[Gdal-dev] srtm warping question

[heinsm]

Thanks Frank. I was wondering the differences between Int16 and CInt16.  I
see now in OpenEV it shows complex coordinates.

Anyways, great news!  --(you're going to laugh at this solution).  The
problem all along was that I wasn't reprojecting into an appropriate utm
zone.  Should have been using zone ~19 for the reprojection of N43W71.

the reprojection now works flawlessly...

For furture user searches here are my BIL HDRs and commandlines I used for
SRTM N43W71:
1. rename SRTM .hgt to .bil
2. create .hdr with same filename as SRTM to describe the ESRI binary format
and to help georeference the raster
see:
http://www.esri.com/library/whitepapers/pdfs/eximgav.pdf
ftp://e0srp01u.ecs.nasa.gov/srtm/version2/Documentation/Quickstart.pdf

(for example N43W71.hdr it would be:)
BYTEORDER           M
LAYOUT              BIL
NROWS               1201
NCOLS               1201
NBANDS              1
NBITS               16
BANDROWBYTES        2402
TOTALROWBYTES       2402
BANDGAPBYTES        0
NODATA              -32768
ULXMAP              -70.99958333333333
ULYMAP              43.999583333333333
XDIM                0.000833333333333
YDIM                0.000833333333333

3. Create appropriate .prj file with same filename to describe source
projection
see:
http://support.esri.com/index.cfm?fa=knowledgebase.techarticles.articleShow&d=14056

(for example N43W71.prj it would be:)
GEOGCS["wgs84",DATUM["WGS_1984",SPHEROID["wgs84",6378137,298.257223563],TOWGS84[0.000000,0.000000,0.000000]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]


4. use gdalwarp to warp original BIL into target BIL coordinate projection
(for exampe, I used the follow to project into utm zone 19 --ensure a
physically close zone is choosen otherwise reprojection may be rendered
outside of the image;  giving you a result of all nulls/black)

gdalwarp -of EHdr -t_srs "+proj=utm +zone=19 +datum=WGS84" -ot Int16
c:\srtmtest\N43W071.bil c:\srtmtest\oututm.bil


-mike
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