Large scene rendering artifacts

[ilmelovfx]

Hi all,

I'm trying to model and animate a correctly scaled solar system for a personal project.
The scene scale is in cm, with Earth radius as 1 cm unit, and all the other planets (and relative distances) modeled in this scale. Earth radius is 1 cm = 6378 Km.
As you can see from the attached images "Distanza dal Sole" (=Distance from the Sun) at Neptune (Nettuno) is correctly reported as 4.495.000.000 kilometers (this is X_coordinate*radius_earth), or 4495 million kilometers.
Neptune X coordinate is at X=704766.
The main light is a Vray sunlight with no sky map and no GI at rendering.

The problem is with the rendering of the planets: the nearest ones to the sun render correctly, but the farthest, as you can see in the attached images, have a lot of artifacts appearing on the surface, like wireframe lines or not smoothed faces. The planets are all spheres with 64 to 128 segments and smooth option enabled.
How can I remove these artifacts? Is this problem a consequence of the scene scale and very far position of planets from origin / light source? Is there any parameter I can tweak to remove those artifacts?

I'm using Windows7, 3dsmax 2016 SP4, VRay is version Next update 1.1 (4.10.02.00001).
Thank you to all who may help

[^Lele^]

It's most likely scale, indeed.
449,500,000,000 centimeters are beyond Max's capabilities.
You'll need to find a unit scale which is more amenable to the (16? 32?) bitness of max's own coordinate system.
EDIT: see here

[Morbid Angel]

Lele I think the distance is 50 million cm not 449 million. I've been doing similar tests and things fall apart after 50 million.

[ilmelovfx]

Thank you very much for your attention, Lele and Dmitry.
The distance is 704.766 cm on the X axis; in the scale I chose for the scene this is the result of (4.495.000.000 kilometers / radius_earth=6378 kilometers) . Earth radius is 1 cm (in 3ds max) = 6378 Km (in reality).
So maybe 704.766 (it's very much less than 50.000.000 you tried) is enough to introduce artifacts...
It's strange because it's about 7000 meters, or 7 Km... It's strange 3ds max can't handle a scene scale conversion this small...
In my first post the firts image is Uranus at X=450.296 cm; the second one Neptune, at X=704.766 cm.
So the artifacts are already visible at 450.296 cm...

[Morbid Angel]

if you raise the ray bias parameter to something like 0.001 or higher it might help. But yeah max will always have this issue. Its not like it is solid from 0-50 million then breaks after, it gets progressively worse the further from grid you are.

[ilmelovfx]

Ok, i'll try the bias thing, thank you. I knew about 3ds max progressively missing precision with large numbers.
Just wondering how it can handle such system units calculation with the numbers I see in the System Unit Setup dialog... (millions and ten digits floats...)

[Morbid Angel]

I suppose you would want to set your system units to km, in that case everything in scene becomes much much smaller and therefore the precision error will go away. But its not really a magical solution because the precision error is not just from grid origin to 50 million, its also affecting the scale. So really really small objects will also suffer from similar rendering artifacts. In this case with planets it will most likely be fine. But if for example you had to fly from orbit to planet's surface and see closeup detail it would not work.

[ilmelovfx]

Yes, I agree. In fact the real problem are the extremes (very near and very far, or, in other words, very small/very large, like in the case of a solar system and planets...).
Just wondering how the big studios handle this kind of animations...

[Morbid Angel]

I'm not entirely sure how its done in max since I never had this kind of extreme. If you were to use another software like maya or houdini which operate with double float precision this would be much better and easier solved since the value truncation happens with a much lower precision error.

[ilmelovfx]

Yes, I was thinking the same exact thing (regarding maya or houdini). This is a problem I occasionaly encounter with max every now and then, and I still haven't found a solution...
Btw, thank you very much for your help and comments.

[^Lele^]

Yes, I was thinking the same exact thing (regarding maya or houdini). This is a problem I occasionaly encounter with max every now and then, and I still haven't found a solution...

There really isn't one in max.
One can cheat splitting it up where possible, and reorganising the chunks so to be centered on the origin, but beyond that, luck runs rapidly out.
Software with higher precision, as stated, is the only reliable solution that i am aware of.

[Morne]

Slightly off-topic, but still kind of related to this, you can read here if you want:
https://help.autodesk.com/view/3DSMA...E3EB41F350_htm

In a nutshell, large values loose accuracy in Max
Scroll down the page almost to the bottom where you'll find a table for Input values, Stored Values and Displayed Value

Maybe one day they will sort this out, but for now......

[ilmelovfx]

Thank you Morne and Lele for all the help and info (and sorry for late reply, I didnt receive notifications of these posts)

[^Lele^]

This is being actively worked on: a fix is in progress.