Question

Downloading and comparing two datasets (from WMS to Shape)

claireproemeren

Hello,

 

I've made a workbench that downloads data to Shape automatically once per month from https://geodata.nationaalgeoregister.nl/hwh/eenheden/wms/v1_0?request=getcapabilities&service=wms (WMS).

 

This time I would like to make a workbench that compares the geometry and administrative data from the Shape files with each other (January-February, February-March and so on). I am thinking about doing this with the ChangeDetector transformer, but that's where my idea stops.

 

Could anyone give me advice on this?

 

Many thanks,

Claire

2 replies

redgeographics
Rank
Userlevel 4
Badge +25

The ChangeDetector is the way to go, you'll have to feed it two datasets (old and new) and based on one or more key attributes and/or geometry it can find the changes. Best advice I can give you really is to just give it a try.

Two parameters to look out for are the Lenient Geometry Matching (whether or not a different vertex order is a change) and Vector Tolerance (to avoid tiny geometry differences due to rounding errors)

caracadrian
Rank
Badge +20

The ChageDetector is the transformer you are looking form.

It's easy to set up, has an intuitive Help section.

I would recommend a PathReader, some grouping of you files by month and sending it 2 by 2 to WorkspaceRunner that runs a workspace containing the Readers and ChangeDetector.

But, I recommend using WMF instead of WMS to get your data if you want to compare features geometry.

Rasters are not suited for this comparison.

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