Question Speculation: RDNA2 + CDNA Architectures thread

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uzzi38

Platinum Member
Oct 16, 2019
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All die sizes are within 5mm^2. The poster here has been right on some things in the past afaik, and to his credit was the first to saying 505mm^2 for Navi21, which other people have backed up. Even still though, take the following with a pich of salt.

Navi21 - 505mm^2

Navi22 - 340mm^2

Navi23 - 240mm^2

Source is the following post: https://www.ptt.cc/bbs/PC_Shopping/M.1588075782.A.C1E.html
 

uzzi38

Platinum Member
Oct 16, 2019
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Hasn't that been a big issue (global illumination via shaders)? As in it was why they decided to push for ray-tracing?

Yeah, there's a reason the performance was so poor in comparison to the visuals.

Heck, when you consider it, you realise that 1440p30 is actually very darn impressive.
 

soresu

Platinum Member
Dec 19, 2014
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Yeah, there's a reason the performance was so poor in comparison to the visuals.

Heck, when you consider it, you realise that 1440p30 is actually very darn impressive.
It's early days yet, probably a year or near to it until first preview builds, so I imagine that it has been built for shaders first, like Niagara which did not have all features working with RT when RT first landed.

Having said that, is it just me or did the Niagara bugs/beetles seem to lack shadows? Even with 4K it seemed very hard to tell if they were casting shadows or not.

I don't think that Nanite and Lumen will be the only new features of UE5 at launch either.
 

soresu

Platinum Member
Dec 19, 2014
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simplifying geometry and focusing on using super high quality textures.
This is the eternal problem with jagged low detail meshes and normal maps that only work at the right view angles.

Displacement mapping is a partial solution, but not an ideal one by any means.

As far as game development goes this will be a big boon in terms of simplifying their production pipelines, but it will force them to be very economical about the geometry and texture size in storage, probably meaning them having a library like Quixel Megascans (or just using QM) and just selecting what assets they absolutely need for the game, and just reusing those assets a lot in varying ways.

This ties in well with the storage decompression/compression co processing hardware in both new consoles - but compression will only go so far, and I fear that the co processing HW won't be terribly flexible for new compression formats once they exist.
 

soresu

Platinum Member
Dec 19, 2014
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Example from the demo is all the talk of that statue consisting of "more than 33 million triangles", first shown solo then shown as group of 500 statues. Without downscaling this kind of data wouldn't fit in the memory, nevermind be able to be rendered in real time by the GPU.
Instancing? If they are static this surely shouldn't be such a stretch - besides which the guy said that what you see in screen was being "losslessly compressed down to 20 million triangles".

I imagine this is probably making use of the Primitive Shader in the PS5 GPU somehow, and likely the Mesh Shader on XSX.
 

mikegg

Golden Member
Jan 30, 2010
1,813
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As the last decades of tech demos have shown, the reality will be, well, far less real. It won't look anywhere close to this.
False.

This is Unreal Engine 4 demoing on the PS4 in 2013:

New PS4 games like FF7 remake and God of War look significantly better than that 2013 demo.

So if anything, games on the PS5 in 5 years will look much better than the new demo.
 

moinmoin

Diamond Member
Jun 1, 2017
4,988
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Having said that, is it just me or did the Niagara bugs/beetles seem to lack shadows? Even with 4K it seemed very hard to tell if they were casting shadows or not.
They are those new advanced particle effects, like the bats.

the guy said that what you see in screen was being "losslessly compressed down to 20 million triangles".

I imagine this is probably making use of the Primitive Shader in the PS5 GPU somehow, and likely the Mesh Shader on XSX.
losslessly, lol.

So you are saying the GPU is crunching on downscaling the "terabytes" of decompressed data at the same time as rendering the whole scene at a high resolution and framerate? Seem unlikely to me. Many developers would instead opt to go back to the old model of preparing all the assets at different LODs as long as that means freeing up the GPU for actual rendering.
 

soresu

Platinum Member
Dec 19, 2014
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They are those new advanced particle effects, like the bats.
I used its predecessor Cascade years ago, particles can still cast shadows.
losslessly, lol.
Their words from the video, not mine.
So you are saying the GPU is crunching on downscaling the "terabytes" of decompressed data at the same time as rendering the whole scene at a high resolution and framerate? Seem unlikely to me. Many developers would instead opt to go back to the old model of preparing all the assets at different LODs as long as that means freeing up the GPU for actual rendering.
The thing is here, they are not merely trying to keep interest in their future game product (ie Fortnite etc), or by extension the PS5 they claim to be running it on - they are also advertising the future version of their licensed engine which is a big money maker for them.

If it doesn't work as claimed then devs will know pretty fast next year.
 
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soresu

Platinum Member
Dec 19, 2014
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False.

This is Unreal Engine 4 demoing on the PS4 in 2013:

New PS4 games like FF7 remake and God of War look significantly better than that 2013 demo.

So if anything, games on the PS5 in 5 years will look much better than the new demo.
True, though I seem to remember something about them using some technique for that original demo that proved too much and was cut to keep the engine as streamlined as possible for consoles.

Ah, just looked it up, Voxel Cone Tracing/Sparse Voxel Octree Global Illumination (SVOGI).

Not sure how far along PBR shading was when that demo was done either - I think they kind of substituted heavy compute stuff like SVOGI and over time added advanced PBR, SSS, open world optimisations (Kite demo is still pretty memorable), albeit all with a view to being console focused I think in optimisation terms.

For sure though, as you say the current gen games are far more impressive.
 
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moinmoin

Diamond Member
Jun 1, 2017
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I used its predecessor Cascade years ago, particles can still cast shadows.
Sure. I mean it's obvious there's a trade off going on, isn't it.

Their words from the video, not mine.
I know, it was not directed at you. Talking about reducing the amount of vectors and calling that process lossless is just silly talk. If it removes information it's not lossless, if one can remove vectors without reducing information, then there are duplicate vectors, the model is not optimized, and removing the duplicates is not compression.

The thing is here, they are not merely trying to keep interest in their future game product (ie Fortnite etc), or by extension the PS5 they claim to be running it on - they are also advertising the future version of their licensed engine which is a big money maker for them.

If it doesn't work as claimed then devs will know pretty fast next year.
Exactly. This is why I highly doubt in engine proper the downscaling happens on GPU or the whole process requires a dedicated DSP (as much as it may helps the PS5).
 

beginner99

Diamond Member
Jun 2, 2009
5,216
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Exactly. This is why I highly doubt in engine proper the downscaling happens on GPU or the whole process requires a dedicated DSP (as much as it may helps the PS5).

Maybe the dsp is built into RDNA2? Unlikley but possible. AT least that would make a compelling use case for the need of pcie4 (and5) increased bandwidth as that data will somehow need to get to the gpu for decompression.
 

IllogicalGlory

Senior member
Mar 8, 2013
934
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Talking about reducing the amount of vectors and calling that process lossless is just silly talk. If it removes information it's not lossless, if one can remove vectors without reducing information, then there are duplicate vectors, the model is not optimized, and removing the duplicates is not compression.
It isn't lossless as far as model detail goes, it's lossless as far as what's actually rendered to the display. Geometry that would be smaller than a single pixel is resolved to that single pixel, with some geometry, which would be invisible, being discarded. Hence, visually lossless.
 

moinmoin

Diamond Member
Jun 1, 2017
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If it can be in the PS5 why can't it be in a dGPU?
Well, sure it can be. Just like the 10 GbE IP on every Zeppelin CPU nobody except embedded board owners can actually access.

It isn't lossless as far as model detail goes, it's lossless as far as what's actually rendered to the display. Geometry that would be smaller than a single pixel is resolved to that single pixel, with some geometry, which would be invisible, being discarded. Hence, visually lossless.
I understand that (though it always depends on how close the camera can get to models whether it stays lossless in all cases). At which point we go back to the question where exactly that "compression" happens. Though now rereading it's odd that they talk about a 33 million triangles model "compressing" down to 20 million, that makes it seem like the model size is not actually scaled dynamically, just downscaled once to a size feasible for the screen size and hardware. In my opinion yet another possible indication for UE5 using CPU cores for that purpose. (Wait, the 20 mil refers to the scene, not a model, doesn't it?)
 

Ajay

Lifer
Jan 8, 2001
15,783
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Well, sure it can be. Just like the 10 GbE IP on every Zeppelin CPU nobody except embedded board owners can actually access.


I understand that (though it always depends on how close the camera can get to models whether it stays lossless in all cases). At which point we go back to the question where exactly that "compression" happens. Though now rereading it's odd that they talk about a 33 million triangles model "compressing" down to 20 million, that makes it seem like the model size is not actually scaled dynamically, just downscaled once to a size feasible for the screen size and hardware. In my opinion yet another possible indication for UE5 using CPU cores for that purpose. (Wait, the 20 mil refers to the scene, not a model, doesn't it?)
33M polys per statue. 500 statues in the scene

PS Good thread going at Beyond3D.
 
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moinmoin

Diamond Member
Jun 1, 2017
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PS Good thread going at Beyond3D.
Thanks for the mention, this is what I wanted to read:
"So from what I'm reading, the researcher at Epic who started this initiative for revamping the geometry engine has come up with a solution based on a few things that were proposed in the past. One is geometry textures that store a polygon per texel, or something like that, and one is a sparse voxel octree which does essentially the same thing. So essentially it's analagous to virtual texturing for geometry. You don't have to load the whole model from the ssd. You load the parts of the model that are visible in the scene, or close to it. You can avoid sub-pixel polygons and get roughly one polygon per texel. That massively cuts down on the amount of geometry they need in memory. You can probably avoid loading the entire model into memory and then culling the whole thing. At least that's how I'm understanding what I'm reading."

That researcher is Brian Karis who lists some of his bolg entries from back in 2009 in his twitter thread.


Exciting stuff!

Edit: Haha, later in the thread somebody name dropped Reyes rendering which may actually explain how the lighting system is realized in an efficient way in this demo. What a great way to loop back nearly 40 years in CG tech.
 
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moinmoin

Diamond Member
Jun 1, 2017
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Turns out Brian Karis himself mentioned Reyes back in 2009 already.

"If the performance is there to have the two at the same resolution a new trick becomes available. Vertex density will match pixel density so all pixel work can be pushed to the vertex shader. This gets around the quad problem with tiny triangles. If you aren't familiar with this, all pixel processing on modern GPU's gets grouped into 2x2 quads. Unused pixels in the quad get processed anyways and thrown out. This means if you have many pixel size triangles your pixel performance will approach 1/4 the speed. If the processing is done in the vertex shader instead this problem goes away. At this point the pipeline is looking similar to Reyes."

*mind blown*
 

coercitiv

Diamond Member
Jan 24, 2014
6,279
12,295
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Eurogamer published an article on UE5 that mentions hardware type used for Nanite and Lumen:
"The vast majority of triangles are software rasterised using hyper-optimised compute shaders specifically designed for the advantages we can exploit," explains Brian Karis. "As a result, we've been able to leave hardware rasterisers in the dust at this specific task. Software rasterisation is a core component of Nanite that allows it to achieve what it does. We can't beat hardware rasterisers in all cases though so we'll use hardware when we've determined it's the faster path. On PlayStation 5 we use primitive shaders for that path which is considerably faster than using the old pipeline we had before with vertex shaders."
"Lumen uses ray tracing to solve indirect lighting, but not triangle ray tracing," explains Daniel Wright, technical director of graphics at Epic. "Lumen traces rays against a scene representation consisting of signed distance fields, voxels and height fields. As a result, it requires no special ray tracing hardware."

To achieve fully dynamic real-time GI, Lumen has a specific hierarchy. "Lumen uses a combination of different techniques to efficiently trace rays," continues Wright. "Screen-space traces handle tiny details, mesh signed distance field traces handle medium-scale light transfer and voxel traces handle large scale light transfer."
 
Mar 11, 2004
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I was pretty lukewarm about it initially, but sounds like its pretty impressive. I wondered if there wasn't some tessellation like auto-generated geometry, but figured that'd be woeful as I thought geometry throughput was one of the aspects of GPU hardware that wasn't really increasing at the pace of the rest. Sounds like they're mostly bypassing that issue by doing it in software and then it does a good job of culling. And then them being able to bring in highly detailed models and then cull them based on the scene is impressive (although them touting the number of same models makes me feel like a lot of the benefits will be based on utilizing the same assets multiple times). Its also something that I don't think would've been possible without the SSD. And now, I wonder if the best way wouldn't be to add an SSD socket to video cards, or NAND directly.

And, this seems to actually show that Primitive Shaders was everything AMD had hyped it to be. I might be reading that wrong (and they're saying that for when the hardware rasterizer is faster they use primitive shaders). But now we have to consider the compute performance, so would Vega actually be a really good architecture for this?

I'm guessing they were developing that since they didn't know for sure what the ray-tracing hardware would be (but they knew what GPU hardware they had to work with otherwise). And same for Crytek. I wonder how much benefit they'll get from dedicated ray-tracing hardware.

This is the eternal problem with jagged low detail meshes and normal maps that only work at the right view angles.

Displacement mapping is a partial solution, but not an ideal one by any means.

As far as game development goes this will be a big boon in terms of simplifying their production pipelines, but it will force them to be very economical about the geometry and texture size in storage, probably meaning them having a library like Quixel Megascans (or just using QM) and just selecting what assets they absolutely need for the game, and just reusing those assets a lot in varying ways.

This ties in well with the storage decompression/compression co processing hardware in both new consoles - but compression will only go so far, and I fear that the co processing HW won't be terribly flexible for new compression formats once they exist.

Its not like they've been running N64 models with crazy levels of bump mapping, so its not like it was that big of a disparity. Plus I believe geometry hardware was languishing compared to the overall improvements put into the GPU hardware so there were reasons that they were balancing geometry. And yeah there's still going to be a tradeoff where they have to juggle constraints. I could definitely see that, where they have a certain amount of base objects then work it into different configurations (not unlike they used to do with tiles back in 2D era, where they'd have simple blocks and then use them multiple times in different ways to make more complex things, so stuff like stone/bricks/etc).

This is showing what the big increase in overall data throughput (which is the next big thing in computing) can bring. Its highlighting one of our current issues that could become a big problem as this next generation pushes this. Getting that data into the system (i.e. we're going to see game sizes continue to balloon), and Blu-rays can hold a lot but getting the data off is a hassle (long load/install times). And downloading 100GB+ games takes a long time. Plus flash is expensive still, so while it enables that, its still a limitation in that we're not going to see them exponentially increase that size to keep up, and there's only so many games you could install on one before its full.

I now see why they're putting fairly large amount in, as I expected that they would put a lot less (mainly using it as a buffer, or enough to hold a single game at a time, where they'd load the game fully in, and then purge it when you wanted to play something else and needed to make space). Which they'll need to protect the write endurance some.

I wonder if someone might make a MIDI fontset type of thing, where they make a library of assets, and then games just pull from there for a lot of base assets. I kinda think that's already what this is about, as there's super high quality asset libraries that companies can license or buy assets from and then use instead of having to build so much new assets for each new game. But I was thinking how Sony was saying they'd keep a certain amount of game data on the SSD so that it doesn't have to be written a bunch, and improves the overall responsiveness. What if they dictated a library of base assets (that they'd tune for size/usability/etc) and say games should use those.

Also would need to develop a program that consistently formulates geometry on the fly based on the base asset, so it could create buildings out of bricks, etc. Think of it like Minecraft where it procedurally generates the world using the base assets, but at modern gaming quality. I think that's kinda what No Man's Sky was going for. This also reminds me a bit of...forget the one company, but they had the "infinite detail" where I think they were talking about using base "atoms" to build more complex things. And I believe they were talking about pulling assets from photorealistic libraries, where instead of needing to pull all the assets separately you feed it simplified information and then it builds the asset out of the base building blocks.
 

Geranium

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Apr 22, 2020
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People forgetting one thing about the PS5 demo : Unreal Engine runs crap on AMD''s hardware, both CPU and GPU. It need Microsoft's first party studio's optimization just for RX 5700 XT to come close to RTX 2070S. Where in other case RX 5700 XT betting RTX 2070S with same level of optimization in different engine.
 
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Stuka87

Diamond Member
Dec 10, 2010
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People forgetting one thing about the PS5 demo : Unreal Engine runs crap on AMD''s hardware, both CPU and GPU. It need Microsoft's first party studio's optimization just for RX 5700 XT to come close to RTX 2070S. Where in other case RX 5700 XT betting RTX 2070S with same level of optimization in different engine.

Yeah, Epic is very pro-nVidia. Which I always found odd as the vast majority of games using Unreal Engine are for consoles, which are all AMD. But we will have to wait and see with UE5. I doubt UE5 is a ground up new engine, and just an update from UE4 (which sadly means it may have the same bugs as UE4). But its possible work was put into it to make it easier to get performance on RDNA based GPUs.
 

Geranium

Member
Apr 22, 2020
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Yeah, Epic is very pro-nVidia.
Could be. Many game benchmark suggest that. Even AMD's sponsored one.

Which I always found odd as the vast majority of games using Unreal Engine are for consoles, which are all AMD. But we will have to wait and see with UE5. I doubt UE5 is a ground up new engine, and just an update from UE4 (which sadly means it may have the same bugs as UE4). But its possible work was put into it to make it easier to get performance on RDNA based GPUs
Well we will have to wait and see that. Though AFAIK the demo didn't use the hardware of the RDNA2 GPU fully.
 

GodisanAtheist

Diamond Member
Nov 16, 2006
6,999
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I know its garbage that ultimately comes from Videocardz, that has been laundered through other more reputable sites, but here is this:


A guy can dream...
 
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soresu

Platinum Member
Dec 19, 2014
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Well we will have to wait and see that. Though AFAIK the demo didn't use the hardware of the RDNA2 GPU fully.
From what I've read it only made use of the Primitive Shader specifically from the PS5 variant, and that only for Nanite - no optimisation was done for special fixed function RT hardware in Lumen.

From the way it was described I'm not even sure that the new DXR compatible hardware can accelerate Lumen as it uses a mixture of tracing methods that are not triangle RT - though obviously it seems likely that it would eventually, these features have been in development for much longer than the current UE4 RT features by the looks of it.
 
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