[GRASSLIST:4487] Re: hgt to bil (SRTM)

[William K]

I had to wrestle with this and here's what I figured out.  First, the 
cells in the SRTM are center-based, so you need to take into account 
1/2 the cell for the UL corner.  And there is a 1 cell overlap between 
tiles.  So, if you have a cell as your example:

1. add 1.00041666666667 to latitude for ULYMAP
	12.00041666666667
2. subtract 0.00041666666667 from longitude for ULXMAP
	43.9995833333

this will put the corner in the correct position 1/2 cell outside the 
upper-left.


On May 17, 2006, at 4:50 AM, ivan marchesini wrote:

> Dear Users,
> I'm trying to understand how to create the hdr file for the .bil srtm
> dem I downloaded....
> I have found too much different information... so I try with you....:
> if I have a N11E044.hgt file I have to rename the file to  N11E044.bil
> and then to create a N44E011.hdr file...
> can you help me to insert the right value in the ULXMAP and ULYMAP
> sections of the hdr file below.... ???
>
> BYTEORDER M
> LAYOUT BIL
> NROWS 1201
> NCOLS 1201
> NBANDS 1
> NBITS 16
> BANDROWBYTES 2402
> TOTALROWBYTES 2402
> BANDGAPBYTES 0
> NODATA -32768
> ULXMAP  ??????????????
> ULYMAP  ??????????????
> XDIM 0.000833333333333
> YDIM 0.000833333333333
>
>
> Thank you very much....
> Ivan
>
>
-----
William Kyngesburye <kyngchaos at charter.net>
http://webpages.charter.net/kyngchaos/

All generalizations are dangerous, even this one.