Dew condensation on glass

[wayoutwestmultimedia]

Hey KS peeps,
I'm trying to recreate this type of water condensation using keyshot.  I've created a slightly frosted glass, but not sure how to go about creating the actual water drops. Should I use displacement maps? Bump map? My mind runs our or ram trying to figure out the logic behind this...

Also if I wanted to put an image in my shot should I find a good model, or just place my model over the image using photoshop?  I'm trying to create product shots that aren't boring and have some organic sense to it.

Any help would be awesome!! Thanks.

[sloanelliot]

Assuming you're running KS 8 or newer, the easiest (not necessarily the best) way to do this would be to use the "Spots" texture node on a plane with Solid Glass material applied (play with the density, scale, levels, falloff, distortion, etc., to get a realistic degree of randomness/variety to the spots) and use that node as a displacement map (and bump). You'll have to invert the black/white so the dots are white, background black and play with your displacement settings (i.e., more/smaller triangles, probably lower-than-default height, etc.). Once it looks nice, drag that same spots node over to the opacity channel which will remove the rest of the plane and leave only the droplets behind. Then make a duplicate plane for your base glass material and make it a slightly frosted material (i'd use a map to control the frost so it's not universal, you could even play with using the same spots map/inverse) to fog only areas that don't have drops. And I'd even do a second pass of spots for the fine mist in between larger droplets as well.. It's a lot of fun to play around with.

Outside of that, the "better" approach would be to get your hands on RealFlow or Houdini and run a particle simulation with surface tension/friction, etc. which would make the droplets have a more interesting falloff and realism upon closer examination. Just depends on how far you want to take it. With RealFlow, you could obviously make the droples run down the glass at random, if you were to do an animation of any sort..

Hope it helps.

[Finema]

Hi,
Yes you use displacement and a mask for roughness. 

[mattjgerard]

There are plenty of texture based ways to make this happen that it is getting less and less necessary to model the actual drops in a 3rd party program. Poliigon has many water drop based image textures that are both bump and displacement based. You should try that before going into the modeling route. Most of the time you should be able to get what you are looking for.

[sloanelliot]

Correct. Haha I definitely wasn't suggesting modeling anything (super tedius); instead using fluid dynamics to create more realistic droplets, as real droplets often have a negative falloff where they meet the surface, have runs, etc. that you just can't convincingly achieve with simple displacement maps. Nonetheless, the main suggestion offered was a proceedural displacement map, about as quick and dirty as it gets!

[bharris]

Correct. Haha I definitely wasn't suggesting modeling anything (super tedius); instead using fluid dynamics to create more realistic droplets, as real droplets often have a negative falloff where they meet the surface, have runs, etc. that you just can't convincingly achieve with simple displacement maps. Nonetheless, the main suggestion offered was a proceedural displacement map, about as quick and dirty as it gets!

I've used things like Houdini or RealFlow to make water splashes and droplets in the past. Also Blender can do a good job. However, all three require a lot of trial and error (until you've really learned the program), understanding of what is actually being simulated, and time to play around. If you have that, simulating the drops will be the most accurate since you will get real geometry you can use. Otherwise, I agree with Matt that a texture based approach will work fine. For this instance, a more of less head-on, flat plane I wouldn't even consider trying to simulate it.

[sloanelliot]

Ha, verrrry true (re: a deeper understanding of the software). It always boils down to the application. So many times I've done client work as a set of still images and then 3 months later they come back and say, "Hey, can you do an animation of this??" and then I'm forced to go back to square one. Lately, I've tried to make all of my setups animation-friendly because it tends to be a common request..

But we're *definitely* not in disagreement here, my initial reply suggested precisely what the three subsequent replies did.. Forums crack me up sometimes. 

[TGS808]

Gotta be honest.... I'm stunned that anyone would even mention RealFlow or Houdini much less recommend them as the "better" way to do this. Assuming that the image the OP attached is what he wants to achieve (and we have to assume that) it can be done with a single normal map.

[TGS808]

I've used things like Houdini or RealFlow to make water splashes and droplets in the past. Also Blender can do a good job. However, all three require a lot of trial and error (until you've really learned the program), understanding of what is actually being simulated, and time to play around.

And if one did decide to go that route, Blender won't cost a dime where as RealFlow and Houdini may require taking out a second mortgage. 

For this instance, a more of less head-on, flat plane I wouldn't even consider trying to simulate it.

100% agreement on that.

[sloanelliot]

I don't know why this is annoying me so much haha..

If anybody would actually read my original reply, the very first option I mentioned was a procedural displacement map (via Spots node) which is coincidentally the same or similar approach that every reply since has also redundantly suggested. Yes, I also mentioned simulation as a solution for more advanced control and animation. I'm not going to assume anything about the OP's inquiry, so I presented several options from highly basic to slightly more involved/advanced if the application should require animation, macros, etc. lol.. My intent was to help educate on the possible options/scenarios.

[TGS808]

I don't know why this is annoying me so much haha..

Strange that it would.

If anybody would actually read my original reply, the very first option I mentioned was a procedural displacement map (via Spots node) which is coincidentally the same or similar approach that every reply since has also redundantly suggested. Yes, I also mentioned simulation as a solution for more advanced control and animation. I'm not going to assume anything about the OP's inquiry, so I presented several options from highly basic to slightly more involved/advanced if the application should require animation, macros, etc. lol.. My intent was to help educate on the possible options/scenarios.

It would appear that we did all read your original reply and after reading it, offered different opinions and options than you did. That's kind of how it works here. The more options for the OP to try, the better. There really, were no "redundant" replies as everyone else offered a different option than you did. Matt mentioned going with a texture, I said a normal map would get it done. Neither of those is the same as the "building a displacement procedural with spots" solution that you offered. So that's three things he can try. Also, I think that in order to give an appropriate response to the OP request, you have to make the assumption that the image that the OP presented is the look he wants to achieve otherwise, why would he show it?

[Finema]

No need to fight because there are many options.
For me, the easiest way is a displacement and a roughness mask. Afterwards, everyone is free to find more complicated solutions.

[sloanelliot]

Yeah, that's my bad. I was having a garbage day yesterday (backed myself into a corner with KS9 and the file is crashing upon render).

I wasn't trying to unnecessarily complicate things; my first suggestion was also displacement and was simply providing an alternate solution in the event animation was required (it's 2019 after all). I was just surprised at how much pushback I got.

Water under the bridge!