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Author Topic: Calculating area from satellite images  (Read 841 times)

bairgon

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Calculating area from satellite images
« on: December 21, 2016, 11:54:24 AM »
Given an image like http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201612191227.NOAA.jpg how can I calculate the area of the Lincoln Sea "polynya"?

There are Sentinel images like http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/20161220s01a.ASAR.jpg with lat/long, but these don't cover the complete area to be calculated.

As an alternative, can the images be accessed using Google Earth or similar, with polygon drawing tools? I tried importing an image as an overlay but found it difficult to match it up.

Tealight

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Re: Calculating area from satellite images
« Reply #1 on: December 25, 2016, 06:07:21 PM »
If you want to calculate area from images you need to know the exact resolution. The rest is pixel counting.

I do most of my area calculations and length meaurements with SNAP. It has a polygon drawing tool and can directly tell me length measurements of satellite images with geo information.


http://step.esa.int/main/download/

bairgon

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Re: Calculating area from satellite images
« Reply #2 on: December 31, 2016, 02:10:28 PM »
Thanks for that hint. Downloading now.