5

I have a polyline made of curves and I would like to know if there is a way in QGIS to calculate the radius of the curves?

1 Answer 1

2

It is possible to calculate the radius of a curve in QGIS using the Field Calculator using this expression :

sqrt( 
    ( $x_at(1) - ($x_at(-1) + $x_at(0) )/2 )^2 
    + ( $y_at(1) - ($y_at(-1) + $y_at(0))/2 )^2
     ) /2
+
( ( $x_at(-1) - $x_at(0) )^2   +  ( $y_at(-1) - $y_at(0) )^2 )
/ ( 8 * sqrt(
            ( ($x_at(1) - ($x_at(-1) + $x_at(0) )/2 )^2
            + ( $y_at(1) - ($y_at(-1) + $y_at(0) )/2 )^2
             )))

I have modified and correct the original expression proposed by CM1 in this post QGIS calculate radius of an arc to attributes, where is possible to have a geometry explanation of the used formula.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.