jmckenna / libgeotiff

Official repository of the libgeotiff project

About LIBGEOTIFF:

This library is designed to permit the extraction and parsing of the "GeoTIFF" Key directories, as well as definition and installation of GeoTIFF keys in new files. For more information about GeoTIFF specifications, projection codes and use, see the WWW web page at:

http://geotiff.osgeo.org/

or the download archive at:

http://download.osgeo.org/geotiff/

Use of LIBTIFF

The default configuration assumes that the public-domain LIBTIFF package for reading and writing TIFF files has been installed, with the development kit (include files). The latest version of libtiff may be found at:

http://www.simplesystems.org/libtiff/

For this build to work you must use libtiff version v3.6.0 alpha or newer.

Use of PROJ

PROJ 6 or later is a required dependency of libgeotiff 1.5 or later. The latest version of PROJ can be found at

https://proj4.org/

Building LIBGEOTIFF:

Assuming that whatever TIFF library you use has been built, and installed may now build the rest of the geotiff library with:

% cd libgeotiff % ./configure --with-proj=/contrib/proj-6 % make

Common Configuration Issues:

o If you want to alter the compiler used, set the CC environment variable before running configure.

% setenv CC cc % rm config.status % ./configure % make clean % make

o If you want to control the compiler files, set the CFLAGS environment variable. This can be used to override the default optimization/debug flags for instance.

% setenv CFLAGS -O4 % rm config.status % ./configure % make clean % make

o If you want to force use of a locally built libtiff that was never "installed" you can point to the directory like this:

% rm config.status % ./configure --with-libtiff=/u/contrib/libtiff-3.6.0/libtiff % make clean % make

o If you have installed libtiff in a location other than /usr, then you can point to the install tree like this:

% rm config.status % ./configure --with-libtiff=/usr/local % make clean % make

o The logic to build shared libraries is pretty weak, and is likely to only work on systems with the GNU tool chain (gcc, and ld) installed. On other systems you can try hacking on Makefile after running configure. It may be necessary to set the GEOTIFF_SO macro to "libgeotiff.1.2.x" as it is made empty by default on systems configure doesn't think can build shared libraries.

Test Programs:

There are two demonstration test programs "makegeo" and "listgeo" that create and list-out the GeoTIFF tags and keys associated with a small TIFF file, as well as a full-featured utility called "geotifcp". These will all be built in the bin/ directory as a matter of course, though may require modification if you are not using LIBTIFF, as they make explicit calls to LIBTIFF for opening the files and setting the tags. To run them simply call:

% bin/makegeo % bin/listgeo newgeo.tif

to generate and list an example GeoTIFF file. To see the "geotifcp" utility in action, first call:

% bin/listgeo newgeo.tif > metadata.txt

to create a GeoTIFF metadata file "metadata.txt", and then

% bin/geotifcp -g metadata.txt newgeo.tif newer.tif

to copy the TIFF file newgeo.tif to newer.tif, using the GeoTIFF metadata as stored in "metadata.txt". See "docs/manual.txt" for further uses of geotifcp.

To convert a projection metafile, an ESRI world file, and a raw TIFF file into a GeoTIFF file do something like the following:

% bin/tiffcp -g metadata.txt -e abc.tfw abc.tif geo_abc.tif

Non-Standard Configuration:

If you are using a TIFF software package other than libtiff, then you must override the TIFF file methods used in LIBGEOTIFF. To do this, go into directory libgeotiff and edit the files:

"geo_tiffp.h"
"geo_tiffp.c"

which contain all of the TIFF externals. You will need to define your own versions of the TIFF tag reading, writing, and memory allocation calls. See the comments of those two files to see what needs to be changed. Also, whatever software package you use will have to recognize the GeoTIFF tags listed in the include files, and permit variable-length arrays to be passed in to those tags.

Credits

o This library was originally written by Niles Ritter (also the primary author of the GeoTIFF specification).

o Eric Brown of Universal Systems, who contributed a bug fix to GTIFPCSToImage().

o Safe Software (www.safe.com) who supported by upgrade to use the EPSG 6.2.2 database for libgeotiff 1.2.0.

o Many others who contributed before it occured to me to maintain credits.