Viewing 15 posts - 1 through 15 (of 36 total)
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  • #17558

    Sonny
    Participant

    I want to inform the readers of the English Forum, that there’s a thread in the German Forum about the theory und use of these precise LIDAR elevation files:

    https://www.openandromaps.org/oam-forums/topic/neues-genaueres-hoehenmodell-fuer-oesterreich

    These files are right now available for: Austria, South Tyrol, Slovenia, Luxembourgh, Spain, several German provinces. They are already used by OpenAndroMaps to create the contour lines of these countries. You can download them too and use them to create map-shading and elevation readings within Apps like Locus or Orux.

    If you have questions, please post in the linked thread (in English or German). Not in this thread, thank you!
    (For non-German readers you can simply translate the whole thread using Google Translate: translated Thread)

    • This topic was modified 2 years, 7 months ago by ChristianK ChristianK.
    • This topic was modified 11 months, 3 weeks ago by ChristianK ChristianK.
    1 user thanked author for this post.
    #26378

    Sonny
    Participant

    Dear OAM-Friends,

    I’ve spent lots of hours during the last months to collect, check and resample data. Just before Christmas I’m going to give you the result – several new DTMs – as a present:

    Belgium:
    http://data.opendataportal.at/dataset/dtm-belgium

    Denmark:
    http://data.opendataportal.at/dataset/dtm-denmark

    Estonia:
    http://data.opendataportal.at/dataset/dtm-estonia

    Finland:
    http://data.opendataportal.at/dataset/dtm-finland

    Lavia:
    http://data.opendataportal.at/dataset/dtm-latvia

    Netherlands:
    http://data.opendataportal.at/dataset/dtm-netherlands

    Norway:
    http://data.opendataportal.at/dataset/dtm-norway

    Sweden:
    http://data.opendataportal.at/dataset/dtm-sweden

    Enjoy them within new maps, Sonny.

    #26380

    Sonny
    Participant

    As far as I know, I’ve now completed the list of European countries where Opendata LIDAR source data is available. If you notice that there are new European countries providing high quality Opendata DTMs in the future, feel free to contact me!

    Finally something regarding myself: During the last 2.5 years I spent many, many Hundreds of hours during my leisure time to search for new Opendata source files. I’ve written hundreds of Mails – mostly in foreign languages ;-) – to contact public authority of the individual countries to help me with finding free and often hidden source data of their country. I had to download giant amounts of source data. I had to search for errors, plug holes within the data, compile, resample it and create files in useful formats. To provide them to you, the community for free.

    It would make me very happy, if you honor this work by supporting me with a Donation. I’ve created a DONATIONLINK via PAYPAL . THANK YOU VERY MUCH, Sonny.

    #31012

    Sonny
    Participant

    I have created new files of the Germany-Saxony, which you download here:
    https://data.opendataportal.at/dataset/dtm-germany

    #32538

    Sonny
    Participant

    After lots of hours of work, finally the latest version of DTMs of Spain are ready for Download:
    https://data.opendataportal.at/dataset/dtm-spain

    I therefor used the latest available source-files of Spanish survey Institute. Most improvements are in regions which lack of LIDAR source data in the previous DTMs: Andalusia and the Balearic Islands.
    Now the whole territory of Spain is covered by high quality LIDAR data.

    2 users thanked author for this post.
    #33937

    Sonny
    Participant

    There’s a new DTM, of Northern Ireland which you can download here:

    https://data.opendataportal.at/dataset/dtm-united_kingdom

    1 user thanked author for this post.
    #34223

    Sonny
    Participant

    Good news: After lots of hours research, contact with different institutes across the country, quality checks etc. there’s for the first time a high-quality DTM of the whole United Kingdom

    https://data.opendataportal.at/dataset/dtm-united_kingdom

    For about 75% of England, Wales, Northern Ireland fine LIDAR source data available, Scotland
    unfortunately (beside river valleys and coasts) is not covered as well. For the areas not covered with fine LIDAR-data I used OS DTM-50m which is wider gridded but also based on LIDAR source data and hence especially in wooden areas more accurate than SRTM data.

    Enjoy the new DTMs of the UK!

    1 user thanked author for this post.
    vsa vsa
    #41576

    Sonny
    Participant

    Since some weeks LiDAR source data of the whole territory of France in its finest resolution is available as OpenData. So during the last weeks I created enhanced DTMs of France:
    https://data.opendataportal.at/dataset/dtm-france

    Additionally Wallonia (Souther Belgium) also provides their LiDAR sources in its finest resolution as OpenData. So I created enhanced DTMs for Belgium too, now the whole country is complete in highest resolution:
    https://data.opendataportal.at/dataset/dtm-belgium

    Have fun, Sonny.

    3 users thanked author for this post.
    #41773

    tartiflette74
    Participant

    Hello Sonny,
    Thanks a lot for your work on DTM; I downloaded French 1″ strm files and they are better than ever when used in Locus.
    For a different project I tried to use 5 meter precision data from IGN (RGE Alti 5 m). This seems incredibly precise, however there are large errors in some small specific areas, especially the top of Mont Blanc (altitude wrong by 50 m) and its north-west face (wrong by 180 m !), or the Dent du Géant (wrong by 110 m). I converted some of this data to 1″ .hgt files (I also tested 0.5″ and 0.25″ resolution, this is working fine in Locus however it uses a lot of space!!). But I am not sure this should be used as is, with this problem in Mont Blanc. What do you think?
    From which data are the contour lines generated in oam maps? From your .hgt files? from the 20 m geotiff ? Is it possible to use 5 m resolution (or 0.25″ .hgt) to generate the contour lines?
    Thanks

    #41775
    ChristianK
    ChristianK
    Keymaster

    From which data are the contour lines generated in oam maps? From your .hgt files?

    Contourlines are created from *.hgts using phyghtmap.

    Is it possible to use 5 m resolution (or 0.25″ .hgt) to generate the contour lines?

    No, the maps will be bloated too much (countourlines are ways in vectormaps and not only same pixels more)
    .. and the the max hgt resolution for phyghtmap is 1″

    #41777

    Sonny
    Participant

    @tartiflette74: I’m not sure if OAM already uses the new French DTMs ;-) As you can read in the readme-File of my files, I also used the RGE Alti 5m as major source for the whole country.

    RGE Alti 5m is the best available source of the whole country. It’s of finest quality in lots of areas. But not each Area is already scanned with this finest quality by IGN. One example are parts of the Alps, for example around Mont Blanc as you noticed correctly. It’s position and elevation and and fineness of terrain is rather rough compared to the quality in the lowlands or midlands of France.

    But since I’m always compareing the quality of different source DTMs in border regions and choose the best one to create my DTM files, I’ve choose the source DTM of Italian region “Valle d’ Aosta” to be used for Mont Blanc. So its position and elevation in my DTMs is visible better than those of French IGN 5m.

    But in general even in this still rough scanned regions, the positions and elevations of IGN 5m are more exact than any other OpenData source (IGN BD Alti 75m, individual regions DTMs, and of course SRTM or Viewfinderpanoramas)

    1 user thanked author for this post.
    #41782
    ChristianK
    ChristianK
    Keymaster

    I’m not sure if OAM already uses the new French DTMs

    Update for February is running and will be available for download begin of next week.

    #41819

    tartiflette74
    Participant

    Thanks Christian! However I currently can’t download from the new server: “Failed to connect to http://ftp.gwdg.de port 80: Operation timed out” (or sometimes “Connection refused”)

    #41842

    tartiflette74
    Participant

    Thanks Sonny for the details; in fact in some areas, the new .hgt files are really better, while in some other areas, they are less good than before. In this map, orange regions (radar source) have a bad precision and are smoothed in RGE Alti 5m.
    Maybe there is a geotiff layer that let know the areas with a radar precision? But I didn’t find it (and I don’t know how to parse geotiff).
    I am thinking writing a tool to compare two .hgt files for the same tile, and automatically detect the “blurred” zones to merge them. But maybe you already did something like this?

    #41844

    tartiflette74
    Participant

    Thanks Christian for the details. In fact, the contour lines are already much less precise that what 1″ resolution allows. I understand that the maps should not be too much bloated, but maybe you could reduce the epsilon value (or other phyghtmap setting) a little bit? Attached are two samples where the contour line are too much simplified; especially in the first one, the couloir that ends at the cursor location is not visible at all looking at the contour lines. (coordinates are shown in the top bar)
    Thanks!
    PS: I can now download the maps from the new server, and my IP is no longer blacklisted after 3.5 days :)

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