Arctic Sea Ice : Forum

AGW in general => Developers Corner => Topic started by: bairgon on December 21, 2016, 11:54:24 AM

Title: Calculating area from satellite images
Post by: bairgon on December 21, 2016, 11:54:24 AM
Given an image like http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201612191227.NOAA.jpg (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 (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.
Title: Re: Calculating area from satellite images
Post by: Tealight 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/ (http://step.esa.int/main/download/)
Title: Re: Calculating area from satellite images
Post by: bairgon on December 31, 2016, 02:10:28 PM
Thanks for that hint. Downloading now.