lev2grid Documentation

lev2grid - Create file for plotting graticules(PostScript).
Programmer : K T Thompson
"lev2grid" generates a PostScript file for drawing latitude/longitude
graticules, latitude and longitude ticks and/or an extra grid.  This
file is generated in PostScript format.  "lev2grid" will draw the
latitude and longitude (LATRANGE,LONRANGE) boundaries and internal lines
as defined by each "lev2grid" parameter. The x,y origin (0,0), internal
to this plot file, is established at exactly the minimum x and minimum y
position of the grid, therefore the grid is drawn within the 1st
quadrant of the Cartesian coordinate system. When a PostScript format
file is created, the file is centered on the page according to the main
grid dimensions and the input PAPER(width & height) or the input SCALE.
This plot file can be displayed on the screen using ghostview or printed
to a PostScript device.  Use your usual print command lines when sending
your file to any PostScript translating plotter or printer, else you
will have to get into the plotter/printer machine documentation.  For
'ghostview':

bug{927}>  ghostview grid.ps

  or

bug{927}>  ghostview 




 _
           -----------
 H         |         |
 E         |         |
 I         | y       | PRINTER
 G         | |       |
 H         | |       |
 T         | ---> x  |
 _         -----------

           <--WIDTH-->

Thousands of maps have been produced by many different agencies for var-
ious purposes. A common problem may occur when matching a new map to an
older map or matching to maps from other agencies. In this situation
there are many variables which affect the size and/or geometric shape of
a grid. If the mismatch is strictly a size difference, then the problem
is possibly the scale, planet radius or the old map is on an unstable
material. If the mismatch seems to be a geometric difference, then the
problem may be eccentricity, standard parallels or a central latitude or
longitude.

Data file to create.  Will
contain drawing instructions
for this grid.

NONE

Width of the grid line
Width of the ticks
[SMALL,MEDIUM,LARGE]

NONE

Paper width & height
in inches.
   (or)

NONE

fractional map scale, (i.e.
for 1:1,000,000 scale=1.0)

NONE

Target or target
definition file

NONE

Map projection parameters
(e.g., sinu,0)

NONE

Longitude system
(default 0 to 360)

360

Latitude system
(default OGRAPHIC)

"OGRAPHIC"

Grid/tick latitude range

NONE

Grid/tick longitude range

NONE

Grid/tick latitude base line
Grid/tick longitude base line

NONE

Grid increments: latitude
longitude.
null, --, means no grid

NONE

latinc
loninc
bigspace 0 = no big ticks
null, --, means no ticks

NONE

latinc
loninc
bigspace 0 = no big ticks
null, --, means no ticks

NONE

Vary ticklength with latitude

NONE

Tick Bounds When Not On Inc

NONE

Extra Grid Latitude Range

NONE

Extra Grid Longitude Range

NONE

Extra Grid Increment: Latitude
Longitude
null, --, means no grid

NONE

Plot XLAT and XLON Boundaries

NONE

Base for Extra Grid: Latitude
Longitude

NONE

ADDITIONAL NOTES:

Parm	Description
TO	File name to be created by "lev2grid". This file contains the drawing instructions in PostScript format. The Post- Script version must be downloaded to a PostScript device.
LINESZ	First element is width of the line for gridding. Second element is width of the ticks. SMALL = 0 thinnest line possible MEDIUM= 1 LARGE = 2
PAPER	Paper width and height in inches. If scale is input, the paper width necessary to print the plot will be reported. Else if paper height and width are input, the resulting scale will be reported. Notice what might appear to be contradictory outputs: For a sinusoidal projection & for LATRANGE = -90 to 90 and LONRANGE = -180 to 180 WIDTH = 4 HEIGHT = 6 program calculates: WIDTH scale (divided by million) = 210 HEIGHT scale (divided by million) = 70 chooses larger scale to make projection smaller to fit in both directions: SCALE (divided by million) = 210 user inputs SCALE = 210 back into program and gets: Paper size calculated from input scale: (in Inches): 4.000293 x 2.000147 This is because WIDTH = 4 determined scale; then user inputs scale, which with LONRANGE = -180 to 180 gives 4 inches for WIDTH. LATRANGE = -90 to 90 will obviously be about half as big in the sinusoidal giving 2 inches for HEIGHT. Also for a sinusoidal projection & for LATRANGE = -90 to 90 and LONRANGE = -180 to 180 WIDTH = 4 HEIGHT = 1 program calculates: WIDTH scale (divided by million) = 210 HEIGHT scale (divided by million) = 420 chooses larger scale to make projection smaller to fit in both directions: SCALE (divided by million) = 420 user inputs SCALE = 420 back into program and gets: Paper size calculated from input scale: (in Inches): 2.000147 x 1.000073 This is because HEIGHT = 1 determined scale; then user inputs scale, which with LATRANGE = -90 to 90 gives 1 inch for HEIGHT. LONRANGE = -180 to 180 will be about twice as big in the sinusoidal and using the same scale results in 2 inches for WIDTH.
SCALE	The map scale is defined by the user or more commonly defined by a specific map series. Most map series have specific scales which vary throughout the series depending on the projection. For all projections except CYLI, SIMP and SINU, the map scale is expressed as the ratio or proportion between comparable measurements on the map to the surface represented by the map. This ratio is often called the Representative Fraction (RF). The RF is usually expressed as 1:5,000,000 or 1/5,000,000. At this scale, 1 cm on the map represents 5,000,000cm (50km) on the planet surface. Enter the second number of the RF divided by 1,000,000 for the SCALE. ( i.e. for 1:10,000,000 RF , SCALE = 10 for 1:18,261,561 RF , SCALE = 18.261561 for 1:502,000 RF , SCALE = .502 for 1:24,000 RF , SCALE = .024) For CYLI, SIMP, and SINU projections, the scale is related to kilometers per degree on the planet. To match a CYLI, SIMP or SINU to another projection (will match only at the equator), divide the desired RF scale by the number of kilometers in one degree of longitude on the equator of the planet. For example, to match a SINU to an existing 1:25,000,000 (SCALE=25) Mars map of another projection: Mars' equatorial radius is 3393.4 km. The circumference of Mars is 21,321.36 km (2 * PI * 3393.4). One degree of longitude is 59.226km (circumference/360). So the scale to use for the SINU is 25/59.226 or SCALE = .422112. See HELP PAPER for more info. See HELP * for more info.
TARGET	Either enter a target string that is a body that can be used to form a system target definition file, example: TARGDEF=mars The software will try to find files: $ISISDATA/targets/mars.def.1 $ISISDATA/targets/mars.def.2 $ISISDATA/targets/mars.def.3 etc. Or enter a user written target definition file path and name: TARGDEF=/work1/elee/mars.def.3 If you want radii different from the defaults in the system, you cannot enter the radii numbers here. Copy the system target definition file to your area and edit, putting the radii you want into the definition file. Then TARGDEF=your_ file. Note also that the target definition file name will be written to the cube labels, and you will help yourself if you use a version system as is being done in ISIS. Each time you make edits to your target definition file, rename it and keep the old versions lying around somewhere where you can find them.
MAPPARS	tutor mappars in TAE.
LONSYS	This parameter is used to define the longitude system computed by "lev1" programs. Valid values are either 180 or 360. The default is 360 which implies longitudes will be output in the range of 0 to 360. The value 180 implies longitudes will be output in the range of -180 to 180. Your selection is written to the labels of the cube or table file. This effects programs which output or use the latitude, for example, "qview", "lev1stats", "lev1tolev2".
LATSYS	This parameter is used to define the latitude system computed by "lev1" programs. Valid values are either OGRAPHIC or OCENTRIC. The default is OGRAPHIC. Your selection is written to the labels of the cube or table file. This effects programs which output or use the latitude, for example, "qview", "lev1stats", "lev1tolev2".
LATRANGE	The latitude boundaries (range) of the main grid and ticks. The valid range is from -90. degrees to 90. degrees.
LONRANGE	The longitude boundaries (range) of the main grid and the ticks. When creating a grid which includes the prime meri- dian (zero longitude line), be sure the longitude range is defined correctly: i.e. if your desired longitude range starts at 340° and crosses the prime meridian and ends at 10°, the longitude range should be defined as: LON = 340,370 or as LON = -20,10 The valid range is -360. degrees to 540. degrees.
BASE	BASE defines the base line for the grid increment - GINC and for the ticks increments - VERTTIC, HORIZTIC. Latitude lines will be drawn every GINC(1) degrees relative to BASE(1) for all lines within the latitude range (LATRANGE). Longitude lines will be drawn every GINC(2) degrees relative to BASE(2) for all lines within the longitude range (LONRANGE). Some examples: If LATRANGE=0,30 LONRANGE= 0, 30 GINC=(10,10) BASE=(0,0) Latitude lines 0,10,20,30 will be drawn. Longitude lines 0,10,20,30 will be drawn. If LATRANGE=0,22 LONRANGE=100,135 GINC=(10,10) BASE=(0,0) Latitude lines 0,10,20,22 will be drawn. Longitude lines 100,110,120,130,135 will be drawn If LATRANGE=-22,22 LONRANGE=10,40 GINC=(10,10) BASE=(0,5) Latitude lines ±22,±20,±10,0 will be drawn. Longitude lines 15,25,35 will be drawn If LATRANGE=10,20 LONRANGE=10,20 GINC=(5,5) BASE=(2.5,2.5) Latitude lines 10,12.5,17.5,20 will be drawn. Longitude lines 10,12.5,17.5,20 will be drawn. Short vertical ticks will be drawn every VERTTIC(1) degrees relative to BASE(1) for all latitude lines within LATRANGE, (and then the vertical ticks will be VERTTIC(2) degrees apart.) Short horizontal ticks will be drawn every HORIZ- TIC(1) degrees relative to BASE(2) for all longitude lines within LONRANGE, (and then the horizontal ticks will be HOR- IZTIC(2) degrees apart.) The third element of VERTTIC and HORIZTIC determines how of- ten a vertical or horizontal tick will be big rather than small.
GINC	GINC is latitude and longitude line increment for the grid. These define how frequently latitude and longitude lines will be drawn within the main grid boundaries. These in- crements are based on BASE(). See HELP BASE for more info.
VERTTIC	VERTTIC(1)=latitude increment for | , ticks VERTTIC(2)=longitude increment for | , ticks VERTTIC(3)=How often a tick should be long rather than short
HORIZTIC	HORIZTIC(1)=latitude increment for - , ticks HORIZTIC(2)=longitude increment for - , ticks HORIZTIC(3)=How often a tick should be long See HELP BASE for more info.
TICKLEN	Vary ticklength with latitude. TICKLEN=NO gives all small ticks the same short length and all big ticks the same long length. TICKLEN=YES gives ticklengths that vary with the latitude, getting shorter toward the poles. This and BIG- SPACE increment are the only control the user has over tick length.
TBWNOI	YES means the boundaries will be ticked if they are not on the grid increment. NO means they won't be ticked if they are not on the grid increment, but if the boundaries lie on the grid increment, they are always ticked.
XLAT	The latitude boundaries (range) of the extra latitude lines you wish to plot. These boundaries are plotted only if XBOUND = Y.
XLON	The longitude boundaries (range) of the extra longitude lines you wish to plot. These boundaries are plotted only if XBOUND = Y.
XGINC	Latitude and longitude line increment for the extra grid. These define how frequently latitude and longitude lines will be drawn within the extra grid boundaries. These in- crements are based on BASE(). If bound is no, the grid boundaries themselves will not be plotted. See HELP BASE or HELP BOUND for more info.
XBOUND	This determines if the XLAT and XLON boundaries are plotted. If XBOUND=N , only internal lines within XLAT and XLON will be plotted. For example: If XLAT=20,30 XGINC=(2,5) and XLON=100,120 and XBOUND=N Latitude lines 22,24,26,28 will be drawn from longitude 100 to 120 and Longitude lines 105,110,115 will be drawn from latitude 20 to 30. If XBOUND=Y in the previous example, the XLAT and XLON boundaries will also be plotted.
XBASE	Extra grid base latitude and longitude for XGINC. Defines the base line from which the extra grid increments will be counted. If no input then BASE, for regular grid will also be used for extra grid.