What do closed polylines have to be converted to in order to measure their area? This doesn’t seem to be a problem in Grasshopper, but somehow it seems to be with Rhino.Common. Is it necessary to first fit a curve through the polyline?

.ToNurbsCurve(); no, it doesn’t work directly as massproperties expects a curve as input, which has another structure than polyline.

are you looking for the area or the area centroid? for any area calculation you need a planar polyline or a surface. If you’re looking for the areacentroid, you can bbox the polyline and get the bboxes center or areacentroid best – Ben

I am looking just for the area value. I meant that AreaMassProperties cannot be used on a polyline.

it can only be used on a planar (flat in any sense) polyline. if it is not planar, you can patch (command _patch) the polyline to get a approximate surface and get the surfaces area. it’s a math issue. you cant have a area from just lines. a planar curve or polyline can be transfered to a trimmed …

Why not just do this: import rhinoscriptsyntax as rs object = rs.GetObject("Select the closed polyline") if object: print(rs.Area(object))

[image] benedict: if it is not planar, you can patch (command _patch) the polyline to get a approximate surface and get the surfaces area. One can also triangulate the polyline and compute the area of the resulting triangles: [image] Mesh from closed polyline when it fails t…

did you try with a no planar polyline? from my point of view its the same function whether you call the function by python, c#, grasshopper or rhino. but maybe I’m wrong

[image] AndersDeleuran: One can also triangulate the polyline and compute the area of the resulting triangles: I usually triangulate closed non-planar polylines first, using Polyline.TriangulateClosedPolyline , and then generate a mesh from this. Works pretty well: [image] true!

Maybe I am missing something very basic. Area_Calc.gh (6.4 KB) Here are two planar objects. One is a polyline, the other a curve. The same script works on one and not the other. var tmp = Rhino.Geometry.AreaMassProperties.Compute(x, .001); A = tmp.Area;

[image] Zemleroi: Here are two planar objects. One is a polyline, the other a curve. The same script works on one and not the other. var tmp = Rhino.Geometry.AreaMassProperties.Compute(x, .001); A = tmp.Area; set the c# element to Curve instead of polyline and it works fine

Ok, so I suppose this way it changes the type to curve automatically? But if I obtain the polyline inside the script (e.g. from intersecting a plane and a mesh), how would I have to change the type? I know that the polylines are planar, but the function doesn’t seem to work on them directly.

Area of closed polyline

Scripting

AndersDeleuran June 9, 2021, 3:00pm 17

Here’s a quick implementation of the logic I described:

210609_NonplanarPolylineArea_00.gh (5.8 KB)

VB - Extracting Area from a Closed PolyLine

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Area of closed polyline

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