Global Mapper v25.0

line from KML file seems not correctly rendered as a great circle

Luc Van Linden
Luc Van Linden Global Mapper User
edited July 2012 in Technical Support
Hi

I have a "strait" (great circle) line coming in from Google Earth KML (defined with start and end point only). (WGS84 obviously).
It seems this is rendered Cartesian instead of being rendered as a great circle.

I tested it to measure the line from its start to end point and then saving the measure as a feature.
This feature is correctly rendered as a great circle. these lines do not lie on top of each other, which seems to confirm at least my observation.

Are there any specific settings to set on the KML import in order to hav these correctly rendered?
This is important as after some further analysis and and output is equally not great circle any more.

GM 13v2

Thanks

Luc

Comments

  • global_mapper
    global_mapper Administrator
    edited July 2012
    Luc,

    Vector features are always rendered by converting the location at each vertex from its native projection to the current view projection, then they are connected using a straight line between them in the current view projection. So for lines with vertexes a large distance apart you may get different shapes depending on your view projection (often the desired effect of changing projection). If you want features to maintain the shape of their original projection (such as a great circle for lat/lon coordinates), you can resample your features to have more vertices along the length of the feature. You can do this by selecting the features with the Digitizer Tool, then right-clicking and select the Advanced Feature Creation submenu option to resample the feature, then add points spaced close enough to maintain the shape in the original projection even when reprojected.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com