Like a grate or a fence or a lattice, some sort of shape that will cast a lot of shadows with straight lights.
We can talk here for the next hours, simply try it, i’m working that way since months, actually since i figured out that i’m getting the best lightmap results this way. It works also perfect for more complicated round and cylinder meshes and when using higher lightmap resolutions you get almost perfect results.
Somewhere in the archviz section a UE4 developer wrote that you don’t have to keep the form of the mesh for your lightmaps, you can strech them etc… That was the start point for me to try it on round / cylinder meshes.
Actually i’m not here to start a debate 
I just wanted to share my way of doing things that worked for me good. Every one is free to try it or to use a different way to handle lightmaps.
ZacD, here with more shadows… still with 64 x 64 lightmaps. I can’t build a fence “thing” cause my cylinder has no face on the backside. It was just created to show off the effect / ligthmaps. But it’s a very simple mesh, i think every one can try / experiment with it.
I just showed you how it’s mapped, it’s very clear that causes some extreme warping. If you think your results are OK then most likely you don’t have a lot of cases where the warping is apparent.
And i just showed you that it is working fine… There is no more proof to made, the most imortant point it that it looks good in the engine. And like i wrote before, of course it is not the right way to unwrap meshes, casue it would look weird. But for some reasons it is working good enough and better “less artifacts” than keeping the uv shell of the round mesh round…
And you don’t need to show me how it is looking mapped, i mean i saw it by creating the mesh / uv shells… And yes it looks totally wrong, but it works for some reason…
this is how weird it looks on my mesh… lightmap UV chanel…
Well, i am still with Adik here and he is just showing an extreme example, cant get that much worse. And yeah, the front face of the cylinder is warped but this just resuklts in some more or less resolution on this face but there wont be a lot of distortion in the lightmap because its getting baked etc. And of course its a lot of work and in the case of a cylinder makes no sense, Adik just wanted to proof a point. The main point for the OP is another one, break your UVs at hard edges for your quite high res model and simplify it as shown. You will get good results 
Here another test… I mean i can’t explain why the shadows are written correctly on the map, even with such stretched UV’s but it workes just fine for some reason. But like i wrote before i’m just sharing my experience here and the results i’m getting by doing so are good enough for me to practice them on all my meshes / work “imortant work”.
@LeFxGuy, Yeah this is also very important, brerak the UV’s on hard edges and keep always your smoothing groups good. And you are right doing this makes not always sense, casue it is really a hell of “stupid, brain dead, boring” work i simply hate it :rolleyes:
I meant you should make a fence with a separate mesh, shrinking a cube down to a skinny pole and duplicating it 6 or so times would work. And have that mesh cast a shadow onto your skewed cylinder.
Well i think the sample above shows clearly that the baked shadows are very acurate even on the edge of my cylinder. This methode worked so far just fine for me… But everyone is free to make his own experience / test.
The red market areas are usually magnets for artifacts, especially which such a sharp corner projected on them. Basially you will find always some issues, no matter how acurate your UV shells are, light mass is not perfect, by far. So we have to made the best out of it.
It would be interesting to see each person’s results using different techniques on this model here.
Doing it properly gives a better result:
There’s a huge number of things where you’re not going to be able to make it match a grid, there’s little point in doing that at all.
I stay with my opinion, pixel perfect uv shells even on round / cylinder meshes gives me much more clean and artifact free shadows / bakes. I think i proofed my point, so there is nothing more to say or write.
Users are free to decide which way is the best for them, the only negative point is of course the time, it simply takes to much time to make your uvs pixel perfect.
And again it’s simply not true, there was no case so far i had issues doing my UV’s so, i don’t see the point to disinform users here by claiming first it doesn’t work and than ok it works but not for all cases.
@darthviper: This is not good, first of all, you are welding hard edges, which is bad because you will get bleeding if you dont position that edge pixel perfect or have a high LM resolution. Also, you could take that circle and easily break it up into a rectangle like the one it is welded to! Your unwrap is quite bad for a cylinder and wastes some space, especailly since most standard packers can’t pack inside closed shells and because it’s harder to pack then 2 rectangles and a small top face. Matching a grid is a completey other story.
It clearly doesn’t work, you can see how it warps any texture that’s applied, even in your example there’s strange edges on the shadow due to the warping. The only time where your method works is if the object is in complete shadow or light, which is not going to be most of the time. You’re recommending a very poor UV method that’s very impractical and will cause people a lot of headaches and wasted time when they should be mapping things correctly from the beginning.
Not sure what you’re saying. For any UV map you’ll want to reduce the amount of UV seams, sure this method wastes space, but this gives the fewest seams while also keeping warping to a minimum.
Yeah, less UV seams is nice but not to the point where you get bleeding and combine hard edges. Also your first unwrap of the object in question def. has more warping then a simple flatten mapping combined with manual fixes to maintain longer stripes for chamfer edges in 3dsMax.
Anyway, as I said, i think there is more than 1 solution and I also dont think yours gives better results than what adik with his method posted, looking at the screenshots its more vice-versa but that is my humble opinion. Nevertheless, this is now a bit of topic so I wont be participating in this discussion any more if it is not back to topic. If you dont understand what I am saying, you can send me a PM (p.s. smaller typos fixed in my post from above)
I don’t get it, how can it be wrong when the result is absolut right. There are pictures, there is nothing more to proof. My methode works just fine, just life with this fact. The last sample shows you very clear that shadows can be projected on the cylinder without any problems, the result is just right. The cylinder is even in the sun but partly covered with the object above, even the chamfered edges are fine. There are no strange edges, the cylinder has a lightmap which is 64 x 64 pixels small, so you wont get ultra sharp edges on your shadows. You have to understand that you can stretch the UV’s of your lightmaps without any problem, so claiming here to users that it is not working is just nuts, i mean we have the proof here in this thread.
@LeFxGuy I see it the same way, usually you should break hard edges for your lightmaps… It’s the same like with normals, usually you break hard edges for a clean baking result.
We are really going offtopic here, so see you guys in the next disscusion 
It’s not though, the way you want to do it messes up the shadows
Plus, in a lot of cases, you’re still going to have pixels misaligned since you have to have the same number of pixels on each outside edge:
As far as hard edges, there can be some cases where you get better results if you split along the edge, depending on the situation for example if you have a box and the box is against the wall then the shadow on the back can bleed over to the top of the box, but that’s not always the case.
The cylinder is big and the lightmap resolution was set only to 64 x 64, you wont get better and sharper shadows with a light map resolution that low. I can set the lightmap resolution higher and i will get sharper and better looking shadows on my cylinder. Have a look at your fantastic sample you posted, the shadows look the same or let’s better say thea have the same typical lightmass issues. Really, this is just nuts dude…
You’ll still have the same issues, the lightmap resolution won’t change anything about how the UV’s will warp things
Last sample cause i’m getting tired…
All meshes on the Left site are unwrapped pixel perfect and square like on all my cylinders before.
All meshes on the right site are unwarpped with a good space between the UV Shells but not pixel perfect, and the main uv shell is round.
Light map resolution of every mesh is 256 x 256 pixels
What we can CLEARLY see is… there is like no quality diference between both meshes, the shadows are looking indentical! The meshes on the left site have totaly streched UV Shells to a square. This shows us CLEARLY that for some reason you can stretch UV shells without messing up the shadows like on a texture. The left mesh with streched UV’s looks absolutly fine, no artifacts at all. The right mesh with round uv shells, however shows some little artifacts, nothing worth mention but you can see it.
Main Conclusion: What you wrote was simply not true, you can see CLEARLY that even streched UV’s have proper looking shadows “for some reason”. The only difference i noticed, that in some cases i’m getting simply less artifacts, cause every uv shell is pixel perfect.
