By dvhouw
#376383
Hi everyone,

I'm trying to once and for all find a good method for creating realistic droplets and "sweat" on glass bottles.
There several topic to be find online and lot's of techniques but I haven't found one yet that works for me.

What I'm after:
Very dense populated fine "sweat" drops, suited for close ups and some bigger droplets here and there -> see Heineken image example.

What I've tried so far:
- Maya paint brush with water droplets brush from the visor (Beck's image). Problems: it created drops that go inside each other which can't happen in real life. Only way around this is to delete all the drops that are sitting in each other but it's a painfull and inefficient process.
- Realfow with texture maps from this tutorial: http://www.digitaltutors.com/tutorial/1 ... n-RealFlow . Problems: could not get enough detail (the texture maps I use are high resolution with lots and lots of small drops).
-Bump maps and displacements: Bump maps doesn't cut it for me with close-ups and the sides of the bottle. Displacements are better but take too long to render and I cant find a good way to create water displacements on the labels. Even only on the glass, for me it's noticeable if you just use the glass material for displacements instead of true water material (because of the different refractive index).
- I even tried to convert displacement to polygons in maya, then use that geometry with a opacity mask so only the drops would show. It's getting there but again with the labels I run into problems.

I believe the best way (in terms of realism and render speed) is having polygons for drops. But I'm all out of ideas to try :p. The becks image is done with maya paint brush but as you can see some drops sit in each other and is not acceptable for me.
If there's somebody with the magic method I'd love to hear it!


My best try:
Image

Desired result:
Image





Cheers
By dvhouw
#376394
That looks interesting!
Will the substance painter be able to generate meshes (drops) as well?
What I've seen from the substance designer is great for texturing but I haven't seen anything related to generating mesh, or am I missing something?
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By Mihai
#376413
Use Softimage :mrgreen:

"Dart throwing" approach:

http://blog.ioxu.com/?p=60
http://vimeo.com/2749969
http://vimeo.com/6145824

But well, maybe search for something similar using Maya's particle system. It's a basic brute force approach to placing particles on a surface - you attempt to place a randomly sized particle on the surface, but first check if it's going to be far enough away from any neighbouring particle, based on its diameter and distance to neighbouring particles. If it is, place it, if it's not - try placing another particle at another random location on the surface. Repeat many times per second :)

The particles can of course be replaced with instances of differently shaped droplets, size/rotation randomized etc.
By dvhouw
#376436
Thanks for the replies.
Dart throwing looks very promising!
Only I have zero experience with Softimage, so I'll first do some research on a similar technique with Maya (any maya dynamics experts here on the forums?).
But I'll keep the dart throwing in mind since it looks like exactly what I'm looking for..
#376706
This has always been a difficult thing to do well. Over the years I have tried just about every conceivable option. :)

I haven't tried Maxwell Scatter yet, but my guess is that you will need to use something like Forest Pack Pro in order to get the more complex scattering and interactions needed.

In terms of the overlapping geo - that has always been a problem with Maxwell unfortunately. Just the nature of how transparent objects intersect and how it handles it. My advice is to cheat a bit: use 1/2 dome shapes as the base to minimize the amount of geometry overlapping, and then use the same IOR for the droplets as you use for the glass.

/b
By dvhouw
#376768
That's a good tip, thanks. Only when I change the glass bottle to the refraction index of the drops (water) I see (small) changes in lighting and the glass refractions.
Unfortunately I have to throw in the towel for now. These drops are driving me crazy :shock: and I need to focus on some other stuff as well.
I collaborate with professional retouchers that are able to create the drops in post until I find a better solution.
Thanks for all your replies guy! Hope to post new results of this challenge soon.
#377068
Did you try anything in modo with like texture replicators? I don't know maybe replicate an image map of the droplets across the mesh, then bake out the map and somehow give it a gradient for lift on each one then give it a water material. Just an idea, never tried it.

I did just do a diamond pattern fabric, and I used a diamond black and white pattern for the seems then put gradients inside each diamond to give it a nice rounded lift. So maybe putting a map across the surface with white circles and black outlines. Get the sizes how you like, then bake it out, open in photoshop and apply gradients to each of the circles for lift, reapply as a displacement with a water material. Sounds like a ton of work but seems possible.
By dvhouw
#377228
Thanks for your idea CodyKallas.
Only I prefer a method that doesn't uses displacements. I have some good water drop texures with gradients, only to use it as displacements costs a lot of render time, and I run into problems when coming across the labels.
I thinks the most flexible option is to have meshes as drops. But I've still to find the best way, maybe investing time in a custom maya script perhaps that generates mesh from texture maps.
By feynman
#377682
Another idea... If you have access to Rhino 4.0 or 5.0, you can use one of the scattering scripts http://www.rhinoscript.org/scripts/129 or a grasshopper script to scatter your drops as geometry, correctly placed on top of your bottle, then save the entire drop group as an OBJ. You could even go as far as to generate a library of various sized physically correct looking drops with http://www.susqu.edu/brakke/evolver/evolver.html which is a killer application for simulating that sort of thing. The output can be in OBJ file format.
By dvhouw
#377823
Thanks for the tip feynman and bograt. I'm going to try the Rhino idea next week with a friend who has some more experience with that software.
Forest pack is only for 3d max right? But it is an powerful option for sure.
User avatar
By vizport
#378015
Nice test so far. I agree that you should use 3D geometry and a proper scatter plugin or something like that. Have you disabled the dispersion checkbox? Maybe I'm wrong, but with dispersion it will look way better.

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