These couches are based on the Collegedale sofas by England Furniture. We have them in our real living room that I'm refining next in my house model, so I'd really like to use them both.
I added a Sketchup import into Blender and was able to select one couch and export that to a DAE, but when imported into SH3D various faces are missing from the model. I don't know enough yet about Blender to dissect it. If I export the DAE model as OBJ in SH3D when I import into Blender I lose half the textures (blue slender triangles) even after doing external data/find missing files to bring in the texture files. OBJ export into SH3D brings in a pure white model with missing faces too. Thanks if you can help.
I think you are on the good path, you should just hide the materials starting by material and edge in the Material modification dialog box of the imported model, before exporting it to OBJ format. Materials named material... are probably used for inner faces which conflict with the outer faces. As these inner faces are not visible from outside, it's not a problem to remove them.
Finally, once you removed the parts you don't want in Blender, select the remaining faces and choose Mesh > Normals > Recalculate outside menu item, and export it to OBJ format.
