Page Comparison

h2. Name

*geo* -- Geographical coordinates handling {alias:geo}

h2. Syntax - Converting between coordinate systems
{panel:|borderStyle=solid|borderWidth=1|bgColor=#ffffaa}

*geo* \[*cvt*] \[*xy*] \[*lla*]

{panel}

h2. Syntax - Displaying geographical lines
{panel:|borderStyle=solid|borderWidth=1|bgColor=#ffffaa}

*geo* \[*dra*] \[*lon* | *lat*] \[*fra*] \[*col*] \[*set*]

{panel}

h2. Syntax - Annotate geographical axes
{panel:|borderStyle=solid|borderWidth=1|bgColor=#ffffaa}

*geo ann* 
{panel}

h2. Description

Handling and display of geographical coordinates. 

The *geo* command has a syntax for coordinate conversion and display of geographical coordinates. The *geo* command is for instance applied in the menu script *geodesy.tcl* that comes up from *Tools > Geographical Management* . In order to learn the command and practical use one can look into the script. (Look in the Geocap installation directory under the Geodesy module).

h2. Geodesywidget

The *geo* command uses coordinate information from the menu. This is handled through a special +widget+ called *geodesywidget* which is designed to be used in tcl scripts. One can think of *geodesywidget* as a complex tcl variable that contains the coordinate and datum information seen in the panel.

The conversion menu in Geodesy.tcl is organized in two parts: 1) *upper* and 2) *lower* . The conversion is from *upper* to *lower* or the other way. *Active data* is alway part of the conversion as the input dataset.

Due to the *geodesywidget* the script code for conversion and display of geographical coordinates is relatively small.

Below is shown how the tcl code reads the upper and lower geodesywidget into two global variables called *_cu_* and *_cl_* . Those variables will be used in conversion control later on.

{noformat:|borderWidth=1|bgColor=#eeeeee}
        # Setting upper and lower geodesywidget into a tcl variables
	set ::cu [geodesywidget]
	set ::cl [geodesywidget]
{noformat}


h2. Arguments
*geo cvt* \[*low*] *coord*
{indent}
Convert *active* data from +upper+ to +lower+. Or the other way if *low* is used. The result is in *active*.

h3. Example showing coordinate conversion of a dataset
*Active* data will be converted from coordinates shown in upper to coordinates shown in lower geodesywidget. For this should work correct it is the users responsibility to secure that the coordinates in the *upper* geodesywidget is set correct to the coordinate system of *active*. Be aware that when a conversion command object is activated upon a dataset in the project, that dataset is make *active* before conversion starts.
 
{noformat:|borderWidth=1|bgColor=#eeeeee}
proc GcGeodesy::convertActiveDataFromUpperToLower { } {
	geodesywidget setasupper $::cu
	geodesywidget setaslower $::cl
	geo cvt coord
}
{noformat}

{indent}

*geo xy* \[*low*] *coord*
{indent}
Convert *active* data from +upper+ to +lower+. Or the other way if *low* is used. The result is in *active*.
{indent}

h2. See also

[axe - Axes display]
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