Gadgetory

we built a fully rate raised game in Unreal Engine 4 which just added DX our support officially last week as a result of the support we have the first look at Nvidia RT X shadows to show you we have looks at graphics with all our TX features enabled path tracing versus ray tracing comparisons multiple reflection bounces off objects roughness comparisons as they relate to reflections and deep dives on traditional graphics techniques to fake realistic visuals versus their ray-traced counterparts and untold side of the global illumination comparisons has been that there are traditional ways developers can fake GI without DXR that's not to downplay DX our today's video will show you how these standard graphics methods of faking GI you can get pretty close but the method NVIDIA has been pushing and Microsoft's that the XR is sometimes easier but resource expensive I'll be joined once again by Andrew Coleman our lead video editor and 3d artist who created all this tech demo in Unreal Engine I'll be talking about global illumination specifically in today's video before that this video is brought to you by be quiet and it's straight power 11 series power supplies the straight power 11 PSU is shipped from 450 Watts up to a thousand Watts accommodating most of the gaming PC build requirements you'd encounter and focuses on delivering a higher quality power supply that doesn't sacrifice on efficiency or stability noise is also a heavy point for the straight power 11 using a 135 millimeters silent wins 3 fan that can spin as low as 200 rpm for quieter low load operation learn more at the link in the description below and as a quick example of a global illumination directly is doing to the room we can show gloom illumination is on currently and then global I'm just gonna call it GI Chloe illumination is really long this is GI off so you can see there's no light bouncing off from the floor onto the bottom of the object which is why it's difficult to see yes this is a bad example we'll talk about this more later in the video yeah this is it's Y metallic objects are not good examples of global illumination so quick for note for all of the other demonstrations we have coming up will be showing those in videos after this one like elections will be showing shadows things like that but in this one it's our first demonstration we'll show you a room that's commonly referred to as a Cornell box it demonstrates global illumination and the the kind of key point here is that gee I can be faked this is not unique it's not new to touring this has the global illumination has been in games it's just that touring has the ability to execute GI with real-time ray tracing instead of fake methods and we'll be showing you those so this representation is actually a recreation of Nvidia's original demo from the RT X launch we're going to use it to demonstrate RT X on vs. off and if we look closely you can see that global illumination is sort of emanating colored light off of the walls and onto nearby services including onto the floor from metallic ball the demo Andrew and I have talked about before is flawed in several ways it's and videos demo but we're just recreating it to match them so Andrew what are some other ways we can tell this is global illumination I guess he already mentioned the light reflecting off onto the objects you can also see it reflecting onto the floors around them yeah we should we should mention this so these lights on the walls I think we agree that they're not really the best way to do this demo so the the important part of a Cornell box that there's one or that all the lights in the room are just white colored so all the color coming onto the objects is just bouncing off of the walls themselves not directly from the light source right and the reason we have these colored lights here is because we're just matching on videos demo which we have a whole different video on why we disagreed with this technique to demonstrate it we don't need to go through that all again today you can check the previous video for that but it's it's still fine we can still do the demo here so global illumination to do one quick primer on this I guess the main thing we're looking at here is the light from the ceiling especially in your more traditional sample on the right side is providing all the light to the room it's hitting colorful objects like the walls and then that light projects onto the services of objects nearby and it is not for example ambient occlusion I think a lot of people saw Metro Exodus where a lot of the time the scenes are just darker and that's from GI it's it's not like a difference in a oh right yeah that has nothing to do with ambient occlusion right and so we have some AO in the corners of this room like in the where the wall walls meet and you can change that separately and Unreal Engine if you want to do but that is not GI is it actually is there an advantage to using DXR if you really try so if you're a developer and you genuinely try hard to make GI look good without needing RT extra DX r the question is can you achieve a similar look with a similar amount of effort and so we actually showing this initial demo we kind of bait and switch to you guys this is traditional global illumination it is not raytrace global illumination and our point is that you can sort of match DX r GI with standard game graphics techniques that sort of fake the lighting there are a lot of shortcomings to this will show you those as well and this Cornell box is the one on the left is a bit flawed but we'll ignore that for now as well so despite looking really convincing there are still downsides and we'll cut to a shot of the true DX r version if we haven't already versus our fake and editing but let's just not label them for a second so that you can just kind of take it in and figure out for yourself which one you think is which one of these uses DX r and ray tracing the other one is our fake so we'll put labels on those now post below if you guessed correctly and so Andrew can you explain first let's walk through we can walk through how you made the fake or maybe or do you want to cover first the shortcomings of the fake which do you think is more I think the latter is more appropriate the way to make this is pretty straightforward it's like a few checkboxes you say do you want global illumination yes and then you say how many light bounce t one say like three or four I don't know but then you also did some stuff like you you have versions of this where you've baked shadows into the floor right yeah and into the objects if you toggle your flashlight you'll I mean they still behave like shadows but but they're baked in so if you have a non-static object that's a flaw I baked all of these aesthetic objects so the the lighting on the ground is assuming that they're not going to move but then after that I told the agent they can move and so you can see that also you can see that the global illumination is also baked into the ground right and there are other ways to do this too like is this current example we're looking at is this using the light mass option yeah so that will only mostly affect it when objects go start to move like this it shouldn't have effect objects that are static anyway but and so yeah one of the bigger upsides one of the I guess easiest way is to fake GI is if you do have a bunch of objects that won't move like a bunch of furniture for example that the player can never interact with non destructible environment then you can get from what I've seen you do the last few days you get pretty damn close to dxr GI if not more or less exact except it's just it's stuck to those static objects right so nothing's calculated after runtime it's like it's basically like the engine is painting underneath what it the accurate lighting physics calculation and then just as like okay that's that's it yeah that's that's what it is so then are there ways I think you can still kind of get I saw you do one demo where you have the shadow still following the marbles I guess yeah with a non DXR version but where they're still downsides to that approach an important thing to note is that all of these are actually unreal engines new rectangular lights I think they calculate shadows a little bit differently because none of these do have shadows but if you bring them over to the the point light that we have they do cast moving shadow right so it might just be a limitation of that specific type of light sure so yes so clearly our fake is pretty good here but if we switch over to a demo with DXR we can show us some of the advantages and and just to be clear here the point of this video isn't to pick a side of DX our verse is not DX our does I think it's been kind of unfairly beaten down by some of the community and there are very fair weight reasons to to criticize the XR and r-tx but one of the oddest comments I've seen and it's regular unfortunately is ray-tracing is a scam our ray tracing is a hoax which is just sort of comical kind of clarify some stuff for the audience ray tracing has been a thin for decades at this point and in terms of computer graphics so ray tracing is a thin real-time ray tracing is kind of the the new thing that they want to do ray tracing is used commonly in movies you like Pixar movies for sure we used it in our intro logo render so the thing to be critical of with RT x and z XR is not that ray tracing is a scam it's that is this present implementation of the different technologies feasible to render on the existing hardware in real time while still looking good like at least as good as the fake graphics so that's what we're really looking at and in the DXR version that you've pulled up in the engine here we can see some of the upsides and downsides the immediate downside is performance everyone knows this side of the story so performance objectively gets worse with DXR on RT x right now we know that and then another downside visually as I'm seeing a lot of noise so do we know what that's like do we know firmly the story behind this amount of noise so in order to get a proper resolution for an image like in order for enough bounces to hit a surface or a pixel in order for there for in order for the noise to go away you need it depends on the scene but in an outdoor scene maybe like 500 ish samples per pixels and if you're trying to do an indoor scene or there's light only coming in from a window and it has to bounce multiple services and render limited light right yeah limited light and one source and many places for the light to rebound off of surfaces you'd probably need around like a thousand to two thousand samples for a clear resolution and right now this is only running it to two samples per pixel before well I think the rectangular lights are set to six and the global illumination is it to two I mean two versus six when you're talking a thousand who cares they're running a denoise er that helps resolve images a little bit faster but you can tell it's not great still yeah has some interesting latent effects like I mean you can see them again or if you shoot you'll see following the ball there's like ghost balls following the Khans can have fun with that one so upsides though if DXR we've we've seen clearly some of the downsides look at some of the upsides you give a balance here you can see the shadows are now accurately following the objects we do have global illumination in those shadows we have global illumination and in the Cornell box right the interesting thing about DX R is that nothing has to be baked before runtime everything just operates how the lights would expect to in real life physics although I'm sure they're doing some kind of optimizations that are different from real-life physics yeah of course but if it's close enough then yes sir we're calculating here and as opposed to having a pre calculated right which would be what baek's lighting is and again you don't have to necessarily bake it into static objects I guess we have some examples where you can fake GI with dynamic stuff as well just they're still shortcomings with that but with with D arcs are I mean what's your kind of opinion of the accuracy of the GI with this versus your your baked version like do you think the the pre baked lighting do you think is significantly outdone by the real-time ray-traced so you asking and if in terms of quality in terms of how realistic it is they're seeing that compared to the static objects yes static objects if we ignore the dynamism that we want with the XR I would say it's pretty close it's up that takes like five minutes to do it before you start the game right it takes it five minutes to do it what I don't like while they're building it yeah yeah which is an important point because if it's taking that amount of time to calculate it then obviously that's not real time so at one frame every five minutes I don't think is an acceptable metric for anybody except for Xbox players but beyond that I the real-time or if we look at dynamism you know you look at a dynamic scene instead of a static scene how do you feel then obviously it starts losing some accuracy so now we're loading in another demo and this is a preview for some of the stuff will show you in videos coming up this rotating logo for example as raytrace reflections yes and it I believe and this is a whole different topic we're not going to talk about it today but so just some tech demos we've built with all these DXR technologies to show what nvidia is trying to do and here's another I guess Cornell box yes and it's a bit different this time so what's going on here basically this the same thing is going on it's if you can see it on objects that are moving on their own and see how it affects different sides of each object things like that even that's shadow on the ground so we're still DXR is on right now so the shadow on the ground you can see is you know green on the green side and spit darker on the not green side yeah the object rotates it gets some light cast on it that's color of the wall next to it and yeah it's just we're just showing a dynamic object which you couldn't achieve this and play the same quality I think with your favorite art right yeah it depends there's you can set objects to be movable in global illumination but it will do a better calculation if you said it's a static so here's our rasterized version you want to talk through the differences of this one versus the other yeah so actually it's it I was pretty impressed when I saw the rasterized version of this the weird thing only is that there's no shadows anymore on the movable objects once again might be because of that this is also using a rectangular light these two rectangular lights so might be a limitation of that but you can see that it's still somewhat dynamic the sides pretty good so we've still got some some GI in here and this can be done at a pretty high frame rate without DXR r-tx but you do lose like you said the shadow quality for exam all right actually that has me curious I'm just gonna do this really quick yeah I'm going to change out the rekt light for a point light so I made a little bit of a mistake I didn't make this light bright enough so it doesn't look exactly like the last scene but you can see that there are moving shadows no just because it's a point light right so this is the shadow thing we were talking about was more result of the specific type of light and Unreal Engine but you can tell it since these are movable objects unreal did not bake the lighting information into the textures of the object right yes so how does when you bake the lighting information into an object it does it effectively they rebuild the texture and apply it to the UV map or what is yeah so there is a thing in each object called a light map movies they're called generate light map TVs and unreal cannon to either do that from your own UV maps or it can make one for you and then that's where it bakes the lighting detail information right a UV map should we bother going into any detail on this let's just do a really short version it's like UV maps are a 2d representation of a 3d object so it's kind of like think about how you would unwrap a face Hey okay let's go let's shift it to a shirt if you're trying to make a shirt as flat as possible only one plane then you'd have to cut both sides down the middle which is how they sell the better faces way back there there are examples of like faces on like 3d objects I have one of those of my face haha tres it's a great example though we can show on from I'm sure we can find some on line but yeah there's your primer of UV map time for different different day but anyway yeah so change the type of light did add some shadows and but the DX our version of GI still has some upside such downsides to of course noise and performance point lights are kind of weird in general because they always produce well necessarily true I was gonna say they always come from a an infinitely small point which is unrealistic but you can change the source radius okay so you can change how large right the light should be calculated from so what about the the white probes you're showing me what let's let's demonstrate those each of these little points says like okay from the top angle I'm receiving this amount of white light from the bottom angle and receiving this amount of green indirect lighting so these B's all calculate indirect lighting in their little specific point in space and then when objects get close to them they can say okay I can sample lighting from a 360 direction onto this surface here right object in this instance is that red ball yes be clear so so I guess the the probe is used as it relates to the as relates the proximity of objects nearby the probe can be used to calculate the correct type of or correct color of light being cast onto that object right correct color and intensity right and this so it is it correct to say them that this gives you more flexibility and having dynamic objects yes because now you can move the ball around the Cornell box and as it moves around the box you're still gonna be able to sample it's just it'll be from all these different light probes yes so you can see that this might be because it's erecting there like once again there's no shadows at all but the lighting is no longer baked into the ground but yes so this is this is another just to be clear this is not DXR right now right which is pretty obvious if you've seen the noise and the other ones but so this is another fake light probes allow it to be a bit more dynamic and still have accurate global illumination without needing ray tracing let's see if we can get some are we trying to get some shadows in here now yeah just some quick so then in order to just kind of eliminate a variable here we're you know are we getting rid of the rectangle lights or just overpowering them okay so these are these planes on the ceiling art art do the light they're just for show just to show where the lights originating from but they don't actually illuminate and he actually cast shadows yeah right so I think any to there's some checkbox or some shader setting someplace to accept lighting from emissive objects that is not turned on but I don't I don't know where that is so just one more quick light bill to get the see how it calculates the shadows in global illumination for the movable objects and how it recalculates the indirect lighting for the light probes we've changed the light types let's let's kind of briefly what are the downsides to the light probe approach that we know of because clearly it seems like it can fake GI pretty well so it's got to be a downside versus DXR which is we think may be performance to some extent right but we're not really sure how much generally you should always use light probes in your scene from what unless you're going for a non-photorealistic approach but if you want indirect lighting then light probes are the way to go okay okay so now we have changed and to just change the the type of light to what is it a point right now yes these are still wrecked lights but right and that's still matching that videos demonstration which we'll talk about in a minute so what's going on now now it looks like there's some shadows as opposed to previously so we have some some shadows now then and and nothing baked into the floor and nothing baked into the objects either yes so this is a this is still a fake approach not a bad one though um let's just we mentioned earlier that this on the left was Cornell box is flawed and as we said earlier this is just choppy and what unbid eeeh made for their demonstration we had a kind of a rant previously where I believe I said I said I think it's a little misleading and you said it's very misleading yes so the the demo on video showed just bring it back up was one example was basically none of these traditional global illumination of facts really implied like or none of the fakes applied I think right and then they also introduced a whole bunch of weird things into the scene where like wasn't it wasn't it the scene of one of them had like the glass marble and the reflective ball and then the other one didn't have those things or something yes so this is actually a this is an exact copy yeah this is their original one it's up with the faked lighting this is their what they changed it to right so on the right side they say this is before this is DX this is our TX off right that's what they say yeah which leads you to think this is traditional lighting well I say this is our TX on our TX does not change the material of the object right and so that is extremely misleading but and it's kind of sad because they don't need to be misleading to say like hey this technology has some promise we've already demonstrated that right they had another example with that Quadro card in the room and that are ticks off and on demonstration was actually pretty accurate yes yeah I don't know why they didn't that was like near the end of their presentation though also yeah I don't know that it was pushed public or not but yes so anyway reasons that it's flawed other than changing the material the objects on the left right comparison is also you're dealing with the colorful lights on the walls and the whole point of the Cornell box is what is it you have a single light and the top that's white yes it doesn't need to be a single light but what a white light I guess right and so adding colorful lights and if we look at the left scene it kind of looks like there's GI in places that it's actually just there's a colored light right so it's like it's really just it it defeats the purpose of the demonstration and also using a metallic object is flawed for this too because what we're seeing is reflections right position to GI elsewhere it's very difficult to see GI in a metallic object because it just bounces off well I guess technically even a diffuse object will be also bouncing off the light like this one over here this is technically a light bounce even though you see it directly on the object but for here do you see it the bounce is so sharp that it's just reflecting the image of what it was right reflecting because it's mostly in real life GI and reflections are the same math it's light bouncing off of an object that just the surface changes how that light bounces off and you can also see it in this metallic surface how little changes between the two yes just to illustrate why this is a bad way to demonstrate GI and you can also see why these colored lights are not a good example of global illumination because it is changing the color of the shadows but not because of indirect lighting but just because the direct lighting is a color and here's the lack of global illumination with ray tracing so it's not appearing in the mirror but it does appear on the objects and this is a limitation I guess it might be an Unreal Engine thing I have pretty sure it's just a limitation of Unreal Engine right now oh we should also point out that we're using Unreal Engine 4.20 to preview too so this is not the final release of 4.22 so they might add more things and they've already added lots of things since the first preview like multiple reflections right things like that so also global illumination was not in the first preview also yeah all right so that's it for our GI demo hopefully this gives you some more information work with than just the the Metro execution there's a lot to this story here and clearly as we've demonstrated you can fake GI pretty well if this is one of the biggest points you want to get across global illumination itself is not new it is not new it's r-tx is not unique to RTX you do not need our TX to do global illumination in fact a lot of games already have global illumination baked in but or faked in other ways but RT x and t XR have some unique up sights that are worth considering here and we've demonstrated those as well so just want to give you a look at that we have demos and examples a lot of technical explanation coming up ray tracing of DX r RT x shadows i believe we have we can do some path tracing versus ray trace demonstrations and roughness compares some things like that so definitely subscribe if you're not we have more of these coming up and let us know what you think below of our game does this look like something you'd want to play because I mean I think that IGN would give us at least a seven out of ten which on their scale is about it too so thanks for watching subscribe for more go to patreon.com/scishow and access to support this type of work and you can go to store documents exit on that to pick up one of our shirts or mod mats or something like that we'll see you all next time