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I have about 8000 datapoints of giraffe observations and would like to calculate the surface of the area they spend 90% of their time in.

Anyone who can help me with solving this question?

I use QGIS 2.14.3 Essen.

Kazuhito
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mathias dhaen
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    What have you tried so far? Are the data points of individual giraffes identified by an attribute value? – PolyGeo Jan 23 '17 at 13:05
  • Can you send one pic of the atribute table? – Paulo Martinho Jan 23 '17 at 13:15
  • I added a pic of the attribute table. I didn't try anything yet since I don't know begin on it. I guess it is through the field calculator? – mathias dhaen Jan 23 '17 at 13:45
  • Personally this sounds more like a heat map than it is a calculation. After you create the heat map it seems like you will be able to better define a boundary. – AvidDabbler Jan 23 '17 at 14:05
  • I spent a couple of minutes to reflect on your question. What do mean with area? Giraffe habitation in dry, forested, grassy steppe; dry, wet savanna (based on land-cover classification) or within a well defined area (habitation within a 1km² grid)? And what do you want to achieve in the end? Do you want to know if they where 90% of there time at a watering hole, hang out, drinking and grooming? Or would this be the next step: intersection the calculated surface with the land-cover or other classifications? – Stefan Mar 13 '18 at 09:19
  • Is there an attribute which describes what the giraffe was doing, while observation? This leads to the definition of "spending time" somewhere. Is the giraffe grazing on the spot or migrating to another area during the observation? With a GPS transmitter it would be more clear. You have a track and a timeline. – Stefan Mar 13 '18 at 09:36
  • So it seems that maybe there are 2 solutions:
    1. if you don't have an area designated you could create a vector grid in QGIS then perform a Points in Polygon analysis and calculate out the #/total
    2. if you have polygons already designated then you could just perform a Points in Polygon analysis and calculate #/total

    If this is not what you are looking for you are going to need to provide more information https://gis.stackexchange.com/questions/123444/creating-fishnet-grid-shapefile-in-qgis http://www.qgistutorials.com/en/docs/points_in_polygon.html

     – AvidDabbler Apr 30 '18 at 18:37

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