Re: [Hampshire] Basic CAD software?

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Author: Hugo Mills
Date:  
To: steve, Hampshire LUG Discussion List
Subject: Re: [Hampshire] Basic CAD software?

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On Wed, Feb 17, 2010 at 09:49:49AM +0000, Steve wrote:
> Hi List,
>
> Could anyone point me in the direct of some software that would allow me
> to import a digital photo (JPEG), draw some lines on the image and then
> measure the angles between them?
>
> I've set the subject as basic CAD software as that was my first thought
> as to what I'd need, but open to any software suggestions really. I've
> had a bit of a search on Linux CAD software - a lot of it seems to be
> either commercial or very complex.


You can do this with The Gimp and a calculator. Load up your image,
go to Tools -> Measure, and drag out one of the lines you want to
compare. The (x,y) pixel distances and angle (relative to horizontal)
will be shown in the info bar at the bottom of the window. Do this
with the second line, and add/subtract the two angles as appropriate
to get the angle between the two lines.

I'm going to try this in ASCII art:

   C
    \   B
     \ /
      X------x
     / \
    /   \
   A     D


Measuring A-B will give you the angle B-X-x. Measuring C-D will
give you the angle D-X-x. Add the two together, and you have the angle
B-X-D (or C-X-A).

Hugo.

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
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