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OS Terrain 50 question

[Deleted User]
  • Deleted user
  • Rating: 1 points Newbie
    • 16 January 2014 12:50AM
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    • Registered: 16 January 2014 12:40AM
    • Last active: 19 January 2014 06:57PM

    Hi

    I just downloaded the Terrain 50 data - ASCII grid and am using QGIS Desktop 2.0.1 to view the data.

    My problem is that the seperate data files dont seem to be using the same scale, ie they start at a different greyscale value, hence some are darker than others and u can clearly see the borders of the tiles.

    Is there a way I can calibrate the tiles, so i can get accurate data without the borders?

    Thank You in advance.

    3 responses

    OS OpenSpace TeamOS OpenSpace Team
      • 24 January 2014 02:12PM
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      • Registered: 31 January 2008 01:50PM
      • Last active: 4 January 2018 08:36AM

      Hi Steve

      A colleague has kindly contributed the following advice;

      'There is a way to generate more pleasing images using the following piece of code:

      SET DATA_DIR=

      SET GDAL_DIR=C:OSGeo4Win
      SET GDAL_DATA=C:OSGeo4Wshareepsg_csv

      FOR /R "%DATA_DIR%" %%A IN (*.asc) DO (%GDAL_DIR%gdaldem hillshade "%%A" %%~NA.tif -z 3 -az 315 -alt 60 -of GTiff -compute_edges)
      pause
      exit

      This piece of code should be copied into a text editor and saved as a .bat file.

      The directory that the asc files sit in should replace the in the code above and saved and the .bat file copied to the directory that holds the data. Once the .bat file is double clicked geotiff files will be created from the asc files. These .tif files can then be bulk loaded into QGIS; they look much, much better!

      However to make this work the customer should download and instal GDAL and OSGeo4W (the 4W indicates that this is for Windows). The path to GDAL (C:Program FilesGDAL for example) should be saved to the customers Environment Variables.'

      Regards

      Alan
      OS OpenData Team

      kithgrave
        • 18 October 2017 04:15PM
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        • Registered: 18 October 2017 04:06PM
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        Maybe this tutorial will help you:
        https://mltconsecol.github.io/QGIS-Tutorial/QGIS-Tutorial/Treglia_QGIS_Tutorial_2_12.pdf

        If you don't find the solution to the problem, you can go to the site answershark.com/programming and ask your question to expert or read the blog to find necessary information.

        rickkanagy
          • 11 December 2017 03:26PM
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          • Registered: 11 December 2017 03:17PM
          • Last active: 11 December 2017 03:17PM

          'There is a way to generate more pleasing images using the following piece of code:

          SET DATA_DIR=

          SET GDAL_DIR=C:OSGeo4Win
          SET GDAL_DATA=C:OSGeo4Wshareepsg_csv

          FOR /R "%DATA_DIR%" %%A IN (*.asc) DO (%GDAL_DIR%gdaldem hillshade "%%A" %%~NA.tif -z 3 -az 315 -alt 60 -of GTiff -compute_edges)
          pause
          exit

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