I have a dataset of species distribution in latitudes and longitudes extracted from geo-tagged photographs. I have plotted them on a map to see how distribution looks like. My attempt was to check whether this distribution falls within the previously documented species distribution range. For this, I have the data (lat. and long.) of the previously documented species range. I have overlayed these documented data over the map which I have created. To be more precise, I have read that I can buffer the documented points. My problem is how to determine the buffer distance for each point for documented latitude and longitude. I have read that I can use uncertainty range for this (e.g. let's say 20km from a point).

How do I calculate this uncertainty from the decimal coordinates that I have?

I'm new to GIS.


Uncertainty of a point is usually due to GPS. So if you are using standard GPS the uncertainty could range from 5-20m depending on the terrain. If it was differential GPS then the uncertainty range is in cm. This isn't helpful to you.

You have a few options, either do some research and look at what the typical home range of a species is and use this to calculate the buffer radius.

You could try using a convex hull, which gives the polygon of minimum area around those observations.

Lastly you can go down the path of modelling the species distribution, which sounds like it might be a bit of a stretch if you are inexperienced.

If you can specify what species it is, there could be distribution maps available through IUCN or similar conservation sites.

  • Many thanks @LiamG for your idea, My species is blue whale (Balaenoptera musculus). I went through the IUCN and other sites, it's bit tricky to find a home range for this ones. Anyway thanks again for your idea, I may go with convex hull option :)
    – Tharindu
    Jan 13 '18 at 8:38

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