Point cloud generation on a surface
Point cloud generation on a surface
(OP)
We have some SW models with "surface revolved" elliptical surfaces (a reflector). These are to be CNC machined to a high degree of accuracy, but we need to prove that the model itself is accurate. Ideally it would be desirable to generate a point cloud on the surface and extract the numbers to do comparison with the calculated values.
There is a long and tedious way of doing this by generating intersection curves on the surface, measuring points, and manually recording these in a spreadsheet. We would like to get this done this year tho’!
Anyone come up with a smart workaround to achieve this?
There is a long and tedious way of doing this by generating intersection curves on the surface, measuring points, and manually recording these in a spreadsheet. We would like to get this done this year tho’!
Anyone come up with a smart workaround to achieve this?






RE: Point cloud generation on a surface
If you have the data try using Insert\Curve\Curve through XYZ points.
Regards,
Scott Baugh, CSWP

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RE: Point cloud generation on a surface
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RE: Point cloud generation on a surface
I have tried saving the models as ACIS files and inserting them into AutoCAD where I can chop 'em up and place points onto corners. When it works it's fine if a little time consuming. However, for some reason not all the models will read into AutoCAD, even though they are all just configurations of the same model ???
RE: Point cloud generation on a surface
Your customer's concerns are valid. Especially with lofted surfaces, sometimes a CAD surface does deviate from its mathematical ideal. Fortunately, this is less likely with analytical surfaces like planes, and cylinders, where a modeling kernel can create exact models of those types of surfaces.
A revolved ellipse could go either way. However, I don't think you would need to check too many points to verify whether it is an exact analytical representation or an approximation. Either it's exact or it ain't.
One possibility would be to export the surface to IGES, then examine the text of the IGES file to determine the entity types. If the surface type comes through as revolved surface and the driving curves come through as ellipses, you're in.
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RE: Point cloud generation on a surface
Typically I need about 120 points on each surface, plus edge definition for approval.
Is it possible to export just the surface from the model as an IGES file?
RE: Point cloud generation on a surface
RE: Point cloud generation on a surface
I found this query by “APPENG” (http://www.eng-tips.com/viewthread.cfm?qid=55648 ) from 2003.
Using his Macro, we can extract the points to a spreadsheet (thanks Jon).
Now if we can come up with a speedy way of generating the points, I think we have it more or less cracked.
Thanks to all for the suggestions so far. Any more ideas are still very welcome.
Paul
RE: Point cloud generation on a surface
Wondering if there is a way to do the reverse here. That is to take a table of points and generate a surface?
Will that surface still be linked to the table of points?
Thanks