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View Full Version : Planet objects - Bad sphere geometry



Schwing
09-23-2007, 08:32 AM
I'm making a simple planet/solar system flythrough. All was going well until I got to Jupiter and some of its moons. What's causing this sphere (Io) to be so badly deformed?
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Lightwolf
09-23-2007, 08:40 AM
What scales/dimensions are you using in your scene?
Did you position the planets in Layout or in Modeler?

Cheers,
Mike

Schwing
09-23-2007, 09:16 AM
What scales/dimensions are you using in your scene?
Did you position the planets in Layout or in Modeler?

Cheers,
Mike
Moons are parented to Jupiter. Jupiter's scale in layout is .5. Planet/Moons are positioned in layout and are all centered (0/0/0) in Modeler. Jupiter's diameter is ~14.5 m, Io's is ~8cm (not true planetary scale) in Modeler. I had a simular problem trying to setup a scale version of the full solar system. But Uranus and Pluto would end up with the same bad geometry. So I'm accomplishing the flythough by using the same camera and motion path and rendering different planets at the same location. Piecing it together later.

Lightwolf
09-23-2007, 09:28 AM
Hm, weird... it sounds allright, nothing abviously wrong with your approach from what I can see.

Would you mind posting a sample scene, maybe just with blank spheres?

Cheers,
Mike

Schwing
09-23-2007, 10:16 AM
Hm, weird... it sounds allright, nothing abviously wrong with your approach from what I can see.

Would you mind posting a sample scene, maybe just with blank spheres?

Cheers,
Mike
Instead of moving the camera closer, I let the camera become stationary. Then scaled the planets up to create the illusion of the camera getting closer. This gives me a nice smooth effect, but it may be where my problem begins. But I wouldn't know why it would do this.
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Lightwolf
09-23-2007, 10:31 AM
What a weird scene...

try moving everything a lot, lot, lot closer to the origin. This is a problem related to the precision of floating point numbers (in general, on any computer and any app) - which basically comes to play when you attempt to mix huge and tiny dimensions in one go.
You have tiny distances between objects and cameras... but ate a huge distance from the center of reference for Layout... the origin.

Cheers,
Mike

Schwing
09-23-2007, 11:58 AM
What a weird scene...

try moving everything a lot, lot, lot closer to the origin. This is a problem related to the precision of floating point numbers (in general, on any computer and any app) - which basically comes to play when you attempt to mix huge and tiny dimensions in one go.
You have tiny distances between objects and cameras... but ate a huge distance from the center of reference for Layout... the origin.

Cheers,
Mike
I'll give that a try. I see what you mean by scale and distances. Years ago I setup an actual scale solar system with FormZ and didn't have any of these issues.

Lightwolf
09-23-2007, 12:36 PM
Years ago I setup an actual scale solar system with FormZ and didn't have any of these issues.
I built one in LW as well, but only had a broad camera move and that was fine. I also didn't move close to something that was far away from the origin, which is fine as well.
But once you combine that - a large distance from the origin with a small distance to something close to the camera ... you've got a recipe for disaster.

Basically, the precision of floating point numbers changes with their magnitude.

Cheers,
Mike

BeeVee
09-24-2007, 01:55 AM
You just can't make a model of the entire solar system, the numbers exceed those allowed by Layout, and it doesn't matter if you scale things down, because they exceed Layout's value relatively, so whether you have Jupiter at Mm big, or mm small, it won't help. You should just be able to map out to Jupiter, but the outer planets after that are a no-go (so I've found).

B