MapInfo Pro

Expand all | Collapse all

A .pprc file is created when MapInfo v16 opens a cloud optimised geotiff

  • 1.  A .pprc file is created when MapInfo v16 opens a cloud optimised geotiff

    Posted 01-16-2019 02:09

    Hello all,

     

    I have a lot of raster imagery in cloud-optimised geotiff format.

    https://www.cogeo.org/

     

    I am running MapInfo v16.0.3 (64-bit) on Windows 7 (64-bit)

     

    When I open a cloud-optimised geotiff for the first time, MapInfo generates a .pprc file. Which is a pyramid index.

     

    I understand that a pyramid index is useful for the old-style geoTifs, which use LZW compression. But a cloud-optimised geotif should not require pyramid layers. The image format is designed to not require pyramid layers. (When the image is read, it only returns those pixels that are appropriate for the user's zoom and extent).

     

    I looked at the Preferences for MapInfo Raster | Raster Formats and GeoTiff Image is both in the list of Native Formats and GDAL Formats. But there is no distinction made between the old-style geoTiff (LZW compression) and this new cloud-optimised geoTiff. My suspicion is that the old-style geotiff is in the list "Native Formats" and the cloud-optimised geotiff is in the list "GDAL Formats". However, if either one of these is ticked (Enable Display ticked) then a pprc is created next to the cloud-optimised geotiff.

     

    Cloud-optimised geotiff ought to display very quickly and should not need a pprc created.

     

    Thanks,

    Nick



    ------------------------------
    Nick Lawrence
    Mr
    TMR-Policy and Planning
    Brisbane
    ------------------------------


  • 2.  RE: A .pprc file is created when MapInfo v16 opens a cloud optimised geotiff

    Pitney Bowes
    Posted 01-17-2019 18:40

    Hi Nick,

    The first point to make is that MapInfo Advanced (what we engineers more sensibly call the "Raster module") does not explicitly provide support for the COG format. I will consider this post as a request for that functionality.

    However, a COG is just a TIFF file with internally stored overview levels and a network friendly internal data arrangement. There are two ways to access a COG - either by directly opening the TIFF file in the usual way or by using HTTP GetRange requests. In Pro, we do not have any support for HTTP access to these files. We do allow users to load the TIFF file directly.

    Your guesses in the post are mostly correct. We will load a TIFF file via a "Native" TIFF driver, or via a driver using GDAL or via the old Pro raster handlers. The native driver gets first shot at it and it decides the TIFF needs a PPRC (which is really an MRR format raster that contains a complete overview pyramid). If you skip the native driver then the GDAL driver gets a shot at it. I tested this in 17.02 and found that it loads the COG appropriately and does not create a PPRC - it acquires data from the internal overviews in the COG when available and fabricates levels that are not supplied as best it can on the fly.

    So, for the upcoming 17.03 patch we could make a change to the native TIFF driver to recognise these COG's and pass over them so that they are loaded by the GDAL driver. This would be a step forward. Support for HTTP access to COG's could be considered for a future release.

    Regards,
    Sam.



    ------------------------------
    Sam Roberts
    Knowledge Community Shared Account
    Shelton CT
    ------------------------------



  • 3.  RE: A .pprc file is created when MapInfo v16 opens a cloud optimised geotiff

    Posted 16 days ago
    Yes please do improve support for COG's
    My organisation has thousands of them, stored on network drives, so rapid display over a network will be welcomed by us

    ------------------------------
    Nick Lawrence
    Mr
    TMR-Policy and Planning
    Brisbane
    ------------------------------