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

[Ben Hur Pintor]

That's odd. I redid the entire thing just now (restarted QGIS, made scratch
point layer, created a 100m buffer) and the values I get are now correct.
Even the area computations were off in the first one but after redoing the
process, everything looks good.

 point-buffer2.png
<https://drive.google.com/file/d/1EmWTh3mgyOAvNRUzxMQgxVmMJZqg_-pg/view?usp=drive_web>

Weird. Maybe I missed something during the first one. Hahaha.

Anyway, sorry for bothering you all.

Cheers!

On Thu, Sep 27, 2018 at 11:07 PM DelazJ <delazj at gmail.com> wrote:

> 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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>

-- 
---

*Ben Hur S. Pintor*
bnhr.xyz


Consultancy · Training & Support · Development & Innovation
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