Why is "ground" so difficult to make photorealistic?
Leonides02
Posts: 1,379
So, it's generally accepted Daz has the best customizable, ready-to-render human characters. I have a ton of Genesis 3 / Genesis 8 characters, and many of them approach photorealism. Sure, often the hair gives it away, but even this is getting better.
However, it seems to me, for many environments we can buy, the ground has barely advanced at all from the days of Xbox textures. Now, I'm not talking about interior scenes, although some of these are bad, too. Mostly I mean natural ground. For instance, the recently released:
https://www.daz3d.com/the-great-forest
To my eye, the ground here would look bad even in a modern video game, let alone a PBR image. Now, this isn't meant to pick on that particular PA. It's a problem I see all the time.
You would think humans would be far more of a challenge to model.
Is there anything that can be done to create realistic ground? Frankly, I think they're holding back our renders. While the human characters are near photorealistic, the scenery is far from it.
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Texture size would be my semi-educated guess. Ground planes can be huge and texturing them takes a lot of memory. Take into account that ground is made of of different materials with different levels of glossiness and reflectivity, and things get really complex really fast.
I think it's a decision based on where to use the "budget" of the geometry in the scene. To get a good ground with proper shadows, etc, you need to have real geometry in it. A bump or normal map won't be enough since those don't really change the surface, they fake it. That means you're either modeling all those details into the scene, or you're adding enough small polygons to be able to use a displacement map. In either case, you're significantly increasing the number of polygons that are used in the ground which may or may not be seen at all depending on how the artist that bought the content is using the set.
Could it be better? Definitely! And I, for one, wouldn't mind at all. But some people will be frustrated at how much memory and processing power the set piece requires.
One of the criticisms about a product like Stonemason's Jungle Construction Kit is that his sets can be pretty "heavy" on a machine because he spends the effort to get all those details right.
Ground has a lot of stuff on it that needs to be dimensional for it to 'read' correctly; for many shots, that kind of realism is simply overkill. There's also many different kinds of ground, so it may be diificult to make something everyone (or even most) people accept as accurate.
The simplest thing to do is 'build' your own; there are many grass models, and small stones, bugs, bushes, flowers, weeds, fallen leaves, moss... use instancing, and create your own perfect ground, when you need that kind of versimilitude. There are many basic ground planes to start with that you can add to (Flinks are my fave.)
The one thing I have yet to find pre-made are small sticks/branches for ground litter, so I simply shrink small dead trees :-)
Making ground of one single plane, even if it has a dozen morphs and bumpmaps, just won't look real. Such "ground" only looks believable if covered with a lot of other props, like rocks, foliage, litter. And you'd have to add so many of those, that the ground plane is hardly more than a shadow between all that stuff. Even in computer games, the ground is nowadays often designed from multiple layers and props. Just a flat plane doesn't cut it anymore. But, do note that most games now also have a special setting to limit the drawdistance for grass, simply because making the ground look pretty takes more resources than many gamerigs (which usually are slightly above-avarage in performance) have to spare.
Good point. I feel like PA's don't take advantage of instancing enough. I understand why: It's complicated, hard to perfect, and comes with its own challanges.
I was hoping displacement maps might do the trick, or something like Quixel's Megascans which (I believe) primarily uses textures / normal maps / displacement maps:
https://www.redshift3d.com/blog/creating-photoreal-graphics-with-megascans-rendered-in-redshift
I just finished instancing 40 shells over a characters head... it is slow :-) However, if you're clever, you can use Ultrascatter and maps... I've never managed to make it work, but very often my cleverness fails me when my vision outstrips my skills :-D
I have noticed that on a lot of scenes bought as environments. I've tried to do multiple scenes camping or in the woods but always abandon them, unsatisfied with the look of the ground and much of the objects on the ground. There are several environments with decent grass and meadow type plants and such and such, if you've careful how close and what angles you render at.
@Leonides02 "You would think humans would be far more of a challenge to model."
You really think human skin at normal viewing distances has more geometry than a littered forest floor??
@JonnyRay has the right of it. People want detail like Stonemason, but they want to be able to render those scenes instantly on a laptop that's barely capable of internet browsing.
cough UE4 cough
I more meant the materials. I've never purchased a plant from the Daz story that approached the photorealism of its humans. This isn't because of geometry, necessarily, but because of the materials.
Many of Megascans products are actually geometry, with displacement or normal/bump maps added for fine details. Like their name implies, their products are typically created from "photoscans" of real objects (i.e. close range photogrammety or SFM). These "scans" initially are very geometry heavy, but through the use of smart decimation to retain the major geometric features of the original models, and then the addition of displacement and/or normal/bump maps, the final product looks virtually as good as the original model with the full geometry.
cough UE4 can use megascans cough
Very interested, @DustRider. Do you know, can Megascans be imported into Daz? I believe the Quixel says you can export as MDL.
LOL - Yes, but we don't use UE4.
No, it's the lack of geometry that causes the problem. There's only so much you can do with bump/normal/displacement maps in the materials to counteract that problem.
Human skin is, for the most part, smooth. It still takes a lot of polys to represent the shape with any accuracy, but having done so you can use materials to represent all the other properties of human skin.
A grassy forest floor is not at all smooth. There are zillions of blades of grass (plus leaves, twigs, etc.) sticking up from the ground, each casting their own shadows and having their own translucency and so on. You can try to simulate that with clever materials on a flat plane, but it's always going to look like a picture of grass drawn on a flat plane because that's what it is! If you're aiming for a photorealistic representation of a grassy surface, you're never going to do it with materials alone, you need real geometry of some sort.
It is possible to make photorealistic but it is resource heavy on both geometry mesh polygons and textures, atleast 4k - 8k. There is always tradeoffs in 3D, and keeping background environments reasonably light makes it possible to have everything fit on a 4 gig graphics card for iray rendering. simple as that.
Again, I must point towards Quixel's Megascans which is being used in game engines. They don't use zillions of polygons. When rendered with PBR, their textures manage to look very close to photorealism.
Certainly. I don't mean to imply you can make the ground realistic with zero geometry.
I haven't used any of their assets (have used my own created from "photoscans"), but it looks like the 3D assets (like shown above) are downloadable in FBX and OBJ. So either one "should" work in DS, though you would probably need to set up the shaders yourself. The pure texture assets (which are easy to identify because they are displayed on a 3D ball rather than a 3D object), have several different "formats" available, you would probably want to either get the PBR Metalness, or the Custom download option for use in Iray (custom you can select all texture file types). You would need to then set up the shaders/textures manually in Iray.
Flat ground with an image on it is so 1998. I've noticed this in a great many renders in the gallery.
I'm pretty sure that if you covered a hill with the equivalent of V8 HD's skin, that would take a lot of resources and cause viewers a great deal of discomfort.
To say nothing of how poor Victoria would feel about it.
This is actually something 3Delight is better at than iray, it’s called micro displacement and one would use a random noise node to drive it.
Iray instancing could work with bits of debris such as stones, sticks, leaves etc
what game engines use is levels of detail where the closer stuff is higher poly
I suggest ShaaraMuse3D and her 3D Scenery sets. The terrain planes are often useless for closeups, but the props and outcrops make highly photorealistic ground surfaces. Used below for the rocks.
I can't focus on the rocks because I'm too busy trying to figure out what in the hell is even happening in this scene.
Oh this is easy. You just need some imagination! The girl is showing her friend how closely her new razor shaves her legs. The deer was hitchhiking and lost consciousness due to dehydration. The driver of the red car is here for the free venison. The roadsign in the middle ground on the right side of the scene is really a portal into the past. The deer is still alive in that time. The city is sinking into the ocean. It's in the UK because everybody is sitting on the wrong side of their cars, driving on the wrong sides of the road.
I kid, I kid! Drive on the side of the road that you're SUPPOSED to drive on where you are! Driving on the "other" side is what's really wrong and that could get you killed!
It's a question I have pondered too. There are other packages where the ground texture is 'difficult' (as in the link in the OP's post), but the ground is relatively easy to disguise with real polygons & the performance doesn't seem to suffer seriously. I know 'FlowScape' is without the rendering performance of DS, but in its native state it doesn't do a bad job of vegetation. Imported DS figures, that's another story, but the scenery ain't bad:
[That image went into my gallery at 1980 * 1018 & now seems to be limited to the size above, not sure why.]
Anyway, that scenery took under an hour to create, and it was 'rendered' at a mere 60 frames a second. I do wish DS had similar capability, with its much better renderer. On the image above there were several hundred trees out of shot, all with foliage, thousands of bushes, thousands of grass clumps and thousands of flowers, along with hundreds of loose rocks and dropped branches (I wasn't sure where I was going to plonk the figures, so opted to vegetate the whole landscape and select the best location afterwards). Despite that polygon load from the thousands of plants loaded and the 2 G8F OBJ figures, the PC responded no nore slowly than it does with DS showing three figures 'rendering' in texture mode.
Movement in the FS scene was vastly quicker than in DS when Andrey Pestryakov's Pine Grove ( https://www.daz3d.com/pine-grove ) scene is loaded and displayed in texture mode, despite the fact the Pine Grove has far fewer trees an individual bits in it. I have not done a polygon count on the FS image above, as there is no means to export from it [yet - the developer is responsive & is being asked regularly] but it looks to be a great deal higher in polygon count. Even if there are 10 'leaves' per polygon, the trees alone in the scene would contribute millions of polygons, and that's ignoring everything else.
I suspect there is an issue with DS [and Poser? (The reason I say Poser is that Jefferson AF seems to aim for both DS & Poser, and may be wanting to use the same models on both platforms if possible)] that means it doesn't handle large polycounts as well as the game engines, so slows down more when heavily loaded. This in turn affects the vendors, who are trying to get a balance between detail and usability. It seems to me the trend has been for the 'optimum point' to have been biased in favour of usability in preference to detail. If DS could handle large poly counts better, then the optimum point would shift towards more detail.
Regards,
Richard.
Edited to add the full size image as an attachment.
You know, I thought it was in Australia, the city Cairns, hence nice & warm, and the road from Port Douglas does overlook the city with the sea on the left and have a nice sweep down after a good view. The hitchhiking deer had seen a Kangaroo and the surprise made it pass out. As for the cars, I'd not even noticed the fact the steering wheels were on the correct side of the car. They are shown where wheels are meant to be, where I was expecting them to be, and the cars are driving on the only logical side of the road. After all, the driver is on the RIGHT [ie 'correct'] side of the car.
Regards,
Richard
thats because in the UK like us Australians and Japan we don't have guns so need to be the right side to make rude gestures etc out of our driver's windows
Has to be Gibraltar - it's too sunny for mainland UK. We're on the Rock, and mainland Spain is off in the distance. The girl is clearly indicating a right turn, which is totally appropriate as the blue car's turn signal is defective. The red car is spraying tranquilising gas, since it's time for the annual census count of Barbary Apes on the Rock. The deer is an unfortunate collateral casualty, but it'll be okay unless the green car gets there first. The mirror on the bend is the usual portal into an alternate dimension where left and right are strangely reversed. Behind the camera, 3 kids on skateboards are in a race, and vying to get past each other on the bend . . .
Getting back on topic, there are decent example of detailed and realistic "grounds" available in the landscape category.
I think it depends rather heavily on the terrain you are accustomed to; there's nothing that looks like the prairie around me, or the forested areas up by the Rockies... differences in plants, trees, and even rocks add up. I suppose I'll have to wait for someone around here to become a landscape vendor :-D You don't realize how integral your surroundings are until something fails to match - it has its own 'uncanny valley' effect.