Troubleshooting Sketchup (.SKP) model conversions
Sketchup has a free version, so it seems rather simple, right? I'm afraid not. The free version only lets you export...if you pay. So let's take a look at the alternatives - with or without the Sketchup app.
Pick the right format
You probably already know which format you need, but just in case you need a quick refresher.
- GLB / glTF 2.0 - web, PBR-ready, small size
- FBX - film/game-engines (see Exporting FBX Files from Sketchup if you have it, if not, don't worry)
- OBJ - simple text mesh + .mtl side-car
- 3DS - legacy; 65 k-polygon limit (Sketchup 3ds help)
- STP - potential intermediary format if you just need the mesh. Free export from Sketchup Free. See below.
Strategy by scenario
You Own Sketchup Pro (desktop)
Go to File > Export > 3D Model > Choose GLB, FBX, OBJ or 3DS or the format you need.
In Options, set units and tick Export two-sided faces to avoid inverted normals.
You're on Sketchup Free / Make / Web / iPad
The free version of Sketchup isn't completely useless when it comes to converting. You just have to jump through a few hoops.
Get a free STL and use it with Convert3D
If you don't need materials (e.g. you're printing or prototyping) you can use Sketchup Free on the web. You can't export to the common formats for free, but you can export to StereoLithography (STL):
From the Sketchup Free App > Menu > Download > STL. You can then use the Convert3D STL converter to get to any of our formats, including OBJ, FBX, USD, GLB, and so on.
Get a Simlab trial
This is where it gets trickier. You could try installing a Simlab exporter with a 14-day trial. They have a ton (that previous link goes to an overview), including Sketchup to GLTF/GBL, FBX, OBJ.
You don't have or don't want Sketchup
Here's a few browser-only tools, nothing to install first.
ImagetoSTL
It can be a little confusing at first, but it does the job. The ImagetoSTL Sketchup Converter supports a wide variety of destination formats: 3mf, abc, amf, ase, blend, dae, fbx, glb, gltf, idtf, kmz, ojb, off, pcd, ply, stl, usd, vtk, vtp, wrl, x, x-plane, x3d and xyz.
I tried the GLB converter, and it worked. No textures, though, and the scene's center was moved a bit, but you may be ok. It's free and worth a shot.
Aspose
Let's just be honest, Aspose's converters are riddled with ads, confusing buttons, even downright misleading buttons, but their converter may be able to help you. You can download in 3ds, amf, rvm, gltf, glb, drc, dae, fbx, 3mf, obj, stl, u3d, ply, usd, usdz
(... and pdf, html, Excel, Powerpoint and Word. And that's probably what I mean with confusing. I tried the PDF option and it's just a white page, so maybe don't waste your time there. )
I tried the GLB converter and it worked. No previews. No textures and the model seems to have confused z and y axes. But I got my mesh.
Dorchester 3D
Here's another ads-filled converter that does the job. Their converter can output in 3mf, blend, dae, fbx, glb, obj. If you can find the download button among the ads. An interesting thing is that it can convert your Sketchup file to a webm video with the camera circling around it. Low quality, low framerate, low resolution, but a video nonetheless. It can also create GIFs.
3D Encoder
It's a lot cleaner, only a few ads at a time and a promising array of output formats. However, the converter failed when importing my test model (the Garden+Gate model from Sketchup's library), so I can't tell you if it works or not.
FAB Convert
I tried their converter and it gave me a working OBJ and mtl, meaning that there was some sense of texture/material going on (the lock on the gate sure is another color).
For Blender users
(or you don't mind installing it, it's free)
The Red Halo Studio Importer seems to be the most popular Blender extension. It simply adds .skp to the list of supported import formats.
If you're on Windows, it should just work. Just download it from the Releases section on their Github repo, then head to Edit > Preferences > Add-ons > Install and choose the zip file.
If you're on Mac you have to install a bunch of stuff, see the Github repo's README for more information.
This could be worth it if Blender is a part of your workflow or you're doing a lot of conversions.