Global Mapper Pro

Retrieving UTM from Tif

thejerrytan
thejerrytan Global Mapper User
edited October 2009 in SDK
Hi, I need to extract/ UTM co-ordinates from a .tif map.

Currently GM_ConvertCoordPixelToGround extracts out the lat lon. Is there any function to convert or get the UTM instead?

Comments

  • global_mapper
    global_mapper Administrator
    edited September 2009
    Yes, if you call GM_SetProjection and set the projection to a UTM projection in the proper zone prior to calling GM_ConvertCoordPixelToGround then the returned ground coordinates will be in that UTM projection rather than lat/lon.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited September 2009
    Hi,

    Thanks for the reply.

    Is it possible to convert from lat/long into UTM after calling GM_ConvertCoordPixelToGround?
  • global_mapper
    global_mapper Administrator
    edited September 2009
    Yes, you can do that using the GM_ProjectPoint function.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited September 2009
    I am handling it in C# and did a wrapper class using 'IntPtr' for 'const GM_Projection_t*'.

    If I were to convert from lat/long to UTM, what would be the 2 arguments in the function GM_ProjectPoint?
  • global_mapper
    global_mapper Administrator
    edited September 2009
    Don't use IntPtr, use 'ref GM_Projection_t' instead for the 2 projection parameters.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited September 2009
    In the SDK reference, one of the lines for GM_SetProjection has the following lines for UTM:

    theUtmProj.mAttrList[0].mAttr = ZONE;
    theUtmProj.mAttrList[0].mValue = 15;
    theUtmProj.mNumAttrs = 1;

    I've tried to map it in C# equivalent and the possible match I've found for mAttrList[0].mAttr would be Attr1.mAttr. Is it correct?

    And how do I set the declaration for 'ZONE' in this case?
  • global_mapper
    global_mapper Administrator
    edited September 2009
    Your declaration should look like the following (at least if you are using the GlobalMapperDLLWrapper.cs from the C# sample app):

    theUtmProj.mAttr1.mAttr = PROJATTR.ZONE;
    theUtmProj.mAttr1.mValue = 15;

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited September 2009
    There are no variables in theUtmProj with the name mAttr1. I can only find Attr1,Attr2 .... up to Attr16.

    Am I missing something in the wrapper? (I took it from the C# sample app)
  • global_mapper
    global_mapper Administrator
    edited September 2009
    In the wrapper I am using the GM_Projection_t type is declared as:

    // This type is used to fully describe a projection.
    public struct GM_Projection_t
    {
    public PROJSYS mProjSys; // Projection system
    public DATUM mDatum; // Horizontal datum
    public UNIT mUnit; // Ground units
    public UInt32 mNumAttrs; // Number of attributes in attribute list
    public GM_ProjAttrValue_t mAttr1; // Attribute value list items (C# doesn't support fixed length arrays)
    public GM_ProjAttrValue_t mAttr2;
    public GM_ProjAttrValue_t mAttr3;
    public GM_ProjAttrValue_t mAttr4;
    public GM_ProjAttrValue_t mAttr5;
    public GM_ProjAttrValue_t mAttr6;
    public GM_ProjAttrValue_t mAttr7;
    public GM_ProjAttrValue_t mAttr8;
    public GM_ProjAttrValue_t mAttr9;
    public GM_ProjAttrValue_t mAttr10;
    public GM_ProjAttrValue_t mAttr11;
    public GM_ProjAttrValue_t mAttr12;
    public GM_ProjAttrValue_t mAttr13;
    public GM_ProjAttrValue_t mAttr14;
    public GM_ProjAttrValue_t mAttr15;
    public GM_ProjAttrValue_t mAttr16;
    };

    However it is declared, use either Attr1 or mAttr1.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited October 2009
    Hi


    Thanks for the answers, I managed to get the function working.



    Now I am struggling to call out the function "GM_GetMGRSCoordinates" using a wrapper class.

    It kept throwing the exception "Unable to find an entry point GM_GetMGRSCoordinates in GlobalMapperInterface.dll" whenever I call the function.

    My code for the wrapper class is as followed:
    [DllImport(DLLFileName, EntryPoint = "GM_GetMGRSCoordinates", CallingConvention = CallingConvention.StdCall)]
    public static extern GM_Error_t32 GM_GetMGRSCoordinates(double aX, double aY, int aLatLong, out String aMgrsStr)



    Did I put in wrong inputs or have some files missing that throws out this exception?
  • global_mapper
    global_mapper Administrator
    edited October 2009
    What SDK version are you using? This is a relatively new function so you need to make sure you have the latest SDK release otherwise the function won't be there. I would suggest maybe getting the latest beta SDK build at http://www.globalmapper.com/GlobalMapperSDK_v132_beta.zip and using that.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited October 2009
    Ah okay. Mine should be outdated.


    Will there be any function to convert from MGRS to lat / long in the future?
  • global_mapper
    global_mapper Administrator
    edited October 2009
    I could add that if you need it. Global Mapper internally has support for parsing a MGRS coordinate string into lat/lon, so adding it to the SDK is just a matter of me adding a function and calling the internal stuff. Do you need that?

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited October 2009
    Wow if you could add in that would be great! Initially I was planning of using some linear approximation and cross referencing through a table to convert.
  • global_mapper
    global_mapper Administrator
    edited October 2009
    Ok,, I'll throw that in a new build and point you at it when I get back to the office Sunday night.

    Mike
  • global_mapper
    global_mapper Administrator
    edited October 2009
    I have added a new GM_DecodeMGRSCoordinate function and placed a new SDK build with that function at http://www.globalmapper.com/GlobalMapperSDK_v132_beta.zip for you to test.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited October 2009
    Hi,

    I have tried calling GM_GetMGRSCoordinates and it kept throwing System.ExecutionEngineException in my code.

    The only details I have is that it points to System.Collections.EmptyReadOnlyDictionaryInternal.


    Any possibility of reproducing the exception on your end? From reading MSDN, I suspect it could be my machine
  • global_mapper
    global_mapper Administrator
    edited October 2009
    I just rechecked your declaration and the aLatLong parameter should be of type 'Byte' (or an equivalent), not 'int', which is a different length. I'm guessing this is your problem.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited October 2009
    Yup, its the parameter that is causing the issue. However i have tried 'Byte' or boolean and doesn't work as long as the input value is 1 or true. (threw the same exception).


    Only when I put 0 as the parameter that it return GM_Error_NoProjectionSet without the exception.
  • global_mapper
    global_mapper Administrator
    edited October 2009
    Looking again at your declaration I'm not sure that 'out String' is the proper way to declare the output string buffer. I think instead you should use IntPtr and provide an address to an allocated buffer of sufficient size (32 bytes should be more than enough) in which to store the output string, then you can convert that to a String when you get back into C#.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • thejerrytan
    thejerrytan Global Mapper User
    edited October 2009
    Ah great that was the problem! Thanks!


    Do you have the reference for GM_DecodeMGRSCoordinate? I couldn't find in the SDK reference.
  • global_mapper
    global_mapper Administrator
    edited October 2009
    We haven't officially documented GM_DecodeMGRSCoordinate yet. Here is the function header and declaration:

    //===================================================================
    //
    // FUNCTION:
    // GM_GetMGRSCoordinates
    //
    // DESCRIPTION:
    // Decodes a MGRS (military grid reference system) coordinate into
    // a X/Y or lat/lon location.
    //
    //===================================================================
    GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_DecodeMGRSCoordinates
    (
    const char* aMgrsStr, // IN: buffer with MGRS coordinate text
    double* aX, // OUT: point X/longitude coordinate
    double* aY, // OUT: point Y/latitude coordinate
    boolean aLatLon // IN: TRUE - return coordinates are lat/lon, FALSE - return coordinates are in the current projection
    )


    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
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