Calcuating total area of polygons in one feature class within the boundary of another feature class?

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03-23-2018 01:22 AM
SineKelly
New Contributor

I have two polygon layers - one of the wards (a uk zonal geography) within an area in the north of England, and one of all the buildings within that area. For each ward, I would like to know the total area covered by buildings within that ward. Ideally I could then add the total building area value as an attribute field in the ward layer attribute table. Any ideas on how to go about all this? I have tried using the spatial join and the split tool but neither of these seem to do what i'm asking. 

Really need to work this out for my final year uni project so all help is greatly appreciated. 

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4 Replies
DanPatterson_Retired
MVP Esteemed Contributor

Tabulate Area .... requires the spatial analyst extension

Tabulate intersection .... requires an advanced license

available in arcmap and ArcGIS Pro

otherwise it gets messy with intersections and joins

XanderBakker
Esri Esteemed Contributor

To explain a little more about the "messy" solution than Dan mentioned )in case you don't have access to Spatial Analyst nor an Advanced license:

Do an intersect: Intersect—Help | ArcGIS Desktop , this will yield a featureclass with only those areas that are within a ward and a building and the attributes of both featureclasses (write it to a file geodatabase, not a shapefile). The field that indicates a unique ID for the wards can be used to summarize the areas stored in the field Shape_Area (choose the Sum of the Shape_Area field). See Summarizing data in a table—Help | ArcGIS Desktop . 

As a result you will have a table with the unique ID of the wards and per ward the total area of the buildings. Now you can use join to join the data back to the ward featureclass: Join Field—Help | ArcGIS Desktop 

Links were provided for ArcMap but the same applies for ArcGIS Pro. In this case no additional licenses are required.

SineKelly
New Contributor

I tried using the Tabulate intersection tool as the description seems to match what I am after. However, I compared the results from the output table to the total building area for each ward in another shapefile (previously when using the split tool I produced a different shapefile of building data constrained by perimeter of each ward, so I looked at the sum statistics for the area of one of these shapefiles) and the values were very different. Also in the output table you can tell that the percentage values (I assume building area of total area) are cleary wrong when you look visually at the data (output table has 3% for one ward when looking at the data the buildings cover more than half the ward area). 

This doesn't seem to have worked although I am confused because the tool description seems to match what I'm after. 

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DanPatterson_Retired
MVP Esteemed Contributor

Of course, none of this would make any sense unless your were using projected input data.  You might want to show an example of what you got and what you were expecting.