This is from the perspective of someone using Unreal Engine mostly for Image and Video rendering, so if you are a game dev, it might not be interesting for you.
I decided to post this here in the because a lot of these issues are actually rendering related and where mentioned here again and again over the last years. Of course we could always use the pathtracer, but besides it being limited, it also kind of defeats the purpose of using UE5 at all.
Unreal Engine 5 is no longer free to use for people outside the gaming industry, but compared to other software with a similar or even lower price tag, it’s hardly production-ready. And if you run into problems, you are pretty much on your own. Not great if your clients are waiting for your output and everything stopped working 3 hours ago.
After working with Unreal for almost 3 years, rendering dozens of animations, these are some of the biggest issues:
“Cinematic Quality” is not cinematic. We need one or several quality presets that really deliver the maximum possible quality for rendering. In our industry, projects often have to be built and rendered within the same week. We can’t really afford spending days searching the web for that one console command fixing the flickering, ghosting, or slow GI.
Lumen can’t do clean mirror reflections. EDIT: Lumen reflections did improve a lot with the last few updates but we still cant have a simple mirror in an archviz shot. There isnt even great workarounds for this.
Lumen does not provide a good solution for refraction. EDIT: Ray-traced refraction seems to now be able to sample the lumen translucency volume. This might be an option for some things that dont require a very clean refraction but its limited.
VSMs are not good enough for automotive, archviz, and product viz. Soft shadows just dont look good enough and there is blending issues. Ray-traced shadows are great, but they currently cause artifacts and don’t work with subsurface scattering.
The pathtracer will often crash your GPU when rendering using higher sample counts in the MRQ, while it works fine with the same settings and (native) res in the editor.
Even if some of the problems are skill issues and there is always some workaround or console command, you need to understand that people outside the gaming industry often lack the technical knowledge and/or time to fix these things.
I’m writing here with the hope that someone at Epic sees this and advocates for us. The issues mentioned above are currently preventing us from using Unreal throughout our entire production process, which is a real shame.
Lumen IS raytracing. Like, literally. The reason lumen’s mirror reflections are blotchy is because of the real time global illumination. If you use lumen reflections with baked global illumination and hardware RT enabled, reflections are perfect.
I agree with most of what Manuel has posted here. Though at our automotive studio, we are fully using it in production, despite the drawbacks of Lumen.
I have been using Unreal actively for about 4 years, and so I have seen the progression of the engine over that time, and I am hopeful for the future based on that. The biggest areas of improvement I still see are the accuracy of hardware raytraced Lumen reflections and refractions. 5.4 added some great options on these, but we’re still not quite there.
For example, in the scene below - The chrome spheres have the reflection of a Rect Light from up above. The material sphere should be overlapping the Rect light reflection, but it does not. The reflections of the chrome spheres reflecting each other is also very inaccurate.
Disabling Screen Traces on Lumen reflections makes the reflections of the chrome spheres correct when reflecting each other, but causes the reflections of ray traced shadows to be come hard shadows, and does not solve the Rect light reflection issue:
Since this is a topic about how to maximize the quality of rendering for cinema and vfx, I will post again this picture, maybe someone knows how to get this kind of quality from shadows. In theory raytracing should be able to produce this, but as far as I know it can’t. At least not with vegetation, wind animation and double sided sss.
I’m trying to make a plugin for this, if I’ll be able to do it, I’ll edit and update this post.
I’ll also post this too, another plugin I’m working on. As far as I know you also can’t get this kind of DOF (depth of field) like this. Maybe with pathtracing, but both my solutions aim to work with Lumen.
You are technically correct and I will change my original post. So we need some sort of cleanup step for the lumen scene visible in mirror reflections.
I tested raytraced refraction and it seems to not be production ready. There is some sort of GI going on there but it wont cut it.
