Global Mapper v25.0

Mismatch between generated countours and areas

oreste.tommasi
oreste.tommasi Global Mapper User
edited January 2012 in Bug Report
Generated contours and areas do not exactly match in any of the following two cases:
  1. some simplification is applied;
  2. smoothing is enabled.

It seems that the simplification/smoothing is applied only on contours, not on areas.

This has been observed in GM12 and GM13.

Oreste

Comments

  • global_mapper
    global_mapper Administrator
    edited January 2012
    Oreste,

    This is possible since the smoothing is done on an area as a whole and that may be different since it will go down a side and wrap around. In general the simplification won't be affected by this, do you ever see the difference without the smoothing option enabled?

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • oreste.tommasi
    oreste.tommasi Global Mapper User
    edited January 2012
    With simplification=0 and smoothing=OFF, I see no mismatch between contours and areas.
    However, with smoothing off, contours can be very sharp; but smoothing cannot be enabled because the produced mismatch causes serious topological issues for us. Thus the result is not so satysfying...
  • global_mapper
    global_mapper Administrator
    edited January 2012
    Unfortunately I don't have a good solution for applying the smoothing and getting areas and lines that stay coincident. Do they stay coincident with just the simplification applied?

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • oreste.tommasi
    oreste.tommasi Global Mapper User
    edited January 2012
    No.
    The mismatch happens with smoothing turned on, OR with simplification != 0.
  • global_mapper
    global_mapper Administrator
    edited January 2012
    I will take a closer look and see if there is anything I can do, but I'm thinking there isn't too much that can easily be done.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • oreste.tommasi
    oreste.tommasi Global Mapper User
    edited January 2012
    Actually differences arise rather seldom, 99.5% of cases lines and areas correspond, sometime it is not easy to find a difference, but it is there.