While HiRISE, HRSC, THEMIS, MOLA Teams release their products in formats which are map projected (GIS-ready with some caveats), this is not true for CTX images. HiRISE are released as geoJpeg2000 (tip
), HRSC are released as well-labelled map projected PDS images and GeoTiff
!, THEMIS IR released as a derived mosaics controlled
(and you can process them in THMPROC
). MOLA DEMs
released in map projected PDS formats.
But for CTX you have process them in ISIS or POW. Or do you...?
Obviously there is Jmars
GIS to view them, but if you want them in your own GIS, with a little scripting help, you can get them almost fully processed from ASU's Mars Space Flight Facilities' CTX search website (and very nicely stretched). Although not all images will work in all GISs because of a potential longitude system issue (see below). http://viewer.mars.asu.edu/planetview/inst/ctx#startUPDATE, Oct. 2015: ASU is slowly rolling out properly labeled GeoJpeg2000 CTX images. It makes this post unnecessary - which is great!
So let's try this image. This is a method from loooonggg ago that I actually had to revive. But it seems to work.
(1) download both the jpeg2000 and
ISIS header from the ASU site. If you load the (yes map projected) Jp2 file there is NO geospatial header in the header - ahhh -- whaattt.... So let's "fix" it.http://viewer.mars.asu.edu/planetview/inst/ctx#/planetview/inst/ctx/B07_012195_1750_XN_05S222W
(2) download my isis3world.exe or isis3world.pl (*nix machines) script into the same directory. See the date on those apps -- 2009! ftp://pdsimage2.wr.usgs.gov/pub/pigpen/Perl/
(3) run this in a command line on the ISIS3 header. tip: in Windows, shift right click your directory and click on "open command window here".
> isis3world -J -prj B07_012195_1750_XN_05S222W.scyl.isis.hdr
> perl isis3world.pl -J -prj B07_012195_1750_XN_05S222W.scyl.isis.hdr
-- that is a capital "-J" not lowercase. This makes an old-school GIS worldfile and projection file. But you need to attach the projection file to the image so.
(4.1) In ArcCatalog, stand-alone app or the pop-up window in ArcMap, right click on the B07_012195_1750_XN_05S222W.jp2 , select properties. Under "Spatial Reference" click edit... Now under the globe icon pull-down select "import" and select the newly created file B07_012195_1750_XN_05S222W.prj. While you are in the image's properties, select the NoDATA "edit..." and set band1 to "0".
(4.2) in GDAL, you can attach the prj virtually (this VRT file should also work for ArcMap)
> gdal_translate -of VRT -a_srs "ESRI::B07_012195_1750_XN_05S222W.prj" -a_nodata 0 B07_012195_1750_XN_05S222W.jp2 B07_012195_1750_XN_05S222W.vrt
Now use the VRT file to open the image in QGIS, Arc, etc. (any GDAL supported GIS). Or translate to a GeoTiff in GDAL. gdal_translate B07_012195_1750_XN_05S222W.vrt B07_012195_1750_XN_05S222W.tif"
lonsys issue: If you drag the image into you GIS and it complains about the image's extent (or doesn't draw it), that is because the image is not using the lonsys recommendations below. There is a method to move it using the georef toolbar, shift button, and radius * PI (but that is for another time). BTW, in VRT you can just edit the X Offset.
I also have an old ArcMap toolbox batch
method to attach many *.prj file to many images but I haven't tested in a long time.
Write to ASU... ;-) and ask for geoJpeg2000 files! We did and they now support geoJpeg2000!
tip -- again GIS rule for processing:
if lonsys = 180 then set clon = 0 (or center of image) --- recommended for ArcMap
if lonsys = 360 then set clon = 180 (or center of image). --- works in ArcMap not Arcglobe or Google