topic Re: Create catchment area for stores in ArcGIS Pro Questions

Create catchment area for stores

HectorBorro1 — Fri, 17 Jun 2016 18:01:15 GMT

I need to create a polygon showing where my customers live (several million) for each of the locations of my stores (150)

Visually, it is very simple to see where they are:

The problem arises when I need to create a polygon in order to run some additional analysis down the road like demographics and such...

Any ideas? I tried running HotSpot Analysis, but it is very very slow even when doing it for only two stores and 100k customers as a trial...

cheerrs and thanks!

Re: Create catchment area for stores

RickeyFight — Fri, 17 Jun 2016 18:31:29 GMT

Have you tried this:

How To: Convert a point feature class to a polygon feature class

Re: Create catchment area for stores

HectorBorro1 — Sat, 18 Jun 2016 01:32:58 GMT

Many thanks but I think this marks the extent of the whole points:

Whereas I would need something like the following (drawn by hand, apologies) where the density is greater

Rickey Fite Any ideas on how to achieve it?

Re: Create catchment area for stores

DanPatterson_Retired — Sat, 18 Jun 2016 02:57:02 GMT

that is approximating a convex hull and for that many points would be difficult to do.

You could approxiate the bounds in raster, by converting points to raster for each class which will effectively fill in the interveneing space without having to do buffers (which would fail). The result could then be converted back to vector.

The issue would be the appropriate selection of cell size and extent

Re: Create catchment area for stores

HectorBorro1 — Tue, 21 Jun 2016 00:23:28 GMT

well, I thought I had replied yesterday but I did not click POST... dumb of me....

Thanks for your suggestion. I tried converting to raster and back, but the polygons were too "ugly and non-descript"

so, I kept looking around and found the toolbox AGGREGATE POINTS which seem to do the trick.

Now the question is: Is there a way to remove the small "islands"? (marked in orange circles)

Re: Create catchment area for stores

DanPatterson_Retired — Tue, 21 Jun 2016 00:29:47 GMT

To quote me... using an appropriate cell size and extent.... I guess you used the default cell size which is pretty crummy since it defaults to 1/250th of the extent on the long axis... you could have tried a smaller cell size.

As for removing small areas, then you can perform a Regiongroup Region Group—Help | ArcGIS for Desktop

then do a query keeping only those areas greater than a certain threshold (you can also use Con if you want to do stuff with the areas smaller, like set them to 0 or some other value or nodata. ie. what do you want to do with the fiddly bits besides remove them

PS filtering is a possibility, but it will impact the other areas, whereas the regiongroup won't. But it could be an option if you only want to produce a visual of general conditions.

Re: Create catchment area for stores

HectorBorro1 — Tue, 21 Jun 2016 17:04:32 GMT

Well, many thanks!

It looks like we are getting there....

I managed to delete the "islands" and kept the larger masses.

Now... how can I fill the holes? as I need a large mass?

Thanks for your kind help!

PS. I'm working with vector as I can't convert this layer to raster.

Re: Create catchment area for stores

DanPatterson_Retired — Tue, 21 Jun 2016 17:14:07 GMT

A quick and dirty method is a buffer outward by some amount dissolving buffers...call this buff1.

then take buff1 and buffer it inwards by the same amount...

in a perfect world and a brilliant selection of buffer size and spatial geometry, all the holes should be removed.

For fun give it a try while I ruffle through non-programming approaches to remove the interior rings

Re: Create catchment area for stores

HectorBorro1 — Tue, 21 Jun 2016 17:25:12 GMT

Sounds like a plan. Let me run it and let you know how it goes....

Re: Create catchment area for stores

HectorBorro1 — Tue, 21 Jun 2016 17:57:21 GMT

well, it's rough but it helps... I can do with it...

Re: Create catchment area for stores

DanPatterson_Retired — Tue, 21 Jun 2016 18:27:22 GMT

now to step it up with a graduated fill pattern... all the cool mappers are doing it

Creating fill symbols—Help | ArcGIS for Desktop

Re: Create catchment area for stores

HectorBorro1 — Tue, 21 Jun 2016 18:36:10 GMT

Last, but not least...
how can I remove half of the overlapping area between 2 catchment areas we defined using the abobe process?

I tried Intersection but then I end up with only one area in the midlle...

The resulting polygons should not overlap...

Re: Create catchment area for stores

HectorBorro1 — Tue, 21 Jun 2016 18:37:57 GMT

this will come quite handy for the resulting analysis. thanks!

Re: Create catchment area for stores

DanPatterson_Retired — Tue, 21 Jun 2016 18:42:04 GMT

check out the other Analysis, Overlay tools... probably Union would do, or update depending on what you want but you may have to split the result and fiddle with the parts in an edit session to join parts together if needed

Union—Help | ArcGIS for Desktop

Re: Create catchment area for stores

HectorBorro1 — Tue, 21 Jun 2016 18:47:00 GMT

Tried that already... I need the Inverse Union, or a scissor that cuts the overlapping area in 2 so I get 2 distinct areas that do not overlap.

Something like the Create Thiessen Polygons—Help | ArcGIS for Desktop but that works only for points...

Maybe the Split—Help | ArcGIS for Desktop may work, but I don't have a Split feature. The split feature would be half of the intersection between both catchment areas...

Re: Create catchment area for stores

DanPatterson_Retired — Tue, 21 Jun 2016 18:51:35 GMT

a quick edit would do it since your splitting feature isn't one of the polygon boundaries, but a polyline.

Re: Create catchment area for stores

HectorBorro1 — Tue, 21 Jun 2016 18:59:07 GMT

Dirty but it dos the trick. Super help, many thanks!

Now I need to do this for 100 locations

Re: Create catchment area for stores

DanPatterson_Retired — Tue, 21 Jun 2016 19:05:46 GMT

at least you have a plan, which you could automate in modelbuilder or python, but sometimes manual is faster based on my views seeing others implementating modelbuilder workflows for anything other than the simplest operations

Re: Create catchment area for stores

HectorBorro1 — Tue, 21 Jun 2016 19:12:02 GMT

indeed.

I might try ModelBuilder to create the polygons then delete overlapping areas manually

Cheers and thanks for the pointers!