[Marble-devel] Marble and Google Earth

[Torsten Rahn]

Hi Maurizio,

Great to see that you've found your way here (make sure that you subscribe to 
this mailing list or at least have a look at the archive if you want to follow 
the discussions here).

On Saturday 25 October 2008 10:16:50 Maurizio Pozzobon wrote:
> Hi, I'm Maurizio, from google groups
> I just wanted to point out that I'm not pessimist about open and maps, just
> about open and satellite photos.

Yes, satellite imagery is indeed a less easy to solve problem than street 
maps. So let's have a look at street maps and satellite imagery separately:

Looking at the progress that OSM has been making in the last few years I'm 
pretty sure that in about 2 years it will be better than google maps for most 
of the part.
Even now there are lots of cities that are already better mapped than google 
maps already: On one hand several bigger cities in europe are already mapped  
with much more love to detail (especially with the important focus on spare-
time activities). On the other hand there are lots of cities which seem to 
suffer from the lack of commercial interest for google maps:
Take e.g. Timisoara (Temesvar in Romania): Although it's a beautiful city with 
about 300 000 people in Google Maps it's nothing but a bus stop! In 
OpenStreetMap it looks like it's extensively mapped in detail!
Looking at the high momentum that OpenStreetMap has got these days (also 
compared to Wikipedia's early development) I'm pretty sure that this issue 
will be solved very soon.

For the satellite imagery you're right: it's a lot harder (but from what I see 
that imagery is also subject to higher restrictions in terms of Google's 
permissions concerning their data).

I think there are several things we need to approach:

- Make complete usage of freely available data for Marble:
 Currently we are just using Blue Marble for the satellite imagery.
 The resolution of that data is just a cumbersome 500m per pixel.
And yes, that is a completely unacceptable low resolution.

 If we'd make use of the LandSat data (the one that NASA polished up for 
WorldWind) that would bring us down to 15m per pixel for all continental 
areas: That is about the same resolution that Google Earth has got on 
"unoptimized areas: I'm currently in Tampere, Finnland which in terms of 
population is a 208 000 inhabitants city. 
If you look at Google's Satellite photos you'll see that it has got that 
15m/pixel resolution although it's the third largest city in Finland!

So that would already be a major mile stone for Marble (We are talking about 
approximately 120GB of imagery here).

In the next step we'd need to deal with the aerial photos: Unfortunately there 
are very few free aerial photos out there: we'd need to identify where to get 
the free ones (especially for big cities).
Beyond that the whole issue becomes more tedious: people need to approach 
their government or offices of cities which have access to that kind of 
"governmental data" and need to ask whether aerial data with a proper license 
is available (and/or to persuade them that they should make such data 
available).

> I really would like to know if you (as a group) are working on trying to
> get better imagery, like contacting the copyright holders and asking them
> to donate them or something like that.

That would be a task that especially non-programmers could help with to 
improve Marble and the state of freely available maps.

> About OSM I'm trying to get a GPS to update the images of my zone since the
> imagery of yahoo doesn't have a quality high enaugh to let me add new
> roads.

Just out of curiosity: where are you located? :-)

We got a few active OSM mappers on this list - like e.g. Inge Wallin who has 
mapped most if not all of Linköping (and probably during the last few months 
much of Sweden ;-)

Maybe Inge (or somebody else on this list) can give you a few suggestions and 
tipps on that topic :-)

I'm myself currently preparing the NASA public domain moon imagery for 
inclusion with Marble. Thank god most of the planetary data that exists is 
freely available. So beating all other existing solutions out there on this 
topic is just a matter of compiling the data together and editing it in a way 
that it becomes more appealing to the interested public.
I'm also currently about to prepare a HOWTO for how to prepare satellite 
imagery so that it can be displayed in Marble.

Regards,
Torsten

>           Maurizio
>
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