[Marble-devel] altitude profiles
Torsten Rahn
torsten.rahn at basyskom.de
Sun Sep 26 16:17:33 CEST 2010
Hi,
Great that you want to look into this.
Here are a few thoughts by me:
Am Sonntag, 26. September 2010 11:48:12 schrieb Niko Sams:
> Hi,
>
> I'd like to implement altitude profiles and would like to do a bit of
> brainstorming beforehand.
>
> * it should be an overlay widget showing the graph
You mean a float item? Or a Dialog? Maybe you can make the code generic enough
so that it can be used for both.
> * it should read data either from a GPX file (if avaliable) or use
> locally avaliable SRTM data.
Well, the atlas theme is currently using a very coarse srtm data set already
(encoded as a grayscale image). This SRTM dataset was actually created using
GMT mapping tool.
> using a webservice might also be an option, but I haven't found a good
> one yet * it should calculate statistics like total incline/decline
> * it should be available for opened tracks and routing tracks
There are basically three options for implementing this feature:
1.) Ask the user to download huge chunks of SRTM data in advance and then run
some code over it which figures out the height profile. This is certainly the
worst idea and I wouldn't want to see this in Marble since it's not the way
that Marble users are supposed to interact with data. We already do this
approach with offline routing. And the only reason that we accept this
approach there is the complexity of retrieving chunks of data that can be used
offline to determine a good route.
2.) Use a webservice. This is probably the easiest approach and a good
temporary solution. I guess this one would be the best option for now.
3.) Use tile data: This is an approach that we have to take in the future to
render 3D surfaces anyways: The DEM/SRTM data should get tiled in a tile
layout and should be downloaded seemlessly like the image data.
One possible option would be to demand the same tile layout for the srtm data
as for the imagery, so that it could be stored as part of a StackedTile.
Another option would be to have it downloaded in a tile layout that is
different from the one used for the various map themes. I guess the latter
option would make most sense ...
> UI issues:
> Where to choose the track to display?
> - gpx files can contain multiple tracks, currently all are shown
> - what happens if a track is opened and a route is shown
> Maybe a combobox where the track can be choosen
I think it would also be cool if the feature worked together with the measure
tool to get more accurate measurements. :-)
> Implementation issues:
> * a new plugin that adds a info box like Routing does
> * data available in the track can be read from GeoDataCoordinates and
> displayed * where to store altitudes that the plugin needs to figure out
> itself?
See above. I guess it would be cool if eventually we'd store the srtm data in
the map data directory as tiles. Currently we are kind of doing this already
for the Atlas theme which contains coarse SRTM data already.
Best Regards,
Torsten
> Niko
> _______________________________________________
> Marble-devel mailing list
> Marble-devel at kde.org
> https://mail.kde.org/mailman/listinfo/marble-devel
--
Torsten Rahn
Senior Consultant
basysKom GmbH
Robert-Bosch-Str. 7 | 64293 Darmstadt | Germany
Tel: +49 6151 3969-961 | Fax: -736|
torsten.rahn at basyskom.de | www.basyskom.de
Handelsregister: Darmstadt HRB 9352
Geschaeftsfuehrung: Eva Brucherseifer
More information about the Marble-devel
mailing list