Moving an edge on a geometry, far from origo

Hi,

I’m having issues when I try to move a control point or edge on a solid that is far from origo (on Windows 10, using Rhino Version 5 SR13 64-bit (5.13.60523.20140, 23/05/2016)).

In my example I have the following geometry. MoveEdge-issue.3dm (51.6 KB)

One of the corners is at (168381105.794, 6200158247.368, 700.000) so it’s far away from origo. If I move the an edge, using “Move Edge” under the “Solid Tools” tab, the result is very strange. In the example below I move the selected edge straight along the z-axis (vertically).


If I move the geometry to origo and move the same edge along the z-axis, the result is as expected.

I tried to work around the problem and move the geometry to origo, move the edge, and then move the geometry back to the original position. The result is much better, but there are still graphics issues as seen in the picture below where I changed the perspective of the geometry to better show the problem.

Is there a way to solve this? I could change the units to meters instead, but I’d rather use millimeters if possible.

Thanks!

Why are you working so far from the origin? Are you trying to use geographical coordinates?

6200158247.368 mm is 6,200 kilometers.

The solution is to move all of your geometry much, much closer to the origin.

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It is quite a long way off the origin… Using the command ShrinkTrimmedSrf at that point returns some strange results but if you move it to the origin it’s fine.

In plan it looks a bit skewy - is it supposed to be? You could rotate it and then use the SolidPt command to move edges with the gumball.

If you don’t want it to be skewed you can use the SetPt command to move the point back into alignment:

Andy

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As was said already, you can either move closer to the origin or use meters.
What is going on here is that the math in Rhino 5 uses double-precision accuracy for its operations on geometry but the display mesh is only single-precision. This has been changed for Rhino 6.

If you search a bit here on the forum you will find a lot of threads on this. Just one example:

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Thanks guys! I understand the problem now, and I guess I have to work around it by moving closer to origo.

The coordinates are geographical coordinates and are important to my model, but it’s not necessary to use millimeters.