Calculate a surface area with Inkscape
This can be connected to the real world, using a photography of a real object, that would have been imported in the software and scaled to real size first.
Obviously, the total surface of the holes composing the footprints must be equivalent to a 12cm disk.
Calculate the surface that we need to respect : 12 cm diameter = 113.1 cm².
- Find a model : exemple : deux_pieds.png. You can also start from a photo.
Import this bitmap image in Inkscape :
File / Import ..., then select the image and answer "embed" to the following question.
Vectorize the bitmap, that is to say transform its contours into a vectorial path:
Path / Trace bitmap ...
You need to play a little bit with the setup of the different parameters to get a suitable preview (Update button) :
Once the path has been created, you can discard the bitmap image, wich is still behind.
Move the path object that is at the foreground and delete the image that is at the background :
In my case, it is a filled shape,it is more handy to get only the contours, with no filling.
Take care to have a single contour. Sometimes, the vectorization function ends up with a kind of wide contour, like a filet,
and the calculated surface will not be the inner surface, but the surface of that filet (For that reason, do not select contour detection).
Take care also to get a single object. If not, you can gather the bits with Path / Union.
We can now measure the surface area of our feet :
Extensions/ Visualize Path / Measure Path ...
Measurement Type : Area
Length Unit : cm (in my case !)
Font size : (widen)
Offset : 0
Click the "Live preview" check box to see a preview of the calculated area appearing in the middle of the drawing :
We still have to resize the drawing to reach the exact area we are looking for.
You need to grab and move one corner of the selection box, while pressing the CTRL key to keep the width/heigth ratio respected.
And after a few attempts, we eventually obtain the wanted area !
Voila ! Comments are welcome.
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Last update : 06/09/2013 : 12:05
Category : - Some tricks
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