How to Create Wear Paths for Your 3D Transportation Visualization
“Having looked at hundreds of transportation renders over the past few years, a few details start to jump out that show a separation between the experts and those still figuring it out (although project budget is often an important caveat). Most of these are subtle- the texturing of buildings adjacent to a project, ambient occlusion, ‘flat’ cars or trees cleaned out of an aerial image, good traffic animation or professional camera directing to name a few. One of my favorite additions to a 3D model- and ultimately the final rendered images or videos- are the wear paths that are naturally generated from months or years of cars driving over asphalt. There is some discussion about whether these are created from wearing the asphalt down to the natural gravel, dust tracked on top of the asphalt from the tires or grease down the middle dripping from millions of oil pans. The truth is probably a combination in most cases but regardless, almost every road ends up having some sort of wear patterning and matching that look can really take your visualization to the next level.
While we included these nearly 4 years ago on Project Neon, we’ve actually only started to include them consistently over the past year. Even then, the project budget and schedule can often be a limiting factor in whether or not a project gets the wear path treatment.
While there are a variety of ways to develop these patterns, this is a step by step process of how we currently create them for our projects. Credit to Civil FX artist Justin Gould for putting this incredible guide (3ds Max to Unity) together! If you have comments, additions or revisions, email email@example.com or reach out on LinkedIn and we will try to get them updated into this post.” -Sam
How to Create Wear Paths for Your 3D Transportation Visualization (in 3ds Max and Unity)
- (in 3ds Max) Create a Spline in between the stripes. (Adjust accordingly and follow car paths)
- Use the “Glue” plugin and glue the newly created Spline to the surface. (NOTE-If the Spline is over multiple surfaces, break the Spline into multiple Splines, glue each, reattach, and weld vertices.)
- Select the new Spline that was generated using “Glue” and go to the “Modifier” tab, and open the tab labeled “Rendering”
- In the “Rendering” tab, turn on “Enable in Renderer”,” Enable in Viewport”, “Generate Mapping Coords.”, and “Real-World Map Size”
- While still looking at the “Rendering” tab, select “Rectangular” instead of “Radial” and change the width to 12’
- Adjust the Spline if anything looks off (You can Right-Click and select Corner Bezier, Bezier, Corner, or Smooth to help adjust the Spline)
- Add an “Edit Poly” modifier onto the spline
- Right-Click and select “Isolate” the Spline, and use the “Select Polygon” tool to select all the faces except for the ones on top
- Delete the selected polys so only the top remains.
- Right-Click and select “End Isolation”, then got to the top of screen and go to the tab that says “Freeform”
- Where it says ”Grid” select the down arrow and change it to “Draw On: Surface”, select “Pick” and select the surface you wish to Conform to, then set the “Offset” to 0.200
- Click “Conform” and a toolbar should appear with 3 options, Set “Full Strength” to 200, “Falloff” to 200, and “Conform” to 100
- With the Spline selected, Click and drag across the vertices of the Spline to conform them closer to the road. (Make sure the vertices are conforming flat to the chosen surface. If any issues occur, you can adjust the vertices manually. Also check to make sure the spline you are conforming is above the correct surface)
- Open the “Materials” window (Keyboard Shortcut is “M”) and attach your grease texture to the “Diffuse Color” node on a “Standard Material” Then assign the material to your Spline
- The texture will appear tiled wrong on your Spline, go back to the “Materials” Window and double click on your texture. Here you can adjust the tiling until you get the desired look to your grease/ wear path
- Rename the Spline and go to File>Export>Export Selected… Name your file and then hit “Save” (Must export as an .fbx to keep the texture data) A window will appear asking with a bunch of options, Open the “Include” tab and then open the “Geometry” tab, Make sure “Smoothing Groups, Tangents and Binormals, Triangulate, and Preserve Edge Orientation” is selected. In “Advanced Options” tab make the “Axis Conversion” is “Y-up”, and the “FBX File Format” type is set to “Binary”
- Open your Unity Project and “Import” the file. Extract the “Textures” and “Materials”.
- Select the imported “Material” and change the “Shader” to “Legacy Shaders/Particles/Multiply”, adjust the ”Soft Particles Factor” to the desired effect. Adjust the “Tiling” and “Offset” if needed.
*Bonus tip- These wipe videos were created by rendering the exact same cameras with the wear paths on and off and then fading the video in Premiere Pro by matching them up exactly in the time line.