Hi, Martin, thank you for your answer.

Well, the problem is that QgsDistanceArea class provides a function to (that's what I think due to my limitations in C++) calculate the distance an bearing between two points (start-end points). This is what INVERSE Vicenty Formula does, and I think thatthat's the formula implemented in QgsDistanceArea with its method computeDistanceBearing. This metod, as stated in the API documentation,calculates distance from two points on ellipsoid based on inverse Vincenty's formulae: given a departure point P, and destination point P2, it yields the distance between the two points and the bearing from P to P2 as well as from P2 to P.

But I want to perform another calculation: Calculate the destination point P2 given an departure point P, a bearing B and a distance D. That's what direct Vincenty Formulae performs and it's what I'm looking for :(

Thank you very much,

Jorge Tornero





El 12/12/13 13:24, Martin Dobias escribió:
On Thu, Dec 12, 2013 at 2:36 PM, Jorge Tornero - Listas
<jtorlis...@gmail.com> wrote:
Dear all.

I'm currently working on a python plugin for QGIS which deploys points along
lines on a given distance basis. The lines, say transects, are created
placing an initial point and then providing a bearing for the line. Then, n
stations/smapling points are deployed in its place.

I'm using Vincenty's Formula to get the coordinates for the points. So far,
I've found an python implementation for this, but I haven't been able to
know under which license is released the code, as far as I have found the
code in a forum
(https://isis.astrogeology.usgs.gov/IsisSupport/index.php?topic=408.0) but
the link provided in the message for the original code can't be followed.

As far as I know, in QGIS API there is no direct Vincenty's formula to
compute in this way (point, azimuth/bearing + distance to destiny), and I
want to make the plugin dependence-free as possible, so my questions are:

1) Do you know if, in QGIS API, is there and usable implementation of
Vincenty's direct formula?
Hi Jorge

What about QgsDistanceArea class? It does the calculation of distance
/ bearing on ellipsoid.

Regards
Martin

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