I’m trying to move from lightmaps to lumen (maybe megalights too)
But I still finding the same problems, the hidden light sources are hard to work, and the thing lineal light are to noisy.
For example a lineal light under the steps bullnose, you don’t see the light source but it will light the step. Or a hidden light on the ceiling that you shall not see directly but it will light the full room.
What I have found until now:
Option 1: Using emissive material is really convenient since you can so any shape for example working with curvy steps.
to make it work I use:
r.lumen.screenprobegather.screentraces 0
and Ray Tracing mode: Hit Lighting
Option 2: testing now with Megalights
using rectangular lights and giving them a very thing shape.
It just works perfectly, except when you have a non-straight surface.
I have a BP to do those lights to more or less follow the shape, but in narrow spaces if force to use too many lights, and when you use many lights in each step not even megalights can help.
So, do you have any idea how to improve it?
I also have a proposal, maybe it will be impossible, but in case someone from epic developing team reads it: Spline lights
will be possible to create a light source that will be a spline line, so we can do any shape and it counts just like one light source? (if you do it it will be really cool that the intensity was divided by the length. Like 10cd/m. (actually, that will be also good on surface lights…but in that case cd/m2)
well… you can apply translucent emissive materials to anything and it will not contribute to the scene lighting aka lumen scene nor megalights. this avoids the noise from small emissive light sources, which lumen doesn’t handle that well.
you also can “fake” that effect you desire of just using a simple light representation this way. it’s already working like that.
Not sure if I understand you well, if this hidden light Mesh does not contribute to the scene light, we can not see it at all. and the point is to not see the geometry because is ocluded by other geometry but see the light from that bouncing around
it’s not hidden. it is visible. it has full opacity. you just make it translucent, so… it is not rendered in the (opaque) main pass, but in the seperate translucency pass. means it’s not influencing lumen’s nor megalights’ lighting computation. you use a proxy lamp to light the scene. that’s what you described.
(xcuse the quick blender “spline”. i don’t do this stuff in engine. but…) you can already do that.
yeah. i get that. for that kinda curved light you gotta use real emissive mesh lights. and it will produce noise in the lumen scene. unless you crank up the lumen scene detail. it’s a “limitation” of lumen.
it’s for gaming not archviz, really. you could bake that. or path trace it if you need it for just an animation. hmmhmm… : )
I have baked the light for that mesh in external software and added that texture as emissive on the material, it’s so soft that does not cause noisy light around but it looks perfect and it does not have visibility problems in distance
