Rhino exported .SAT geometry appeared a bit fractured


(Jacob Cw Ma) #1

I lofted some polysurfaces like this.

then exported .sat file.
The sat file imported in autodesk inventor and appeared like this…

I am not sure what’s going wrong.
The model is about the size of train. Does it matter?

Any advice is appreciated.

Thank you.


(Willem Derks) #2

Hi Jacob,

Could it be these objects are very far from the world origin?
Far from the origin floating point errors in the rendermesh start to be visible.
Many geometric calculations will suffer from accuracy issues as well.


(Jacob Cw Ma) #3


Thank you very much…

It’s actually part of a railway project. The model geometry is expected to meet geographical system.

I can move everything closer to world origin, just wondering what the “comfortable zone” size would be? The project ranges about 10 miles. Would that has been too far? I hope I won’t have to cut the model piece by piece, As that would be pretty tedious…

Thank you again.


(Willem Derks) #4

Hi Jacob,

I think this partially covers your question: https://wiki.mcneel.com/rhino/farfromorigin



There are a few tricks to working with this. One is to create a reference point somewhere as your “from” point, put that on a layer and lock it, then move everything else from that point to the origin. Just don’t forget to move everything back when you’re done, and don’t delete the reference point! Anything new imported into the file will also need to be moved from the reference point to 0.

Another way is to have your master geo-referenced file basically as an assembly file, and all your real modeling work done in separate files which are near 0. You will still need to have the coordinates of the georeference point relative to world 0. Then you insert your model files into the master file as linked blocks - using the georeference points that correspond to the “real” location of the objects as the block insert point. The result is that the master file will have your georeferenced scene with real coordinates, but all your modeling is done in files with the objects close to the origin. Every time you make changes to one of the model files, you just update the blocks in the master file via the block manager. IIRC, in theory, you can even model your objects in different units than the master file, Rhino should take care of the unit scaling between files automatically…


(Jacob Cw Ma) #6

Hi, Willem

It is very informative. Thank you very much.


(Jacob Cw Ma) #7

Hi Helvetosaur,

Thank you very much…

In my case, Rhino was originally intended to represent hundred thousands of calculated point data graphically.
I did not intend to get involved more than that… Now, having read your suggestion, not sure if I can still keep it as simple as I had expected… probably I will try per your suggestion.

Thank you very much…