Vertice manipulation is "jumpy" while working on large scale model.

[revel68]

I am working on a very large scale model in 3dsmax and the vertices jump around when you manipulate in the viewport.  Grabbing a vert and moving it around "pops" to locations. I am not using any snaps at all.  This is not a grid thing. It feels like it is happening because the model is so big and the scale is so large that max is having issues.  

This is like if you are working on a building / skyscraper sized, and you go to move a vert for a window slightly downward but it pops downward.  

It is not my mouse or speed of mouse because I tried plugging in a high DPI mouse and lowering the speed very low and the verts still pop around.  

If I zoom in on the verts up close the fidelity gets better, not great, but better, and the further I zoom out (allowing me to see what i'm really doing) it gets worse and really hard to place the vert where you want it.

Any tips on how to fix this?

Thanks

[revel68 · Accepted solution]

Ah I had this idea in the back of my head for a long time now and I should have tried it out before posting - If I move the model to the origin it gets far better.   The models I'm working on are far-ish away from the the origin 0.0.0.  

If any of you out there has elegant solutions to this please let me know.  May be there is a way to save being able to work on my task in-place. The reason its far from origin is i'm working on top of somebody elses world model setup and it allows me to visulize and update his models without issue. If anybody has a solution let me know.

Here is what I've done in the past. For anybody running in to this thread with this issue I'll explain my trick i've done that I think helps for this kind of developments

I like to use groups in max a lot. What I'll do is group up chunks of the task and then I'll animate the chunks between basic orientation on 0.0.0 where I work on the model. Then when I need to see them (or even work on them as well) in placement I just move the animation slider to the frame I want and the pieces move to the spot.  This involves using a lot of Isolation to 3d model inside groups.    I have a few other things I might do for this form of work but i'll keep it simple. Animated/Keyframed groups.  

[leeminardi]

3ds Max stores coordinate data in a 32 bit floating point format. 8 bits are for the exponent and sign leaving 24 bits for the mantissa.  2^24 = 16,777,216. As a result a coordinate can have about 7 significant digits or 1 part in 16,777,216.  This means that Max can distinguish points as close about 0.00000012 if they are within 1 m of world 0,0,0.

However, if you now look at the location of vertices about a million meters from 0,0,0 then the closest two vertices can be without blending together is about 0.0625 m

You would think (at least I did) that creating geometry near 0,0,0 and then making a group of it would allow you to move the group far from world 0,0,0 and retain the precision because the group's pivot would serve as the datum for the geometry.  Unfortunately, fine detail in the group geometry will degrade if the group is move far away.

I am unaware of any "elegant" solutions to this limitation of Max.  Keep your geometry as close to world 0,0,0 as possible. 

In contrast, AutoCAD has about 16 (2^56) significant figures.