #15
RE: Help needed modelling raindrops
ofnuts, thanks. Of course, it still took me 10 minutes of poking around everywhere to find it, over by floating > refreshing > carbonated > non-fruit > non-dairy. Managed to count the number of times I found the word Layer or a form of it, was up to 8 when I gave up. Wasn't until I saw the Lock button when I figured it out.

Still looking for a tut on animated rain hitting a puddle. Found 1 useful, the rest are about rain in the air.
I suppose I'm looking for what might be called multi-seeding ripplets effect, if anyone can link or post a vid tutorial, please do so.

Thanks again,
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