Hi!
I' ve been scratching my newbie head trying to replicate exactly this:



I understand there are several elements involved:

1. The ground. In the attached scene, just a simple grid, with a gravel material or a Houdini concrete material, displaced and bumped, like in the attached scene.
2. The water. I created a box defining the water level and assigned a Houdini basicliquid material. I don't understand why, but there are some bright lines appearing around the displaced geometry where it contacts liquid… really strange:(Well, after a bit of research, I came to the solution to those border rendering artifacts: as simple as reducing raytracing bias)



3. The wet gravel around the water. Would it be posible (or recommendable) to approach this by modifying material parameters (such as roughness, basic color) depending on the height of the grid to simulate the same material but wet? Not that I know (yet) how to do it, I'm a newcomer to Houdini and 3D in general, I'm speaking just out of informed intuition…
4. Fluids: By now I only need this for a static scene, but I'm open to simulated fluids solutions…

I've seen some instances where wetness and the puddle itself are emulated using one shader, but I'm more interested in something I could use and learn for a different set of conditions, such as deeper holes full of water in the ground, proper refraction in the puddle, etc.

Also, sorry for my English, not my mother language…

Hope you can help me with some tips, thanks in advance!

There are a couple of different approaches to this, one is the one you're doing with geometry. The other is entirely through textures and maps.

You could do everything with a gravel/concrete texture with its relative maps like one from here:

https://www.poliigon.com/search?category=Ground [www.poliigon.com]

And then alter the various maps in Photoshop so that for instance, the border gets progressively darker and wetter looking, the roughness map becomes solid white in the middle, the displacement becomes solid grey in the middle and so on.

I think you would be able to get good results just from that strategy.

The second strategy is basically what you're doing, although I would approach it slightly differently:

I would still begin with a good quality texture with maps so that I have normal, bump, displacement, roughness etc. available. I could create a grid and apply the texture to that. Then I would use a Mountain node with appropriate noise to further indent the geometry of the grid so that it creates a slight drop in the middle. Lastly I would apply another grid with a water texture and adjust the height to where you want your water level to be.

Regarding the wet border, I would create a mask (honestly I'd just do it in Photoshop based on a quick top-down render from your geometry as general reference. You can then use the mask to blend two textures, one the dry asphalt and a second dark wet material (could be as simple as a black material with the same bump/normal/displacement maps attached).

Does that help?

P.S.

I would stay away from FLIP for something like this. Unless you're trying to animate the water, like in Jurassic Park…but even then there are better ways to get that effect.

First of all, thanks for your detailed answer.

Midphase
You could do everything with a gravel/concrete texture with its relative maps like one from here:https://www.poliigon.com/search?category=Ground [www.poliigon.com]

I already knew Poliigon, some good hi-res textures. By the way, any other textures/materials site recommendations? I'm very focused on creating high resolution stills for printing large format, so sometimes using the highest maps resolutions available is mandatory.

Midphase
Regarding the wet border, I would create a mask (honestly I'd just do it in Photoshop based on a quick top-down render from your geometry as general reference. You can then use the mask to blend two textures, one the dry asphalt and a second dark wet material (could be as simple as a black material with the same bump/normal/displacement maps attached).

The problem in my case is I'm creating some sort of procedural ground asset, so I need a way to create that mask (or whatever) based on the current ground geometry and a specified water level, that's why I thought there could be some sort of attribute or VEX way of achieving it…

Again, thanks!

I also like these guys, but not as big of a choice as Poliigon:

https://www.rd-textures.com [www.rd-textures.com]

Regarding the procedural aspect, I don't know exactly how to set it up, but I know that you could use an Intersect Analysis Tool in Houdini to determine the points of intersection of geometry, which in turn might help you create a color attribute wet mask for your texture.

You can watch this tutorial to get a basic idea of how the intersect tool works:

https://youtu.be/BubpaVDlhic [youtu.be]

Midphase
I also like these guys, but not as big of a choice as Poliigon:

https://www.rd-textures.com [www.rd-textures.com]

Regarding the procedural aspect, I don't know exactly how to set it up, but I know that you could use an Intersect Analysis Tool in Houdini to determine the points of intersection of geometry, which in turn might help you create a color attribute wet mask for your texture.

You can watch this tutorial to get a basic idea of how the intersect tool works:

https://youtu.be/BubpaVDlhic [youtu.be]

A big thank you! I had not learnt about this tool yet and pretty interesting… After watching the tutorial, it never ceases to amaze me how logical and powerful Houdini appears to be, where you can connect everything with everything… really happy to had started learning 3D with this application by now, it really clicks with my (old software engineer + photographer) way of thinking.

Just q quick post to share progress:



Well, the texture scale is all wrong, etc. but I finally managed to get a more or less credible water surface and variable wet texture (using material override according to an attribute based on the water level).
Now I'll try to make water a little murky / dirty. Is the liquid smoke material the way to go for this? or an uniform volume material under the surface?

Looks good!

BTW, if you haven't discovered it yet, ODForce is also a great resource for Houdini info and techniques:

http://forums.odforce.net/ [forums.odforce.net]