|
Prototype and description of the function coordtransextraind() (Function of the unlock requiring group "Coordinate Transformations") |
|
coordcalcextraind()
Calculation of Extra Pparameters independent from coordinate transformations.
Meridian Convergence, Origin Center and Geographical Point coordinate.
Prototype of the DLL function in C++ syntax (attend lower case!):
extern "C" __declspec(dllimport) unsigned long __stdcall coordcalcextraind(
double nCoordX,
double nCoordY,
const char *pszCoord,
double nEllHgt,
unsigned short nCoordSys,
unsigned short nRefSys,
unsigned short nUnit,
unsigned short nStrip,
unsigned long lNoStrip,
unsigned long l3D,
double *nGeoLon,
double *nGeoLat,
double *nOrigin,
double *nConvergence);
Prototype of the DLL function in Visual Objects syntax:
_DLL function coordcalcextraind(;
nCoordX as real8,; // 8 Byte
nCoordY as real8,; // 8 Byte
pszCoord as psz,; // 4 Byte, char*
nEllHgt as real8,; // 8 Byte
nCoordSys as word,; // 2 Byte
nRefSys as word,; // 2 Byte
nUnit as word,; // 2 Byte
nStrip as word,; // 2 Byte
lNoStrip as logic,; // 4 Byte
l3D as logic,; // 4 Byte
nGeoLon ref real8,; // 4 Byte
nGeoLat ref real8,; // 4 Byte
nOrigin ref real8,; // 4 Byte
nConvergence ref real8); // 4 Byte
as logic pascal:geodll32.coordcalcextraind // 4 Byte
The function calculates the Extra Parameters Meridian Convergence, Origin
Center Meridian and Geographical Point Coordinate for a coordinate in any
coordinate Reference System (CRS). In contrast to the function
coordcalcextra(), the use of the setcalcextra() function is not required.
The following Extra Parameters are available:
Longitude of the Geographical Point coordinate.
Latitude of the Geographical Point coordinate.
Longitude of Origin Center.
Meridian Convergence at the Geographical Point
Coordinates in arbitrary coordinate Reference Systems (CRS) can always be
converted into Geographical Point Coordinates.
The Longitude of Origin Center is the north-aligned central meridian of the
Coordinate System.
The Meridian Convergence is often also referred as map convergence or grid
convergence. The Meridian Convergence is the angle between the north
direction of the coordinate grid and the geographic north direction at the
Geographical Point. It can be calculated e.g. for all Mercator and Lambert
projections.
Note that the calculation of Extra Parameters is not possible with every
coordinate transformation. In this case, the values -9999 are returned for
the corresponding Extra Parameters.
The Meridian Convergence and the Central Meridian are currently supported
by the following systems:
All Transversal Mercator systems
All normal Mercator systems
All Lambert Conformal Conic systems
If no Extra Parameters could be calculated, the function is terminated with
the return value FALSE and the Extra Parameters have the value -9999.
For transferring the numerical coordinate nCoordX / nCoordY or the
alphanumeric coordinate pszCoord as well as the CRS settings nCoordSys,
nRefSys, nUnit, nStrip and lNoStrip please read the detailed notes in the
description of the function coordtransex().
The parameters are returned as follows:
nCoordX Longitude, East or X component of the numeric coordinate.
During processing of an alphanumeric coordinate this
parameter is without meaning. The input format of the
coordinate (notation) is described in the list "Defaults
of the Coordinate Systems".
nCoordY Latitude, North or Y component of the numeric coordinate.
During processing of an alphanumeric coordinate this
parameter is without meaning. The input format of the
coordinate (notation) is described in the list "Defaults
of the Coordinate Systems".
pszCoord Alphanumeric source coordinate.
During processing of a numeric coordinate this parameter is
without meaning. In this case for pszCoordQ a NULL pointer
can be passed. The input format of the coordinate (notation)
is described in the list "Defaults of the Coordinate
Systems".
nEllHgt Ellipsoidical height of the target coordinate
(ref) or
Z component of a cartesian coordinate.
With 3D transformations in the case of using different source
and target Reference Systems (nRefSysQ, nRefSysZ), the
ellipsoidical height of the target coordinate is calculated.
nCoordSys Coordinate System of the coordinate.
(see list "Coordinate Reference Systems").
nRefSys Geodetic Reference System of the coordinate.
(see list "Coordinate Reference Systems").
nUnit Measurement Unit of the coordinate.
0 The coordinate components are specified in a standard
Measurement Unit, as for the Coordinate System preset in
GeoDLL. If necessary, they are translated in meters for
internal use.
(see list "Default settings" [source code: settings_e.txt]).
› 0 The coordinate components are specified in a particular
Measurement Unit and are translated in meters for internal
use.
(see list "Coordinate Reference Systems alphabetical"
[source: sysalpha_e.txt]).
1000 No effect. The coordinate components are not converted to
another Measurement Unit.
nStrip Meridian strip to use with the Coordinate System.
This parameter has only an effect, if a "Transversal Mercator
meridian strip system" is registered in nCoordSys.
0 Using of the leading digits of the easting for the
calculation of the natural meridian strip.
› 0 Using of the value in nStrip for the calculation of the
natural meridian strip.
lNoStrip Setting for the suppressing of the meridian strip number in
the eastings. This parameter has only an effect, if a
"Transversal Mercator meridian strip system" is registered in
nCoordSys.
TRUE Eastings must be passed without leading meridian strip
numbers.
FALSE Eastings must be passed with leading meridian strip numbers.
l3D Setting for coordinate transformation in 3D mode. When the
3D mode is on, a value must be passed in nEllHgt.
TRUE Execution as 3D coordinate transformation.
FALSE Execution as 2D coordinate transformation.
nGeoLon Geographical longitude in decimal notation calculated from
(ref) the coordinate (Geographical Point).
Or -9999, if the value could not be calculated.
nGeoLat Geographical latitude in decimal notation calculated from
(ref) the coordinate (Geographical Point).
Or -9999, if the value could not be calculated.
nOrigin Longitude of Origin Center.
Or -9999, if the value could not be calculated.
nConvergence Meridian Convergence at the Geographical Point.
(ref) Or -9999, if the value could not be calculated.
returnVal In case of error the function returns FALSE, otherwise TRUE.
The following topics are explained in detail in the descriptions of the
functions coordtransex() .and. coordtrans3dex():
Range validity
Notations
Standard Reference Systems
3D Coordinate Transformation
Unlocking:
This function is a component of the unlock requiring function group
"Coordinate Transformations". It is unlocked for unrestricted use
together with the other functions of the group by passing the unlock
parameters, acquired from the software distribution company, trough the
function setunlockcode(). Without unlocking only a few function calls for
test purposes (shareware principle) are possible.
|