How to adapt roads, buildings, and texture zones to a sloped terrain/topography?

hello everyone new sketchup user here I’m working on a SketchUp topography model and I’m trying to achieve a good result like this one

i don’t know why my last post and my previous account got silenced when im just asking for help ,
In my model, I tried using Sandbox tools like Drape and Stamp, but the geometry becomes messy and I’m not sure about the correct workflow. I want to project roads onto the terrain, create clean building platforms, divide the terrain into areas for different textures, and keep the contour lines visible. I will attach my SketchUp file and a reference image. Any advice on the best method or plugins would be appreciated. this is my sketchup file here and a picture

topographie 1.skp (12.3 MB)

I would probably drape.

yeah, if your terrain is a solid group, you can use the solid tools to perform clean excavations in it.

I’m minutes away from retrning to work, but you should go check this live and the plugin (holigon) in it if you want to make big scale terrain.

it’s really crazy stuff

Thanks! The difficulty is that my terrain is not a single solid group. It is made of many sliced levels , so shaping it or using Solid Tools becomes much harder. I’m not sure if I should explode everything and rebuild it as one terrain surface, or if there is a cleaner way to work with it while keeping the pieces organized. That’s the part I’m struggling with the most.

every level of the terrain topography is sliced in a group

well, the first solid tool is a merging tool, you could… merge them all :innocent:

Yeah don’t do that. Unless your site is a current rice paddy farm…terrain in real life doesn’t step by contour like that. The contours don’t actually exist…they are a 2D representation and expression of vertical elevation data.

Here’s how I’d approach instead:

  1. Separate just the top faces (teal) from your ‘stepped’ terrain group (blue) - ie no sides as they’ll mess up Sandbox fm Contours in the next step. Pro Tip - you can paint just the top (ie flat) faces between contours a different color from your vertical faces, then right click on face and choose ‘select/all on same material’ and then you can group and copy separate.

  1. Next, Sandbox the newly separated contour faces to get a nice clean terrain mesh (green). Then flatten the stepped faces using an extension like Eneroth’s 'Flatten to Plane’. This will allow draping the flattened contours over our nice new clean terrain mesh to get just the surface contours.

  2. Now you can group the contour lines separately from the terrain mesh by using an extension like ThomThom’s ‘Selection Toys.’

  1. Create faces and cleanup your flat road and parcel linework using an extension like Eneroth’s ‘Face Creator.’ Drape onto clean terrain mesh using Sandbox Tools/Drape.

  1. You can then apply different colors to the clean terrain mesh based on land use or roads designations. Again note that the contours are grouped and tagged separately so they can be toggled on and off as needed and will not break the terrain up into smaller pieces - which would make it much harder to work with.

  1. Build out your 3D elements on your 2D plan placed directly above your terrain mesh. Buildings, cars, trees, furnishings, etc should all be grouped or made components by individual object - meaning keep a single tree as a component but keep all your trees ungrouped from each other.

  2. When ready, use an extension like 'DropGC’ to literally drop the various bldgs, trees, etc down vertically onto the terrain surface. Continue to refine grading or entourage placement as desired.

Or just go buy the LandShape extension. This kind of complex work is exactly what it was designed to do.

Check out this video. It describes the process for the most part: