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It appears that many posts that result in a 'Tip of the Week' come from user requests in Austria (see another here). Vienna-based CADPower user Alexander Schratt asked if we could split an ELLIPSE or SPLINE object into a polyline with specified number of parts ? In other words, how do you represent an ELLIPSE object as a polyline with a fixed number of equal length polyline segments.
This was a complex 3d modeling using point-cloud data-sets and this is what he said:
Just to describe the recent 3d-modelling topic a bit more: I derived multiple slices from an Aerial Laser Scanning 3d-pointcloud representing several formative elliptical outlines of a church dome. Snapping at three points in each of the selected point cloud slices (= horizontal layers) using Autocad´s ellipse tool, I tried to draw „best fitting“ ellipses (related to the pattern of each 3d-pointcloud slice) in order to reconstruct the outlines of the elliptical dome. Converting the ellipses into polylines, consisting of a certain number of segments, was necessary to have sufficient vertices available to build a dense wireframe mesh of the dome.
Alexander's request could be easily fulfilled using the Spline to Polyline conversion tool in GeoTools and CADPower. Unfortunately, users wanting to convert an ELLIPSE into equal parts polyline could never guess that the SPL2PL tool accepts ellipse objects also well. The fact is that it does accept ellipses and does the job just as good on ellipses as with splines.
This is what was created finally (see below). The top view of the church dome made up of elliptical shaped closed polylines.