Jump to content

Wet Pavement

Andrew West

Recommended Posts

I have been beating my head against my keyboard all weekend trying to get a decent result for this.  If you study great architectural photographs they often wet the streets down in front of the buildings. It pools up into puddles in spots. This would add so much drama to my images if I could make it work.  What I am after is a single material in Vray that can mimic this accurately.  The asphalt needs to have a bump map which is easy.  Then it needs a layer on top of that which is the water and that  needs to be highly reflective and have a bump map to raise it up off the surface a bit.  I have watched several tutorials on this for Max and Sketchup but our editor is drastically different from theirs.  In the Sketchup tutorial they use Blend Material for the water surface but in our editor we can only add from the drop down list into the Blend.   I want to add a generic material and make that white and highly reflective and transparent.  That is not possible.  Does anyone have a clue on how to achieve this using our editor?  Tech has suggested making physical puddles on top of the asphalt which seems to me to be really time consuming and awkward.  Here is a good example of what I am after:


Link to comment
Share on other sites

Hi Andrew,

Interesting, I have wondered how I would do this too. Just off he top of my head, water all sits at one level, in theory, can you use a single water plane that pokes out here and there where the bump gets low enough, or would that be displacement to actually have a geometry interaction? Of course this precludes a little bit of surface and level variation that you would have with a road. There is a hump in the middle,, ruts where the wheels go, even if it is only an inch or so. Maybe this would keep the water pools forming in the ruts. There is a heck of a lot of variation in your example.

I was hoping that applying a reflection to the asphalt texture map would provide the "wet" look and reflection.

I have always been suspicious that for the map we would like a whole big section of street that doesn't have tiling anywhere. A huge drone shot would be great to start with, but, alas. I suppose there are enough huge commercial road textures out there.


Link to comment
Share on other sites

I see that a gray scale reflection map that allows the reflection to vary over the surface appears to be an ingredient to this. I have been meaning to add this to my regular process after seeing all of these real-time substance painter results. I think I have underestimated how much this would add to the realism of all sorts of things. For ex, a kitchen counter that has the reflection falloff where hands have contacted it over the years. Very subtle, but I suspect one of the bigger things I could do to level up on renders in VRay.

Link to comment
Share on other sites

Here is a quick test of creating puddles using formZ displacement. I have just noticed that the reflections that run across the wet asphalt and the water are two whole different things. They would be diffused by the roughness of the asphalt, while the water would be close to smooth. The water is a cube object. I meshed the top of the asphalt object at 8" before applying simple displacement.


I used the stock asphalt d diff and bump. That should take care of the tilling aspect of the surface. The displacement would have to be one image for your whole area, and painted with more time on the irregularity of the puddle shapes.


I know this isn't there yet, but it moving in the right direction.



Edited by johnalexander1571
Link to comment
Share on other sites

I think I got lost on what you did to achieve this. Could you please explain a bit more. 

Tech sent me an example of how to do it with a plane suspended an inch above the pavement. That highly reflective plane has a B&W Opacity map of blotchy spots in various densities from white to pure black.  The white areas are opaque and the black are transparent.  I also put that map into the reflection channel and set the reflectivity to 1.  The asphalt plane below is also fairly reflective since it would not be dry at all. It has a specular map and a subtle bump map.  The result was not nearly as good as what you have achieved and it was very difficult to control.  Even the pure black areas of the opacity map affected the pavement below to a large degree.  Looked kind of muddy and unrealistic.

For what its worth the Vray tutorial for Sketchup had the best result in the fastest manner.  You also create a material that can be applied to any model in the future without displacement.

Here is my pathetic attempt


Link to comment
Share on other sites

Yeah, Interesting, I see how it is being done in that video. I have looked in the VRay material editor, and if there is a way to blend materials so this happens in one shot, I don't know how to do that.

I used one block and meshed the top at 8" and applied a displacement map to make lower areas where water would appear. The water itself is a separate object that sits just below the asphalt, and shows up where the dips are. I just went with my gut as to what would work and look ok in the render.

The asphalt is a generic material made with the supplied diff and bump for asphalt d cracked. For the water I used either water or alcohol. This would mean that the asphalt would tile, but the displacement would not, and would have to be applied to the street mesh. Since we are using a map for the puddles anyway, I was hoping that it would be fine to add this step.  If there is no blend option like in the videos, I think you will have to separate the objects and map them separately. I don't know if there is a one VRay material that would work in formZ. However, I think the video you present would work just fine if we have the blend capability available somewhere.



Ps. my 2 cents, I suspect that even as subtle as it may be, using displacement to create actual dips in the geometry for the puddles will ultimately look more optically correct, as there is a real dip there, not a 'fake" one. I think computers are fast enough now to handle a limited ground plane faceted with a reasonable mesh on top. The edges won't be able to be as detailed as the one material method, tho.

Support, can we blend materials like shown in the video?


Edited by johnalexander1571
Link to comment
Share on other sites

I have spent hours trying to figure out how to blend materials in V-ray like you can in most other editors.  It does not exist in the current build according to Tech but they hope to unlock more of the V-ray features in the next build.  One thing that has been lacking in our editor has been the ability to stack materials on top of each other and control the amount of blending that happens on each layer.  That would be a real game changer for me.  Adding rust, dirt or in this case water over a surface would increase the realism tremendously.

Thanks for your help.

Link to comment
Share on other sites

Andrew, apologies. That is not what I thought you meant when you asked why the editors are not identical. To clarify I will address the issue here for everyone.

So the VRMaterial Editor is standalone when used through form•Z, but it is embedded in Sketchup and is paired with the material list, lights, settings, etc. While the Settings section of Sketchup does contain some extra features that we currently do not offer (but hope to offer in future releases), the Material editor itself is identical to Sketchup's version 3.x's editor. That being said, it will NOT be identical to Sketchup's V-Ray Next VRMaterial editor.

To address your request, this is how you can set up "stacked materials."

Start with a New or Opened material and click one of the checker patterns next to a map type.


From the next screen. choose Texture Blend (3rd option).


You will then be presented with this page where you can select up to 2 materials. When you go to choose the texture map, you will be presented with the previous screen again, so you are able to define one of these textures as another Texture Blend if you'd like.


I've taken my asphalt texture and set it as Texture A, and my puddle pattern is Texture B. Now I can use the Blend Amount value and adjust it to show more of one or the other.


NOTES: At the bottom left of all of these pages is a Back button you can use to go to the previous page. If you decide you want to change the type of effect (Bitmap, Blend Texture, Smoke, etc) you can do so by clicking the small list button to the left of the name of the effect. So above, you'll see the icon to the left of where it reads "Texture Blend."

So all of the features in the VRMat Editor should be the same across the board.

Now for Andrew's favorite part, the workaround! Having run into some occasional strange behavior myself while loading these VRMats in, here is a sure-shot way to bring these materials into form•Z:

1) Create a new material in the Materials palette and name it appropriately


2) Open the material in the Material Parameters palette and choose the 'VRay' Material Type


3) Select the Libraries drop-down menu and select one of the V-Ray libraries (it will be the last section, split by dividers)


4) Double-click one of the Materials in the library to make it the active material


5) Now you can click the Select Material button and locate the VRMat that you've made already without form•Z running into any issues!


If anyone has any issues with my steps or has any further questions, please contact us at support@formz.com!


Link to comment
Share on other sites

That is a good way to blend two basic materials.  But now how do you control the Reflection, Bump and Transparency of those materials individually?  For instance, in Maxwell's material editor you can create a material that simulates rust on metal by adding a rust map over the top of a steel map, then give the rust a transparency Noise map so that it only appears in places.  Adjust the amount of noise to adjust the amount of rust.  It works almost like a procedural material and this would be an easy way to do puddles on the street or dirt on the floor.  V-ray does work this way in other programs, just not in here yet from what I can tell.  Correct me if I am wrong. 

Edited by Andrew West
explanation and example
Link to comment
Share on other sites

Some great information already shared in here.  I wish it were easier to play with displacement.  We could really use some baseline presets, just like VRay Fur.  Still, I do not think you have to use displacement to achieve this effect.  Especially if it's not the focus of the scene.

I did a quick test to see if I could follow this Wet Asphalt example using VRay for FormZ - 

Here are the files they provide - https://www.sketchuparchive.com/product/wet-road-1/

I tweaked it a bit using our VRMAT Editor and got this quick result -  It's not bad considering the minimal effort with a simple VRMAT file.  If you play with the Fresnal IOR as shown in the example, you can make the reflection channel (puddles) more or less dramatic. 



Wet Asphalt - JM.vrmat


Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...