[Qgis-user] pixel counts

[Jonathan Moules]

Hi Aaron,
Well, the bad news is that this is on the trickier end of the GIS spectrum.

It depends on the exact nature of the conversion you want to perform when changing to polygon.

http://gis.stackexchange.com/questions/23203/how-to-calculate-raster-statistics-for-polygons

http://www.qgistutorials.com/en/docs/sampling_raster_data.html

Should hopefully get you started though.

Cheers,
Jonathan


From: qgis-user-bounces at lists.osgeo.org [mailto:qgis-user-bounces at lists.osgeo.org] On Behalf Of Aaron Stoler
Sent: Monday, February 23, 2015 8:42 PM
To: qgis-user at lists.osgeo.org
Subject: [Qgis-user] pixel counts

Hi all,

I am brand new to QGIS and have pretty minimal GIS experience, so I apologize for my crude terminology. I was recently handed a large number of ARCInfo files (adf) containing information on species abundance at 30 m2 resolution. Each file (well...group of files since they are adf files) describes the abundance of a single species. I would like to analyze single species density within a custom-defined polygon. Species abundance within a 30 m2 is defined by color intensity (black = 0 abundance, white = max abundance).

I have figured out how to view single adf files as raster layers in QGIS. From there, it seems like I should be able to generate a polygon and tell the program to analyze pixel count for each level of color intensity.

I haven't had much GIS training, but I would really like to conduct an experiment that needs this data. Could someone please point me in the right direction?

Thank you for your time,
Aaron
abstoler at gmail.com<mailto:abstoler at gmail.com>


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