[mura_gadi (Steve)]

Thanks JA - have updated the link.


For Trivia:

TYVM for your link it click some old memory mine didn't with the altitude data.

From what I read the under lying dataset is MODIS for the altitude, which is based on 250m squares. These squares were referred to as DEM blocks when I was a GIS user, someone else more current can say if that's a 30sec DEM.

DEMS.
DEM squares get smaller as you move away from the equator. (More accurate as you move N/S, exceptions see last point)
DEM altitude is normally a mean average of a small amount of points. (Its not many data points 16/25 4x4/5x5 grid points sort of thing).
DEMs are prone to error near slopes/buffs/cliff/ravines etc where you can get a large variance in the 250m block.


*MODIS is legacy stuff, so I'd be pretty sure the number of read points in a given grid square would be limited due to the size of the data collection. Been a long time since 30secs DEMs were the end game.

To save the high school brain from being woken - mean average is the lowest and highest point removed and the average of the remainder(I think...).