Newbie question: calibrating maps

wonk · November 15, 2008, 8:50pm

Hi,
as new user I first want to test the maps. I want to export a map for Oziexplorer ( it uses image maps).
It is easy to export the image file, but I do not understand from the wiki, how to calibrate it. It seems to me from the wiki, that I have to show the calibrated points on the image and than create the calibration new with oziexplorer ???
Is there no image-file-format, which INCLUDES the calibration and can be converted in formats for different moving-map-programms?
Wolfgang

emj · November 16, 2008, 8:55am

At this moment no there is no such support, though if you ask Ozieexplorer to include support for Openstreetmap I’m sure they could add it quite easily if they have support for image tiling mechanisms.

How does oziexplorer want the georeference of images to be done?

JRA · November 16, 2008, 2:47pm

Hi,

Two alternatives if you don’t especially want to learn how to do calibration manually:

OSM Map at http://alpo.hassinen.googlepages.com/osm-map
Nik2img.py utility that is now in 0.2 version. It can be used to create maps which are georeferenced with ESRI world files, and those can be imported with OziExplorer. This involves installing PostGIS database, downloading osm2pgsql program and a little bit learning, but it would give fine results. For example I have now a Mapnik map covering the whole city of Helsinki as an OziExplorer map on a PDA and it seems to be perfectly georeferenced.

wonk · November 16, 2008, 8:25pm

Hi

Wow, that is a nordic language, I have no idea.

    Wolfgang

wonk · November 16, 2008, 8:51pm

Hi!

The calibration is written to a text-file, but the iamge-file is also converted in a for me unknown way.
I’ll try now, to write down the coordinates of the exported region. That should be the edges of the image. If I fix this coordinates to the pixel-counts of the images edge, it schould get a calibration???

                                   Wolfgang

emj · November 16, 2008, 9:45pm

Well. It’s a bit harder the images are rendered in a spherical mercator, and you should reproject the export coordinates in to that. These are not included because as far as I know there is no way to include that in the images you download.

Even though Finland is our brotherland and their cause is ours, Finnish is a Finno-Urgic language more relation with Hungerian than Swedish (scarily so). But then again it’s still Nordic…

JRA · November 17, 2008, 6:06am

Hi,

There is no need to understand much Finnish if you get the program installed. That goes by

download the zip
unzip it into c:\osm-map
run c:\osm-map\setup

After that find your area in the map window showing OSM slippy map. When you are satisfied press “Lataa kuvat” (“Download images”). It downloads the image tiles on the local computer. Then press “Tallenna kuva” (“Save image”) to save the downloaded images in a single mosaiced image file. If “Tallenna MAP” is selected it creates Ozi calibration file at the same and image is ready to be used in Ozi PC version, or to be converted to ozf3 format with Image to ofz program. You may contact the author and ask if he would like to translate the program.

wonk · November 17, 2008, 5:04pm

Hi!

Thank you.
It works after i found out, that is not possible to choose other directories.

                                       Wolfgang

wonk · November 17, 2008, 8:05pm

wonk:

Hi!

JRA:

There is no need to understand much Finnish if you get the program installed. That goes by

download the zip

unzip it into c:\osm-map

run c:\osm-map\setup

After that find your area in the map window showing OSM slippy map. When you are satisfied press “Lataa kuvat” (“Download images”). It downloads the image tiles on the local computer. Then press “Tallenna kuva” (“Save image”) to save the downloaded images in a single mosaiced image file. If “Tallenna MAP” is selected it creates Ozi

Thank you.
It works after i found out, that is not possible to choose other directories.
                                       Wolfgang

Hi,
as far as I see, the program has a small bug. In the map-file in the 9th line, I find “Map Projection,Transverse Mercator”. In my opinion this should be “Map Projection,Mercator”. With this correction I get exact positions. Could someone check this? As Newbie I don’t want to write to the author, when I’m not sure.
Wolfgang

JRA · November 17, 2008, 10:09pm

You are probably right. Using Mercator was suggested in the Ozi mailing list when I asked about what projection to use with these spherical Mercator which are not directly supported by OziExplorer. I will check that some day and if it seems to be correct I can contact the author.
If you are using maps in PDA try also Osmarender layer. For my mind it is better for outdoor use.

wonk · November 19, 2008, 9:17am

Hi!

I use a PDA. Do you mean to alter layers to get other icons depending on the scale?
That would be useful.
I think, I would have to install Osmarender for that?

                                                  Wolfgang

JRA · November 19, 2008, 5:07pm

Hi,
I meant that OSM Map lets you select the layer in the main map window with the usual ble “+” button. Unfortunately not all of the servers on the menu are no more active and obviously they are hard coded in the program and user cannot add new servers. But Mapnik and Tiles@home seem to work.