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how do you light the environment? roads and sidewalk etc.

hi mates, we mostly do archviz projects, we are making our transition from unity to unreal and trying to figure out best workflow, so far we have done our experiments on interiors and now we are trying to build the exteriors.
my question is how do you light the objects such as long roads and side walks and lawns etc. do you use lightmaps? the problem we are facing is that we have to give these big objects a huge lightmap resolution to get good quality, on low lightmap settings the shadows on them look like a blob, or do you guys use a combination of dynamic lights/shadows on such objects and lightmap for smaller objects?
Thanks and Regards

Yes you have to use lightmaps sadly… cause there is no other “well working” possibility, you can play around with LPV but you will have no GI…
For good lightmaps you have to invest some time and you also need a good UV layout… I’m working right now on streets and sidewalks and i’m using 64X up to 128x lightmaps…

thanks for the answer Adik, i have to push my lightmap res to 2048 to make shadows look anything close to real.

Look into LPV or normal dynamic lighting with Movable lights if the exterior is huge.

Try LPV like jacky wrote but i’m not a huge fan of it… can you post your mesh? and UV’s “Pics” would be interesting to see why you need such a big lightmap resolution…

@Jacky thanks for the suggestion, i will look into LPV but i fear it might increase draw calls and i need to keep this project judder free in oculus dk2.
@Adik, thanks for taking time to respond, i have attached a screenshot of the model, the main problem are side walks and roads, their lightmap uv is just simple planar, i dont want to cut seams in them as it might produce seams in lightmaps.

What if you set the road and sidewalks as movable? Because i dont think even 4k lightmap resolution will give you excellent shadows for a mesh that big.
Btw, what else are you going to add to this map?

Thanks Jacky, i think i will add some terrain, and trees / grass that sort of vegetation. i will test setting road and sidewalks as movable.

now they receive no shadows if i set them to movable.

I would definitelly cut the road into pieces and here’s why:

  1. with the lighting setup on the screenshot there isn’t much happening in terms of shadows on the road and pavement, so there are no areas that could cause some serious problems with seams
  2. the color for roads and pavements as well does help to hide some small missalignment in lightmaps
  3. if you do have any pattern on your pavement texture, just use it for the UV cuts
  4. making sure that lightmaps are not stretched to much and that there are enough margins between the UV islands should make seams invisible

This will give you some freedom in terms of sizes and quality of the lightmaps. And if you are planning on adding some foliage, you can also place it strategically to mask the problematic areas.

very useful tip rimau, i will try cutting road and sidewalks and see how it goes.

Yeah definitly cut them in peaces, this is a way toooooo big :slight_smile: and not only in 3 or 4 peaces… when using “normal” size meshes you can put the lightmap resolution to 64 or 128, the building time will also go a way quicker like with this huge 2k light maps…

guys another question… how do you light your terrain? do you use dynamic light or you prefer to lightmap it? i know i have to do some experiments on my own to find best balance between quality and performance but i need a nudge in right direction. :slight_smile:
thanks for your helps, i now have a better understanding of how to handle exterior environment.

It depends on how big it is, a large environment is too big to do lightmaps because of the amount of memory involved, including how much data needs to be stored since you don’t want a game to waste tons of hard drive space.

that is what i was thinking. but it is not going to be a big environment. just as you see in the attached image, and a little environment around it.

In that size you can use lightmaps, the biggest issue will be the houses, since they have more detail you can’t lower the lightmap resolutions too much.

For the ground and the roads if it can be mapped to a square shape then you can fill the UV’s with it and won’t have any issues with the lightmaps. And if it’s receiving direct light then it shouldn’t have issues with the smoothing of the lightmap so you’d be able to place seams where you need to. Also, depending on how much detail you want in the lightmap you can use a lower resolution.

thanks for the advice mate, houses’ uvs are packed rather nicely so for the moment they are not the problem. but i cant think of what to do with grasses and small plants, surely i can not lightmap all of them and i wanted to avoid any dynamic lighting.

Foliage can be used with lightmass, but you’re right, you need to keep the lightmap resolution for those very low. Luckily, since they’re just planes you can set the resolution really really low and it’ll look fine, but it can certainly add up when you have thousands of grass meshes.

i wonder how unreal handles lightmapping on foliage, does it divide in clusters, does it use same lightmap on multiple objects, or each instance is handled as a separate object… and this might be noobish, but how do i exclude foliage from lightmap like it used to be before 4.6? i want to compare performance with direct light and with lightmap :slight_smile: