RASTER CADRG exporting quality

Wes
Wes Global Mapper User
edited April 2015 in Raster Data
Hello,
I am trying to export a navigational chart to CADRG format at the Operational Navigational Chart 1:1000000 scale. My source data is a set of High resolution Geo referenced TIFFs. I generate the CADRG files. Then I read the generated files back into the Global Mapper program and the quality is poor. I assume this is because of the standard CADRG file compression for that scale. Is there a way that I can improve the quality of my output CADRG files for my Operational Navigational Chart 1:1000000?

Thanks,
Wes

Comments

  • global_mapper
    global_mapper Administrator
    edited December 2013
    Wes,

    The scale of the CADRG is going to determine the resolution at which the source data is sampled. Sub-sampling high resolution data to low resolution like 1:1000000 scale is going to produce terrible looking results in most cases. Is it possible for you to use a CADRG chart type with larger scale that more closely matches the resolution of your input data?

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • MartinRS
    MartinRS Global Mapper User
    edited April 2015
    What ever came of this? Every time I search google for this issue I only come up with this thread. I'm not really wanting to necro a post but I don't want to a start a new thread for an existing issue.

    JNCs/TPCs/JOGs become so severely degraded when the 55:1 compression algorithm for CADRG is used that it's difficult to actually use in the jet.

    ADRG doesn't seem to be available from NGA any longer, either.
  • SNAP
    SNAP

    Since this is the only one of two threads I've been able to find regarding CADRG export quality, I'll post this again over here.

    I've been looking for ways to improve CADRG exports and ended up on this old thread. The only way I seem to be able to improve quality of let's say a GEOTIFF to CADRG conversion is to downscale the map eg. if the GEOTIFF is a 1:500k export it to a 1:250k CADRG. I haven't found a way to bring the map scale back up without losing quality again..

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