[QGIS-Developer] [Qgis-user] Buffer Algorithm (Buffer distance of output polygon is not equal to the Distance parameter)

[DelazJ]

Hi,
There might be more information in the *Info* drop-down menu. Expand it,
please.

Harrissou

Le jeu. 27 sept. 2018 à 16:55, Ben Hur Pintor <bnhr.dev at gmail.com> a écrit :

> Hi everyone.
>
> I apologize if this has been asked before but I would just like to clarify
> if this is how the buffer algorithm in QGIS should function.
>
> *Issue:* The actual distance from the input layer to the buffer polygon
> created by the Buffer processing tool (and v.buffer) is not equal (only
> around 80%) to the Distance parameter provided in the said tool.
>
> *Example:* My coordinate reference system is WGS84/UTM Zone 51N (EPSG:
> 32651). I create a 100m buffer around a point but when I measure the
> resulting circle, its edge is only ~80m from the point (see buffer-point
> and buffer-point-distance below).
>
>  buffer-point.png
> <https://drive.google.com/file/d/1SAptLcRKnGVc8zyESkl-sJZ23a5OWEsy/view?usp=drive_web>
>
>  buffer-point-distance.png
> <https://drive.google.com/file/d/1aQ0mfadGnEzISkPnu-GGX9SUu1GXhGMs/view?usp=drive_web>
>
> I create a 50m buffer around a line but when I measure the resulting
> buffer, its edge is only ~40m from the line (see line-buffer and
> line-buffer-distance below).
>
>  line-buffer.png
> <https://drive.google.com/file/d/11cNTRNbHxB3cFCaZEhXDWqKYEdWJX31K/view?usp=drive_web>
>
>  line-buffer-distance.png
> <https://drive.google.com/file/d/1PGRabSqF-zrOCpAboncQ_yQxx_0ulByN/view?usp=drive_web>
>
>
> Clarifications will be much appreciated. Maybe I just missed some part of
> the documentation.
>
> Thank you.
>
> Sincerely,
> Ben Hur
>
> --
> ---
>
> *Ben Hur S. Pintor*
> bnhr.xyz
>
>
> Consultancy · Training & Support · Development & Innovation
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