I have had the same problem with southern hemisphere Landsat being
registered as northern hemisphere with negative northings. The best
solution I found was to reproject the image. You can use GDAL with
something like
gdalwarp -t_srs '+proj=utm +zone=34 +south +datum=WGS84' -srcnodata 0
-dstnodata 0 -multi -of GTiff -co COMPRESS=LZW -co TFW=true -co
INTERLEAVE=BAND $1 Z34S_$1
where $1 is the name of the original file (the output file has Z34S_
prepended). I just put this into a script file and call it from the
command line, or from another script if you have a list of images to
convert.
Regards,
Roland
Micha Silver wrote:
Agustin Lobo wrote:
No, what I was doing was different:
I was setting the project to 18S (not 18N) with OTF reprojection, the
raster to 18N
and the vector layers got reprojected to 18S but the raster
was not displayed.
Since QGIS doesn't deal with on-the-fly reprojection of rasters, we
know that you have to set the project CRS to whatever projection the
raster is in. In this case, since the Landsat are (wrongly) set to UTM
N, I guess you have to stay with that in order for vectors to be
properly registered.
Cheers,
Micha
I was expecting the raster to be located in the S hemisphere because
the coordinates are negative. In TNTmips, as the coordinates are
negative, even if the raster CRS is set
to 18N, the raster is displayed in the S hemisphere. Not sure if this
is what qgis should do, though, as we are dealing with wrongly annotated
raster layers: in UTM, S is S, not negative N.
On the other hand, I assumed that if you set the project to 18N, then
the vector layers would projected to the N hemisphere.
But have tried defining the project as 18N as you say, used
Coordinate capture to check lon,lat, and actually get correct lon,lat
coordinates (in the S
hemisphere). The vector layers are reprojected to
18, no matter the S or N, the original latitude correctly defines the
hemisphere.
So it works "your way", thanks!
Agus
Micha Silver wrote:
Hi Agus:
I am actually able to do just that. I also am using some Landsat
GEOCover images from below the equator, projected, as you say in UTM
39_N_.
I load the raster, set the project CRS to that (UTM Northern)
projection, and enable OTF projection. Then I can overlay vector
layers, which are WGS84 Lon-Lat., and they are correctly located.
It's usually not very helpful to say "works for me" but...
Anyway, HTH,
Micha
Agustin Lobo wrote:
The global set of Landsat images on GEOCOVER
https://zulu.ssc.nasa.gov/mrsid/mrsid.pl
is on UTM/WGS projection
but with the Southern hemisphere tiles as UTM zones in the N with
negative coordinates. For example, a tile that should be at 18S is
actually 18N with negative coordinates
("Non-standard UTM definition: For the southern hemisphere, the
GeoTiff files
contain positive zone numbers with negative northing coordinates")
https://zulu.ssc.nasa.gov/mrsid/docs/GeoCover_circa_2000_Product_Description.pdf
As we have some vector layers on geographic coordinates WGS84 and a
Geocover tile for 18S,
I've set the project as 18S, enabled CRS reprojection on the fly,
and set
the raster CRS to 18N. Unfortunately, QGIS does not display the
raster, even
selecting zoom to layer extent. (Using Mimas).
This is probably not a problem of QGIS, the Geocover projection is
just wrong,
but would like to know if there could be a way to circumvent this
problem to
be able to use GEOCOVER tiles of the S hemisphere within QGIS.
A way could be making a world file with the Georeferencer plugin,
but perhaps
there is a more general way.
Thanks
Agus
_______________________________________________
Qgis-user mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/qgis-user
This mail was received via Mail-SeCure System.
_______________________________________________
Qgis-user mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/qgis-user
This mail was received via Mail-SeCure System.
_______________________________________________
Qgis-user mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/qgis-user
_______________________________________________
Qgis-user mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/qgis-user
