[Proj] Finnish KKJ in proj 4.4.9 - Linux vs. Windows

[Roger Oberholtzer]

On Wed, 2005-12-14 at 15:44 +0100, Roger Oberholtzer wrote:

> 
> I have sorted out using proj 4.4.9 to obtain KKJ X/Y values from WGS84
> LAT/LONG values.
> 
> To be more precise, I have this sorted out on Linux. I compiled the same
> 4.4.9 code on Windows using MS VC++ 6.0 and the makefile.vc in the proj
> source. The problem is that I do not get the same results on the two
> systems! The error is in the neighborhood of 100 meters.
> Has anyone used proj on Windows and had any such problem? I have used
> other similar libraries on both platforms before, so I did not expect
> this.
> 
> I was thinking of trying the 4.4.6 binary that is available for
> downloads, but it does not contain a proj.lib file, making linking
> problematic. Any reason there is not a windows binary of 4.4.9, and only
> of 4.4.6?


I have now verified that I am doing the exact same thing on both
platforms. I have attached a small amount of test data that demonstrates
what I am seeing. The data contains eight columns:

Columns 1 and 2 are the X/Y that an external reference system (customer)
claims the values should be.

Columns 3 and 4 are the X/Y that I get with PROJ on Linux. Matches
Columns 1 and 2 within acceptable limits. This was my first test of proj
that I initially reported and was happy with.

Columns 5 and 6 are the X/Y that I get with PROJ on Windows (MSVC++ 6.0
compiler). Do NOT match Columns 3 and 4, to which they should be almost
identical, and also are farther away from reference in Columns 1 and 2.

Columns 7 and 8 are WGS84 lats and longs in minutes. I have verified
that both the Linux and Windows calculations are using the exact same
values for these. These are the values that all calculations are based
on.

The PROJ command used on both Linux and Windows is:

Initialization:

    pj_init_plus("+proj=latlong +ellps=WGS84");

    pj_init_plus("+init=esri:2393");

Calculation:

    set lng and lat to the location in radians, then:

    pj_transform(fromProj, toProj, 1, 0, &lng, &lat, &alt):

The code on both platforms is the same. The utility that is doing this
also does other transforms, and these are always the same on both
platforms.  So, in a way I do not understand, there is some difference
that, by process of elimination, must be in the proj code.

Could there be any constant that proj defines if it is not defined by
the system? Like a PI or some other value? So if I have not included
some expected system file on the windows platform it could get some
different default value?

I would imagine that the altitude value is not used? Right?

The 'esri' file is the same on both platforms. It is the one that comes
with proj.

Any ideas (other than tell the users to do this on a Linux platform for
best results)?

-- 
Roger Oberholtzer
OPQ Systems AB

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