I have 25km by 25km squares of the world in a relational database. Each square has coordinates for the top left and lower right corner as latitudes and longitudes. Each square also has an index ilat and ilong value starting at the lower left corner with (0,0) to (maxlong, maxlat) for the top right corner. Each square also has measurements (X, Y, Z). I would like to transform this data into the ASCII Grid Format:
link
for each measurement. Here is some example data taken from the Internet:
ncols 419
nrows 407
xllcorner 823678.99884033
yllcorner 1151760.4752197
cellsize 14.314150820378
NODATA_value -9999
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999
I understand what ncol and nrows is but I am not too sure about xllcorner, yllcorner, cellsize. Could someone please advise me what these values would be in my situation? Do you reckon I can transform my data from my tile/square format into the ASCII Grid Format.
Actually my grid is as follows:
Latitude is in the range [-90 ... 90] and longitude [-180 ... 180]. A square’s cell’s size is 2.5 degrees
I have been told that corresponds to 25 square kilometres.