not fully smooth water base surface

[Armada01]

when rendering the sea, I get some lines on my waves which have a rectilinear / square character.

Any idea how to solve this? Is it the bump map? It's quite a big one (2048 pix sq).

Does Vray maybe have some sort of smoothing function?

[Armada01]

Seems like it's to do with the displacement. I used a second map for bump, but when I render the sea with that one only, there are only very very faint bumps. So that one's not the problem.

Do I need to subdivide the base surface to provide more resolution for the displacement? Where do I do that? Rhino? Vray?

[Micha]

Maybe it's caused by limited grey values. Is your map 8bit/16bit/32bit? Maybe it helps to convert it to 32bit and blur it a little bit.

[Armada01]

Hello Micha,

thanks for your reply.

I tried as you suggested, but no difference. I assume the problem lies in the subdivisions of the base surface the displacement is acting on?

I've had this same issue many years back with Maxwell as well, and in the end I just modeled tileable blocks of a wavy sea to substitute the displacement. Doesn't seem the thing to do anymore in 2019...

How come there are so many examples of high-end displacement online with other softwares, while in Rhino, I seem to always get less than ideal results?

Is it because rhino lacks the flexibility to add subdivisions to the surfaces because it's NURBS- based? Or does Vray have this functionality? (I can't find any tutorial on this really)

Very frustrating, all this!

[Micha]

You need to keep in mind that the underlaying display/render mesh is subdived by V-Ray. So, if at your mesh settings "simple plane" is enabled than it could be not enough initial polygons. Often I used a defined polygon count per "minimal initial grid quads" like 100000.

[georgi.georgiev]

Armada01

Could you please share with us a sample project where the issue is reproducible to further investigate? If this is alright, please send us an archived copy (V-Ray > Pack Project) to support@chaosgroup.com via email or a file-sharing service of your choice.

[Armada01]

Another issue, within the same topic, is that the edges of my (tileable) textures for the bump of the waves become visible when I combine several differently scaled bump maps.

Just as a background info, the basic idea is that I'd use a single texture map for three different levels of waves, since waves are essentially built up like fractals, just copying the same structure at different scales.

The highest level of wave (swell), I just model in 3D.

The second level of wave will be created through displacement with the texture map in original size. (this will allow to see some uneven intersection of the water with objects floating in it)

The third level of wave (wavelet) will be created through bump map with the texture map repeated 5-7 times.

The fourth level of wave (mini-wavelets) will also be created through bump map texture, repeated 25-50 times.


This is where I'm at:

The highest level of wave has no issues.

The second level of wave (displacement) has issue with the subdivisions and the resulting strata-like waves as shown in the image on the top of the thread.

For the third and fourth level of wave, I'm not sure how to approach best:

I first started by making a texture map in PS in which the third and fourth level texture maps were already overlaid. But the resulting texture map shows edges when I render. (see image attached below). Somehow PS messes with the edges when it's saved. Something to do with jpeg format or some sort of antialiasing. Any idea how to save the image without any loss or change to the pixels? Also, there are still some small bumps on the water surface, even though the texture map is very even and of high resolution.

The second approach would be to try and place an extra (smaller) bump map on top of the already bumped and displaced material. I believe this should be done with a "Vray bump material". (not much resources exist on this!) However, when I do this, the displacement is gone. An idea why that is?

I hope anyone can give me some insights on how to get a real (and I mean real) sea with Vray without reverting to Phoenix or Realflow. I'm surely not the only person banging his head against the wall each time the subject of sea, waves and rendering is approached (with extreme caution!)
..
Tx!

[Armada01]

Hey Micha,

I tried meshing as per your suggestions, but it doesn't change anything, it seems.

In the image attached, you'll see there is a left side and a right side of the water with a straight split in between. The split is the edge two "sea tiles" I modeled for the swell. (so nothing to do with the bump map issue (showing edges) mentioned above)

The left one was re-meshed to high definition, while the right one was the standard setting. I personally can't see any difference in quality.

[Armada01]

It seems like it's something to do with the CPU.

When I render in CPU I get this "strata" effect, like the surface is made up out of blocks. No matter if I use progressive mode, or the highest quality level.

When I render in GPU, the blocks are gone after the initial light cache , what remains is some faceting.

See the first two images below for the resulting renders (again with left side fine meshing, right side coarser meshing (no difference here))

Now, when I render in GPU mode, and set quality to maximum, while setting the displacement "edge length" setting to 1.5 (pretty high I'd say), I get no difference still.

[Armada01]

When I render again, but this time also including the bump map for the wavelets, I get the result below:

Better than a sea surface like it's made in Minecraft, but still, no smooth reflections...

You can see some straight lines (creases) from the faceting of the displacement, as well as small bumps all over from the bump map.

[Armada01]

even though GPU rendering would give a less than ideal outcome, as shown above, it would result in another issue that I had before, again to do with CPU / GPU rendering.

In this case it was the GPU rendering that caused the problem (blurred backplate image). So whichever render engine I use, there's always a problem.

https://forums.chaosgroup.com/forum/...becomes-blurry

[Armada01]

I've sent the file to be tested by you guys at support.

I managed to get rid of the little bumps and the edge line of the texture that was used for the bump map.

Basically took the original texture (without issues) and saved it to .tif in PS before scaling it to a 3x3 repeat matrix and overlaying it over the original. (this to make a combined map for the 3rd and 4th level waves). Then saved it in .tif. No loss of quality, no edges.

So, issue that remains is the CPU render messing with the displacement (block/strata effect), the GPU messing with the backplate (motion blur effect) and the GPU still leaving a facetted effect on the water surface.

[Armada01]

Just as an exercise to see whether the Vray subdiv setings can have any effect on the quality of the sea surface, I made two renders with different maximum subdivisions.

The first was with standard 256. The second was at the other end of the spectrum: 8

The result is hardly anything. Some facets are shifting when the two are looked at in scroll mode (one showing right after another). With the naked eye, no difference.

Which makes me wonder under which conditions this setting does have effect, as well as the edge length? (Which I also tested at settings between 1.5 and 7, with no discernable difference)

So, it seems that subdiv settings have little to no effect, changing the mesh density in Rhino itself also showed no results. So where can one actually have some control over the quality of rendered surfaces? Am I missing something? (I'm not a render specialist, my knowledge is mid-level at best)

[Armada01]

It must be an issue with the texture I used for the bump and displacement map.

When I use another texture for the bump map (this time a 1024 x 1024 normal map) and render with just the bump and no displacement, I get a good, smooth result:

[Armada01]

Since I really want to use my original texture, because it has more choppy, peaky waves, I'd like to see if I can optimize it and get rid of any pixelization.

The texture is high res as I mentioned before, 2048 pix square, but it is in 8 bit. So my first step is to see if I can get any better result by upping the bit depth.

I've tried for 16 and 32 bits as well and made comparative renders for all three modes. (see below) There's no difference in pixelization, all create the same bumpy/bricky texture. However, the 32bits image distorts the waves, making them have flatter flats and steeper peaks, like the image adds an exponential function to it.

So my guess is I'd probably stay away from doing anything with a 32 bits texture in this case, as I don't know how to counter-treat the texture to get a normal effect again.

So, does anybody have knowledge on de-pixelizing the texture, without loosing the peaky-ness of the waves? (I suspect just blurring will make them more dull again)