+5FME 2020: How to pass the Blocks number to their Parcels?
In the screenshot below, there are two layers: parcels and blocks. I wanted to pass the blocks number to all parcels contained in it to end up with a new layer that has two fields: parcel number and block number
What might be the best practice to perform this?
The data is attached
Best answer by chrisatsafe
Very much appreciated chrisatsafe for the prompt answer.
The “AnchoredSnapper” and “AreaOnAreaOverlayer” might not lead to the expected result due to snapping distance. This needs critical tunning in order to end up with same number of parcels
What I wanted here is to transfer the “blocknumber” to each parcel that has its center within a block.
In ArcGIS, the “spatial join” tool can do this with the “one to many” and “have their center in” options. Is there an equivalent tool in FME?
That makes sense, if you need the result to be one to many you can do that with the SpatialRelator as it will tell you which blocks it overlaps with. Additionally, if you prefer to test based on their center point, you can first extract the center points and then perform the analysis with the SpatialRelator.
You have a lot of options here ;)
+2Hi @jamal ,
There are a few ways you can do this. One thing I noticed when opening up your dataset is that the blocks dataset doesn't fully line up with the parcels. With that in mind, I used an AnchoredSnapper to help correct this.
I would handle this by first sending the blocks and parcels into the AnchoredSnapper, from there you can either use the AreaOnAreaOverlayer or SpatialRelator to perform the overlap analysis and merge the attributes from the blocks onto the Parcels.
We have a great determining spatial relationships article and a Merging or Joining Spatial Data article with more tips in case you are interested!
+5Thank you chrisatsafe for the help.
I couldn’t figure out what the snapping distance represents here. Is it the maximum distance the “blocks” can move to the “parcels”? if so, why if we set it to be 3 meters then different result is obtained while setting it to be 4 meters brings the expected results?
+2Thank you chrisatsafe for the help.
I couldn’t figure out what the snapping distance represents here. Is it the maximum distance the “blocks” can move to the “parcels”? if so, why if we set it to be 3 meters then different result is obtained while setting it to be 4 meters brings the expected results?
Hi @jamal ,
The output is 12 polygons when you set it to 3 because those vertices aren't snapping. Their distances are ~3.3 and ~3.8 from the closest anchor vertex.
It all depends on the Snapping Type used in the AnchoredSnapper - for example if you set it to segment with a distance of 3 it would produce similar results to Vertex Snapping with a distance of 5 in this case.
+5Very much appreciated chrisatsafe for the prompt answer.
The “AnchoredSnapper” and “AreaOnAreaOverlayer” might not lead to the expected result due to snapping distance. This needs critical tunning in order to end up with same number of parcels
What I wanted here is to transfer the “blocknumber” to each parcel that has its center within a block.
In ArcGIS, the “spatial join” tool can do this with the “one to many” and “have their center in” options. Is there an equivalent tool in FME?
+2Very much appreciated chrisatsafe for the prompt answer.
The “AnchoredSnapper” and “AreaOnAreaOverlayer” might not lead to the expected result due to snapping distance. This needs critical tunning in order to end up with same number of parcels
What I wanted here is to transfer the “blocknumber” to each parcel that has its center within a block.
In ArcGIS, the “spatial join” tool can do this with the “one to many” and “have their center in” options. Is there an equivalent tool in FME?
That makes sense, if you need the result to be one to many you can do that with the SpatialRelator as it will tell you which blocks it overlaps with. Additionally, if you prefer to test based on their center point, you can first extract the center points and then perform the analysis with the SpatialRelator.
You have a lot of options here ;)
+2That makes sense, if you need the result to be one to many you can do that with the SpatialRelator as it will tell you which blocks it overlaps with. Additionally, if you prefer to test based on their center point, you can first extract the center points and then perform the analysis with the SpatialRelator.
You have a lot of options here ;)
Here is what the workspace could look like. Let me know if that helps @jamal
+5Thank you very much chrisatsafe for the help and solving the issue.
I think that the SpatialRelator tool needs to be enhanced in two ways:
1) To include more options as the ones available in the “spatial join” of the ArcGIS
2) To be able to take the attribute fields from all layers
+2Thank you very much chrisatsafe for the help and solving the issue.
I think that the SpatialRelator tool needs to be enhanced in two ways:
1) To include more options as the ones available in the “spatial join” of the ArcGIS
2) To be able to take the attribute fields from all layers
Hi @jamal ,
With regards to merging attributes, you can merge all attributes between the datasets using the Merge Attributes parameter in the SpatialRelator. Since you mentioned one to many relationships, I opted for generating a list in the workspace I provided (which is then exploded in the ListExploder to expose the BlockNumber as an attribute) but you could use merge attributes instead.
I can't say whether all of the other match option types have been considered for the SpatialRelator, but you can likely produce similar results with other transformers (or a combo of transformers). If you'd like to see more match spatial predicates to test on in the SpatialRelator feel free to post the ones you'd be interested in seeing in addition to your use case as a new suggestion on the ideas Page!
+5Great. I checked the “merged attribute” options and found out that the bocknumber field is transferred to the parcel layer
Getting more spatial options means that “CenterPointReplacer” and “FeatureJoiner” will be not needed in addition to being able to apply a wide spectrum of analysis.
All in all, your assistance does resolve the issue
+5Please, Vote
FME Desktop 2022: Having an equivalent tool to “spatial join” that’s available in ArcGIS,
