Continuing the news from SIGGRAPH, Chaos Group announced V-Ray for UE4.

At the first ever UE4 user group meeting at SIGGRAPH, Chris Murray At Epic Games and Vladimir 'Vlado' Koylazov, cofounder and VP of Engineering of Chaos Group introduced a pipeline for both importing Detailed CAD data into Unreal, (without going through Maya or 3Ds Max etc) and then rendering using V-Ray directly in UE4.

Apparently, Chaos decided that they would start with one primary Game Engine, so they informally consulted their users and the clear preference was for UE4 support. While Chaos may at some point support both Unreal and Unity, for now it is only supporting EPIC's UE4. The port was done with one developer working "with one 3D guy", according to Vlado when he spoke to fxguide in LA. One of the team had done the V-Ray for Nuke port, so they were very familiar with this style of work. "In a couple of months we had a version of V-Ray working inside the Unreal Engine and now we are at a point we can show something to our customers". Vlado commented that the Epic team were very supportive once they started working with them, and extremely keen to see V-Ray for UE4 working.

The use cases for needing V-Ray in UE4 is to allow content from other Digital Content Creation (DCC) into the real time engine using either

  • .vrscene files from 3ds Max, Maya, Modo, Rhino or SketchUp.
  • import CAD files from ...

This allows users to render directly for when exact lighting is needed. There are a range of applications from VFX to Architecture and Product design can require the sort of precise lighting and reflections that a true ray tracer can provide.

You can also export content from the real-time UE4 engine for use in other DCC using the .vrscene files, this connects with VRayScene nodes in other programs such as Maya and 3ds Max.

Complex GI in UE4 requires texture baking, so looking forward, Vlado comments that  "V-Ray has a very good texture baking engine so being able to use that inside UE4, in the future, to bake light maps would be useful especially now we have both a CPU and GPU renderers which are very fast".

VRay can provide immediate views on a GI setup.The VRay implementation actually started separately from the UE4 team, built on top of the V-Ray App SDK.

There is also support for custom shaders for the VRayMtl materials. "We try and preserve all the V-Ray materials as much as possible inside Unreal editor, with the same controls as people are used to", commented Vlado. "Obviously once you are in UE4 data can come from other places. You can render out or you can also export a scene file out and use it in another V-Ray application.. so it is a good round trip workflow, which different users want to use different parts of".  At SIGGRAPH a range of customers were interested, including VR based clients. Getting a scene into VR is key for a range of Chaos client. "More than half our artist customers are doing VR on a daily basis, it might just be 360 video, it might be walk throughs,... but it something that comes up all the time now, so anything that simplifies that workflow is hugely beneficial".

The UE4 option is working and is in the hands of a few key customers, "if everything goes according to plan we will have something public in late Fall, maybe sometime in November, but it is hard to say, after all it is development". No word how this will be sold or distributed, there is no decision on if it will be sold separately or as part of a wider release.

In other news, V-Ray now supports Cryptomatte from Psyops. While Vlado initially doubted its usefulness in comparison to a Deep Pipeline he came to see that some clients would end up with 50 or more special render passes or Multi-mattes. "Working that way  just slows down the render and uses memory, Cryptomatte solves this problem in a very elegant way, because it just requires a few render elements,.. with multi-mattes you have to set them up in advance with Cryptomatte you can just solve it in post, after the fact. Once I realised that I thought it was a no brainer to implement it", explained Vlado.

Chaos has also had great success with this hybrid GPU and CPU rendering, "It seems to work really well, even people who are focused on GPUs then to have those cards in machines with very good CPUs - so why not use them?" he jokingly remarks.

Rumour has it that Chaos will soon be tightening up the V-Ray SDk, as it has been out for some time, modernising it and simplifying it should ultimately make such V-Ray implementations in UE4 faster and even better.


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