Unity 5: Efficiency of lightmap packing?

Hi all,

I just looked at some of my baked lightmaps and they seem to be packed pretty inefficiently. I guess with better packing the number of the lightmaps in my example could probably be reduced from 7 to at least 5 or even without reducing size or quality of the individual patches.



Now I'm wondering if there's somewhere a setting that lets us pack those patches more efficiently. Or if not, can we expect an update for the packing algorithm in the near future?

Since Bake Selected is not available anymore and we still require some objects to have differently baked lighting we currently store those objects in an extra scene and transfer the objects (including ligthmaps) into the original scene.
But this workflow requires some extra manual work for each lightmap that's generated. So, the fewer ligthmaps the better

 

UV packing has been improved in 5.2 beta 4.

 

Nice! Looking forward to it

 

You can expect the update to the packing algorithm in 5.2b4 (released last Friday).

One issue that was fixed that has to do with taking UV bounds into account properly and is described in more detail here:
http://issuetracker.unity3d.com/iss...irection-uv-maps-overlapping-causing-blotches

The other thing that will improve your case is that the size of the last lightmap is now reduced to pack the instances more tightly and not waste space. So in your case, where you lightmap some objects in a separate scene and, possibly, they occupy only a part of one lightmap -- now this lightmap will be made as small as possible (while still being square though).

 

Hi, I have still not been able to get the UV packing to improve with Unity 5.2 ( Installed in mid Sept). Also the Shading on my light map UV do not match in tone giving odd artifacts in the light map. Why does the Unity light map UV give such inconsistent seams? Thanks.

 

Also, can we please PLEASE (did I say please?) switch to the tighter packing that we had back in the 3.x days? The bounding box type packing wastes SO much space, especially when you generate your lightmap UVs (which has a tendency to put the uvs in an L shape)

I believe it was changed to work better with bake selected, but bake selected is no more, so.... why are we wasting so much lightmap space?

 

This thread is a couple of months old but it seems that either the latest algorithm still needs work or I'm missing something (I'm on 5.2.3f1). My atlases have 70% wasted space and opening them in PS shows there really is nothing in those spaces.

 

I am also experiencing this using Untiy 5.3, i am getting 13 lightmaps and 3 of them are 90% empty and some others 75% empty.

Am i missing something?

 

Something similar had been driving me crazy for a while in the last few months too. I had been getting a whole scene packed into one map and then ONE object getting its own one whole 1024 even though it was about 4x4 pixles, the rest 99.9% of the map black.
It turns out the Layers you assign objects to matter in the new packing process. Correct me if I am wrong, please, but for me, making all of the objects I needed packed together be on the same layer fixed that problem.

 

http://issuetracker.unity3d.com/iss...ed-down-in-the-lightmap-due-to-being-too-wide

Here's one bug related to lightmap packing. Supposedly it should be fixed in 5.4. psycocrusher's case above looks similar.

 

@KDurzy I tried your solution but it didn't work fro me.

 

Alternatively if the unity Devs could tell us exactly how they want our lightmaps, we could set them up ourselves and set preserve Uvs coming from the art package? Can you give us an intermediate resolution that describes how you need them to look in order to pack them efficiently?

 

This is still a problem. If I try to have all my scene in one image I get either of these two results, there's no way to utilized completely the whole area of the lightmaps.
Is there no way to manually fix this? I'm using 5.3.4.

 

Yeah Unity really needs an improved texture packing system. Still really poor packing in 5.3.4. Might be worth noting that it's sometimes possible to get better packing by switching to a different texture size (eg 2048 vs 1024). It's pot luck but might help someone else out

 

Packing is still pretty poor in 5.4b22

 

This is still a problem in 5.4, regardless of the supposedly "fix" via the bug report listed above.

 

BTW, I discovered that changing things in the lightmap parameters (like the "is transparent" checkbox), forces the objects that have those parameters to be on a separate lightmap.

I don't have a complete list yet. It would be nice if these sort of things were documented.

 

I hate to bring up direct engine to engine comparisons (since different engines usually have things going on under the hood totally differently) but I wish Unity 5 had support for user defined lightmap UV's like UE4 does. I was reading outdated documentation (not realising that things had changed since it didn't have a Unity version number on) and was under the impression I could lay out the lightmap UV's manually for a scene, so spent a day doing that in Maya, giving high resolution to areas the player would get close to while compacting areas the player wouldn't. Then imported it into Unity and discover that the UV's are rearranged anyway.

 

Hey Adam. Yeah that is a nice feature in UE4. Having used both engines though I'd say there are benefits to both systems (I like being able to see an entire atlas and edit it in PS). Regarding your particular issue though - you can still use your per object UV2 layouts as well as set custom texel resolutions in Unity. Whereas in UE4 you'd set per object texture sizes; Unity lets you specify a texel ratio. It's a little more trial & error (though you can enable resolution grids in the scene view for better visualisation).

If you want to completely control how every piece is arranged relative to one another (probably not necessary but it's an option) then you can export the entire scene from Maya (I've done the same from Max).

 

i confirm this, this one totally confused why i have another small atlas in the lightmap list.
Turned out isTransparent object are baked in other atlas

 

So even after figuring out a variety of undocumented reasons for why lightmapping might generate a new atlas, the packing algorithm is still pretty poor.

-It's still bounding box based instead of texel tight, which was changed because of bake selected back in Unity 4, which doesnt exist any more, so I don't know why it's still being done this way.

-It's unable to rotate the UVs (I'm guessing it has something to do with directionality, but it doesn't even on non-directional mode, sooo...)

-It's pretty poor in general. I don't know how it decides to place UVs, but it seems like it takes the smaller UVs first, place them clumsily in the bottom left corner, creating gaps, and then tries to fit the bigger ones. And it's a little too eager to create a new atlas. If something doesn't fit in the place it decided it wants to put, it creates a new atlas, even if there is space elsewhere.

Overall, it's very poor. I'm trying to fit everything in one map and I often find myself massaging values by +-0.1 or editing the models and rotating the UVs manually, in hopes the packing algorithm decides to produce half decent results. Which again is very fragile, because the most minute change might again make it create a new atlas.

 

It's 2020, and Unity's lightmap packing still looks like a joke.

I've heard some explanations as to why objects end up in separate lightmaps while each of those lightmaps has around 70 to 80% of free space (some stuff related to LOD levels being assigned to separate lightmaps god knows why, specific lightmap parameter assets ending up rooting object ot separated lightmaps again).

I understand Unity has a lot of stuff to put up with, and overall I think it's a fantastic tool ,but sometimes I just can't understand how some stuff like UV packing which has many efficient solutions documented in academia and is properly implemented in a lot of other software remains so poor in Unity... Been doing programming work for twenty years, so I know that in complex software there are often reasons why things don't get fixed quickly, but in that particular case, well... (ok, I'm done with the whining, I guess I just had to get it off my chest ;-)

 

In fairness it’s better than in 2016 and some of the points I mentioned specifically are addressed.

It still isn’t very good though, yeah.

 

Do not scale objects that share the same lightmap UV to different lightmap packing sizes in the mesh renderers (I should confirm this, maybe it happens if different meshes are involved in sharing the same UV). This fixes it, but you lose the ability to properly scale lightmaps in-editor, as Unity doesn't pack UV islands (it should, as it automatically fixes island spacing issues and makes it faster to lightmapers to not care about these things).

I haven't found an easy way to pack the UVs. So this is the current direct solution. Maybe someone knows better.

 

Unity's packing is indeed a joke. Even more you can't even use your own lightmap uvs exported from DCC. Unity is always overrading them with it's own. So many years and it's still unusable. At least we have bakery now.