Global Mapper Pro

Projection and Datum zones

andresfpc
andresfpc Global Mapper User
edited July 2009 in Projection Questions
Hello!
Does anybody know any way to obtain the projection system and datum of a specific place/country??? Because almost each country has its own projection system and datum.
When I start a new project I have to select the projection from the "projection tab" on "Configuration" but sometimes I don't know which projection and datum correspond to the place I'm working on.

thanks
Andrés:)

Comments

  • global_mapper
    global_mapper Administrator
    edited July 2009
    Andrés,

    There isn't typically just one projection system/datum used in a particular place. Pretty much everywhere makes use of the Geographic (Lat/Lon), UTM, and Mercator projection systems, with some places having their own specific grid systems based on some other projection, like the State Plane projection system in the US or British Grid in GB. There isn't some way to automatically choose one as there isn't just one in use for a particular location.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Frank2
    Frank2 Super Moderator
    edited July 2009
    While this is overkill for most people, the "Grids & Datums" column is a good resource to find out what is used in many countries.

    American Society for Photogrammetry and Remote Sensing
  • andresfpc
    andresfpc Global Mapper User
    edited July 2009
    Hello again!
    How can I create a new projection and datum for a new project. This is because I don't have one for Uruguay but I have some information that can help me to create one.
    Sometimes you can't find a suitable projection and datum for a specific zone to select from the list and you've to generate it.
    Thanks :D
  • Frank2
    Frank2 Super Moderator
    edited July 2009
    This shows how you can change the projection & datum. Then save it to a PRJ file for later use.

    Global Mapper - User's Manual
  • Matt
    Matt Global Mapper User Trusted User
    edited July 2009
    I think you may be overthinking this. Just because there isn't one specifically for Uruguay doesn't mean you can't just use one of the other more generic global projection/datums. Unless you're near the poles, Geographic Projection will usually work fine.

    It also depends on what exactly it is you're doing. If you're trying to georeference an existing map, then it doesn't matter what Projection/datum the country uses. What matters is what projection/datum that map uses, which may be different. Sometimes you just have to guess.

    If you're creating a new map from scratch, then you can pick any projection/datum you want, depending on how you want the map to look. If you want the lat/lon lines to be parallel and equidistant then use Geographic. If that makes things look too distorted, then pick UTM or something similar.
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