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Automatic 2.25km buffer when .5 or 1 km input
Posted: Thu Jun 09, 2022 11:29 am America/New_York
I'm trying to use the Global Subsets tool within EarthData to extract data around latitude and longitude points using buffers of .25km, .5km, and 1km. Things have been fine with a .25km buffer in that the citation appears correctly once run. However, when I try to input a buffer of .5km or 1km, it automatically produces data with a citation appearing indicating a buffer of 2.25km, even though that is not what I input and told the system to do. Is this a bug in the system? Will this be fixed with the maintenance that is occurring today? I'm hoping for some answers so that I may progress with my data collection.
Re: Automatic 2.25km buffer when .5 or 1 km input
Posted: Tue Jun 28, 2022 10:57 am America/New_York
Although we've already answered this question via our Ticket Management system, I'm posting the answer here in case it is helpful for others.
The Global Subsets tool only allows setting the x (E-W) and y (N-S) as integers. If you order a subset with x and y as 1km for MOD13Q1, it should result in a subset size of 2.25km x 2.25km with a total of 81 pixels. The 41st pixel (center) will be your 0.25x0.25km subset, and you can retrieve pixels for other subset sizes accordingly. I have attached an example numbering scheme with this email. Please refer to https://modis.ornl.gov/documentation.html#data_format
for more information on the data format.