Game Development Reference
Right now, bOverrideLightMapResoluion is checked, and
OverriddenLightMapResoluion is set to 0 . The 0 means it's using vertex lighing.
On CSG surfaces, a smaller number meant more detail. This is because the number
speciies how far apart lightmap pixels will be calculated. On a staic mesh, you
control the size of the lightmap image directly. If you type 4 , it'll calculate a 4x4
image to paint the lighing onto, which deinitely isn't enough detail. You'd get
beter results with vertex lighing.
Change the number to 64 and also bake lighing. You'll see that the hard lines are
gone, and the lighing generally looks beter. You can go higher to get even more
precise results, but again, baking will start to take a lot longer and for an object this
small, it's probably not necessary.
If you open up the generic browser again and look at your map, you can see that the
lightmap has updated again. It's got the six sides from the room, plus an addiional
patch of scatered detail. This is the lightmap for your ire hydrant: