Question on checking GPS coordinates

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11-24-2015 07:55 AM
AlexiGeorge
New Contributor II

Hi,

I am mapping GPS coordinates and then manually zooming into each coordinate to make sure that it is falling near evidence of a village (near buildings, roads, or a deforested area), and that the points are not falling within a water body.  I am just overlaying the GPS layer with the Basemap.  Essentially, I am "cleaning" the GPS data by checking each point for its accuracy. 

I am wondering if there is a certain way to sort the GPS layer so that points "within a water body" or a "certain distance away from buildings/roads/deforestation" could be made apparent? 

This way, I would not have to go through each point, zooming into each one to visually assess this.

Please let me know if this makes sense and if there is a way to do this!

Thanks

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6 Replies
ChrisDonohue__GISP
MVP Frequent Contributor

If you are using ArcMap, there are several ways you could run an analysis to find the points that do or do not fall where you expect them.  The general topic to read up on is "Overlay Analysis".

- For example, if you have a polygon feature class of water features, you can use it to Clip the GPS points file and the result will be points that fall within the water features.

Clip (Data Management)

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

- Another way to find the points in water is to do Select By Location  to determine which GPS points fall within the water and then export the resulting selection as a new feature class so you can then review them.

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

- A third way would be to use a Spatial Join, which will add attribute information to your GPS points which can then be used to differentiate if they fell in water or not.

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

- In regards to proximity to buildings, if you want the GPS Points to be within a certain distance of a building, if you have a building feature class, you can Buffer the building feature class by that distance to create a "capture area", then use one of the processes above to establish whether the GPS points fell within that capture.

Buffer (Analysis)

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

Chris Donohue, GISP

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DarrenWiens2
MVP Honored Contributor

To state the obvious, the key point is: you can do this overlay analysis if you have the data. If you're interested in whether your points overlay (or are within a distance of) a water feature, you need a water body feature class. You will not be able to automate the process very much if you only have a WMS basemap - you don't have access to the data.

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ChrisDonohue__GISP
MVP Frequent Contributor

Good point - I probably should of put that as a statement in the beginning, in case the original poster is unfamiliar with ArcGIS and the requirements to do analysis.  Definitely have to have data.

Luckily, there are potential sources of data that potentially could work should the original poster not have water, building footprint data, etc.  In that case, the big question then is, where is the project?

Chris Donohue, GISP

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AlexiGeorge
New Contributor II

I am doing this analysis for sets of GPS coordinates in many countries.  Mainly asia (India, Bangladesh, cambodia), Ethiopia, and some other African countries. 

I am pretty confident I could find a world water bodies layer, however I am not sure I could find a buildings layer since the locations I am mapping are very rural (not many buildings around, just small villages).

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AlexiGeorge
New Contributor II

is it possible to do these processes in arcgis online?

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ChrisDonohue__GISP
MVP Frequent Contributor

I have not used ArcGIS Online for analysis, but it appears from this document from ESRI that you can do analysis:

Perform analysis—ArcGIS Online Help | ArcGIS

There will likely still be the issue of having the data you need to accomplish the analysis.

Chris Donohue, GISP

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