GI (lightmass) for large scale scene (landscape) don't work ?


As a newbie, i tryed multiple interiorscenes to learn how to manage the lightmass GI. It work well. Lights in statics mobility can show greats GI precomputation in interior scene.
But…i tryed to make a landscape, and i front 2 problems and some questionments :

  • First of all, my GI doesn’t even work at all in this scene, i made a little test with 2 cube to know if maybe the scale doesn’t match my lightmass settings, and no… (even the little static spot light on this green little cube, close to a withe cube, don’t give GI).
    PS : All my scenes (interior and little scene) habitually work well (i start with the firstperson project, and my recent landscape also)

  • Simply : Do a directional light/lightsource (the sun) can generate GI set on static or stationary ?

  • Why after building my statics lights (even spot lights) shadows and lights deseaper and apear back when i simply moove the sources of lights (but give “preview” vision back also, that’s normal…) ?

  • Do it’s simply possible to generate GI lightmass in big scale (for landscape, with precomputing (building light) ? Or do i need Enlighten to do that (that work with landscape and large scale maps : - YouTube) ?

Thanks everyone :slight_smile:

You won’t be able to use lightmass for large scenes as the lightmap texture data will be taking several GBs worth of RAM. Dynamic lighting is the way to go for that kind of setup.

How large? We use lighmass without problems for maps that are around 1km x 1km.

Hi DamirH, Hi Kalle-H,

Tanks for your answers :slight_smile:

First of all, what do you mean by “dynamic lighting” DamirH? Something like the Enlighten plug-in ?
But, it’s GI that work as lightmass but IRT no ?

Kalle-H, my scene is 4x4km, but i can reduce all my ratio to 1x1km using the same contents, i just need to reduce the ratio of the map and my characteractor in the same ratio (firstperson view) :smiley: (?)

After, for larger map, its really become impossible to have GI ?
Maybe can i add GI in some little places only but inside my global scene ? (as an 50m² interior that is in the 4x4km scene) ? Or i need to make 2 project/scene separetly and make some instance to see it “in a single game” ?

Ha no, by “dynamic lighting” you speak about the Light Propagation Volume ?

First of all, Lightmass does work well with Landscapes! The bigger problem for Lightmass is looooots of vegetation. Thats where you have to work smart to make it work.

A couple of things to think about:

  • I would always use the skylight and directional light in stationary mode since static doesnt give nice results!
  • I would always use stationary local lights as well until you start adding fill lights…those would be set to static instead of stationary then (you dont get specular from baked static lights)
  • Also, your shadows probably disappear because the landscape lightmap rez is not high enough to make shadows if you use static lights. Using stationary lights should fix this
  • Shadows reappear when you move the light because its showing you a fully dynamic (not baked) shadow as a preview
  • you can also have a bigger landscape, and then move some components where the gameplay area is to different streaming levels and then bake the game area in higher quality than the rest of the landscape making it easier to work with Lightmass and its baking times. There might potentially be seams where the 2 parts meet, but you could hide those by placing objects there

I would highly suggest that you check the link in my signature since I just uploaded a video about lighmass in an outdoor environment and how to set things up so this might actually be the perfect help for you.

Tanks you :slight_smile: You answer here much of my questionments. I understand the shadows and light deal.

But as DamirH said, and if he did mean that : the Light Propagation Volume (dynamic lighting/GI) is working better for large scale scene right ?
But, i can not use that dynamic lighting/GI with statics and stationary spotlight to produce interior GI ? If in the same time i have a light propagation volume (dynamic) on my directional light ? (i think, only the Enlighten plug-in propose that for now ?)
The Light Propagation Volume manage spotlight (even statics i don’t care, i will see the movable seting later, with raytracing, iam not here) ?
If not, it mean i need to use the lightmass to have some GI in the interior, and deal the outside (my interior is in the middle of 2 mountain surrounded by others mountain, and i need to be able to travel mountain and go in the home) with the lightmass… :s

Whats good is that : lightmass is a precomuting system and doesn’t take any ressources after the computing… :slight_smile:
But it’s looking so hard to catch the lightmass method with an interior small room in the same scene than a medium/large environment that i want also to beeing affected by GI to make it real (or any fake GI i don’t care ! :)).

I feel like i need to unify the quantum mecanics with the general relativity :smiley:
I think that Enlighten plug-in would be the unifying solution, waiting that Epic Games finish to dev their own dynamic GI in a final version… :s

(and for my bad luck, my english is bad and my understading reading is not that good haha, sorry for that)

PS : different streaming levels is for you some kind of areas instances in a same scene ? That’s look pretty hard to do no ? Need to manage the C++ i think ? XD
PS 2 : for my shadow/light deasapering, it desappear even in a verry small scene, i need to increase the resolution of the shadows, i can not use only stationary light cause they have a number limited (can not use more than 2 close to eachoser).
But…also my directional light shadow’s desappear…(i need to put it in stationay and back in movable to make it come back).

[SPOILER]Hey Guys, i can not put on the LPV…

I did follow that :

Then that :

And that :

I restarted all that 3 methode 2 times…
And it doesn’t work, do its normal ? I need a special version fo the UE4 to make it work ?[/SPOILER]

No its ok…i redid it for an other time (4/5 over all) and it worked ! :slight_smile:
The result is here, but not that good…in fact, it doesn’t look even close to the capacity of something like Enlighten (not even close to Svogi in CryEngine…hope they make it better or they buy the licence for Enlighten as Unity did…)…After maybe for a landscape its largely enought ! :slight_smile:
Then passing to lightmass GI precomputed and raytraced GI (DFGI ?) for small area of the map…(need to know now how to make instances).

After, if i want to have this LPV far (for landscape), i need to put the size very far. Cause, apparently, the GI is generated around the view (camera or actor character). It mean it loose totally it effect/power and precision when i push it to have the effect far for seeing it on the mountains.
If i want precision and power, i need to set the size close, and with this setting the GI doesnt have any effect farther that 150m from the my view (far objets doesn’t generate LPV GI)… :frowning:

Best will be a LPV capable to generate GI from also spotlight, for now it manage only the directional light right ?
hope Epic will success to develop a better RT GI, or implement Enlighten (who manage the RT GI with everykind of lights…) :confused:

Trust me…you dont want to work with Enlighten! :wink: Its by no means close to the holy grail its advertising makes you believe it is^^ You still need to bake with Enlighten and it takes waaaaay longer than lightmass if you dont have a server farm.

Also, I doubt that you have the money for Enlighten since its probably the most expensive middleware you can find on the market and they dont sell indy licenses :wink:

Hihi :stuck_out_tongue:

Lightmass, i can manage little, it’s a precomputing system, not in real-time, and iam used with Vray :slight_smile: *

What is new for me is the “real time” GI. And i see that the actual LPV (dev in progress) in UE4 is not that good, or maybe a super-nightmare to settle, and it manage only one kind of light (and the scale of it don’t permite to render details depending the size or/and the field of view… :s
Anyway, enlighten is far from my budjet yep, i have no budjet XD

I just mean (no…hope) that, Epic will need to include a good quality realtime GI if they want to face the competition that already propose it (and look like it permit a integration in everykind of scenes and lightings).
Or maybe, its me who is really blind or bad to manage settings for the LPV, that i can believe also :o

  • Honeslty, i need to learn things about materials, shadering and texturing (on large or small meshes)…iam so bad in this area where i dont understand that much (i will creat soon a post about specific automaterial that i don’t even understand the nature of :o)…but lighting is for me like hearing music (it doesn’t mean iam good with lighting, but i simply love it) :slight_smile: