How Nvidia and Valve Gave Portal its Ray Tracing Makeover

Nvidia’s Alex Dunn dives into the tech behind Portal with RTX, the upcoming ray tracing makeover for Valve’s classic first-person puzzler Portal.

Welcome to the Aperture Science computer Aid admission Center You know everyone on the team loves Portal it's a great game we all remember Playing it we all loved it importantly As well my name is Alex Dunn I work at Nvidia light speed Studios currently Developing RTX remix and portal with RTX For the rendering team we were really Excited about adding Ray tracing into Portal it gives us this opportunity to Build something really cool like Obviously objects go through portals in The original game but with race facing It really enables us to take that to the Next level right we want light to go Through portals and behave as a poor old Might in the real world so let's just Take a walk around shall we Gotta get that Cube So working with valve's been pretty fun Um you know it's good collaboration uh They were pretty excited to see a lot of Stuff come online and excited to sort of Talk with us about the original art Style and intent of a lot of these Things that we're seeing especially it's Super important when you're redesigning A lot of the materials in the original We want to keep the soul of the original Game sort of alive and not completely Break things when we're you know Remastered or enhancing a game like this So for instance the cube sitting on top

Of the pedestal here it's reflected in All of the sea and its lighting is Pretty prominent which is important I Guess because it's you know it's a main Gameplay mechanics actually the first Thing you kind of need to do when coming Into this chamber so it's important that These things are highlighted as much as Possible for the player Another good example of that is actually The portal and their placement in the Scene is you know very obvious given That you know they're casting so much Light both in Reflections but actually Even the light that's coming through Them as well Another great example is these blue dots Which turn to orange dots they're there To guide the player through these Puzzles And the fact that they're illuminated in The scene and just made a little bit More prominent but also it lets us react Dynamically to change in Lighting in the Environment which is something that's a Little bit more difficult to do with a Environment map or cube map so you can See as I've moved the portal around here You can see that reflection being Updated not only in the effect as it Shoots out of the portal gun but when That Port will go to effect intersects The world and you know creates a portal We can see that change reflected in the

Reflections pun intended and you're Probably familiar this looks a little Bit more like the Portal 2 button than The Portal 1 button but in starting with The Portal 2 button that really gave us Sort of more high resolution bass line To go from and it allowed us to you know Make these screens and stuff on the Button itself Perhaps probably the most obvious thing Is that we turned you know the top of The button into glass and that's really Just to you know sort of emphasize the Object in the screen solidify sort of Placement of key of key gameplay aspects Like the portal itself which you can see Reflected in here And yeah just to kind of show off the Reflections and refractions of path Tracing a little bit so you see the Inner mechanism here Let's try and progress through the Puzzle shall we So the high energy pellet is called in The original game Uh we we didn't feel like it was high Energy enough so we we attached the Light to it And so you can see now how that light is Affecting all the shadows and even the Reflections in this room if I turn Around and look at these metallic panels Here Not only that but this being a dynamic

Light is also going to be propagated Through portals Coming towards us and you can see that Light being reflected on the floor and On the walls and anywhere where that Light would generally reach This might be a good place to stop and Sort of look at some of the individual Technologies that make up this Experience I'm going to bring up the dev Menu here and then we'll first of all Just turn a few things off So when path tracing a scene Um The the raw output which you generally Tend to get is actually just Pure Noise There's many factors for this First of all the amount of Lights in the Room You can't generally com there's no Consumer GPU generally powerful enough To compute All of the Lights per pixel And remember there could be millions of Lights all of these little blue dots Emit light the portal rings themselves Emit my like these decals that are you Know indicating where the player should Move to these all emit light And generally we can't compute light Exactly perfectly for each of those so We take a stochastic approach where We're selecting a number of Lights per Pixel picking ideal candidates and then Doing proper sampling for these and it's

This stochastic approach that gives rise To all this noise The noise is not generally a problem Using our nvidia's nrd technology we can Denoise the signal pretty effectively as You can see with these Technologies Alone this signal is pretty cohesive There's really not a lot of noise left Here and not much left to do but just Enable that denoising to to produce this Final output image So continue walking through we you know We have a fantastic art team in-house at Nvidia Lightspeed that has been working On not only Um reimagining a lot of these textures Re-authoring them at much higher Resolutions where the original game Might be in 512 by 512 Dimension Resolution like our remastered textures Are you know mostly 4K by 4K 8K by 8K so They're pretty detailed in high res now Here we go and then it's not only about The lights as well but of course we came In and we took a look at most of the Models actually too so like maybe the Portal gun is the most obvious one in View just now it's a complete rebuild With just higher resolution geometry you Know we added that extra realistic glass In in the that hides sort of the I guess The fuel for the portal again the energy That's contained in the middle there The best experience is going to be had

On the you know the Ford eae 498 class GeForce gpus Um but you know we're also implementing Support all the way down to the 3060. Actually so we'll it should run Perfectly fine on any RT capable GPU I Mean everything you see here in fact Will be releasing all of this such that These results could be replicated via RTX remix and you know that includes Um like changing lights Materials obviously this is probably the The easiest to spot change looking at This image right now and of course Meshes and you know Remeshing up scaling the geometry so It's a bit higher fidelity all these Things will be available to users of RTX Remix

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