USGS

Isis 2 Documentation


size Documentation

size - Compute map size
This program will compute the number of lines and samples and the size
in inches for any map projection.  It will also compute any one of four
parameters given the other three.  These parameters are: resolution,
raster size, enlargement factor and map scale, where:

	map scale = resolution * 1000 / enlargement / raster size

This program will also print the scale factor and map scale for a given
latitude range in increments defined by the user.  This information can
be useful in deciding what raster size to use when creating hard copy
with a film writer.

Programmer: Kay Edwards, USGS, Flagstaff, Az

ParmDescriptionDefault
PLANET
Planet name
NONE
PROJ
Projection
NONE
KM
Image resolution (km/pix)
    or
1.
DEG
Image resolution (pix/deg)
0.
SCALE
Map scale (millions)
0.
MICRON
Micron setting
50.
ENLARGE
Enlargement factor
1.0
INC
Increment of scale factors
90.
LAT
Latitude range
-90.,90.
LON
Longitude range
-180.,180.
MAPROT
Map rotation
0.
PLAT
Latitude of new pole
0.
PLON
Longitude of new pole

The following parameters are
only needed for certain
projections:
0.
CLON
Center longitude of projection
0.
CLAT
Center latitude of projection
Note: this parameter is used
by MERC and POLA
0.
PAR1
First standard parallel
900.
PAR2
Second standard parallel
900.
SCFA
Scale factor
1.
TIM1
Time of planet rotation (min)
0.
TIM2
Time of satellite rotation (min)
0.
INCL
Orbit inclination
0.
ASCN
Longitude of ascending node
0.
DIST
Height above planet (km)
0.
LAT1
Latitude of control point 1
0.
LON1
Longitude of control point 1
0.
LAT2
Latitude of control point 2
0.
LON2
Longitude of control point 2
0.
MLIB
Maximum libration
11.

ADDITIONAL NOTES:

ParmDescription
PROJ
Each projection is identified by a four letter keyword.
The following table lists the keywords for all possible
projections and the parameters that are required for each
projection.

KEYWORD  PROJECTION                      PARAMETERS REQUIRED
ALBE     Albers Conical Equal-area       CLON,CLAT,PAR1,PAR2
ALEX     Modified Lambert Azimuthal      MLIB
AZEQ     Azimuthal Equidistant           CLON,CLAT
CYLI     Cylindrical Equal-area          CLON,CLAT*
ECON     Equidistant Conic               CLON,CLAT,PAR1,PAR2
                                      or CLON,CLAT,PAR1
GNOM     Gnomonic                        CLON,CLAT
LAMA     Lambert Azimuthal Equal-area    CLON,CLAT
         (+90 to -90 from CLON,CLAT)
LAMB     Lambert Conformal               CLON,CLAT,PAR1,PAR2
LAMG     Lambert Azimuthal Equal-area    CLON,CLAT
         (+170 to -170 from CLON,CLAT)
MERC     Mercator                        CLON,CLAT*
MILL     Miller Cylindrical              CLON
MSC      Modified Stereographic Conformal
OMER     Oblique Mercator or Hotine      CLAT,SCFA
                                     and CLON,INCL
                                      or LAT1,LON1,LAT2,LON2
ORTH     Orthographic                    CLON,CLAT
POIN     Point Perspective               CLON,CLAT,DIST
POLA     Polar Stereographic             CLON,CLAT*
POLY     Polyconic                       CLON,CLAT
ROBI     Robinson                        CLON
SIMP     Simple Cylindrical              CLON,CLAT*
         or Equidistant Cylindrical
SINU     Sinusoidal                      CLON
SOM      Space Oblique Mercator          TIM1,TIM2,INCL,ASCN
STER     Stereographic                   CLON,CLAT
TRAN     Transverse Mercator             CLON,CLAT,SCFA
UTM      Universal Transverse Mercator   CLON,CLAT,SCFA
VANG     Van der Grinten I               CLON

*CLAT defines the latitude of true scale for the following
 projections: CYLI, MERC, POLA and SIMP.

These projections are described by John Snyder in the
U.S.G.S. Professional paper 1395 titled "Map Projections -
A Working Manual".
LAT
The latitude boundaries of the projection. The valid range
is from -90. to 90. degrees.
LON
The longitude boundaries of the projection. On Earth, Venus
and the Uranian system longitude is positive to the east.
The rest of the solar system is positive to the west.  The
valid range is -360. to 360. degrees.
KM
Resolution is usually specified in kilometers/pixel,
degrees/pixel or pixels/degree.  KM is the resolution of
the image in km/pix.  Either this parameter or DEG can be
used to enter the desired resolution.  The equations
relating the two parameters are:

      KM=RADIUS*.0174533/DEG or DEG=RADIUS*.0174533/KM

If DEG=0., then KM will be used to define resolution.
DEG
DEG is the resolution of the image in pix/deg.  The default
will be to use KM to define the resolution.  If the desired
resolution is given in degrees/pixel such as: 1/32 deg/pix,
or .03125 deg/pix then the inverse must be used which is
DEG=32 (pix/deg) and any value in KM will be ignored.
SCALE
The map scale of a paper product is given in millions.  For
example if the product is to be 1:10 million, SCALE=10.
MICRON
This is the micron setting or spot size of a pixel.
MAPROT
This parameter defines which way is up.  For most
projections, North is at the top when MAPROT=0.  When
MAPROT=90.,  the image will be rotated clockwise.  The
valid range is -360 to 360 degrees.
PLAT
Latitude of the pole of a new spherical coordinate system.
For the majority of cases, the default of no rotation is
what should be used. The valid range is -90 to 90 degrees.
PLON
Longitude of the pole of a new spherical coordinate system.
For the majority of cases the default of no rotation is what
should be used. The valid range is -360 to 360 degrees.
CLON
Projections requiring a center longitude are: ALBE, AZEQ,
CYLI, ECON, GNOM, LAMA, LAMB, LAMG, MERC, MILL, OMER, ORTH,
POIN, POLA, POLY, ROBI, SIMP, SINU, STER, TRAN, UTM and
VANG.  The center longitude defines the central meridian of
the projection, not necessarily the center of your input or
output image.  It is a parameter defined by the user of the
final product.  If working with images which will be
computer mosaicked, then the center longitude for all those
images must be the same.  If the TRAN is being used on
Earth, there is a convention used of defining the center
longitude of 6 degree wide zones (Universal Transverse
Mercator or UTM).  These zones are defined by measuring 6
degree increments from 0 degrees longitude.  This means
that the center longitudes of these zones start at 3 and go
in increments of 6 degrees through 357 degrees.  Or from
-177 degrees to 177 degrees.  On Earth, Venus and the
Uranian system longitude is positive to the east.  The rest
of the solar system is positive to the west.  The valid
range is from -360 degrees to 360 degrees.
CLAT
Projections requiring a center latitude are: ALBE, AZEQ,
CYLI, GNOM, LAMA, LAMB, LAMG, MERC, OMER, ORTH, POIN, POLA,
POLY, SIMP, STER, TRAN and UTM.  The center latitude
defines the latitude of origin of the projection, except
for the following projections: CYLI, MERC, POLA and SIMP
where it defines the latitude of true scale.  It is a
parameter defined by the user of the final product.  If
working with images which will be computer mosaicked, then
the center latitude for all those images must be the same.
The valid range is from -90. degrees to 90. degrees.
PAR1
Projections requiring standard parallels are: ALBE, ECON
and LAMB (The ECON may have one or 2 parallels).  Standard
parallels must have the same sign as the latitude range of
the projection.

Default standard parallels for Lambert Conformal are:

PLANET    PAR1   PAR2
-------	  ----   ----
CALLISTO   30.    58.
EARTH      33.    45.
GANYMEDE   30.    58.
MARS       35.83  59.17
MERCURY    30.    60.

Default standard parallels for Albers Equal-area are:

PLANET    PAR1   PAR2
-------   ----   ----
EARTH     29.5   45.5
PAR2
See PAR1
SCFA
The projections requiring a scale factor are: OMER, TRAN
and UTM.  This is the ratio between true scale at some
standard point such as a standard parallel and the scale
at any given point.  This value is normally left at 1.
The UTM overides the default and sets SCFA=.99996.  The
UTM should only be used for Earth.
TIM1
The SOM is only projection requiring the time of planet
rotation.  TIM1 is the length of Earth's rotation with
respect to the precessed ascending node of the satellite
orbit in minutes.  For Lansat this value is 1440 minutes or
one day (See Snyder).
TIM2
The SOM is only projection requiring the time of satellite
rotation.  TIM2 is the time required for one revolution of
the spacecraft in minutes.  For Landsat 1,2,3 TIM2=103.267,
for Landsat 4,5 TIM2=98.884.
INCL
The projections requiring the orbit inclination are: OMER
and SOM.  INCL is the angle of inclination between the plane
of the planet's equator and the plane of the satellite
orbit, measured counterclockwise from the equator to the
orbital plane at the ascending node.  For Landsat 1,2,3
INCL=99.092, for Landsat 4,5 INCL=98.20.
ASCN
The SOM is only projection requiring the longitude of the
ascending node of the orbit.
DIST
The POIN is the only projection requiring the height above
the planet.
LAT1
The OMER is the only projection requiring the latitude and
longitude of two control points.  These control points
must be on the great circle chosen for the projection.  The
Mercator is a special case of the Oblique Mercator where the
Equator is the great circle chosen for the projection.
LON1
See LAT1
LAT2
See LAT1
LON2
See LAT1
MLIB
MLIB is the maximum libration.  ALEX (Modified Lambert
Azimuthal) is the only projection that that requires MLIB.
This projection was developed for telescopic observations of
the Moon from Earth.

Last updated: Jan 31 2005
File: pdfs2.html

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