Spatial join including attributes - like SQL right join?

Question

I've run in to a little problem. I have two sets of polygons with important attributes. I need to join over the attributes from the first set to the other, but I can't seem to figure out how. Theoretically it seems like an SQL right join, I think. Can you help?

The only way I can get this to work, I think, is the somehow copy the blue polygon. The first problem is that not all of the red polygons are completely inside the blue, but I have selected by centroid (I need to do this). The second problem is that there could be 1, 2, 3 or more red polygons per blue.

The example below would be Blue1+Red1 and Blue1+Red2 and so on.

I have ArcEditor 10.1, QGis and FME.

I need to join the attributes from the red polygons over to the blue polygon.

Answer 1

in arcgis you want to do a spatial join.
from the arctoolbox select analysis tools, overlay, spatial join.
spatial join
choose the one to many operation.

"ESRI desktop help 10.1"
use the intersect match option.
In my example the first time I got the target features switched so pay attention to the target and join features.

Answer 2

I would use the Union tool of ArcGIS for Desktop to do this:

Computes a geometric union of the input features. All features and their attributes will be written to the output feature class.

How it works is described here:

Union calculates the geometric union of any number of feature classes and feature layers.

All input feature classes or feature layers must be polygons.

The output feature class will contain polygons representing the geometric union of all the inputs as well as all the fields from all the input feature classes.

• Teresa: I can't use the Union-tool, as I will get null-values where there is no overlap. I need the geography of the blue polygons with the attributes plus the red attributes.
• PolyGeo: Have you looked at Intersect instead? It's just like Union but only keeps areas of overlap.
• Aaron: +1 Union would be my first choice. @Teresa have you experimented with the parameters of the union tool? Otherwise, try other options in the overlay toolset.

Answer 3

It sounds like you need to do a Many-To-One join instead of the typical One-To-Many join. This is possible with ArcGIS and FME.

In ArcGIS simply perform the spatial join as usual, but uncheck the "Keep All Target Features" option. This will create an output with a copy of each target feature for each joined join feature. If you need to have the attributes from each join feature on the same target feature you can simply perform attribute joins.

FME can do the same thing with the SpatialRelator. Just choose to load all related into a list and use the ListExploder.