[Mapserver-users] Proj problems

[Vincent Schut]

Gerry,
please if you reply, include the list. Others might want to follow our 
discussion, maybe learn from it, correct me, or even add better ideas...

There are a bunch of documents on the internet that say proj=longlat (google 
for it, you'll be stumped!). I believe they are wrong... However, if it is in 
the mapserver docs/wiki somewhere, we should track that down and have it 
corrected.
I see about the meteorologists being not gis people...
I might have overlooked a main projection block.
According to the gdal docs, the world file for your gif should be named .wld 
(if your gif is radar.gif, your world file should be radar.wld). Then 
mapserver (gdal) should automatically recognize it. .tfw means Tiff World 
File, thus should be used for tiffs...
If it worked without reprojecting, adding a valid projection block into the 
map block and accordingly changing the extent and eventually units should 
suffice to get your output in a different projection. However, I would try to 
start simple to get that working. The degree of confusion did not escape my 
eye ;-) Once you got reprojection working with one layer, adding more layers 
that previously worked should not be any problem.
I am not a projection expert and certainly not Lambert, but a typical thing to 
forget/do wrong might be to have an extent that does not fit the used 
projection...

Well I hope you'll succeed somehow.
Cheers,
Vincent.


On Friday 01 August 2003 13:42, Gerry Creager N5JXS wrote:
> Helps a lot.  Thanks!
>
> One note:  Somewhere in the docs or wiki, and I don't recall now, the
> reference is to 'proj=longlat'... I recall seeing it and scratching my
> head, but, well, documentation is documentation, and the folks who write
> it are usually better informed than I am.. that's why I'm reading THEIR
> docs!
>
> So: Let me go make some changes
>
> As for complexity, it works sans projection info, as I've gotten
> everything into a geographic projection, but the presentation is
> criticized since the tpical meteorologist inour parts believes that
> nothing can be represented save in Lambert, and appaently the rain can't
> fall nor the wind blow, unless all maps are thus represented.  So, I'm
> trying to reproject.
>
> Oh, and I thought I DID have a main projection defined.  There are
> several in there, and I thought I'd left one in place, active.  If not,
> it's representative of the degree of confusion I've managed to create
> for myself.
>
> Finally, there is a world file for the gif (tfw) as well as one for the
> png (pngw).  Now I've got to figure out how to reference it.
>
> Thanks again.  These tips might get me on-track.
>
> Regards,
> Gerry
>
> Vincent Schut wrote:
> > Gerry,
> >
> > I don't presume I will solve your problem, but let me add me 2 cents:
> >
> > - I saw a line 'proj=longlat'. This is definitely not going to work, as
> > it should be 'proj=latlong'.
> > - I think you can't use a full proj definition and a epsg:xxxx line
> > together in the same projection block (in the PWV layer). An epsg line is
> > a shortcut to a full projection definition. Either use that, or define
> > the projection yourself in the projection block, but don't do both, cause
> > you'll end up having 2 projections defined...
> > - mind that layers that do not have a projection defined in the map file
> > and do not have an internal projection definition (e.g geotiff files do,
> > but shapefiles don't have an internal projection def) are assumed to be
> > in the defined output projection of the mapfile. If they are not in the
> > same projection, there is a pretty big chance that they will fall outside
> > of your defined map extent.
> > - your mapfile is quite complex, having some different layers with
> > different projections. I'd say, try to start with a stripped down mapfile
> > with only one layer which is in the same projection as the output
> > projection, get that working, then start adding new layers one by one.
> > This greatly increases your chances of tackling the problem. Now it can
> > be anywhere in your file. - it might be on purpose but the mapfile you
> > attached doesn't have any main map projection defined: they are all
> > commented out. Don't forget to uncomment one, as you will need at least
> > one... And adjust the units according to the uncommented projection, e.g.
> > if you uncomment a utm proj, change units to meters. And of course change
> > your main extent accordingly.
> > - remove the minscale and maxscale items from the web block while
> > debugging to prevent them to fool you.
> > - STATUS should be on|off|default, not false, according to the documents.
> > I wonder why you don't get a parse error about that. Or it might work but
> > be undocumented ;-) BTW while debugging I always prefer status default,
> > because that makes sure your layers will be displayed, while with status
> > on you will have to activate them explicitly in your cgi request. For
> > more info on this search the mailing list archives.
> > - for raster files that are not in some remote sensing format and thus do
> > not contain any coordinate information (like the radar layer: it's a gif
> > file) you probably need to use a world file to define the corner
> > coordinates and raster cell size.
> >
> > Hope these help...
> > Good luck,
> >
> > Vincent.
> >
> > On Thursday 31 July 2003 23:28, Gerry Creager wrote:
> >>OK, I'm pretty much at my wits' end.  I've tried looking at this on a
> >>time-available basis, and I'm just not getting it.
> >>
> >>A mapserv -v yields the following:
> >>[root at mesonet cgi-bin]# ./mapserv -v
> >>MapServer version 3.7 (development) OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP
> >>OUTPUT=PDF OUTPUT=SWF SUPPORTS=PROJ SUPPORTS=TTF SUPPORTS=WMS_SERVER
> >>SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=GD2_RGB INPUT=OGR
> >>INPUT=GDAL INPUT=SHAPEFILE
> >>
> >>PROJ support is there, so it should allow me to specify a projection
> >>section, either with the EPSG shortcut or the long way, with everything
> >>specified.  I've tried that and what I end up with is essentially a
> >>blank screen...
> >>
> >>If someone's got suggestions, great.  The mapfile is attached.  I'll
> >>keep looking at it, but it's looking like my hair's on fire and I can't
> >>get it put out...
> >>
> >>Thanks in advance,
> >>Gerry

-- 
______________________________________
Vincent Schut
Sarvision B.V.
Wageningen, The Netherlands
www.sarvision.com