[postgis-users] Problems with PostGIS and Proj4 on Cygwin

[Armin Burger]

Dave,

I used Postgres 7.2.1/PostGIS 0.7.1 and Proj4.4.5. I tried to reproject
an Italian projection system (it is similar to UTM).

I had to modify a bit the makefile for Proj4 in order to continue the
'make install' procedure, but then it seemed to work. Maybe the
compilation/installation was not complete, anyway. I don't if that
matters, but I could not compile the dynamic libraries for Proj4, only
the static ones were produced. But PostGIS compiled with the USE_PROJ=1
option without complaining.

I will also try to test the cygwin version of Norman Vine.

Armin

>> Any ideas what could cause the problems on Cygwin? Problems with the
Proj
>> 4
>> installation?

> I just recently added some code to PostGIS that covers up a 'feature'
of
> proj4.
> If you attempt to do a NAD conversion for a point were there is no
'grid
> nad converting data', PROJ4 will fail.  I recently patched PostGIS so
> that it will re-try the projection w/o the NAD conversion.
> Unfortunately there is no way to get it to do a ellipsoid conversion
w/o
> doing a NAD conversion.  Perhaps your 2 version of postgis are
> different?

> Also, make sure you're using PROJ4.4.5 (not 4.4.4) because its NAD
> conversion is incorrect.

> PROJ4, by default, only actually uses the conus (the lower 48 states)
> and basic canadian 'grid nad converting data' - you have to modify one
> of PROJ4's .c files (pj_datums.c) to get it to use other ones.

> I dont know of any differences between the linux and windows versions
of
> PROJ4.  What is the version number used by windows?  Which version of
> PostGIS are you using?

> dave

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