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Creates a mosaic file from any number of input source files. Note: when processing a large number of files with the Mosaic tool you may likely need to increase your memory allocation. To do this edit the file gpt.sh. |
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Example 1 Geographic Lat/Lon Projection Example 2 Oblique Stereographic Projection Example 3 Lambert Azimuthal Equal Area Projection Example 4 Lambert Azimuthal Equal Area Projection (alternate) Example 5 Lambert Azimuthal Equal Area Projection of Full OC Suite L2 File Notes 1 Resampling Options |
Example 1: Geographic Lat/Lon Projection
This uses the SeaDAS Mosaic tool in GPT (command line) mode to combine several input level-2 files into a single mapped output file. The level-2 files were imaged January 23 2017 over the Gulf of Mexico by both the VIIRS and the MODIS Aqua instruments. The output file is specifically geographically bounded to this Gulf of Mexico region. Level-2 quality flags are used to constrain the source pixels being used. Two products are created: chlor_a and apparent_optical_depth. The product chlor_a exists in the source level-2 files and the product apparent_optical_depth is derived using a mathematical expression from the level-2 product Kd_490. The projection is standard geographic lat/lon with a pixelSize=0.009 (roughly 1km resolution). A parameter properties "par" file is used to store the variables needed for the xml graph file.
Note: you can readily modify these parameters in this "par" file to adapt to your own specific region, products, and quality criteria.
Note: the Mosaic GPT call acquires the input files from individual arguments in the command line. A convenience system call (`cat level2Files.txt`) is used here instead of entering each file as a command line argument.
Command Line Entry
gpt MosaicGeneralGraph.xml -p MosaicEx01.par `cat level2Files.txt` -Pofile=AquaVIIRS_2017023_MosaicEx01.dim |
File = MosaicGeneralGraph.xml
<graph id="MosaicGraph">
<version>1.0</version>
<node id="MosaicNode">
<operator>Mosaic</operator>
<sources>
<sourceProducts>${sourceProducts}</sourceProducts>
</sources>
<parameters>
<variables>
<variable>
<name>${band1}</name>
<expression>${band1Expression}</expression>
</variable>
<variable>
<name>${band2}</name>
<expression>${band2Expression}</expression>
</variable>
</variables>
<conditions>
<condition>
<name>condition_0</name>
<expression>${qualityExpression}</expression>
<output>false</output>
</condition>
</conditions>
<combine>OR</combine>
<crs>${crs}</crs>
<resampling>${resampling}</resampling>
<westBound>${west}</westBound>
<northBound>${north}</northBound>
<eastBound>${east}</eastBound>
<southBound>${south}</southBound>
<pixelSizeX>${pixelSize}</pixelSizeX>
<pixelSizeY>${pixelSize}</pixelSizeY>
</parameters>
</node>
<node id="Write">
<operator>Write</operator>
<sources>
<sourceProduct refid="MosaicNode"/>
</sources>
<parameters class="com.bc.ceres.binding.dom.XppDomElement">
<file>${ofile}</file>
<formatName>BEAM-DIMAP</formatName>
</parameters>
</node>
</graph>
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File = MosaicEx01.par
band1=chlor_a band1Expression=chlor_a band2=apparent_optical_depth band2Expression=if (Kd_490 != 0) then 1.3/Kd_490 else NaN qualityExpression=!l2_flags.HIGLINT and !l2_flags.HISATZEN and !l2_flags.LOWLW and !l2_flags.HILT north=31.0 south=17.5 west=-98.5 east=-80.0 pixelSize=0.009 resampling=Nearest crs=GEOGCS["WGS84(DD)", DATUM["WGS84", SPHEROID["WGS84", 6378137.0, 298.257223563]], PRIMEM["Greenwich", 0.0], UNIT["degree", 0.017453292519943295], AXIS["Geodetic longitude", EAST], AXIS["Geodetic latitude", NORTH]] |
File = level2Files.txt
level2_files/A2017023193000.L2_LAC_OC.nc level2_files/A2017023193500.L2_LAC_OC.nc level2_files/V2017023190000.L2_SNPP_OC.nc level2_files/V2017023190600.L2_SNPP_OC.nc |
Example 2: Oblique Stereographic Projection
This is exactly the same as example 1 except that it uses a Oblique Stereographic projection. (See example 1 for the files "mosaicGeneral.xml" and "level2Files.txt".)
Note: if you modify this to cover a different region you will also have to modify the crs value (specifically "latitude_of_origin" and "central_meridian"). Also, the pixelSize is in units of meters whereas in example 1 is was in units of degrees.
Command Line Entry
gpt MosaicGeneralGraph.xml -p MosaicEx02.par `cat level2Files.txt` -Pofile=AquaVIIRS_2017023_MosaicEx02.dim |
File = Mosaic02.par
band1=chlor_a band1Expression=chlor_a band2=apparent_optical_depth band2Expression=1.3/Kd_490 qualityExpression=!l2_flags.HIGLINT and !l2_flags.HISATZEN and !l2_flags.LOWLW and !l2_flags.HILT and !l2_flags.CLDICE north=31.0 south=17.5 west=-98.5 east=-80.0 pixelSize=1000.0 resampling=Nearest crs=PROJCS["Oblique_Stereographic / World Geodetic System 1984",GEOGCS["World Geodetic System 1984", DATUM["World Geodetic System 1984", SPHEROID["WGS 84", 6378137.0, 298.257223563, AUTHORITY["EPSG","7030"]], AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]], UNIT["degree", 0.017453292519943295], AXIS["Geodetic longitude", EAST], AXIS["Geodetic latitude", NORTH]], PROJECTION["Oblique_Stereographic"], PARAMETER["central_meridian", -90.0], PARAMETER["latitude_of_origin", 25.0], PARAMETER["scale_factor", 1.0], PARAMETER["false_easting", 0.0], PARAMETER["false_northing", 0.0], UNIT["m", 1.0], AXIS["Easting", EAST], AXIS["Northing", NORTH]] |
Example 3: Lambert Azimuthal Equal Area Projection
This is exactly the same as example 1 except that it uses a Lambert Azimuthal Equal-Area projection. (See example 1 for the files "mosaicGeneral.xml" and "level2Files.txt".)
Note: if you modify this to cover a different region you will also have to modify the crs value (specifically "latitude_of_center" and "longitude_of_center"). Also, the pixelSize is in units of meters whereas in example 1 is was in units of degrees.
Command Line Entry
gpt MosaicGeneralGraph.xml -p MosaicEx03.par `cat level2Files.txt` -Pofile=AquaVIIRS_2017023_MosaicEx03.dim |
File = MosaicEx03.par
band1=chlor_a band1Expression=chlor_a band2=apparent_optical_depth band2Expression=1.3/Kd_490 qualityExpression=!l2_flags.HIGLINT and !l2_flags.HISATZEN and !l2_flags.LOWLW and !l2_flags.HILT north=31.0 south=17.5 west=-98.5 east=-80.0 pixelSize=1000.0 resampling=Nearest crs=PROJCS["Lambert_Azimuthal_Equal_Area / World Geodetic System 1984",GEOGCS["World Geodetic System 1984",DATUM["World Geodetic System 1984",SPHEROID["WGS 84", 6378137.0, 298.257223563, AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],UNIT["degree", 0.017453292519943295],AXIS["Geodetic longitude", EAST],AXIS["Geodetic latitude", NORTH]],PROJECTION["Lambert_Azimuthal_Equal_Area"],PARAMETER["latitude_of_center", 25.0],PARAMETER["longitude_of_center", -90.0],PARAMETER["false_easting", 0.0],PARAMETER["false_northing", 0.0],UNIT["m", 1.0],AXIS["Easting", EAST],AXIS["Northing", NORTH]] |
Example 4: Lambert Azimuthal Equal Area Projection (alternate)
This is basically the same as example 3 except that the crs if defined in the xml graph file with some added variables in order to specify the center of the scene in the "par" file. If you are always using the same projection, but for differing regions this example is a good choice. One other difference here, to illustrate an option, that the same variable is used for convenience for both the band name and the band expression. If you are not creating new bands using a mathematical expression then condensing these two variables into a single variable works.
Command Line Entry
gpt MosaicGraphEx04.xml -p MosaicEx04.par `cat level2Files.txt` -Pofile=AquaVIIRS_2017023_MosaicEx04.dim |
File = MosaicGraphEx04.xml
<graph id="MosaicLambertGraph">
<version>1.0</version>
<node id="MosaicLambertNode">
<operator>Mosaic</operator>
<sources>
<sourceProducts>${sourceProducts}</sourceProducts>
</sources>
<parameters>
<variables>
<variable>
<name>${band1}</name>
<expression>${band1}</expression>
</variable>
<variable>
<name>${band2}</name>
<expression>${band2}</expression>
</variable>
</variables>
<conditions>
<condition>
<name>condition_0</name>
<expression>${qualityExpression}</expression>
<output>false</output>
</condition>
</conditions>
<combine>OR</combine>
<crs>
PROJCS["Lambert_Azimuthal_Equal_Area / World Geodetic System 1984",
GEOGCS["World Geodetic System 1984",
DATUM["World Geodetic System 1984",
SPHEROID["WGS 84", 6378137.0, 298.257223563, AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],
UNIT["degree", 0.017453292519943295],
AXIS["Geodetic longitude", EAST],
AXIS["Geodetic latitude", NORTH]],
PROJECTION["Lambert_Azimuthal_Equal_Area"],
PARAMETER["latitude_of_center", ${latitudeOfCenter}],
PARAMETER["longitude_of_center", ${longitudeOfCenter}],
PARAMETER["false_easting", 0.0],
PARAMETER["false_northing", 0.0],
UNIT["m", 1.0],
AXIS["Easting", EAST],
AXIS["Northing", NORTH]]
</crs>
<resampling>${resampling}</resampling>
<westBound>${west}</westBound>
<northBound>${north}</northBound>
<eastBound>${east}</eastBound>
<southBound>${south}</southBound>
<pixelSizeX>${pixelSize}</pixelSizeX>
<pixelSizeY>${pixelSize}</pixelSizeY>
</parameters>
</node>
<node id="Write">
<operator>Write</operator>
<sources>
<sourceProduct refid="MosaicLambertNode"/>
</sources>
<parameters class="com.bc.ceres.binding.dom.XppDomElement">
<file>${ofile}</file>
<formatName>BEAM-DIMAP</formatName>
</parameters>
</node>
</graph>
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File = MosaicEx04.par
band1=chlor_a band2=Kd_490 qualityExpression=!l2_flags.HIGLINT and !l2_flags.HISATZEN and !l2_flags.LOWLW and !l2_flags.HILT latitudeOfCenter=25.0 longitudeOfCenter=-90.0 north=31.0 south=17.5 west=-98.5 east=-80.0 pixelSize=1000.0 resampling=Nearest |
Example 5: Lambert Azimuthal Equal Area Projection of Full OC Suite L2 File
Similar to example 3 except producing all bands of the OC suite.
Command Line Entry
gpt MosaicGraphEx05.xml -p MosaicEx05.par -Pifile=A2017023193500.L2_LAC_OC.nc -Pofile=A2017023193500_MosaicEx05.dim |
File = MosaicGraphEx05.xml
<graph id="MosaicLambertGraph">
<version>1.0</version>
<node id="Read">
<operator>Read</operator>
<sources/>
<parameters class="com.bc.ceres.binding.dom.XppDomElement">
<file>${ifile}</file>
<formatName>SeaDAS-L2</formatName>
</parameters>
</node>
<node id="Mosaic">
<operator>Mosaic</operator>
<sources>
<sourceProduct refid="Read"/>
</sources>
<parameters class="com.bc.ceres.binding.dom.XppDomElement">
<variables>
<variable>
<name>${band1Name}</name>
<expression>${band1Name}</expression>
</variable>
<variable>
<name>${band2Name}</name>
<expression>${band2Name}</expression>
</variable>
<variable>
<name>${band3Name}</name>
<expression>${band3Name}</expression>
</variable>
<variable>
<name>${band4Name}</name>
<expression>${band4Name}</expression>
</variable>
<variable>
<name>${band5Name}</name>
<expression>${band5Name}</expression>
</variable>
<variable>
<name>${band6Name}</name>
<expression>${band6Name}</expression>
</variable>
<variable>
<name>${band7Name}</name>
<expression>${band7Name}</expression>
</variable>
<variable>
<name>${band8Name}</name>
<expression>${band8Name}</expression>
</variable>
<variable>
<name>${band9Name}</name>
<expression>${band9Name}</expression>
</variable>
<variable>
<name>${band10Name}</name>
<expression>${band10Name}</expression>
</variable>
<variable>
<name>${band11Name}</name>
<expression>${band11Name}</expression>
</variable>
<variable>
<name>${band12Name}</name>
<expression>${band12Name}</expression>
</variable>
<variable>
<name>${band13Name}</name>
<expression>${band13Name}</expression>
</variable>
<variable>
<name>${band14Name}</name>
<expression>${band14Name}</expression>
</variable>
<variable>
<name>${band15Name}</name>
<expression>${band15Name}</expression>
</variable>
<variable>
<name>${band16Name}</name>
<expression>${band16Name}</expression>
</variable>
<variable>
<name>${band17Name}</name>
<expression>${band17Name}</expression>
</variable>
<variable>
<name>${band18Name}</name>
<expression>${band18Name}</expression>
</variable>
<variable>
<name>${band19Name}</name>
<expression>${band19Name}</expression>
</variable>
<variable>
<name>${band20Name}</name>
<expression>${band20Name}</expression>
</variable>
</variables>
<conditions>
<condition>
<name>condition_0</name>
<expression>${qualityExpression}</expression>
<output>false</output>
</condition>
</conditions>
<combine>OR</combine>
<crs>
PROJCS["Lambert_Azimuthal_Equal_Area / World Geodetic System 1984",
GEOGCS["World Geodetic System 1984",
DATUM["World Geodetic System 1984",
SPHEROID["WGS 84", 6378137.0, 298.257223563, AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],
UNIT["degree", 0.017453292519943295],
AXIS["Geodetic longitude", EAST],
AXIS["Geodetic latitude", NORTH]],
PROJECTION["Lambert_Azimuthal_Equal_Area"],
PARAMETER["latitude_of_center", ${latitudeOfCenter}],
PARAMETER["longitude_of_center", ${longitudeOfCenter}],
PARAMETER["false_easting", 0.0],
PARAMETER["false_northing", 0.0],
UNIT["m", 1.0],
AXIS["Easting", EAST],
AXIS["Northing", NORTH]]
</crs>
<resampling>${resampling}</resampling>
<westBound>${west}</westBound>
<northBound>${north}</northBound>
<eastBound>${east}</eastBound>
<southBound>${south}</southBound>
<pixelSizeX>${pixelSize}</pixelSizeX>
<pixelSizeY>${pixelSize}</pixelSizeY>
</parameters>
</node>
<node id="Write">
<operator>Write</operator>
<sources>
<sourceProduct refid="Mosaic"/>
</sources>
<parameters class="com.bc.ceres.binding.dom.XppDomElement">
<file>${ofile}</file>
<formatName>BEAM-DIMAP</formatName>
</parameters>
</node>
</graph>
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File = MosaicEx05.par
band1Name=aot_869 band2Name=angstrom band3Name=chlor_a band4Name=chl_ocx band5Name=ipar band6Name=Kd_490 band7Name=nflh band8Name=Rrs_412 band9Name=Rrs_443 band10Name=Rrs_469 band11Name=Rrs_488 band12Name=Rrs_531 band13Name=Rrs_547 band14Name=Rrs_555 band15Name=Rrs_645 band16Name=Rrs_667 band17Name=Rrs_678 band18Name=par band19Name=pic band20Name=poc qualityExpression=!l2_flags.HIGLINT and !l2_flags.HISATZEN and !l2_flags.LOWLW and !l2_flags.HILT latitudeOfCenter=25.0 longitudeOfCenter=-90.0 north=31.0 south=17.5 west=-98.5 east=-80.0 pixelSize=1000.0 resampling=Bilinear |
Notes 1 Resampling Options
Here is a full list of the resampling options and their specific names as used by the Mosaic operator. Please be aware that these names differ for the Collocate operator. We will address this in a future SeaDAS release.
resampling=Nearest resampling=Bilinear resampling=Bicubic |