Kjell,
On Jul 7, 2008, at 2:03 PM, Kjell Are Refsvik wrote:
On 7. juli. 2008, at 19.19, Dane Springmeyer wrote:
Hi Kjell,
...
You are not alone. Projected coordinate systems can confuse
beginners and experts alike.
:-)
Well, given my completely newbie status as a GIS/Geodata user, I am
very grateful for your patience, explaining these things to me.
no problem. Please do consider consulting the mailing lists of the
specific software that you are using as well.
...
Second, I can see now (from your image links) that your data was
collected in Lebanon, which means that the link I directed you to
will not provide a reference to the correct UTM zone.
There are two possible UTM zones for Lebanon: UTM 36N or UTM 37N.
WGS 84 / UTM zone 36N
http://spatialreference.org/ref/epsg/32636/
WGS 84 / UTM zone 37N
http://spatialreference.org/ref/epsg/32637/
36N seemed to have done thr trick:
PROJCS["WGS_1984_UTM_Zone_36N",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",33],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",0],UNIT["Meter",1]]
great.
Or use the command line program ogr2ogr to reproject your shapefile
to WGS84/EPSG 4326 from your assumed UTM projection. That command
would look like:
$ ogr2ogr -s_srs EPSG:32636 -t_srs EPSG:4326
lebanon_points_wgs84.shp lebanon_points_utm36N.shp
Splendid. I will have a go at that.
Note that if you want to use ogr2ogr like this you can skip the step
of assigning the projection by manually adding a .prj file. In one
fell swoop you are telling ogr that the projection is UTM and a given
zone without requiring ogr2ogr to read the projection information from
the .prj file.
Yes, they are GUI applications... but don't you just need to
automate the processing of your GPS data?
No. In addition to use a unix shell-script to harvest and prepare
geodata from my images using exiftool and some basic text formatting
commands in unix, I also need to prepare the necessary shapefiles
and hopefully find some way of (using shell-scripts) atomatically
export png files to make up the map.
A quick sketch (using a screengrabbed OpenStreetMap) here:
http://www.ia-stud.hiof.no/~kjellare/misc/programming_goal.png
Okay. Well that graphic is nice and simple. However, getting there
through automation will be not be as easy as using Qgis to layout you
map graphics and then exporting them into another design program like
Scribus, Inkscape, or the GIMP to do your photo layout.
I'm assuming that you want to do this with desktop based tools. If you
are up for installing apache then you could utilize a variety of web
based toolkits to automate the generation of the map graphic and the
photo layout. I'd look into Openlayers and Geoserver (in addition to
Mapserver and Mapnik), and any web framework with a powerful
templating engine like django.
If you want to stick to the desktop Mapserver and Mapnik do have the
ability to create map graphics on the command line, but it's not as
simple as automating the conversion of a shapefile to png. You need to
style and label your shapefile data of points along with basemap data.
Therefore you will be looking to render multiple layers into a single
raster png. Shp2img of the mapserver project or a the use of mapnik
python bindings will be able to do this without resorting to
installing and setting up a webserver, but you'll still need to create
a MAPFILE that defines the styling and labeling.
If you want to create one PNG raster then QGIS or uDIG are the
ideal tools to layout your png map. Just open all your shapefiles
(you can even merge them all into one shapefile with ogr2ogr),
label them, then zoom to each group and export a PNG file....
If you truly want to automate the creation of *many* PNG graphics
then you'll need to look into scripting a mapping toolkit like
Mapserver or Mapnik.
Ouch. I see now that what looked like a way out of this (shp2img) is
not accepting a shapefile as a input.
No, shp2img needs a MAPFILE as input (the mapfile points to your
shapefile(s) - or other datasources - and tells mapserver how to
render them):
http://mapserver.gis.umn.edu/docs/reference/utilityreference/shp2img
I'd recommend looking into the QGIS "Export to mapserver" plugin as
well.
Mapnik can use an XML based MAPFILE, but has no command line utility
to generate a png from the MAPFILE, but simple script examples can be
found here:
http://trac.mapnik.org/wiki/XMLGettingStarted#Step2
Dane
Any idea on the complexity in getting the above scripting to work?
Not too complex, but you will need to read up on how to create a
MAPFILE.
Sincerely,
Kjell Are Refsvik
Norway
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