I'm working on a project where, essentially, I'm measuring threat levels based on geospatial patterns. I have different groups with higher or lower threat levels based on the distance from their location. These distances are fixed between different groups, all are roughly 0-30 miles, 31-90 miles, 91-270 miles, etc.
I have a data set that lists these groups and the threat levels based on those distances. It basically looks like:
There will be multiple examples of each group, and I know how to create the points and buffers off the points, but this is where my current skill set fails me and I need help.
- I need to assign values to each groups buffer area.
- I need to identify areas where the buffers overlap, and create a high threat level.
Ideally, the outcome would look something like this, where the points are a various groups locations, the buffer circles are the distances, and the black numbers are the values assigned to each buffer:
The orange numbers show the value of the overlapping buffers, and something like the red area is where two groups threat levels overlap to create the highest overall threat.
1 Answer 1
You achieve this analysis in a multi-step process by extracting centroids and summarising these then join back to your data. This should be wrapped up in a model as then you could repeat/tweak your analysis. The essential steps are:
- Create your buffers, I used the multi-ring buffer tool and create a separate featureclass for each buffered point.
- To each dataset add a new field called threat
- Encode your 1, 2 and 3 values into your data, a simple select and field calculate will do.
- Merge all your feature classes into a single featureclass of overlapping buffers.
- Run the union tool of your merged dataset, where buffers overlap you'll get multiple smaller polygons, each with their threat value.
- Run feature to point tool, ensure point is INSIDE. These will have the threat values.
- Run add XY coordinates on point dataset
- Create a string field and concatenate the X and Y into a unique ID
- Run summary statistics tool on point dataset. Grouping by your string ID field and summing threat.
- Join the summary table to your point datasets by string ID field
- Run delete Identical tool deleting on your string ID field
- Run spatial join to attach the summed threat values back to the UNIONED dataset.
- Run delete Identical tool on your spatially joined data deleting on your string ID field
Steps 1 to 3 could be easily wrapped up into a model using an iterator to step through each of your points to create the respective multi-ringed buffer datasets.
output Rings labelled by their threat, and coloured by the overlapping summed values.
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