Iray Displacement
BradCarsten
Posts: 856
So I was reading on another thread that in order to use displacement maps, you have to up your subdivisions so that there are enough vertices to work with, but that seems like a terrible limitation after 3delight. In my current scene I've got three buildings running along a cobbled street. They are all rendered with displacement maps, but just to get the street approaching anything decent looking I need at least 10 subdivisions, and that is already crashing my system. Now to add enough data to displace the bricks for another three buildings and I'm going to start needing 32GB of ram for a reasonably simple scene. Am I missing something here, or should you just not use displacement maps?
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I can't answer you except to say that I am having the same issue. I was using displacement maps to get the stars and stripes symbols on my superhero character to stand out from the fabric of her clothing. I did not go as high as 10 subdivisions because somewhere I read to be careful going over 3. I went to 4 but it still looked terrible. I am going to have to either find a different way to do it, get rid of the 3D look of the stars, or else go back to 3delight, which did this perfectly for me with no effort.
Yeah I went up to 12 and it crashed Daz. For the cobbles I took it up to 8 and it sort of started working, but even with 8 there still wasn't enough geometry to create nice sharp corners- the tiles were all rounded and simple. I don't know but I get the feeling that I'm missing something here, because there surely can't be such a glaring limitation. I may just keep iray for characters and do the rest in 3delight until I can figure out a solution.
I have stars so the points are a huge issue. Most of the stars look warped, especially the smaller ones.
But yeah I have sort of given up on displacement maps for Iray right now. I don't necessarily need them for much at the moment so if I can get the costume figured out using clothing patterns I will do that instead and not worry about it.
Another thing I noticed, though, was that I needed huge texture file sizes. I had a 2000x2000 file, and the stars looked fine, super crisp, in 3DL. In Iray they looked awful. I had to bump it to 8000x8000 to get them to look reasonably crisp again. Even 4000x4000 was not enough. That just seems insane to me.
have you tried taking the displacement maps in to Photoshop, making them Grayscale if not already and turning them into 32 bit Tiffs?
No, I have not tried that yet, but I will do so and see what happens.
It could be a simple fact that the offending object just doesn't have enough geometry. I haven't tried to see if Sub-D works in Iray but you could export the object Sub-Ded and re-import that and set the Iray displacement to 3. That is what I loved about 3DL, micro displacement at render time.
I have just started to look at displacement in iray.
I get the impression that iray displacement is not implemented in DS. If it is, where are the correct settings for iray displacement?
Here are the settings/info for iray displacement from Autocad:- http://docs.autodesk.com/3DSMAX/16/ENU/3ds-Max-Help/files/GUID-7F5C9E01-8C45-421E-B0AF-67843BEEFF7E.htm
From that information, each triangle on a displaced mesh can be divided up to a max of 65,536 smaller triangles, but it is adaptive with a setting for smallest edge created.
As it is with DS, a simple test plane with displacement can use up all 4GB of my Vram(graphics card memory).
So, saving to greyscale tiff helped a lot. It's not perfect but it's better. However, I could not find the 32-bit option. According to adobe's own documentation, with save-as, one choice is "bit depth," but that option does not come up in Ps when I do the save-as command for tiffs. So I dunno... that might help even more if I could figure out how to get it to do 32 bit.
Just checking, where are you setting the SubD level? :-)
Are you using the "Subd Displacement Level" in the surface settings?
That should calculate the render-time micropolys, like 3Delight, but now we have 'manual' control on a surface by surface level.
(The image is single polys with only the subd level changed.)
Ok you need to convert your image first before saving
For low relief you may be better off with a normal or bump map, which doesn't depend on the mesh resolution. Also, if you have control of the model try to make sure that you don't have big polygons in areas you expect to want to use SubD on - having mor polygons in the basic mesh increases the count, but not as much as having to apply SubD to everything to get the big polygons down to a usable size for displacement.
So Sub-D works for Iray too, good to know.
I got the 32-bit convert to work and with that and subD of 3 it looks good.
However, I went back to an all-fabric top for her. Too complicated trying to get the stars and stripes to look "glued on," and in any case, her costume was made in-story by a professional superhero costume designer, so it should look more integrated anyway.
Hi Richard,
But that is referring to loop_subd, not micro-displacement .
With Loop_subd, when you add 1 level of sub_d, you add 4 polygons to every polygon in the mesh regardless of the size of the resulting polygons.
With iray Micro-displacement, that subdivides triangles(faces) to a minimum set edge length limit, the sub_d is adaptive, or it is supposed to be.
From what I have seen during testing, and the amount of memory used, it looks like loop_sub-d is being used.
Hi Richard,
If I understand right, there isn't any chance to show the displacement of small structural details (without havin billions of subD's) as it was easily possible with 3Delight?
How to do it instead?
Andy
If I understand right, there isn't any chance to show the displacement of small structural details (without havin billions of subD's) as it was easily possible with 3Delight?
How to do it instead?
Andy
Fake it with normals or bump, split out the mesh that you need to displace so that you can up its SubD without overloading other parts that don't need the effect, perhaps do a full render without SubD and then a spot render with to patch that one area. Having grown used to the ease of using displacement in 3Delight I do find Iray a bit of a come-down in this respect.
There is nothing else that handles displacement/subdivision quite like 3Delight. That is one of it's strongest points.
That said, normal maps will do a lot in filling in when rendering in other renders. Another is, actual geometry. Modeling in details, like mortar joints is much less 'costly', than upping the SubD levels to use displacement effectively.
Basically, something like 'gross' details get modeled in, medium details that need to show accurate shadows are displaced (things that don't require too many divisions) and very fine details that don't need to show accurate shadowing use bump/normal maps.
So as conclusion:
This is a big minus for iRay.
For me almost a NOGO.
And there are more negative aspects to be discussed in seperate threads.
This image http://www.daz3d.com/gallery/#images/61143 has displacement on the floor, walls and the platform that the bike is standing on. There isn't geometry there but I did use 32bit tiff for the displacement maps. Iray displacement set to 3.
Ah OK,
looks great.
How many subD's are set for the base?
none I didn't use Sub-D
Szark's last experiment has restored some of my good will toward iRay.
My whole understanding of displacement was that you could ignore the resolution of the underlying mesh at render time and count on the resolution and size of the baked map. (Granted, you still had to bake at high rez to get sufficient detail into the map in the first place, something ZBrush specializes in.)
This whole discussion about having to up the subd count in the mesh was disturbing me until the last few posts :-)
Szark,
These might seem like a silly questions but I need to clarify:
1). Are you talking about 32 bits per channel (floating point values) OR True Color RGB - 24bits PLUS 8 bits for Alpha channel?
2). Are you setting the Iray Displacement Strength to 3.0 with the default min/max values OR Min/Max values to -3.0 and 3.0 respectively with the Strength set to the default 1.0?
Because Dimension Theory's wonderful grass shader doesn't work with Iray (I have tried everything), I have been playing with displacement too using the subdivisions. I have gotten pretty good results. The grass in this scene is just a 2-dimensional picture. I created a normal map and played with the displacement. There are some little white artifacs in there but they look like little weed flowers so I'm leaving them in.
How do you set the iray displacement?
*Edit- never mind, I found it. Once you convert the object to uber iray base, and assign a displacement map, it appears in the objects surface settings.
I am so sorry I didn;t see this post, please forbive me as it wasn'tintended.
Anyhoo I first convert into Grayscale and just use the defualt settings at saving and I use Photoshop CS2, yes old but free a while ago. :)
To add to this conversation I said above, way above, that I didn't have much geometry and the Displacement Sub-D was doing the job. I should stress not much geometry to me may be a lot for others. Suffice to ssy you do need a healthy amount of polygons to start with and I have also encounter some props not like any displacement at all but instead distort the mesh instead but it has been rare. I do take objects un to Blender and provide a little more polys for good measure when needed. Sometimes using DS's Sub-D doesn't cut it.
Recently I am have been moving towards converting Bump and dispplacement maps to Normal Maps and not using Displacemt at all.
Yep,
somewhere in the past I already stated it: If you want to show surface details using displacement (normal map), using iRay render engeene your surface must have a sufficient density of (sub)divisions related to the size of the details.
But above a certain number of sub-D iRay ever crashes on my i5 system without special nVidia cards.
And it takes an eternity before I can see the first render iteration.
As time goes by most of us will upgrade to a system that can have a huge amount of RAM and CPU power (some already have, swines) so in time I think some products will evolve into denser meshes to compensate. I read today that Iray makes use of Bump mapping better than most and that maybe a fact I do know. But what I have found that Nvidia Standard Normal Maps reacts to light a lot better but I would have to presume from 3Delight that displacement is the better option. For now I will sick with Normal Maps, or smaller scenes using displacement on a denser mesh plus DS Sub-D and just use 2 or 3 level of displacement Sub-D.