Initial maps and other things

[Ross Scanlon]

Hi All,

Do we still need the following in data/maps

map_LightYellow.png
map_WhiteBall.png
map_BlueBall.png
map_White.png
top_LightYellow.png
top_WhiteBall.png
top_GPSWORLD.jpg
top_White.png

or could these be moved to say data/maps/testing?

Additionally can we update the nasa maps to say some generated from tiles@home to give a better initial impression.


--
Cheers
Ross
_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[Joerg Ostertag (Tettnang)]

On Thursday 06 August 2009, Ross Scanlon wrote:

> Hi All,
>
> Do we still need the following in data/maps
>
> map_LightYellow.png
> map_WhiteBall.png
> map_BlueBall.png
> map_White.png
> top_LightYellow.png
> top_WhiteBall.png
> top_White.png

I think we can remove these.

> top_GPSWORLD.jpg

You'll have to check this one. Maybe it's the worldmap for max-zoom.

> or could these be moved to say data/maps/testing?
>
> Additionally can we update the nasa maps to say some generated from
> tiles@home to give a better initial impression.

Maybe we can add both?

-
Joerg


_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[hamish_b]

Ross wrote:
> > Do we still need the following in data/maps
....
> > top_GPSWORLD.jpg

Joerg:
> You'll have to check this one. Maybe it's the worldmap for max-zoom.

this is the whole-world map and it should be kept.

also the light-yellow one should be kept for when no maps are selected
in the Map Control window.


> > Additionally can we update the nasa maps to say some generated from
> > tiles@home to give a better initial impression.

my initial reaction is "no; won't work". but if you could provide an
example image or URL of what you think would look better I'd of course
look at it. We have the means to convert any GIS map to gpsdrive tiles,
but not the ability to convert Web Tiles to GIS maps due to map projection
issues ... it looks ok in the browser but mathematically it has been
distorted so no good for an app which has to calc the position of an
overlay.

> Maybe we can add both?

tiles@home (and anything else from OSMarender or 2^n tile servers) is
fundamentally broken at the world scale (badly noticeable at any map
scale beyond about 1:250,000)  see the code for downloading OSM tiles
and the source forge bug for details.

try downloading the 1:147M worldwide OSM map with options->maps->download
and play around in explore mode and turning on the grid overlay. (zoom in
to magnifying glass 8x until the mercator-math no longer explodes)
or even 1:2.3M download and try to explore-more click exactly on a feature
not at the center of the map.

then try the same with downloading the NASA LANDSAT maps to see how it
could work.


sure we can improve our projection code, but we can't fix mercator's
limitations; and mosaicking tiles of varying central lat just compounds
the problem. that is to say, IIUC, tiles@home would have to fix their
projection rendering issues first. (aka the "osmarender bug" -- I'm not
holding my breath but hope to someday be pleasantly surprised by seeing
it fixed by Google Maps et al.)

If someone could find a (public/not 6 months out of date) WMS server for
OSM data it would help.


Hamish



     

_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[Ross Scanlon]

On Thu, 6 Aug 2009 00:01:41 -0700 (PDT)
Hamish <hamish_b@...> wrote:

> > > Additionally can we update the nasa maps to say some generated from
> > > tiles@home to give a better initial impression.
>
> my initial reaction is "no; won't work". but if you could provide an
> example image or URL of what you think would look better I'd of course
> look at it. We have the means to convert any GIS map to gpsdrive tiles,
> but not the ability to convert Web Tiles to GIS maps due to map projection
> issues ... it looks ok in the browser but mathematically it has been
> distorted so no good for an app which has to calc the position of an
> overlay.
>
> > Maybe we can add both?
>
> tiles@home (and anything else from OSMarender or 2^n tile servers) is
> fundamentally broken at the world scale (badly noticeable at any map
> scale beyond about 1:250,000)  see the code for downloading OSM tiles
> and the source forge bug for details.

Found this today and agree.  The initial maps would have to be all less than 1:250000 so no point really.

--
Cheers
Ross
_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[hamish_b]

Hi,

svn note:  in order to preserve file history "svn move" (or "svn
copy") should be used instead of "svn delete" + "svn add".


thanks,
Hamish

ps- I also moved top_LightYellow to testing/, as only
map_LightYellow was used by map_handler.c



     

_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[Ross Scanlon]

Hi Hamish,

Thanks.

First time I've tried this.

Cheers
Ross


On Thu, 6 Aug 2009 04:28:04 -0700 (PDT)
Hamish <hamish_b@...> wrote:

> Hi,
>
> svn note:  in order to preserve file history "svn move" (or "svn
> copy") should be used instead of "svn delete" + "svn add".
>
>
> thanks,
> Hamish
>
> ps- I also moved top_LightYellow to testing/, as only
> map_LightYellow was used by map_handler.c

--
Ross Scanlon <info@...>
_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[Ross Scanlon]

> On Thu, 6 Aug 2009 00:01:41 -0700 (PDT)
> Hamish <hamish_b@...> wrote:
>
> > > > Additionally can we update the nasa maps to say some generated from
> > > > tiles@home to give a better initial impression.
> >
> > my initial reaction is "no; won't work". but if you could provide an
> > example image or URL of what you think would look better I'd of course
> > look at it. We have the means to convert any GIS map to gpsdrive tiles,
> > but not the ability to convert Web Tiles to GIS maps due to map projection
> > issues ... it looks ok in the browser but mathematically it has been
> > distorted so no good for an app which has to calc the position of an
> > overlay.
> >
> > > Maybe we can add both?
> >
> > tiles@home (and anything else from OSMarender or 2^n tile servers) is
> > fundamentally broken at the world scale (badly noticeable at any map
> > scale beyond about 1:250,000)  see the code for downloading OSM tiles
> > and the source forge bug for details.

Does this problem apply to maps cached by gpsdrive when using mapnik?

My thought was to generate the maps in gpsdrive with map cache on then copy the applicable map file to the data/maps directory.

Only issue I have is that I only have the Aus/NZ osm data loaded in so could only generate those files eg map_Australia.png and map_NewZealand.png

--
Cheers
Ross
_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[Ross Scanlon]

On Fri, 7 Aug 2009 09:39:08 +1000
Ross Scanlon <info@...> wrote:

> Does this problem apply to maps cached by gpsdrive when using mapnik?
>
> My thought was to generate the maps in gpsdrive with map cache on then copy the applicable map file to the data/maps directory.
>
> Only issue I have is that I only have the Aus/NZ osm data loaded in so could only generate those files eg map_Australia.png and map_NewZealand.png

Here's an example of the cached mapnik map for all of Australia and New Zealand

http://www.4x4falcon.com/gpsdrive/maps/map_AusNZ.png

It could be changed to a different scale to just show only Australia or New Zealand


--
Cheers
Ross
_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[Joerg Ostertag (Tettnang)]

On Friday 07 August 2009, Ross Scanlon wrote:

> On Fri, 7 Aug 2009 09:39:08 +1000
>
> Ross Scanlon <info@...> wrote:
> > Does this problem apply to maps cached by gpsdrive when using mapnik?
> >
> > My thought was to generate the maps in gpsdrive with map cache on then
> > copy the applicable map file to the data/maps directory.
> >
> > Only issue I have is that I only have the Aus/NZ osm data loaded in so
> > could only generate those files eg map_Australia.png and
> > map_NewZealand.png
>
> Here's an example of the cached mapnik map for all of Australia and New
> Zealand
>
> http://www.4x4falcon.com/gpsdrive/maps/map_AusNZ.png
>
> It could be changed to a different scale to just show only Australia or New
> Zealand

Sounds like a nice Idea to prerender some OSM Maps and put them into the Cache
directory of Gpsdrive. This way you'd have already fast prerendered Maps of
OSM-GpsDrive. Maybe we can try how large (MB) the whole world in the first
two scales would be.

joerg
_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[hamish_b]

Ross wrote:
> Here's an example of the cached mapnik map for all of
> Australia and New Zealand
>
> http://www.4x4falcon.com/gpsdrive/maps/map_AusNZ.png
>
> It could be changed to a different scale to just show only
> Australia or New Zealand

could you throw up a waypoints.txt file or overlay grid lines to
check for obvious distortion/misalignment?

see e.g. http://hamish.bowman.googlepages.com/gpsdrivefiles#oz

I haven't tried this myself yet, but the NZopenGIS google group is
actively working on getting the NZ gov't road data into OSM, so
maybe I'll try soon.

http://linz.dev.openstreetmap.org/~JoeRichards/files.html
http://linz.dev.openstreetmap.org/~JoeRichards/
http://nzopengps.org


Joerg wrote:
> Sounds like a nice Idea to prerender some OSM Maps and put
> them into the Cache directory of Gpsdrive. This way you'd
> have already fast prerendered Maps of OSM-GpsDrive. Maybe we
> can try how large (MB) the whole world in the first two scales
> would be.

OSM already does that with their slippy 2^n URL API,
  http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
  http://search.cpan.org/~rotkraut/Geo-OSM-Tiles-0.02/lib/Geo/OSM/Tiles.pm
  http://ulrichkuester.de/OSM/CoordinateToOSMTile.html

also NASA's OnEarth server pleads that you use their WMS equivalent.
  http://onearth.jpl.nasa.gov/tiled.html


Hamish



     

_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[Ross Scanlon]

On Thu, 6 Aug 2009 22:56:08 -0700 (PDT)
Hamish <hamish_b@...> wrote:

> could you throw up a waypoints.txt file or overlay grid lines to
> check for obvious distortion/misalignment?
>
> see e.g. http://hamish.bowman.googlepages.com/gpsdrivefiles#oz

Here's the screen shot of with the aiports overlaid.

It looks good to me.




--
Cheers
Ross
_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[Ross Scanlon]

On Fri, 7 Aug 2009 07:03:20 +0200
Joerg Ostertag <Joerg@...> wrote:

>
> Sounds like a nice Idea to prerender some OSM Maps and put them into the Cache
> directory of Gpsdrive. This way you'd have already fast prerendered Maps of
> OSM-GpsDrive. Maybe we can try how large (MB) the whole world in the first
> two scales would be.
>
> joerg
> _______________________________________________
> GPSdrive mailing list
> GPSdrive@...
> http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive
>

At max scale (90000000) it takes four files for a total of 500kb in png format or 250kb in jpg to cover the whole world.

Example here:

http://www.4x4falcon.com/gpsdrive/maps/-86.928173_50.028425.jpg

Note this only shows world boundaries and coastlines as I only have Australia and NZ data in the database.

I would suggest putting them in the maps directory rather than preloading the cache as then you do not have to have mapnik enabled to use them.

The relevant set up for map_koord.txt would need to be calculated.

--
Cheers
Ross
_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive

[hamish_b]

Ross wrote:
> The relevant set up for map_koord.txt would need to be calculated.

therein lies the problem: the map projection does not match, and so the
scale factor is not constant over the image and can't be defined.

src/map_projection.c has code for projection type "proj_googlesat", and
although I am not certain, I would guess that is in fact both completely
bogus and perhaps unused at runtime. I'd be glad to be proven wrong about
that though.


.... I have been playing with gpsVP a bit over the weekend, and its tiled
map server download + cache + rendering + live GPX track overlay system
seems to work quite well in my backpack+bicycle taking advantage of sunny
weather field tests :); also currently Tobias Sauerwein is working on a
tiled map download for uDig GIS as his Google Summer of Code project; and
so I will not say it is not possible. But I suspect gpsdrive would need
to include some new code to successfully handle it. Perhaps borrowed from
those other projects?

http://code.google.com/p/gpsvp/
http://udig.refractions.net/confluence/display/COM/SoC+09+-+Web+Map+Tiles+for+uDig
http://udig.refractions.net/confluence/display/COM/Weekly+progress+reports



again, for more authoritative explanations than I have given, do a search
of the PROJ.4 mailing list archive for the terms "google+abomination"

the "official" excuse from google is that they used quasi-Mercator to
preserve map angles which they claim is important for driving directions.
I'm not sure if I really believe that version of history, but one thing
is sure: it lets them do much less math on the server/scripting language.

and I'm quite sure that gpsdrive's map_* projection code could be *much*
improved for scales covering more than say a single 6 degree wide UTM
zone. (UTM uses 60 zones exactly because the map projection only works
for a few degrees east-west of the zone's central meridian; beyond that
it badly distorts)  Due to this I fear no matter how good our code gets
it will always be a losing battle for map_* at global scales.


best,
Hamish



     

_______________________________________________
GPSdrive mailing list
GPSdrive@...
http://lists.gpsdrivers.org/mailman/listinfo/gpsdrive