I had some issues with importing my models on Wednesday night (I build a lot of my architecture in Sketchup). After some head scratching Thursday morning, I’ve come up with a work flow pattern that seems to work for me. Ziggywave, are you familiar at all with Blender? I’ve found that works as a great intermediate step between Sketchup and Unreal 4.
Here’s the workflow I’ve found that works (I know it seems complicated, but once you’ve got the first couple of times down, you find you can pretty much do the blender conversion bit, including adding the lightmap, in around about 1-2 minutes per model):
Workflow Process:
Create item in Sketchup
Export item as a Collada file (only file type possible on basic Sketchup, Pro version has more file options)
Open blender
Delete start up items if they still appear in your work space
Import mesh (remember to select import from Collada file as that is what Sketchup exports as)
As soon as it’s imported, hit Ctrl+J to merge all meshes into one single mesh (as Sketchup has a habit of exporting a single model in multiple parts)
Select either Flat or Smooth Shading from right hand menu in Blender to suit
Scale x100 (this will perfectly align the scale used in Sketchup with UE4’s scale)
Switch to Edit Mode
Go to Menu -> Select all Vertices
Go to Mesh -> UV Mapping -> Unwrap
Select the Mesh button on the left hand tabs
Click the “+” sign next to UV maps
Keep the new UV map selected and switch to UV Editor
Press the “+” sign next to New
Call it Lightmap and click okay (making sure it is at 1024x1024).
Go back to 3D View, switch to edit mode and select whole model
Press space and seek out and select Smart UV Project. Press Okay.
Switch back to UV Editor and select the lightmap channel.
Make sure it is all selected and then hit Ctrl+A and then Ctrl+P
Switch back to 3D View and adjust the margin to 0.1
Export model to FBX
Import model into Unreal 4
Open up the Static Mesh Editor for the model
Add material (I do my texturing inside Unreal 4)
Adjust Lightmap Resolution to 1024 (for me, lower than this just doesn’t seem right, but some people prefer a lower value - just remember to keep it to the power of 2)
Place object into the level. Rebuild Lights. (Don’t forget to have a lightmass volume).
The later part of this workflow I borrowed mainly from Fighter5347’s tutorial on lightmaps on YouTube which is worth watching here, especially if you are not familiar with Blender: http://youtu.be/z5yc-bKbHyc?list=PLyfbinWLdAUwiStRx7Zil-O0OLzpIBB9l