Isis 2 Documentation
lev2raster - Rasterize data using latitude, longitude coordinates lev2raster is a general purpose application that will rasterize data contained in a file to a Level 2 ISIS image cube. The raster data file can be either binary or ASCII in nature. The raster file is assumed to contain data in a record-like format. Each record must contain latitude, longitude and raster data at a specific location within each record. A record is defined in a configuration file given in the CONFIG parameter. Each latitude and longitude coordinate is translated (converted) to a line and sample location. The actual line and sample where the raster data is placed is a result of rounding of the conversion from latitude,longitude to line, sample. The raster data is then "plotted" or placed in to that pixel location. lev2raster supports more than one band of raster data as long as the data is stored contiguously in the raster data file (defined in CONFIG). lev2raster can operate in several modes. The MODE parameter allows the user to create a new level 2 ISIS image cube using the "INIT" option. The MODE="ADD" option allows the user to add raster data to an existing level 2 projected file. The INIT mode relies on the user to provide sufficient information to create a proper level 2 cube. There are several ways to do this. The easiest way is to provide the name of an existing level 2 image cube in the INITFROM parameter. The user can then modify many of the projection characteristics using other input parameters. The second way is to completely provide all the information in input parameters. The following is a list of projection parameters that can be used to specify (INITFROM not provided) or alter (when INITFROM file is given) projection characteristics: TARGDEF - The name of the target object from whence the data came. For example this can be "MARS", "EUROPA" or some other supported planetary body. It is typically only needed to specify planet radii and the direction of postive longitude. See $ISISDATA/targets for supported and recognized bodies. This parameter is ignored if INITFROM is given, required if its not given. MAPPARS - String to specify the name of the desired projection and any parameters specific to it as needed. See the PDF description in mappars.pdf. This file describes all supported ISIS projections and their parameters. This parameter is optional if INITFROM is given and can be used to specify a completely different projection. It is required if INITFROM is not given. Example: "SINU:0,OCENTRIC". LATRANGE - Use this parameter to set the minimum and maximum latitude to represent in the output projection. All raster data that falls outside this latitude range will not be included in the output file. If INITFROM is given, the ranges in this projection are used. It can be used to alter the latitude range in INITFROM if so desired. It is required when INITFROM is not specified. Example: LATRANGE=(-40.5,-10.2) LONRANGE - Use this parameter to set the minimum and maximum longitude to represent in the output projection. All raster data that falls outside this longitude rnage will not be included in the output file. If INITFROM is given, the ranges in this projection are used. It can be used to alter the longitude range in INITFROM if so desired. It is required when INITFROM is not specified. Example: LONRANGE=(10.5,45.0) KM - This parameter sets the resolution of the output projection in units of kilometers per pixel. Only one of KM or DEG can be specified, not both. One of KM or DEG is also required for all runs of lev2raster. DEG - This parameter sets the resolution of the output projection in units of pixels per degree. Only one of DEG or KM can be specified, not both. One of KM or DEG is also required for all runs of lev2raster. LATSYS - This parameter is used *solely* to designate the latitude coordinate system LATRANGE parameter is specified in. This allows the user to specify these ranges in either planetocentric or planetographic. LONSYS - This parameter is used *solely* to designate the longitude coordinate system LONRANGE parameter is specified in. This allows the user to specify these ranges in either -180 to 180 (180) or 0 to 360 (360) ranges. The ADD option for MODE will allow the user to add input raster data to an existing level 2 projected image. This file can come from any source and is not restricted to files created in previous lev2raster runs. In this case, all input projection modification parameters are ignored. These are TARGDEF, MAPPARS, LATRANGE, LONRANGE, KM, DEG, LATSYS, LONSYS, and LONDIR. The file specified in TO defines all these and incoming latitude and longitude data are placed according to the projection in the file. The UPDATE parameter informs lev2raster how to handle the actual incorporation of raster data when it encounters existing data. Only for UPDATE = "REPLACE", does this eliminate the need to read in existing data from the input cube. This option simply takes each raster DN and replaces data at that pixel location with incoming data. The UPDATE mode = "PRESERVE" will look at each input pixel location and determine if any data already exists there. If so, the existing data will remain in the output file and the input data is discarded. For UDPATE = "AVERAGE", the input data is merged, or averaged, with any existing data in the input TO file. An accurate average is maintained if the original TO file was created using lev2raster. A backplane named "RASTER_COUNT" is created for all image cubes created using lev2raster. This backplane maintains a count of the number of "hits", or the number of pixels that were placed at that particular line and sample location. The average of that location is computed using the following formula: odn[i] = ((idn[i] * RASTER_COUNT) + raster_dn[i]) / (RASTER_COUNT + 1) RASTER_COUNT = RASTER_COUNT + 1 This maintains a running average at that line/sample location for all bands in the output image cube. Note that this strategy is applied only when the RASTER_COUNT backplane exists in the TO file. Otherwise, a normal average is computed for each band using: odn[i] = (idn[i] + raster_dn[i]) / 2.0 In the above equations, "odn" is the resulting output pixel, "idn" is the existing input pixel, "raster_dn" is the input raster dn value, "[i]" indicates the band, and "RASTER_COUNT" is the value of the backplane count at that pixel location. The PMEROFF parameter is a special parameter used to adjust longitudes for offsets in prime meridians for certain planetary bodies. The motivation for this parameter comes from the data returned from the Mars Global Surveyor (MGS) Mars Observer Camera (MOC), Thermal Emission Spectrometer (TES) and Mars Observer Laser Altimeter (MOLA) and values used for the prime meridian values for Mars for these data. In ISIS, MOC data was processed using IAU 2000 values for the prime meridian. These values come directly from the contents of target definition files in the $ISISDATA/targets directory, namely mars.def.N where N is the highest occuring integer value. At the time of this writing, MOC used mars.def.3 which uses IAU 2000 values for PRIME_MERIDIAN_0 = 176.7215. MOLA used IAU 1991 values for PRIME_MERIDIAN_0 = 176.868. And TES used PRIME_MERIDIAN_0 =176.901. In order to compare these products directly, one must adjust the longitude values of one to comparable prime meridian of the other. This parameter lives specifically for this purpose. For example, if we want to compare TES data to a specific MOC image (which can be specified in the INITFROM parameter) all TES longitudes must be adjusted to the MOC (IAU 2000) prime meridian value. PMEROFF should specify the difference that will be added to all longitudes in the raster file prior to computing the output sample/line coordinate. In this example, we use 176.7215 (MOC) - 176.901 (TES) = -0.1795. RASTER CONFIGURATION (CONFIG) FILE The file specified by the CONFIG parameter defines the location and type of the latitude, longitude and raster data values. lev2raster supports both binary data and ASCII data. The descriptions of each one is slightly different. In general, the file is comprised of "keyword = value" statements that define the location of the latitude, longitude and raster data values in each record. The file is similar to PDS files but may not be completely compliant to PDS standards. For example, a # character is used to designate a comment. Comments can also exist using the C language style. Text can exist between "/*" and "*/" characters. Note that comments are not allowed on the same line as a statement. Blank lines are also allowed. The configuration file has a general keyword section and three objects that describe the latitude, longitude and raster data. The general keyword section describes information about the actual raster data file and some general information about the data itself. Each object contains information specific to the data it is describing. Following is a description of keywords that are in the general raster configuration keywords section: INTERCHANGE_FORMAT - This required keyword defines the type of raster data file as "BINARY" or "ASCII" in nature. These are the only valid/supported types. LATSYS - This required keyword specifies that latitudes are expressed in the "OCENTRIC" or "OGRAPHIC" latitude coordinate system. LONSYS - This required keyword specifies that longitudes are expressed in ranges of -180 to 180 (180) or 0 to 360 (360). Longitudes contained in the raster data file that exceed the specified range are adjusted to the designated range. LONDIR - This required keyword specifies the direction of positive longitude is "WEST" or "EAST". Longitude values in the raster data file are assumed to be expressed in the designated direction. MAP_SCALE - This keyword specifies the scale of a single pixel or DN in spatial dimensions. MAP_SCALE defines the pixel in kilometers per pixel. Pixels are assumed to be square. This value is also compared with the resolution specified in the mapping labels. The values *must* be equivalent or an error condition will ensue. MAP_RESOLUTION may be used instead of this keyword but one or the other must be present. MAP_RESOLUTION - This keyword may be used instead of MAP_SCALE to define the pixel scale of the projection. This value is specified in degrees per pixel. Only one of MAP_RESOLUTION or MAP_SCALE should be specified. Its definition is the same as MAP_SCALE except its units. ^RASTER - This required keyword specifies the name of the file containing the data to rasterize. This is a binary file for INTERCHANGE_FORMAT = "BINARY" or an ASCII file for INTERCHANGE_FORMAT = "ASCII". Contents of the configuration file describe the format of this raster data file. It is a double quoted string and may contain environment variables and absolute paths prefixing the actual name of the file. RECORD_SIZE - This keyword is required only for binary data files. It is used to specify the size in bytes of each binary record in the raster data file. It is needed to establish proper access to each set of latitude, longitude and raster data contained in the raster data file. This keyword is ignored for ASCII raster data files. START_BYTE - This optional keyword is used only for binary raster data files. It is used to specify the size/length in bytes of a header in the binary data file. It can also be viewed as specifing the number of bytes to skip at the beginning of the binary data file to establish the start of the first record in the file. This keyword cannot be used in conjunction with the START_RECORD and will take precedence if both are specified. START_RECORD - This optional keyword is used to specify where to start reading data from in the raster file. For binary raster files, this is always a multiple of RECORD_SIZE bytes. For ASCII files, this is a line number. Valid ranges start with 1 being the first record/line in the raster file to N being the last record. For binary files, this cannot be used with START_BYTE. RECORDS - This optional keyword specifies the number of records to read from the raster data file. This keyword can be used with both binary and ASCII raster data files. LATITUDE - This OBJECT structure is required and defines the latitude field in the raster data file. The format is similar to a PDS OBJECT definition. The LATITUDE object format is: OBJECT = LATITUDE DATA_TYPE =COLUMN_NUMBER = # For ASCII raster data only -OR- START_BYTE = # For binary raster data only BYTES = # For binary raster data only END_OBJECT = LATITUDE The values of the keywords differs for binary and ASCII. See the relevant sections below for the complete definition of each raster data file type. All latitude values must be expressed in units of degrees. LONGITUDE - This OBJECT structure is required and defines the longitude field in the raster data file. The format is similar to a PDS OBJECT definition. The LONGITUDE object format is: OBJECT = LONGITUDE DATA_TYPE = COLUMN_NUMBER = # For ASCII raster data only -OR- START_BYTE = # For binary raster data only BYTES = # For binary raster data only END_OBJECT = LONGITUDE The values of the keywords differs for binary and ASCII. See the relevant sections below for the complete definition of each raster data file type. All longitude values must be expressed in units of degrees. RASTER - This OBJECT structure is required and defines the raster data field in the raster data file. The format is similar to a PDS OBJECT definition. The RASTER object format is: OBJECT = RASTER COUNT = n DATA_TYPE = ITEMS = COLUMN_NUMBER = # For ASCII raster data only -OR- START_BYTE = # For binary raster data only BYTES = # For binary raster data only END_OBJECT = RASTER The values of the keywords differs for binary and ASCII. See the relevant sections below for the complete definition of each raster data file type. Note that "ITEMS" is only required if there is more than one band in the raster data file. Optional keywords in this object allow the user to specify details about spectral data. These keywords are BAND_BIN_ORIGINAL_BAND, BAND_BIN_CENTER and BAND_BIN_WIDTH. BAND_BIN_ORIGINAL_BAND is an integer keyword and specifies the original band number for each band. If it does not exist in the config file, it defaults to 1 to n where n is the number of bands specified in the RASTER object (COUNT keyword). BAND_BIN_CENTER is a real keyword and specifies the wavelength of each band in micrometers. If this keyword is not given, it defaults to 1.0 to ((n) * 1.0). BAND_BIN_WIDTH is a real keyword and specifies the Full Width at Half Maximum (FWHM). If not provided it defaults to 1.0 to ((n) * 1.0). Generally, any keyword or comment may exist in the raster configuration file but they will be ignored. ASCII RASTER CONFIGURATION FORMAT An ASCII RASTER configuration file is identified by the value of the INTERCHANGE_FORMAT keyword. This keyword *must* have the value "ASCII". The ASCII format for the raster configuration file describes the number of header lines, the text fields for latitude, longitude and raster data and the details about each element. An ASCII raster data text field is defined to be a number, integer or floating point form, that is consistantly delimited by a set of characters. The field delimiters are typically a space or tab character. The default field delimiter characters used in lev2raster are space, tab and carrage return. The CONFIG file can specify a new character set to use as field delimiters using the "FIELD_DELIMITERS" keyword. This will *replace* the defaults with whatever is specified in the value of the characters string. An example adding a comma to the list would be as follows: FIELD_DELIMITERS = " \t\r," Note the characters '\t' and '\r'. These are tab and carriage return characters that are converted to their appropriate binary representation in the lev2raster application. You must specify all possible delimiters in this keyword values. Also note that double and single quoted strings are supported and parsed correctly. Because of this, double quoted strings cannot contain double quotes (single quotes are OK, however) and single quoted strings cannot contain single quotes (but double quotes are OK). Here is a small example of a raster data file named raster.dat that contains 5 columns of data: detector, latitude, longitude, phase and albedo data fields: detector latitude longitude phase albedo 1 66.919998504 30.509999318 20.34 0.1224 2 65.489998536 30.699999314 20.34 0.1233 3 63.179998588 31.069999306 20.34 0.1216 Here is an example raster configuration file that describes this data file: ###################################################################### #_Title raster.conf - Example ASCII config file for lev2raster # #_Descr This file describes four columns of data that is to be # rasterized by lev2raster. # #_Hist Mar 08 2002 Kris Becker, USGS, Flagstaff Original Version #_End ####################################################################### INTERCHANGE_FORMAT = "ASCII" LATSYS = "OCENTRIC" LONSYS = 360 LONDIR = "WEST" MAP_SCALE = 3.150 ^RASTER = "raster.dat" START_RECORD = 2 OBJECT = LONGITUDE DATA_TYPE = ASCII_REAL COLUMN_NUMBER = 3 DESCRIPTION = "Areocentric west longitude of target point" UNIT = "DEGREE" END_OBJECT = LONGITUDE OBJECT = LATITUDE DATA_TYPE = ASCII_REAL COLUMN_NUMBER = 2 DESCRIPTION = "Areocentric latitude of target point" UNIT = "DEGREE" END_OBJECT = LATITUDE OBJECT = RASTER COLUMN_NUMBER = 5 ITEMS = 1 DATA_TYPE = ASCII_REAL DESCRIPTION = "Data to rasterize in output cube" UNIT = "albedo" BAND_BIN_ORIGINAL_BAND = 1 BAND_BIN_CENTER = 0.0234 BAND_BIN_WIDTH = 0.0015 END_OBJECT = RASTER The only valid data types for ASCII fields are "ASCII_REAL" and "ASCII_INTEGER". lev2raster will automatically count the total number of records, or lines in the ASCII case, prior to processing. Users can limit the number of records processed by adding the "RECORDS" keyword with a number that is less than or equal to the lines in the file less the header lines. BINARY RASTER CONFIGURATION FORMAT Binary raster configuration files are identified by the value of the INTERCHANGE_FORMAT keyword. It *must* have the value "BINARY". Binary raster config files have to specify a bit more information than ASCII raster files. The size of a binary record must be provided to establish the size in bytes of each record. The RECORD_SIZE keyword is used to specify the number of bytes in all binary records in the file. Each latitude, longitude and raster data fields must exist in the same location within each record. An additional keyword named START_BYTE can be used to specify the number of bytes to skip to read the first record. This is useful for binary files that contain some kind of header. START_BYTE specfies the first byte of the first record where the first byte in the files is 1 (which is the default). Suppose we have a binary file named raster.bin of the same example we used in the ASCII example with the following configuration: Field Byte Location Data Type Data Byte Size Count Detector 1 PC_INTEGER 4 1 Latitude 5 PC_REAL 8 1 Longitude 13 PC_REAL 8 1 Phase 21 PC_REAL 8 1 Albedo 29 PC_REAL 4 2 Note the different types of each field. lev2raster supports many more types that is needed in ASCII files. Each type has a system prefix prepended to it that identifies its byte ordering. In the above example, the data was created on a PC or DEC Alpha system and is a least significant byte (LSB) order using IEEE floating point representation. Data created on a Sun Microsystems architecture is most significant byte (MSB) order also using IEEE. Only IEEE floating point values are supported. lev2raster has the ability to convert input raster data to the proper byte order based upon these values. So data created on a Sun system can be read and converted on a PC system. lev2raster supports the following data types: Data DATA_TYPE BYTES 1-byte unsigned integer UNSIGNED_INTEGER 1 1-byte signed integer INTEGER 1 2-byte unsigned integer UNSIGNED_INTEGER 2 2-byte signed integer INTEGER 2 4-byte unsigned integer UNSIGNED_INTEGER 4 4-byte signed integer INTEGER 4 4-byte real REAL 4 8-byte real REAL 8 The DATA_TYPE and BYTES keywords are all that is required to define any of these data types. lev2raster internalizes these data as 4-byte real or 8-byte real ONLY. Latitude and longitude values are internalized as 8-byte real (doubles) regardless of the actual representation. Raster data is always internalized as 4-byte real (float) regardless of the actual data type. Refer to the PDS workbook for further information on PDS data type descriptions. Here is the binary raster configuration file for the above binary data description: ####################################################################### #_Title raster.conf - Example binary config file for lev2raster # #_Descr raster.conf contains all the parameters that describe the # binary data described above. # #_Hist Mar 08 2002 Kris Becker, USGS, Flagstaff Original Version #_End ####################################################################### INTERCHANGE_FORMAT = "BINARY" LATSYS = "OCENTRIC" LONSYS = 360 LONDIR = "WEST" MAP_SCALE = 3.150 ^RASTER = "raster.bin" RECORD_SIZE = 36 START_BYTE = 1 OBJECT = LONGITUDE DATA_TYPE = PC_REAL START_BYTE = 13 BYTES = 8 DESCRIPTION = "Areocentric west longitude of target point" UNIT = "DEGREE" END_OBJECT = LONGITUDE OBJECT = LATITUDE DATA_TYPE = PC_REAL START_BYTE = 5 BYTES = 8 DESCRIPTION = "Areocentric latitude of target point" UNIT = "DEGREE" END_OBJECT = LATITUDE OBJECT = RASTER DATA_TYPE = PC_REAL START_BYTE = 29 BYTES = 4 ITEMS = 2 DESCRIPTION = "Data to rasterize in output cube" UNIT = "albedo" BAND_BIN_ORIGINAL_BAND = (1,2) BAND_BIN_CENTER = (0.0234, 0.0249) BAND_BIN_WIDTH = (0.0015, 0.0015) END_OBJECT = RASTER GEOMETRIC COORDINATE SYSTEMS The new ISIS geometry software, referred to as "Lev", has added functionality for supporting different latitude and longitude coordinate geometry. LATSYS, LONSYS and LONDIR are used to specify this information to ISIS geometry software so that projections can be properly supported. In the Lev software, there are 3 occurances of these parameters in one form or another. In lev2raster there is one additional occurance in the raster configuration file that I will describe below. 1) LATSYS and LONSYS appear explicity in user interface PDF files. This is mostly limited to geometry initialization applications such as levinit. lev2raster also has these parameters. They are in level 2 (projection application) PDFs to notify the application which coordinate system input values are specified in. For example, LATRANGE require a minimum and maximum latitude range of representation. LATSYS tells the application if the user provides them in planetographic (OGRAPHIC) or planetocentric (OCENTRIC) latitude coordinates. LONSYS exists to notify the application how longitude ranges as specified in LONRANGE are specified. They can range from -180 to 180 (180) degrees or 0 to 360 (360) degrees. 2) LATSYS and LONSYS are also found in the ISIS image cube labels in the IMAGE_MAP_PROJECTION keyword group. LATSYS is stored in the KEYWORD_LATITUDE_TYPE keyword and used to establish subsequent user inputs and reported values. LONSYS is stored in the LONGITUDE_SYSTEM keyword and specifies how longitudes are used and reported in subsequent ISIS applications. 3) An equivalent to LATSYS is also used in the MAPPARS parameter for some projections. This is of the form MAPPARS="SINU:0,OCENTRIC". Here, this notifies the Lev software the desired latitude system to used to compute physical storage locations (i.e., line/sample) for the geometric data. Note that Simple Cylindrical and Sinusoidal projections can use both OCENTRIC and OGRAPHIC latitude coordinate systems to store data. ALL OTHER PROJECTIONS USE OGRAPHIC!! 4) The lev2raster application needs LATSYS, LONSYS and LONDIR in the raster configuration file to fully describe these elements for each latitude and longitude coordinate read from the raster data file. These can be entirely different than the other sources - lev2raster converts the raster geometry coordinates to whatever is needed for projection compatability. LONDIR is an additional parameter used to specify the direction of positive longitude of the raster longitude geometry. For lev2raster to be thorough and perform correctly, all these parameters must be considered carefully. See also the mappars PDF in the ISIS system for further information. PROGRAMMER: Kris Becker, USGS, Flagstaff, Az
Parm | Description | Default |
---|---|---|
TO | Output rasterized level 2 cube filename to create or add raster data to | NONE |
INITFROM | Optional input ISIS level 2 cube name used to initialize projection and label parameters | -- |
MODE | File processing mode: INIT - Create new file ADD - Add data to existing file | "INIT" |
UPDATE | Update mode for existing data merge: REPLACE - replace any data at output location PRESERVE - do not replace any existing data AVERAGE - Average existing data with new data | "AVERAGE" |
CONFIG | Name of text configuration file for the binary raster data | -- |
TARGDEF | Target definition filename used only to establish planet or body radii (level 2) | -- |
MAPPARS | Map projection and parameters (e.g. MAPPARS="SINU:0,OCENTRIC") | -- |
LATRANGE | Latitude range | -- |
LONRANGE | Longitude range | -- |
KM | Image resolution (km/pix) or | -- |
DEG | Image resolution (pix/deg) | -- |
LATSYS | Latitude system used to report values in: OGRAPHIC or OCENTRIC (default OGRAPHIC) | "OGRAPHIC" |
LONSYS | Longitude system used to report values in: 360 - 0 to 360 180 - -180 to 180 (default 360) | 360 |
PMEROFF | Prime meridian adjustment offset in degrees |
ADDITIONAL NOTES:
Parm | Description |
---|---|
TO | Name of the output cube file for the MODE="INIT" option. For the MODE="ADD" option is also the input file that the raster file will be added/merged to. |
INITFROM | Optional name of an existing ISIS level 2 projected file which will be used to initialize the TO level 2 parameters. This is very useful if the goal is to produce a projected image for direct comparison to an existing product. lev2raster will allow further modification to the projection through other input parameters. For example, you may have a data set that has a different pixel resolution that another product. You would like to compare the two products directly so it needs to have the same LATITUDE and LONGITUDE ranges and projection parameters. The only difference being the pixel resolution, the comparison product can be specified in INITFROM and the user can use KM or DEG to alter the pixel resolution. Once you have created the rasterized product at a different resolution, use the ISIS application "lev2tolev" to specify the same pixel resolution as the original product you wish to compare to. See also lev2raster general help for further details on use of this parameter. |
MODE | This parameter specifies the action for handling the output file specified in the TO parameter. lev2raster can be used to create a new level 2 image completely from scratch using the "INIT" mode. The user must supply the following minimum parameters: TARGDEF MAPPARS LATRANGE LONRANGE KM or DEG The caller can provide the name of an existing ISIS level 2 projected file where all parameters are initialized from in the INITFROM parameter. The caller can also selectively change any aspect of the projection using the above parameters. The other option is to update an existing level 2 projected file using the "ADD" mode. The file specified in TO must exist and be a level 2 projected ISIS file. All parameters but CONFIG and UPDATE are ignored in this mode. |
UPDATE | UPDATE provides users control over how raster data is added to the file. In may cases, data may map to the same line and sample. The user may decide to use the UPDATE="REPLACE" option which is essentially last-in precedence. The last value that maps into a particular line/sample replaces any value previously there. UPDATE="PRESERVE" has the opposite effect - it will honor any exist valid value and never replace it with any raster data that maps to the line/sample location. The last option, UPDATE="AVERAGE" is a compromise of the two options. This option creates a BAND suffix named "RASTER_COUNT" that accumulates the number of raster DN that maps to the line/sample locations and maintains a running average of this location. A "running average" is implemented in such a way that the final result is always readily available after a run of lev2raster. This is acheived by taking the DN value at the line/sample location, multiplying it be the count of DN previously added to it, then adding in the incoming DN value and diving this sum by the old count plus one. The count is then incremented by one and rewritten to the backplane. There are several considerations to be aware of when this option is used. 1) When a file is initialized with this mode, it must be used for any subsequent lev2raster run or incorrect results may occur. 2) Selecting this option for a file that was not originally initialized with option is allowed but it runs in a different mode. It will average any existing value with the incoming DN but does not maintain a running average. It will only average the two values. The problem with this technique is that the last value in will have far more weight if more than two values are averaged. 3) To disable this option, one can physically remove the RASTER_COUNT BAND suffix using the ISIS "dsk2dsk" application and applying an appropriate SFROM. |
TARGDEF | This parameter is used to specify target parameters definitions such as radii, omega 0, etc... For lev2raster, it is used only to define planet or body radii. This is essential for ISIS level 2 routines to compute latitude/ longitude and line/sample coordinates on the target body. This parameter is not needed if INITFROM is provided and it contains the desired target information. TARGEF can be provided as the name of a planet (e.g., MARS) in which case a file of the form "TARGDEF.def.n" will be searched for in the $ISISDATA/targets directory. "n" is the highest occuring number starting with 1. For example, if Mars is the desired target then the default value will be "$ISISDATA/targets/mars.def.n", "n" being the highest version found. Users can also specify an explicit file from which to initialize from. The format must follow the same as those in the $ISISDATA/targets directory and one of these files is a good starting point to developing your own. This parameter is needed only when creating new files (MODE="INIT") *and* INITFROM is not provided or is not of the desired target body. |
MAPPARS | This parameter is used to specify the map projection and its specific parameters. For example, "SINU:0,OCENTRIC" implies Sinusoidal map projection with a central longitude of 0 and values reported in planetocentric coordinate systems. **NOTE** For a detailed explanation of MAPPARS, tutor the mappars.pdf (i.e., TAE> tutor mappars). This parameter is needed only when creating a new output file (MODE="INIT") *and* INITFROM is not specified or does not contain the proper projection parameters. |
LATRANGE | Specifies the latitude range of the output projection. LATRANGE(1) is the minimum latitude, LATRANGE(2) is the maximum. The coordinates specified here are subject to the LATSYS parameter coordinate specification and must be expressed in the system specified in this parameter. |
LONRANGE | Specifies the longitude range of the output projection. LONRANGE(1) is the minimum longitude, LONRANGE(2) is the maximum. The coordinates specified here are subject to the LONSYS parameter coordinate specification and must be expressed in the system specified in this parameter. |
KM | This specifies the map resolution in kilometers/pixel. |
DEG | This specifies the map resolution pixels/degree. |
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". See also lev2raster general help for a very detailed discussion on this and its associated parameters. |
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". See also lev2raster general help for a very detailed discussion on this and its associated parameters. |
PMEROFF | This parameter allows the user to make adjustments to each longitude value to adjust for differing prime meridian values. TES is one example where this parameter is useful. TES used IAU 1994 prime meridian values to compute longitudes. When attempting to compare/overlay TES data to MGS MOC or MOLA data, the longitudes more than likely were computed using a different prime meridian for MARS. By simply providing the difference between the prime meridians for each instrument, TES can be better aligned with MOC or MOLA. This value is *added* to each longitude prior to mapping to an output pixel location. It is assumed to in units of degrees. |
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