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How to find the actual area of a curve or shape


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I am making a landscaping plan and have made a curve representing a pathway, kind of an S shaped curve.

To make life easy I have scaled the plan so 1 cm represents 1 metre and this woprks really well for rectangles etc to fine the sq m, but this is trickier for curves.

So that I can give the paving contractors a good idea of the area they need to quote for, I'd like to be able to work that out from my plan. 

Does anyone know of a way to do this?

 

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PDF-XChange Editor can tell you the areas (and lengths of perimeters) of any vector curves in a PDF file, but it’s only available for Windows. Perhaps someone else here knows of a similar application for macOS.

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ImageJ is a free Java based app (developed on MacOS but in Java) which offers such things, it can analyze and measure from images and there are plugins for other file formats and techical usage areas etc. - See:

 

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Simple measuring tools for distance, perimeter and area, to be used with self-drawn annotations on top of any PDF (similarly as when using PDF-XChange) are included also in Adobe Reader. but this is different from measuring already existing shapes (and having the measures available at design time).

Annotations, though, can be saved and also exported and then imported (to any PDF) as comments (.fdf files) and accordingly be re-used even if the PDF file that was used when this information was initially created is updated. In that sense free measuring tools included in Adobe Reader could be quite useful for the purpose. [The tool allows also setting up the scale and precision.] 

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If you highlight two nodes with the node tool it gives you the length between those two nodes in the Transform panel under L:

image.thumb.png.2d27f635e14b6fbfd00c1c65821c931b.png

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@G13RL Damn, I tested it with a curve and a straight line and there was a difference but obviously I didn't push the envelope enough.

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1 minute ago, G13RL said:

Since you found a difference on Mac, perhaps the problem is related to Windows?

Also on Mac it just measures the straight distance between two nodes in the displayed angle (regardless of the curve). The label L for lengths is misleading.

2057788911_measurenodedistance1.jpg.f9afa7f7f73ac613c8f62d7932b0cc17.jpg

316210914_measurenodedistance2.jpg.68add8f89ebd77bc7b5892dcaaa73bff.jpg

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1 minute ago, thomaso said:

Also on Mac it just measures the straight distance between two nodes in the displayed angle (regardless of the curve). The label L for lengths is misleading.

2057788911_measurenodedistance1.jpg.f9afa7f7f73ac613c8f62d7932b0cc17.jpg

316210914_measurenodedistance2.jpg.68add8f89ebd77bc7b5892dcaaa73bff.jpg

Same as on Windows, so I assume this is "as intended", but, as you say, a bit misleading - also not so useful!

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19 hours ago, Mr Lucky said:

I am making a landscaping plan and have made a curve representing a pathway, kind of an S shaped curve.

To make life easy I have scaled the plan so 1 cm represents 1 metre and this woprks really well for rectangles etc to fine the sq m, but this is trickier for curves.

So that I can give the paving contractors a good idea of the area they need to quote for, I'd like to be able to work that out from my plan.

Well beside what was already said above, doing so with the help of some third party tool, which is capable to measure and calculate curved surfaces, lines and paths etc. there are only more manual options.

  1. Math - If you know the length and width data of the S shape curve, use good old school math formulas for that, aka Integral calculus for area calculations (from Analysis 2 subject areas). - That would give you the most exakt results then.
  2. Visually - A manual method for a visual usage way in case of Affinity software would probably be, to use a very well defined small scaled grid for manual measurement/counting (a bunch of small rects which do fit into the S shape area) combined with performing some good approximation to the surface of that S shape curve.

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