GM_CreateProjection – Global Mapper

Global Mapper SDK

Creates a new projection object using a comprehensive set of codes to define all coordinate system parameters. The only necessary parameter is the horizontal coord system code, all others are optional and will be supplied with defaults by GeoCalc. The parameters can also be used to specify a target projection and transformation to supply a way for users to define conversions between CRS's. The codes are assumed to be GC codes, but if none is found, GeoCalc will fall back to EPSG codes, and then BMG strings.

Syntax

C++

Copy

GM_Error_t32 GM_CreateProjection(
    GM_Projection_t* aProj,                     // OUT: The new projection
    const char*      aHorizontalCRSCode,        // IN: Horizontal CRS code as string(e.g. "4326") Assumes a GC string, or if no match is found, EPSG string, and then BMG string
    const char*      aVerticalCRSCode,          // IN: Vertical CRS code as string (e.g. "5773") Can be left empty
    const char*      aHorizontalUnitCode,       // IN: Horizontal unit code as string (e.g. "9122" for degrees) Can be left empty
    const char*      aVerticalUnitCode,         // IN: Vertical unit code as string (e.g. "9001" for meters) Can be left empty
    const char*      aTargetHorizontalCRSCode,  // IN: Target horizontal CRS code as string. Can be left empty
    const char*      aTargetVerticalCRSCode,    // IN: Target vertical CRS code as string. Can be left empty
    double           aSourceEpoch,              // IN: Epoch for CRS
    double           aTargetEpoch,              // IN: Epoch for target CRS
    double           aCentralLongitude,         // IN: Central meridian for CRS
    GM_CoordTransform_t* aCoordTransform        // IN: Coord transform to use. Can be left empty
);

Remarks

All the code strings can be left empty besides the horizontal.