Question

Unable to output Planning Overlays against Properties - either not all show or I get duplicates.

  • 19 January 2024
  • 4 replies
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I have an FME workflow that extracts planning overlays against the cadastre/properties. Some properties could have 5 or more planning overlays. I am currently using AreaOnAreaOverlay transformer and then a ListExploder to get all planning overlays against each property, otherwise not all overlays appear for some reason. ListExploder seems to show all overlays against each property but it duplicates certain overlays. It doesn't matter which transformer I use to remove the duplicates, the result still has duplicates. Also, when joining the result to the rest of my workflow I have a feeling it chews up too much memory due to the listexploder as I get a non-descript translation error, which online forums suggest it is due to memory usage. What's the best way to show all distinct overlays without duplicates?


4 replies

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I understand what is happening, but I do not understand the result you expect. If you have one parcel overlapped with 2 planning overlays, how many results do you expect?

 

Because this is what the AreaOnAreaOverlayer does. It creates a set of not overlapping areas from the input. To get to the unique parcel vs planning combinations, you can create a list and explode the list. The duplicates you find might be created from the same plan cutting the same parcel multiple times?

 

If you want to keep all parcels with its original geometry, and have a list with all plans it intersects, you can probably better use the SpatialRelator. You probably need to create a list and explode it, but the parcels stay intact.

Userlevel 4
Badge +28

I understand what is happening, but I do not understand the result you expect. If you have one parcel overlapped with 2 planning overlays, how many results do you expect?

 

Because this is what the AreaOnAreaOverlayer does. It creates a set of not overlapping areas from the input. To get to the unique parcel vs planning combinations, you can create a list and explode the list. The duplicates you find might be created from the same plan cutting the same parcel multiple times?

 

If you want to keep all parcels with its original geometry, and have a list with all plans it intersects, you can probably better use the SpatialRelator. You probably need to create a list and explode it, but the parcels stay intact.

Attached sample demontrating this.

Badge +4

I understand what is happening, but I do not understand the result you expect. If you have one parcel overlapped with 2 planning overlays, how many results do you expect?

 

Because this is what the AreaOnAreaOverlayer does. It creates a set of not overlapping areas from the input. To get to the unique parcel vs planning combinations, you can create a list and explode the list. The duplicates you find might be created from the same plan cutting the same parcel multiple times?

 

If you want to keep all parcels with its original geometry, and have a list with all plans it intersects, you can probably better use the SpatialRelator. You probably need to create a list and explode it, but the parcels stay intact.

I expect two overlays. The issues tended to occur when there were quite a few overlays where not all were appearing. For example one property might intersect DDO1, VPO2, EMO2, DPO4 but only DDO1 and EMO2 might appear. When adding the list exploder they would all appear but with duplicates in some cases, so DDO1, VPO2, EMO2, DPO4, VPO2, DDO1 for example. When investigating the property and overlays I couldn't understand why it would duplicate, as the overlay tended to only affect one part of the property and not intersect somewhere else. Then with the list exploder I would join the result to the rest of the workflow using the property number but would constantly get an error in translation. Regards, Josh
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Thanks for your help. That seems to have done the trick.

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