Hey everyone -
This is long-winded but I hope it’s descriptive enough to help others in a similar situation to my own.
I’m an arch-viz professional, originally with 3DS Max / V-Ray, currently with those plus Lumion added into the mix. Myself and another colleague are considering making the jump to UE4. The work that I do often consists of creating scenes for huge developments such as parks and mixed-use. Sometimes they end up being close to 120 acres worth of buildings, foliage, attractions, people… you name it.
At work we have big tanks of desktops with two 10-core CPUs and two Quadro GPUs. At home, in my spare time, I use my own “mid-range work-play” desktop with a stock clocked Intel 6700 and a GTX 1070. For the purposes of this discussion I’ll use my 6700 / 1070 as the base case.
With that in mind, I’m trying to understand what a usable and flexible lighting solution would be for me to start seriously migrating into Unreal.
Pretty much all of my UE4 scenes thus far have been 3DS Max scenes imported into Unreal via Datasmith. Those 3DS Max scenes typically carry everything except for landscape and entourage - people, foliage, etc, with buildings and the like often starting life as Revit models. All of my materials are already set up as V-Ray materials. I’ve instanced geometry where necessary (such as poles for a fence). The scenes also often carry two lights - a V-Ray dome with an HDRI, and a V-Ray sun.
I’m trying to achieve the lighting flexibility I get from Lumion, in UE4. In Lumion, I can adjust time of day, cloud cover, all of that on the fly. It means that I can set up one shot of my big scene in mid-day, or do one with streetlights on at night, and I don’t even need to use my HDRI to get nice-looking lighting. I realize there’s often the stigma of using Lumion as a “just push the render button” solution, but when I spend a lot of time doing technically-oriented model work to then import into Lumion, it becomes important to be able to work artistically, see the changes as they happen, and tweak to my heart’s content. 90% of the time I export still images, but occasionally video animations and real-time flyover demonstrations have to be made as well.
Here’s what I’ve tried so far:
First scenario (what I’ve mainly been trying) - I dump the lights upon import and re-construct them in UE4 with static skylight, stationary directional light, and sky sphere; Repeat for various pre-computed lighting scenarios. Where I run into trouble is when I have to build the lighting. When I’m just working with a small scene, say, a single building exterior, it’s fine. But it becomes problematic when I have this gigantic scene and I need to build the lighting to see how everything looks. Even in preview quality, with only the two lights, the lighting for my gigantic scene could take hours to build. It’s even more frustrating when I need to tweak lightmap resolutions on certain objects, and I can never really see the results unless I build the whole scene again. I’ve experimented with some settings tweaking (such as the static level lighting scale) but it’s hard for me to tell a difference.
As a base case - I have a half-open pavilion constructed like a log cabin, 22 meters in diameter and about 8.5 meters tall, housed in a lightmass importance volume, with a flat landscape surrounding it. My 6700 CPU built the Preview-quality lighting in about 5 minutes, medium 11 min, high 20 min, and finally 48 min for production. Default lightmass settings apart from increasing the indirect lighting bounces to 7 and the sky lighting bounces to 3 (for more light under the roof). I’ve found that keeping the V-Ray lights in the scene really doesn’t do a whole lot to help me, and sometimes actually makes build times worse.
**Second scenario - **fully dynamic / movable lights. As scenes get larger, framerates drop, of course, but I get to see everything right away and adjust on the fly like I can in Lumion. The problem there is that with no real indirect lighting and / or global illumination and / or Lightmass calculations, the scene just looks dull and flat, which is not what I want. I’ve done poking around, reading about LPVs, Nvidia’s VXGI, etc for somewhat of an indirect lighting solution, but I’m not even sure where to begin. I really don’t want to waste time wrapping my head around building VXGI from source. I know UE 4.22 will be incorporating some ray-tracing solutions but that would mean I would have to upgrade my GPU to a new RTX card, right?
Now here is what I’m considering trying:
**Third scenario - **Luoshuang’s GPULightmass plugin. Obviously my GTX 1070 GPU is more powerful than my 6700 CPU, so why not take advantage of that for light building? My GPU performs like a champ in gaming, in Lumion and in V-Ray RT. If that would help to reduce my build times, that would be really helpful. But it still wouldn’t
**Fourth scenario - **Third-party dynamic sky plugin, such as Everett Gunther’s Ultra Dynamic Sky or Simul’s TrueSky. Obviously the $130 for a TrueSky license or $30 for Everett’s plug-in is a drop in the bucket for our company, but as an individual I’m apprehensive about spending the money, considering I’m not 100% confident with using Unreal for my personal work yet. Thankfully TrueSky has a free thirty-day trial so I have some time to experiment with it. Michael Gerard’s work comes to mind in thinking about the results I could get with one of those plugins (apparently he used TrueSky). But that also raises the question - how effective are either of those plugins when dealing with interior scenes?
While I believe that I have a basic understanding of working in UE4 (thanks to those fantastic video tutorials from Matt Doyle and everyone else), I’ve probably missed something… Right now I’m really leaning toward working with one of those dynamic sky plugins. I know that’s probably “the easy, buy your way out” but I want to be able to work quickly and visually, and be able to make new iterations often based on client feedback, my own tastes, etc.
Can anyone give me some advice on how to proceed, based on what I’ve written here?
Thanks in advance!