NAD 1983 StatePlane Hawaii 3 Projection

codemousecodemouse Global Mapper UserPosts: 186Trusted User
edited August 2013 in Projection Questions
Mike,

I'm having issues setting the projection correctly for some imagery data I have (the coordinates are not quite lining up). Can you help with a translation to GM?

Here is the projection info I have:

NAD_1983_StatePlane_Hawaii_3_FIPS_5103


Projection: Transverse_Mercator
False_Easting: 500000.000000
False_Northing: 0.000000
Central_Meridian: -158.000000
Scale_Factor: 0.999990
Latitude_Of_Origin: 21.166667
Linear Unit: Meter (1.000000)


Geographic Coordinate System: GCS_North_American_1983
Angular Unit: Degree (0.017453292519943299)
Prime Meridian: Greenwich (0.000000000000000000)
Datum: D_North_American_1983
Spheroid: GRS_1980
Semimajor Axis: 6378137.000000000000000000
Semiminor Axis: 6356752.314140356100000000
Inverse Flattening: 298.257222101000020000


I set to Transverse Mercator, no Zone, NAD83 Datum, Planar Units of METERS.

Additional Params are as follows:

SCALE FACTOR: 0.999990
CENTRAL MERIDIAN: -158.0
ORIGIN LATITUDE: 21.166667
FALSE EASTING: 500000.0
FALSE NORTHING: 0.0
ROTATION ANGLE (ABOUT ORIGIN): ???

This isn't producing the desired results. I am double-checking the projection and its accuracy, but do you see anything obvious that I may be omitting or doing wrong? Yes, I am doing this via the SDK as a callback but I get similar results when doing via GUI as well.

Brian

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited August 2013
    Brian,

    How are you defining the projection? Since it's State Plane you can actually take a shortcut and define it as follows:

    GM_Projection_t theProj;
    ::memset( &theProj, 0, sizeof theProj );
    theProj.mProjSys = GM_PRJ_SPCS;
    theProj.mUnits = GM_PRJ_UNIT_METERS;
    theProj.mDatum = GM_DATUM_NAD83;
    theProj.mAttrList[0].mAttr = ZONE;
    theProj.mAttrList[0].mValue = 5103;
    theProj.mNumAttrs = 1;

    Note that for State Plane (same as UTM) just specify the ZONE attribute. For State Plane the FIPS zone number is what you use.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • codemousecodemouse Global Mapper User Posts: 186Trusted User
    edited August 2013
    Mike,

    Is this in the documentation!?!? :)

    Thanks - I have NO IDEA where I went wrong defining the projection myself, but doing it this way worked like a charm. Flawlessly. Thank you.

    Brian
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited August 2013
    Brian,

    There is documentation for setting up a UTM projection, but not State Plane. In general to see how it's done call GM_SelectProjection and see how that fills in the structure for the projection you select.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • codemousecodemouse Global Mapper User Posts: 186Trusted User
    edited August 2013
    Mike,

    I was just kidding. Yes, there's enough documentation around to figure out all projection stuffs, thanks.

    Brian
  • codemousecodemouse Global Mapper User Posts: 186Trusted User
    edited August 2013
    Mike,

    Using the shortcut above with FIPS as the UTM zone, is there any way to quickly alter the linear unit to use meters instead of survey feet (the default)? Or would I have to create the projection from "scratch"?

    Brian
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited August 2013
    Brian,

    The FIPS code is the same regardless of units, so just change the mUnits in the GM_Projection_t structure to GM_PRJ_UNIT_US_FEET to switch to feet.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • codemousecodemouse Global Mapper User Posts: 186Trusted User
    edited August 2013
    Yep - figured that out right after I posted. Was trying to troubleshoot issues of scale being off by a factor of .3 (meters in feet approximation). I think the problem is elsewhere. Thank you!

    Brian
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