[Xastir] Heads up for Ubuntu 8.04 users of libproj

[Tom Russo]

This is sort of a irrelevant for most Xastir users, but could be 
significant to any of you who have installed libproj for use by other 
programs, as I do.

I have just discovered that the version of "proj" installed by Synaptic Package
Manager (or apt-get) on Ubuntu 8.04 ("Hardy") appears to have been built 
without correct datum transformation information.  I discovered this while 
writing a bit of code that used libproj and noticed that when I tried to mix 
and match NAD27 and NAD83 lat/lon coordinates it wasn't doing any of the 
transformations right.

You can check your install of proj by executing the following command:

cs2cs +proj=latlong +datum=NAD83 +to +proj=latlong +datum=NAD27

and giving it the following input:
106d38'17.94"W 35d15'40.14"N

It should produce the following output if it's working properly:
106d38'15.843"W 35d15'39.993"N -0.000

When I used the version of cs2cs that was installed by Synaptic (or apt), it 
printed the same coordinates as the input, which is completely wrong.

This has NO impact on Xastir users at all, because Xastir does not use the
proj library for datum conversion, and only does any datum conversion in the
geotiff map display --- it does so with a set of routines that Curt wrote, not
with libpproj.  So  this is totally irrelevant to 99.9% of Xastir users.  As
far as I know, Xastir only requires proj to be installed because libgeotiff
needs it internally --- as far as I know, it needs proj only for functions we 
don't even use.

But if you're on Ubuntu 8.04 and use libproj for anything else, you have to 
pitch the one installed through the package system and install from source with 
the correct datum shift grids (a two step process that requires putting the
grid shift data into the source tree and then building the code).  Since 
the packages for libgeotiff depend on the package for proj, you therefore have
to build *that* from source, too.  Again, almost no Xastir users would need to
bother except those who use proj for programs other than Xastir.

If someone out there is using 8.10, could you check whether the proj package 
there has the same error?  I have chosen to stick with 8.04 for its full
3 year support term and not upgrade to a completely new version every 6 months.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
  In some cultures what I do would be considered normal. 
                                  -- Ineffective daily affirmation