Selecting Show Globe/Obj from the Plot Tools option in the Plot Definition Menu brings up the menu:
This is a generic menu used for a number of Plot Tool definitions and as such not all of the listed options are available to this Plot Tool. For Show Globe uses only the first two Vector Source definitions and Show Object uses all of the Vector Source. The first input vector is the spacecraft position vector, the second is the spacecraft spin axis vector, and the last the vector pointing to the object. Any of the vectors can be input manually or they may be taken from a UDF source. All vectors must be given in GCI coordinates. The advantage of using a UDF vector source is that the vectors are tracked in time and aligned with the data as closely as possible before each operation. If there are multiple occurrences of the vectors within the accumulation time of a single plot measurement then the average of the values is used. NOTE: While the PARENT shows Show Globe/Object, the action chosen is designated by the number of Vector Sources created. If two Vector Sources are created then the Show Globe function will be activated. If all the Vector Sources are created then the Show Object function will be activated. Both Show Globe and Show Object cannot be used at the same time.
The Show Globe tool is designed to display the Earth either as a 2D circle (the Earth's limb) or as a 3D globe in any Plot Definition whose Function Of options have been set to Phase Angle (phi) and Theta (elevation). The Earth is output from the perspective of a viewer on the spacecraft. The Plot Tool was originally coded for to show the Earth with proper perspective in the neutral atom and extreme ultraviolet images from the IMAGE mission.
There are two aspects of this plot tool that should be noted: the output is always the last thing drawn into a plot and so overlays the data; in 3D output the globe does not roll as the satellite passes over a pole but rotates 180 degrees in longitude so that the opposite face is forward.
The algorithm assumes:
The basic algorithm is given below. Inputs to the algorithm are the satellite position (X, Y, Z) and the satellite spin axis (Sx, Sy, Sz). The algorithm returns the effective radius of the earth in degrees (Ra) as well as the geographic latitude (gLaT) and geographic longitude (gLnG) of the satellite and the geographic latitude (gLaTs) and geographic longitude (gLnGs) of the satellite spin axis. The latter four variables are only needed when using a 3D projection of the Earth. Re is the earth radius (6371.0 km) and GsT is the Greenwich mean Siderial Time associated with the satellite in radians.
Algorithm:
R = [X2 + Y2 + Z2] ½)
Ra = atan2(1.0, R/Re)
X1 = cos(GsT) * X + sine(GsT) * Y;
Y1 = -sine(GsT) * X + cos(GsT) * Y;
gLnG = atan2 (Y1, X1);
gLaT = atan2 (Z, sqrt(X1 * X1 + Y1 * Y1));
X1 = cos(GsT) * Sx + sine(GsT) * Sy;
Y1 = -sine(GsT) * Sx + cos(GsT) * Sy;
gLnGs = atan2 (Y1, X1);
gLaTs = atan2 (Sz, sqrt(X1 * X1 + Y1 * Y1));
The globe is plotted by extablishing a relative window inside the plot window and plotting in that window. Normally the relative window is setup according to the scaling along the Bottom X and Left Y plot axis, however if the absolute value of the minimum Right Y axis scaling is identical to the absolute value of the minimum Left Y axis scaling then the scaling along the Right Y axis is used. This allows the relative window to be defined opposite to the plotting window should the data being plotted have been stored opposite to the sense of rotation.
The Show Object tool is designed to display the location of an object in any Plot Definition whose Function Of options have been set to have the Spin Phase (phi) and Theta (elevation). The object is output from the perspective of a viewer on the spacecraft.
The algorithm assumes:
The basic algorithm is given below. Inputs to the algorithm are the satellite position (X, Y, Z), the satellite spin axis (Sx, Sy, Sz) and the object position axis (Ox, Oy, Oz). The algorithm returns the the geographic latitude (gLaT) and geographic longitude (gLnG) of the satellite the geographic latitude (gLaTs) and geographic longitude (gLnGs) of the satellite spin axis and the geographic latitude (gLaTo) and geographic longitude (gLnGo) of the object. Re is the earth radius (6371.0 km), GsT is the Greenwich mean Siderial Time associated with the object position in radians, and Ra is the angular radius of the earth. Not all variables will be produced in any given run. The variables constructed depend on the display format.
Algorithm:
R = [X2 + Y2 + Z2] ½)
Ra = atan2(1.0, R/Re)
X = X / R
Y = Y / R
Z = Z / R
Mag = [Sx2 + Sy2 + Sz2]
½)
Sx = Sx / Mag
Sy = Sy / Mag
Sz = Sz / Mag
Mag = [Ox2 + Oy2 + Oz2]
½)
Ox = Ox / Mag
Oy = Oy / Mag
Oz = Oz / Mag
X1 = cos(GsT) * X + sine(GsT) * Y;
Y1 = -sine(GsT) * X + cos(GsT) * Y;
gLnG = atan2 (Y1, X1);
gLaT = atan2 (Z, sqrt(X1 * X1 + Y1 * Y1));
X1 = cos(GsT) * Sx + sine(GsT) * Sy;
Y1 = -sine(GsT) * Sx + cos(GsT) * Sy;
gLnGs = atan2 (Y1, X1);
gLaTs = atan2 (Sz, sqrt(X1 * X1 + Y1 * Y1));
X1 = cos(GsT) * Ox + sine(GsT) * Oy;
Y1 = -sine(GsT) * Ox + cos(GsT) * Oy;
gLnGo = atan2 (Y1, X1);
gLaTo = atan2 (Oz, sqrt(X1 * X1 + Y1 * Y1));
This is not an option in the conventional definition but contains the name of the Plot Tool which spawned the menu page. This is given as a reference since many different Plot Tools use this menu page.
CLOSE closes the Plot Tool Menu window.
For the Show Globe Plot Tool, only the first two vector options are enabled together with the set of Globe based options.
The first instance of the Vector Source option line defines the spacecraft position vector in GCI coordinates.
LOCATION
Vector to display. The options are:
| Option | Definition |
|---|---|
| USER | The user must enter the spacecraft position in the X, Y, Z entry boxes on the option line. |
| UDF | The displayed vector is derived from a UDF source. Selecting this option will pop up the Vector Source Menu and will make the next three options on this line inaccessible. |
| UNUSED | This option is a place holder. There are some options that don't use the Vector Source and so UNUSED is there as a reminder. |
X is accessible only if the LOCATION option has been set to USER. The option sets the X component of the Spacecraft Position vector in GCI coordinates.
Y is accessible only if the LOCATION option has been set to USER. The option sets the Y component of the Spacecraft Position vector in GCI coordinates.
Z is accessible only if the LOCATION option has been set to USER. The option sets the Z component of the Spacecraft Position vector in GCI coordinates.
The second instance of the Vector Source option line defines the spacecraft spin axis vector in GCI coordinates.
LOCATION defines the source of the Vector to display. The options are:
| Option | Definition |
|---|---|
| USER | The user must enter the spacecraft velocity in the X, Y, Z entry boxes on the option line. |
| UDF | The displayed vector is derived from a UDF source. Selecting this option will pop up the Vector Source Menu and will make the next three options on this line inaccessible. |
| UNUSED | This option is a place holder. There are some options that don't use the Vector Source and so UNUSED is there as a reminder. |
X is accessible only if the LOCATION option has been set to USER. The option sets the X component of the Spacecraft Spin Axis vector in GCI coordinates.
Y is accessible only if the LOCATION option has been set to USER. The option sets the Y component of the Spacecraft Spin Axis vector in GCI coordinates.
Z is accessible only if the LOCATION option has been set to USER. The option sets the Z component of the Spacecraft Spin Axis vector in GCI coordinates.
The GLOBE GRID options define the output format for the Earth's projection and if 3D how to grid the sphere.
FORMAT specifies the how the Earth's projection is to be drawn. The options are:
| Option | Definition |
|---|---|
| 2D | Output just the limb |
| 3D | Output 3D sphere |
COLOR sets the color used for all output. There are 8 colors to select from.
DELTA LAT is accessible only if the FORMAT option is set to 3D. This is the spacing in degrees between output latitude grid lines. Latitude grid lines are drawn from the minimum to the maximum displayable latitude. (See the LAT END within this option line).
DELTA LONG is accessible only if the FORMAT option is set to 3D. This is the spacing in degrees between output longitude grid lines. Longitude grid lines are drawn beginning at 0 degrees (Greenwich) and progressing eastward. In the default mode, 0 degrees longitude is always centered in the longitude axis.
LAT END is accessible only if the FORMAT option is set to 3D. It is used to set both the largest poleward extent of the longitude grid lines and the minimum and maximum displayable latitude grid line. The value represents the termination point of the northern latitude grid lines in degrees from the equator (equator being 0 degrees and north pole 90 degrees). The termination of the southern latitude grid lines is the negative of the value given. The option is used to defeat the convergence of the longitude grid lines in the polar regions.
The GLOBE MAP options are used to specify all options associated with the output of continental outlines on the 3D globe. The options are only accessible only if the FORMAT option under the Globe Grid Opts option line is set to 3D.
FORMAT specifies if the continental outlines are to be drawn on the 3D globe. The options are:
| Option | Definition |
|---|---|
| OFF | No continental outlines are output |
| ON | Continental outlines are output |
COLOR is accessible only when the Globe Map FORMAT option is ON. It sets the color used to display the continental outlines. There are 8 colors to select from.
The LSHELL options are partially enabled under the SHOW GLOBE tool. This option allows a set of terrestial based, magnetic LShell projections to be overlaid onto the plot. The program uses a magnetic pole of 79° N and 70° W. The projected L-Shells are determined from the Start, Stop, and Delta options according to the formula:
The LSHELL options are partially enabled under the SHOW GLOBE LShell = Start + J * Delta
Where J runs from 0 to the value such that the computed L-Shell value is greater that Stop. Labeling of which L-Shells are plotted can be included through the Tool Labels options.
FORMAT specifies the action to be taken when setting up the L-Shell projections. The options are:
| Option | Definition |
|---|---|
| OFF | No L-Shell projections produced |
| ON | L-Shell projections produced |
| ON[trACE/LOWER] | L-Shell projections produced with a plot of the intensity along the projections plotted below the main plot. This option is no available under the PLOT GLOBE and if selected will revert to ON. This option is enabled under the PLOT OBJECT tool definition. |
| ON[trACE/RIGHT] | L-Shell projections produced with a plot of the intensity along the projections plotted to the right of the main plot. This option is no available under the PLOT GLOBE and if selected will revert to ON. This option is enabled under the PLOT OBJECT tool |
COLOR is accessible when the L-Shell FORMAT option is not OFF. It sets the color used to output the L-Shell projections. There are 8 colors to select from.
START is accessible only if the FORMAT option is set to ON. This is the first LShell value to project. Value is given in Re.
END is accessible only if the FORMAT option is set to ON. This is the termination LShell value in the output loop. It may or may not be output depending on the value of DELTA
DELTA is accessible only if the FORMAT option is set to ON. This is the stepping to use in computation of projected L-Shells.
For the Show Object Plot Tool, all three vector options are enabled together with the line of Vec Symbol options.
The first instance of the Vector Source option line defines the spacecraft position vector in GCI coordinates.
LOCATION
defines the source of the Vector spacecraft position vector. The options are:
| Option | Definition |
|---|---|
| USER | The user must enter the spacecraft position in the X, Y, Z entry boxes on the option line. |
| UDF | The displayed vector is derived from a UDF source. Selecting this option will pop up the Vector Source Menu and will make the next three options on this line inaccessible. |
| UNUSED | This option is a place holder. There are some options that don't use the Vector Source and so UNUSED is there as a reminder. |
X is accessible only if the LOCATION option has been set to USER. The option sets the X component of the Spacecraft Position vector in GCI coordinates.
Y is accessible only if the LOCATION option has been set to USER. The option sets the Y component of the Spacecraft Position vector in GCI coordinates.
Zis accessible only if the LOCATION option has been set to USER. The option sets the Z component of the Spacecraft Position vector in GCI coordinates.
The second instance of the Vector Source option line defines the spacecraft spin axis vector in GCI coordinates.
LOCATION defines the source of the Vector to display. The options are:
| Option | Definition |
|---|---|
| USER | The user must enter the spacecraft velocity in the X, Y, Z entry boxes on the option line. |
| UDF | The displayed vector is derived from a UDF source. Selecting this option will pop up the Vector Source Menu and will make the next three options on this line inaccessible. |
| UNUSED | This option is a place holder. There are some options that don't use the Vector Source and so UNUSED is there as a reminder. |
X is accessible only if the LOCATION option has been set to USER. The option sets the X component of the Spacecraft Spin Axis vector in GCI coordinates.
Y is accessible only if the LOCATION option has been set to USER. The option sets the Y component of the Spacecraft Spin Axis vector in GCIcoordinates.
Z is accessible only if the LOCATION option has been set to USER. The option sets the Z component of the Spacecraft Spin Axis vector in GCIcoordinates.
The third instance of the Vector Source option line defines the object position vector in GCI coordinates.
LOCATION defines the source of the Vector to display. The options are:
| Option | Definition |
|---|---|
| USER | The user must enter the object position in the X, Y, Z entry boxes on the option line. |
| UDF | The displayed vector is derived from a UDF source. Selecting this option will pop up the Vector Source Menu and will make the next three options on this line inaccessible. |
| UNUSED | This option is a place holder. There are some options that don't use the Vector Source and so UNUSED is there as a reminder. |
X is accessible only if the LOCATION option has been set to USER. The option sets X component of the Object to display.
Y is accessible only if the LOCATION option has been set to USER. The option sets Y component of the Object to display.
Z is accessible only if the LOCATION option has been set to USER. The option sets Z component of the Object to display.
The VEC SYMBOLS options define the symbol, symbol size, symbol color, and display format used to output the object in the plot. The TAIL option is not used.
SIZE sets the label size. Valid sizes run from 3 to 32767 with character size increasing with value. As a general rule of thumb 12-25 is a good selection. At a size of 1000 a single character will completely fill the plot page. Both the vector head and tail symbols will be displayed at this size. Note that if you do not wish to show the object, which might be the case if you are only plotting the terminator, leave this option blank.
COLOR sets the symbol color. There are 8 basic colors to select from. Both the vector head and tail symbols will be displayed in this color.
HEAD defines the character(s) to output at the location of the vector head. Multiple characters are allowed as long as there are no spaces. In addition to the alpha/numeric symbols there are a number of non-alpha/numeric symbols which can be defined. These are given in the table below. Note: that the apostrophe ' must be included in the symbol name.
| Symbol | Definition |
|---|---|
| 'FSTAR' | Filled Star |
| 'FBOX' | Filled Box |
| 'FUTRI' | Filled Inverted Triangle |
| 'FDTRI' | Filled Triangle |
| 'BLOT' | Filled Circle |
| 'STAR' | Unfilled Circle |
| 'DIA' | Unfilled Diamond |
| 'CIRCLE' | Unfilled Circle |
| 'BOX' | Unfilled Box |
| 'DTRI' | Unfilled Triangle |
OUTPUT FMT specifies how to display the object in the plot. The options are:
| Option | Definition |
|---|---|
| 3D | The object is plotted with its correct phase angle and elevation angle according to the plot scaling. |
| SUB-POINT | The sub-point of the object located on the Earth's surface is plotted. This option should only be used when a 3D projection of the Earth has been included in the plot. |
The TERMINATOR options allow the object terminator to be drawn on a globe if one has been specified for output. If not then selecting this option will have no effect. Terminators can be produce on either 2D or 3D globes. The terminator on a 2D globe is always a line drawn through the center at the correct angle for the placement of the object.
FORMAT specifies if a terminator is to be drawn. The options are:
| Option | Definition |
|---|---|
| OFF | No terminator is to be output |
| ON | The terminator is to be output |
COLOR is accessible only when the Terminator FORMAT option is ON. It sets the color used to display the terminator. There are 8 colors to select from.
The LSHELL options allow a set of terrestrial based, magnetic LShell projections to be overlaid onto the plot. This ideally should be invoked only when the defined object is the Solar Position for reasons which will become obvious.
The program uses a magnetic pole of 79° N and 70° W. The projected L-Shells are determined from the Start, Stop, and Delta options according to the formula:
LShell = Start + J * Delta
Where J runs from 0 to the value such that the computed L-Shell value is greater that Stop. A white 1° segment in each projection shows the equivalent logitudinal location of the plotted object if the projections are in black. A black segment is used if the projections are in any other color. If the defined object is the sun, then this marks MLT 12 Hr.
In addition, the intensites along the projections can be included
as a separate plot. When this is done, the first intensity is obtained at
the location 180 degrees away in the longitude of the location of the
defined object. This is equivalent to a magnetic solar time
of 0 if the defined object is the sun. Plots have the position axis
labeled as MST. The inner most L-Shell intensity always plotted in
white, followed by red, yellow, green, cyan, blue, and purple.
Labeling of which L-Shells are plotted can be included through the
Tool Labels options and the
instensity axis definitions are picked up from the 1D Cut options
in the
FORMAT specifies the action to be taken when setting up the L-Shell projections. The options are:
| Option | Definition |
|---|---|
| OFF | No L-Shell projections produced |
| ON | L-Shell projections produced |
| ON[TRACE/LOWER] | L-Shell projections produced with a plot of the intensity along the projections plotted below the main plot. |
| ON[TRACE/RIGHT] | L-Shell projections produced with a plot of the intensity along the projections plotted to the right of the main plot. |
COLOR is accessible when the L-Shell FORMAT option is not OFF. It sets the color used to output the L-Shell projections. There are 8 colors to select from.
START is accessible only if the FORMAT option is set to ON. This is the first LShell value to project. Value is given in Re.
END is accessible only if the FORMAT option is set to ON. This is the termination LShell value in the output loop. It may or may not be output depending on the value of DELTA.
DELTA is accessible only if the FORMAT option is set to ON. This is the stepping to use in computation of projected L-Shells.
DELETE PAGE deletes the current Plot Tool Definition and all menus associated with it.
The following examples show some of the effects obtainable through the Show Globe menu.
With just the default menu options, the plot tool displays a 2D Earth's rim in white once the satellite position and spin axis information has been set. The following three menus are used in a default setup in which the GCI satellite position and spin axis vectors are obtained from a UDF source.
Displaying a 3D representation necessitates giving the deltas between the latitude and longitude lines as well as the extent of the longitude lines.
Displaying continental outlines on the globe is accomplished by turning the option on and selecting the color to use.
The following set of 4 menus is the setup to show the location of the sun in a HENA neutral atom image. The 3D Earth is also included in the plot.
Addition of the solar terminator to the 3D Earth is accomplished by turning on the terminator option in the menu and selecting the terminator color.
This is the same type of plot as those above with changes to the time of the plot, the color scaling, and the axis scaling. The LShell options in the menu have now been enabled and the LShell projections from L=2 to L=5 are output in black. Also the solar position is now shown as the subsolar projection on the Earth sphere.
LShell Output w/Plotted Intensities
This is the same plot as above but with the intensities along the different L-Shell porjections plotted as a linear plot to the right of the phi-theta plot. Labeling of the projections has been enabled and is seen above the added plot.
LShell Output w/Plotted Intensities
Identical to the above plot but the Plot Gap and Data Storage options in the Plot Definition Menu have been set to Linear Fill and Point respectively.
Because the plot grid has a finer resolution than the data this has the effect of smoothing the data within the data grid. The resultant plot shows the effect on both the phi-theta and the accompanying intensity plot.
| &larr Previous | TOC | HOME | Next &rarr |
| Show Vector Menu | Contour Def Menu |