Looking for feedback on my lightmap UVs please

I’ve been checking out tutorials on how to make lightmaps. The main two things I have taken on board are;

1 - Lots of padding! (2 units)
2 - Edges to line up to grid

Thing is, most tutorials regarding this are on boxes or boxy rooms. What if you’re doing it for something containing lots and lots of shapes? For example I’m working on a bed asset.

1 - Padding with 2 units inbetween seems extreme, forgot the lower right corner of my map but what about the rest? I’m losing so much space because I have so many pieces :frowning:
2 - I’m guessing the snap to grid thing is only for boxy UV islands? I’m using a 32 checker texture and because the islands are so small it just screws up the uvs if I try to snap them to the grid. My bed is using LM resolution 64 in Unreal (bed appears green when showing LM density viewing mode so have set it to correct resolution), should I be making a 64x64 texture?


Scary thing is that in the grand scheme of things this bed isn’t complex at all, what on earth do people do with high budget 5000+ poly assets with regards to these guidelines?!

Only hard edges need to be made pixel snap, or to put it another way: shallow angles may fall between UV textels without consequences. But there is always some exception to the rule.
If you like, I can take a shot at it. Just send me a PM.
It is indeed strange that this would be hard to map…


Here is my current method to get a simple shape working, just seems a lot of work when you consider this is a simple shape? Especially since most shapes are more complicated but by showing you my method on something basic perhaps you’ll see that I’m doing this wrong?

1 - Original UV
2 - I snap each corner to the grid one by one
3 - I snap the inner vertices
4 - I have nothing to snap the middle vertices to, they just snap into an existing vertex. I undo
5 - I carefully zoom in and try to drag the vertex (snap turned off) to align it to the others. I can’t just select the side vertices and align them as they will then not be perfectly sitting on the grid anymore.


I upped my LM resolution from 64 to 128, baked at production level and I still get blurred blocky bakes :frowning: Selected some of the faces to show you the UVs. Looks good to me, not everything is perfectly aligned to the grid but I’ve given them lots of space and size.


Bonus question :smiley: Is it possible to bake lighting on a specific object rather than the whole scene?

Oh what, I changed the LM resolution to 512 and it looks great. So obviously it was just that I had it set too low before. Surely 512 is way too much for such an asset?


I’m so confused, because at 128 the bed appears green in the lightmap density view, which is good according to official documents but making it 256 or 512 turns it red which means it’s too high. Yet only at 512 does it look good.

Can anyone at least let me know

  1. if 512 LM resolution sounds ridiculous for this bed asset?
  2. I have a 32x32 checker texture that I work with in the 3D application, is it worth having 64x64, 128,128, 256x256 ones too? What if I estimate that the bed needs 256 and work with the 256x256 checker map?

Hi Adam,

  1. for something like this that may be fairly high. If I were setting up the UV I’d probably target around 64 as a low end, 128 for my mid, and 256 for high. This would depend partly on if any shadows were being baked in from other objects that are casting shadows and the quality I’d want to be baked for that cast shadow.

You’re lightmap UVs could be packed a little more tightly though. A good rule of thumb as well would be that anywhere there is a 90 degree angle break that into it’s own UV island. Another point would be for anything that is more organic or rounded in its shape it’s okay to have these not be on a grid point for a hard edge. For the bed with the wood parts i would definitely want those to be on grid points for the LM resolution you’re targeting since those hard edges matter more. The point of putting them on the hard edge is so that there is not a any soft bleed of lighting or shadow information across that edge.

  1. I have a UV texture that I use to see any stretching that is 512 x 512, but I personally don’t use anything like that. I’ve not had a use to do so at this point. Hopefully someone else who may use that workflow can offer some tips or reasons they do.

For some feedback on your UV. For the Lightmap I would make your UV islands large enough to fill the entirety of the space. This will help keep a lower LM resolution instead of pumping up to 512. For the areas that are never going to be seen (ie. the underside of the bed, the back face on the headboard, I would make these much smaller UV islands. I wouldn’t reduce them small to the point that they are barely visible, but since they’re never seen, if they have a lower resolution in the LM it’s not that big of a deal. :slight_smile:


Thanks Tim,

What do you think of my padding in the image on the first post? Too much? I recall a tutorial saying there should be at least 2 units (2 checker squares) between islands?

and yes, if anyone can expand on the question of using other sized maps as a template when snapping to grids. 32x32 is too small I think? Confused thoughm would making it 128x128 really affect the process of snapping UV verts to gridpoints?