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

[chris hermansen]

Thanks Carolina, great explanation.

On Wed, Jan 8, 2025, 22:14 Carolina Lang <carolina.lang at ifop.cl> wrote:

> 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: 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: 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
>
>
>
>
>
> <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)
> output file_9as you can see geometries for both categories but no idea
> which geometries belong to which category)
> 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
>
>
> <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>
>
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