[Qgis-user] Help with Buffer and Category-Specific Geometry Outputs in QGIS

[Carolina Lang]

Hello everyone,

I’m back with a solution to the issue I posted on December 29th, in case anyone comes across something similar.

The solution was proposed by Chris Hermansen and involves two steps:

  1.
Calculate the buffers (circles) around each point.
     *   Use "Processing > SAGA Next Gen > Vector general > Shapes buffer".
     *   Set the field APA as the buffer distance and do not check "Dissolve Buffers."
     *   This will create a circle around each sampling point.

[image.png]

    2. Combine the buffers by their file_name to dissolve them.

     *   Use "Vector > Geoprocessing Tools > Dissolve".

     *   Set the field file_name as the "Dissolve field."

     *   This will create a combined buffer for each file_name (e.g., one for L001_P1TV80, another for L002P2TV80, etc.).

     The result should look like this: (provide visualization or reference here).

[image.png]


I also recommend optimizing the process if you have hundreds of files to process by using the Graphical Modeler.

Thanks, Chris, for your help!

Cheers,
Carolina Lang




[cid:834f8d0e-a3a9-49a5-96cc-e9a5c20422de]<https://outlook.office.com/bookwithme/user/265ad61a0f124413aa15a929664619b3@ifop.cl?anonymous&ep=bwmEmailSignature>          Book time to meet with me<https://outlook.office.com/bookwithme/user/265ad61a0f124413aa15a929664619b3@ifop.cl?anonymous&ep=bwmEmailSignature>
________________________________
From: Carolina Lang
Sent: December 29, 2024 9:38 PM
To: qgis-user at lists.osgeo.org <qgis-user at lists.osgeo.org>
Subject: Help with Buffer and Category-Specific Geometry Outputs in QGIS

Hello everyone,
I'm using QGIS 3.34 and working with the vector-geometry-buffer function on a shapefile containing multiple spatial points, categories (or location type) are represented as a group of these spatial points. For each category, my goal is to calculate the geometries (perimeter and area) created by the buffers.
While the output result includes these geometries, it does not properly associate them with their respective categories. Instead, for each row in the output, I see the same category listed but with varying perimeters and areas, making it difficult to distinguish which geometries belong to which category.
Example
input file_(here I use column APA_radius as variable distances for buffer)
[cid:758816fb-ea5b-411d-8cc1-30dc566b1186]
output file_9as you can see geometries for both categories but no idea which geometries belong to which category)
[cid:c6279fc3-a799-4223-b47d-d5a9d61261e3]
Has anyone encountered this issue before? Is there a specific step or method I might be missing to properly link the geometries to their respective categories?
Cheers & Happy Holydays!!

Carolang-Chile

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