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Is MODIS sinusoidal tile boundary in Eathdata website real?

Geographic Information Systems Asked by Roadelse on December 23, 2020

I was using MOIDS data MCD12Q1 (MODIS/Terra+Aqua Land Cover Type Yearly L3 Global 500m SIN Grid V00). I try to use PyProj in Python to transform the Sinusoidal projection to lat/lon. It actually worked, but I mentioned that the the lat/lon boundary I have transformed is not consistent with the boundary information supplied in the Eathdata website.

Details:

tile h27v05, in file MCD12Q1.A2017001.h27v05.006.2018257173250.hdf, it own metadata:

UpperLeftPointMtrs=(10007554.677000,4447802.078667)             
LowerRightMtrs=(11119505.196667,3335851.559000)

according to the mcd12 user guide, I set proj4 to
"+proj=sinu +a=6371007.181 +b=6371007.181 +units=m" then get the upperleft and lower right corners’ lat/lon. But they are different from the boundary in the website. As shown below:

https://search.earthdata.nasa.gov/search/granules/granule-details?p=C186286578-LPDAAC_ECS&g=G1552253044-LPDAAC_ECS&m=22.11328125!108.703125!3!1!0!0%2C2&tl=1531459844!4!!&q=MCD12&ok=MCD12&sb=113.765625%2C23.765625%2C123.2578125%2C31.5703125&ac=true

enter image description here

Why do the tiles in the web site seem to be overlapping?

One Answer

I would think something is not right with your longitude and latitude calculation.

The UpperLeft and LowerRight limits return here other long/lat.

In QGIS that layer shows the LowerLeft and UpperRight limits, I copy the calculation of those coordinates as well.

calculate

The vertices coincide on the site.

Answered by Gabriel De Luca on December 23, 2020

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