Global Mapper v25.0

How to find out sample spacing of original map in WMS Service?

Greina
Greina Global Mapper UserTrusted User
edited February 2012 in Downloading Imagery
Mike, when downloading some WMS raster data it is difficult for me to find the right sample spacing of the source data. On the other hand I discovered that GM saves the source data in its cache, e.g. C:\Users\NAME\AppData\Local\Temp\GlobalMapper\OGCWMS

Is there a chance to find out the original solution of the source data or even to let GM do this job?

Comments

  • global_mapper
    global_mapper Administrator
    edited February 2012
    The WMS source specification allows for a server to specify the resolution range of its data. If that is present Global Mapper will use it. Unfortunately many WMS servers don't provide that information, so Global Mapper has no way of knowing what the original resolution of the source data is (which of course could be many different resolutions for combined sources), so it just lets you pull down the data to a maximum resolution of around 0.1 meters per pixel. What is stored in the cache are just whatever tiles have been downloaded at some intermediate zoom levels that GM decided to download at down to the maximum resolution. If you know the maximum resolution of your layer, you can right-click on it in the Control Center and select to specify the maximum resolution, then it won't go any below that.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • Greina
    Greina Global Mapper User Trusted User
    edited February 2012
    Thanks a lot!