[Mapserver-users] Projection woes, Revisited.

[Ed McNierney]

Chip -

Thanks for posting all the data and samples.  I think it might be helpful to simplify things a bit.

Here's what I see.  You have two boxes, of the same extents, one in Wisconsin South NAD27 Feet, the other in Wisconsin South NAD83 Feet (both LCC projections).  Let's ignore everything else and try to get those two to overlap.

First, you might want to use the EPSG codes for these projections.  They're more obtuse, but they protect against typos when spelling out all the projection parameters.

For Wisconsin State Plane South NAD27, the code is 32054, and for NAD83 it's 32154.  So each of your projection blocks can become:

# NAD27

PROJECTION				
	"init=epsg:32054"
END

# NAD83

PROJECTION
	"init=epsg:32154"
END

This is similar to your last example.  In looking at your last example, however, one wonders whether the NAD83 box is right there UNDERNEATH the red NAD27 box - if it were projecting properly, how could you tell?

Can you set up another example that does the following:

1. Uses the EPSG codes for projections
2. Defines the output projection to be Wisconsin State Plane South NAD83
3. Defines only two input layers
4. Makes the OUTLINECOLOR for the NAD27 box be "255 0 0" (red) and removes the COLOR statement, so it's hollow?

Then let us take a look.  Thanks!

	- Ed


-----Original Message-----
From: Hankley, Chip [mailto:Chip.Hankley at GASAI.Com]
Sent: Tuesday, February 04, 2003 1:18 PM
To: Ed McNierney; MapServer List (E-mail)
Subject: RE: [Mapserver-users] Projection woes, Revisited.


Ed (and everyone) -

OK... showing my ignorance here. I ALWAYS use pre-compiled binaries (I'm
trying to overcome this personal defect...). Anyway, I'm only beginning to
understand the compilation sequence, and how all the parts fits together...
so, patience please!

When I download the binaries from the Mapserver site, the only PROJ related
file that comes with the distribution is the epsg file. I have this in
C:\PROJ\NAD.

I did download the datum shift files (from remotesensing.org) and simply put
them in the NAD subdirectory, but this doesn't seem to make any difference
(not suprisingly). I'm assuming that when you say that I "need to have these
datum shift files set up and PROJ pointed to them in order to do the shift"
that this is an operation that would occur when compiling the PROJ4 library
prior to compiling MapServer? Have I got that sequence right?

If this is right, why don't the pre-compiled binaries that exist already do
this (just curious)? Seems like datum shifts would be a fairly common
task...

Chip



> -----Original Message-----
> From: Ed McNierney [mailto:ed at topozone.com]
> Sent: Tuesday, February 04, 2003 11:36 AM
> To: Hankley, Chip; MapServer List (E-mail)
> Subject: RE: [Mapserver-users] Projection woes, Revisited.
> 
> 
> Chip -
> 
> The PROJ4 FAQ refers to the work you need to do to have the 
> NAD datum shift files built - the code doesn't change.  Do 
> you have your PROJ installation in C:\PROJ?  Whereever it is, 
> look in that directory for a NAD subdirectory and files named 
> CONUS, NAD27, NAD83, ALASKA, etc. (no file extensions).  You 
> need to have these datum shift files set up and PROJ pointed 
> to them in order to do the shift.
> 
> 	- Ed
> 
> Ed McNierney
> President and Chief Mapmaker
> TopoZone.com / Maps a la carte, Inc.
> 73 Princeton Street, Suite 305
> North Chelmsford, MA  01863
> ed at topozone.com
> (978) 251-4242 
> 
> 
> -----Original Message-----
> From: Hankley, Chip [mailto:Chip.Hankley at gasai.com]
> Sent: Tuesday, February 04, 2003 12:17 PM
> To: MapServer List (E-mail)
> Subject: [Mapserver-users] Projection woes, Revisited.
> 
> 
> OK, I'm still unable to do a datum shift between NAD27 and NAD83.
> 
> I've tried to strip out all of the non-essentials and come up with an
> example. You can view it on-line at:
> 
> http://207.250.243.23/projtest/projtest.html
> 
> Basically, I can reproject data FINE when it's in the same 
> datum. It's when
> I try to do a datum shift that things don't work. I'm using one of the
> pre-compiled binaries from the MS site. Here's my version info:
> 
> MapServer version 3.6.3 OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP 
> SUPPORTS=PROJ
> SUPPORTS=TTF SUPPORTS=WMS_SERVER SUPPORTS=WMS_CLIENT 
> INPUT=TIFF INPUT=EPPL7
> INPUT=JPEG INPUT=OGR INPUT=SHAPEFILE 
> 
> Could the problem be with the way PROJ4 was compiled into 
> this binary? The
> PROJ4 FAQ has some specific instructions for building PROJ4 
> to support datum
> shifts... (see http://www.remotesensing.org/proj/faq.html). I 
> don't know how
> to check this on the binary...
> 
> TIA!
> 
> Chip
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