Importing BSQ/BIP/BIL files into R
On Thu, 12 Feb 2004, Jonathan Greenberg wrote:
I was hoping I could get some help with an import question. I work with remote sensing imagery which commonly comes in binary form in various interleaving formats (byte interleaved by line, by pixel, etc..). These files are 2d spatial x B bands in size, and I want to be able to extract the band values from various pixels (so each line of data into R would be one pixel x B bands). What's the easiest way of importing this type of data? These files are often massive (4 - 16gb), so is there a way of having R read the lines of the data as I am running the process, rather than trying to load the whole image into memory at once? Thanks! For those of you with remote sensing experience, I'm using RSI's ENVI package.
You may like to use the R bindings to GDAL in package rgdal. You need to have installed GDAL first, and then install the R source package, so this works on Unix/Linux, and probably Mac OSX, but on Windows you need to build GDAL under MSYS/MinGW, and alter Makevars in rgdal/src by hand. Because rgdal binds to GDAL, it allows selection of subscenes. If you have the PROJ.4 library installed too, it may provide geo-referencing, but YMMV. Contact me off-list if this is worth following up. Roger
Roger Bivand Econonic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Breiviksveien 40, N-5045 Bergen, Norway, voice: +47-55959355, fax: +47-55959393; Roger.Bivand at nhh.no