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Understanding Bufferer transformer: How does it calculate when you create a buffer in meters but the projection is a Geographic Coordinate System?

  • 17 February 2023
  • 5 replies
  • 7 views
M

I am working on a national dataset for Australia. The initial dataset had points that are converted to polygons based on the parcels they overlap using the Spatial filter transformer. For the points that do not overlap with any parcel, a buffer of 20m is created. Both the parcels and buffers are combined and exported as a dataset.

I'm trying to filter those polygons created with buffer of 20m. Logically all the circles should have the same area and length but it is not the same. I wonder if it is because the dataset was in the Geographic Coordinate system when the buffer was created.

However the formula works, is there any way we can filter all the polygons in the shape of circles? It is not working with filtering by area since I have to add a range and it is filtering other parcels which are not circles.

 

I appreciate your response in advance. My boss thinks it's very simple/logical but I can't seem to find a way to filter these circles :(

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Best answer by DanAtSafe 17 February 2023, 01:10

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5 replies

DanAtSafe
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Hi @msahajar​ Try the CircularityCalculator to identify the circles if the areas are different.

M

Hi @msahajar​ Try the CircularityCalculator to identify the circles if the areas are different.

Worked like a charm, thank you @DanAtSafe (Safer)​ 🙂

M

I'm still interested to understand how the Bufferer works

 

DanAtSafe
Rank
Userlevel 2
Badge +11

I'm still interested to understand how the Bufferer works

 

There used to be a GeographicBufferer but its functionality has been rolled into the Bufferer. If the Buffer Distance Units are different than that of the coordinate system set on the features, then the features get reprojected, buffered, and reprojected back.

M

There used to be a GeographicBufferer but its functionality has been rolled into the Bufferer. If the Buffer Distance Units are different than that of the coordinate system set on the features, then the features get reprojected, buffered, and reprojected back.

Ooo that's amazing! I guess if we reproject the dataset to the projection bufferer used, the area of the circles should be the same? I understand that there would be multiple projections used for various zones/regions since Australia is vast and has multiple zones when it comes projected coordinate system. Thank you for responding, I appreciate it.

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