App that can '''measure'' a line on a pic

[snowdog]

Hello,

I'm looking for an app like paint but then that can measure a line if you draw it, eg. so you can apply a scale to it.

So far with straight horizontal or vertical lines I did this by reading the pixels the line started at and ended at, but obv. this is a bit hard ( well hard, I'm too lazy actually) to use on lines that aren't perfectly vertical or horizontal ( yes I can use maths, Pythagoras, but surely an app can do this for me lol ? ).

So kind of like on google earth the measuring tool, you draw a line and it measures the distance, but then for a picture.

Anyone knows such an app ?

 

[BillytheImpaler]

I do this with the Gimp all the time. Tools -> Measure or Shift M brings up the tool. It tells you the distance orthogonally, by the hypotenuse (the length of the diagonal line you drew, and by angle.

 

[snowdog]

Okay thank you seems to work .
Bit iffy to control the app as pasting ( ctrl + v) an image in your clipboard doesnt seem to work but that aside it works and i know how to use *** measure tool, thank you.

Reason I need it is I need to calculate how much force ( in newtons) there is onto the cables of the Erasmusbridge. I have the scematics of it and I know how much upward force there is needed in the point where the cables are attached to the roadway and I need to translate that into force on the cables wich are in various angles. And for that I have to scale stuff on the scematic eg 1cm or 10 pixels is 1 newton...

Anyways enough rubbish talk, I just need to do something for school and you helped me, ty .

 

[BillytheImpaler]

I do similar things with it, basic reverse engineering from photographs when I know a few important details.

It's how I designed my shifter kart. I saw some photos of nifty frames and I read their overall length then started measuring pixels to get a rough idea of the size of everything.

 

[bledd]

paint.net 'might' be able to do something similar

gimp has tons of good features, but it's hard to move to that from photoshop, paint.net seems to follow the same 'logic' that photoshop does

maybe it's a bad logic, but it's one that I'm familiar with