gem install proj4rb
WARNING: Installing to ~/.gem since /var/lib/gems/1.8 and
/var/lib/gems/1.8/bin aren’t both writable.
WARNING: You don’t have /home/user/.gem/ruby/1.8/bin in your PATH,
gem executables will not run.
Building native extensions. This could take a while…
ERROR: Error installing proj4rb:
ERROR: Failed to build gem native extension.

/usr/bin/ruby1.8 extconf.rb install proj4rb
checking for pj_init() in -lproj… no
creating Makefile

make
cc -I. -I. -I/usr/lib/ruby/1.8/i486-linux -I. -D_FILE_OFFSET_BITS=64 -fPIC -fno-strict-aliasing -g -g -O2 -fPIC -I/sw/include -c projrb.c
projrb.c:2:22: error: projects.h: No such file or directory
projrb.c:3:22: error: proj_api.h: No such file or directory
projrb.c:26: error: expected specifier-qualifier-list before ‘projPJ’
projrb.c: In function ‘proj_free’:
projrb.c:36: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c:37: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c: In function ‘proj_alloc’:
projrb.c:45: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c: In function ‘proj_error_message’:
projrb.c:58: warning: initialization makes pointer from integer without a cast
projrb.c: In function ‘proj_initialize’:
projrb.c:87: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c:89: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c:90: error: invalid type argument of ‘unary *’ (have ‘int’)
projrb.c: In function ‘proj_has_inverse’:
projrb.c:108: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c: In function ‘proj_is_latlong’:
projrb.c:119: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c: In function ‘proj_is_geocent’:
projrb.c:130: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c: In function ‘proj_get_def’:
projrb.c:141: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c:141: warning: passing argument 1 of ‘rb_str_new2’ makes pointer from integer without a cast
projrb.c: In function ‘proj_forward’:
projrb.c:153: error: ‘projLP’ undeclared (first use in this function)
projrb.c:153: error: (Each undeclared identifier is reported only once
projrb.c:153: error: for each function it appears in.)
projrb.c:153: error: expected ‘;’ before ‘pj_point’
projrb.c:154: error: ‘projXY’ undeclared (first use in this function)
projrb.c:154: error: expected ‘;’ before ‘pj_result’
projrb.c:157: error: ‘pj_point’ undeclared (first use in this function)
projrb.c:159: error: ‘pj_result’ undeclared (first use in this function)
projrb.c:159: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c:161: error: invalid type argument of ‘unary *’ (have ‘int’)
projrb.c: In function ‘proj_inverse’:
projrb.c:183: error: ‘projXY’ undeclared (first use in this function)
projrb.c:183: error: expected ‘;’ before ‘pj_point’
projrb.c:184: error: ‘projLP’ undeclared (first use in this function)
projrb.c:184: error: expected ‘;’ before ‘pj_result’
projrb.c:188: error: ‘pj_point’ undeclared (first use in this function)
projrb.c:190: error: ‘pj_result’ undeclared (first use in this function)
projrb.c:190: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c:192: error: invalid type argument of ‘unary *’ (have ‘int’)
projrb.c: In function ‘proj_transform’:
projrb.c:236: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c:236: error: ‘_wrap_pj’ has no member named ‘pj’
projrb.c: In function ‘Init_proj4_ruby’:
projrb.c:495: error: ‘DEG_TO_RAD’ undeclared (first use in this function)
projrb.c:499: error: ‘RAD_TO_DEG’ undeclared (first use in this function)
projrb.c:503: error: ‘PJ_VERSION’ undeclared (first use in this function)
make: *** [projrb.o] Error 1

Gem files will remain installed in /home/user/.gem/ruby/1.8/gems/proj4rb-0.3.0 for inspection.
Results logged to /home/user/.gem/ruby/1.8/gems/proj4rb-0.3.0/ext/gem_make.out

http://self.mestrona.net/blog/2009/gedruckter-zoombarer-stadtplan/

dyld: lazy symbol binding failed: Symbol not found: _pj_init
Referenced from: /Library/Ruby/Gems/1.8/gems/proj4rb-0.3.0/lib/proj4_ruby.bundle
Expected in: dynamic lookup

I’ve installed proj 4.6.1 from source and proj4rb 0.3.0 as a gem with no errors. Can anyone help? Are there perhaps some environment variables I need to set?