Global Mapper v25.0

Inaccurate Feathering Inside a Poligone

naugustin
naugustin Global Mapper UserTrusted User
edited December 2013 in Technical Support
Hi,
I have to deal with the combination some AUV derived high resolution grids (3m cell size). One issue is the navigation in deep seas and the resulting grids often have little offsets (some meters) which I already matched as good as possible on visible features in the overlapping grids.However, I have still some problems with the borders of the each grid and wanted to "hide" the edges with a slight feathering. Unfortunately the feathering along polygon borders is not working accurate enough and I loose some information. Thereby it does´t matter if I feather inside a selected polygonal shape of the grid (created with BBOX/COVERAGES) or just inside the shape valid data. The feathering is not following the edges accurate enough. I tried to feather less pixels but the effect is the same - I loose informations in some corners. Any idea to improve that? This function would be great to improve the display/presentation quality and export of my combined maps a lot. I attached a screen grab to illustrate the task I´m talking about.

Cheers, Nico

FeatheringGM.jpg

Comments

  • global_mapper
    global_mapper Administrator
    edited December 2013
    Are the feathering issues just where there are no overlapping terrain surfaces? The feathering of terrain surfaces feathers the actual elevation values to smoothly blend those, then applies normal shader coloring to that. So if you are in a region where there is only a single valid layer you will just see that one exactly as is since there isn't anything to blend with. This is a bit different than feathering of image layers where they can also blend with the background since it is a color feather and not an elevation value feather.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Global Mapper
  • naugustin
    naugustin Global Mapper User Trusted User
    edited December 2013
    The same effect I also get in the other layers where depths are available from underlain terrain layers. Thats also a problem because sometimes I get gaps between two terrain layers because the feathering is not accurately attached to the given border/valid data. If the feathering would work accurate it should not produce gaps as long as I don´t overdo it with the given pixels to feather. In the above picture it looks to me like the feathering is not interested at all in the given border and feathers just along a interpolated line.
  • global_mapper
    global_mapper Administrator
    edited December 2013
    What version of GM are you using and can you provide a sample that demonstrates this? If I can reproduce it I should be able to explain and fix it if there is a problem, or at least tell you how to work around it.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Global Mapper
  • naugustin
    naugustin Global Mapper User Trusted User
    edited December 2013
    Currently I use v14.2.6
    I will try to send some crops of overlapping stripes. Since I´m currently at sea - with a poor internet connection - that will maybe take a little while. But I´ll try to pack a small zip file. Can I send it directly to geohelp@bluemarblegeo.com?
  • global_mapper
    global_mapper Administrator
    edited December 2013
    Yes you can send them directly to that email address.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation