Isis 2 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
Parm | Description | Default |
---|---|---|
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:
Parm | Description |
---|---|
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. |
Contact us online at the Isis Support Center: http://isisdist.wr.usgs.gov