ISIS 3 Application Documentation
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Extracts a sub-area from a cube
A sub-area selected for extraction must be contiguous. That is, the program will not allow non-continuous cropping such as lines 1-5, 10-30, and 80-100. However, the contiguous area can be sub-sampled by specifying how many pixels to increment or skip. For example, to select every third line (1, 4, 7, 10 ...) to be written to the output cube, use a line increment (LINC) of three.
The parameter PROPSPICE applies to Level1 images. The SPICE information must have been propagated to the cropped output cube to obtain any camera geometry or photometric information. The default setting for PROPSPICE is "TRUE." When the default setting is used, all the keywords in the labels of the input file are transferred to the output file. In addition, the keywords that describe the area that was extracted out of the input cube are also added to the AlphaCube group in the labels.
For a Level1 image, the keywords contained within the AlphaCube group in the labels describe the original file size and the area that was extracted. The AlphaCube and SPICE kernels information are very important to compute accurate geometric and photometric information using the cropped Level1 cube.
|Level1 labels using PROPSPICE=TRUE:||Level1 labels using PROPSPICE=FALSE:|
Group = Kernels NaifFrameCode = -53031 LeapSecond = $base/kernels/lsk/naif0009.tls TargetAttitudeShape = $base/kernels/pck/pck00009.tpc TargetPosition = (Table, $base/kernels/spk/de405.bsp) InstrumentPointing = (Table, $odyssey/kernels/ck/m01_sc_ext11.bc, $odyssey/kernels/fk/m01_v29.tf) Instrument = Null SpacecraftClock = $odyssey/kernels/sclk/ORB1_SCLKSCET.00187.tsc InstrumentPosition = (Table, $odyssey/kernels/spk/m01_ext11.bsp) InstrumentAddendum = $odyssey/kernels/iak/themisAddendum003.ti ShapeModel = $base/dems/molaMarsPlanetaryRadius0005.cub InstrumentPositionQuality = Reconstructed InstrumentPointingQuality = Reconstructed CameraVersion = 2 End_Group Group = AlphaCube AlphaSamples = 320 AlphaLines = 3600 AlphaStartingSample = 99.5 AlphaStartingLine = 9.5 AlphaEndingSample = 199.5 AlphaEndingLine = 109.5 BetaSamples = 100 BetaLines = 100 End_Group
Group = Kernels NaifFrameCode = -53031 End_Group Group = AlphaCube AlphaSamples = 320 AlphaLines = 3600 AlphaStartingSample = 99.5 AlphaStartingLine = 9.5 AlphaEndingSample = 199.5 AlphaEndingLine = 109.5 BetaSamples = 100 BetaLines = 100 End_Group
For a Level2 image or a mosaic, the Mapping group keywords in the labels are updated or removed depending on the settings used to crop the input image. Once an image has been cropped, the keywords MinimumLatitude, MaximumLatitude, MinimumLongitude, and MaximumLongitude are recomputed and the values updated in the labels for rectangular projections with straight line meridians and parallels. The keywords are removed from the labels for projections with curved meridians and parallels. Use the map2map application if the keywords MinimumLatitude, MaximumLatitude, MinimumLongitude, and MaximumLongitude must be retained in the labels. If the parameters LINC and SINC are not 1 and the values are equal, then the map Scale and PixelResolution are recomputed and the values updated in the labels. Otherwise, Scale and PixelResolution keywords and values are removed from the labels. The UpperLeftCornerX and UpperLeftCornerY are recomputed based on the settings used to crop the input image and updated in the labels for all projections as shown in the example below.
|Level2 labels of uncropped image:||Level2 labels of cropped image:|
Group = Mapping ProjectionName = Equirectangular CenterLongitude = 0 TargetName = MOON EquatorialRadius = 1737400.0 <meters> PolarRadius = 1737400.0 <meters> LatitudeType = Planetocentric LongitudeDirection = PositiveEast LongitudeDomain = 180 MinimumLatitude = -60.62302099 MaximumLatitude = -59.30333301 MinimumLongitude = -161.213427 MaximumLongitude = -158.574051 UpperLeftCornerX = -2444266.0 UpperLeftCornerY = -1798275.5 PixelResolution = 7.5 <meters/pixel> Scale = 4043.1133898866 <pixels/degree> CenterLatitude = -60 CenterLatitudeRadius = 1737400.0 End_Group
Group = Mapping ProjectionName = Equirectangular CenterLongitude = 0 TargetName = MOON EquatorialRadius = 1737400.0 <meters> PolarRadius = 1737400.0 <meters> LatitudeType = Planetocentric LongitudeDirection = PositiveEast LongitudeDomain = 180 UpperLeftCornerX = -2429273.5 UpperLeftCornerY = -1813268.0 PixelResolution = 15.0 <meters/pixel> Scale = 2021.5566949433 <pixels/degree> CenterLatitude = -60 CenterLatitudeRadius = 1737400.0 End_Group
If the cropped image is displayed with the application qview, the latitude and longitude reported by the application will be correct for the cropped files. The mappt application can be used to compute the latitude and longitude at a specific point in a cropped cube.
The minimum and maximum latitude and longitude range are not recomputed and the keywords are deleted from the labels when the input image is in a non-rectangular projection. Unfortunately there is not a generic way to update the ranges for all projections so only the values for rectangular projections are recalculated and updated in the labels.
The cropped images may be included in a list to create a mosaic with automos. All the cropped images included in the input list must contain the same mapping values. If automos fails because of the cropped images, the user may need to specify the MINLAT, MAXLAT, MINLON, and MAXLON values of the output mosaic for some ISIS versions.
|TO||Output cropped cube|
|NSAMPLES||Number of Samples|
|NLINES||Number of Lines|
|PROPSPICE||Propagate SPICE information to output cube|
This is the input cube that will be cropped.
The smaller output cube containing the results of crop.
This is the starting sample of the area to extract. It must be inside the cube area.
This defines how many samples to extract from the input cube, if SINC is 1. Otherwise, the number of samples actually extracted from the input cube is NSAMPLES/SINC.
|Internal Default||All samples|
This specifies the sample increment to use when extracting from the input cube. This effectively skips samples when the value is greater than 1. For example, if SINC=2 and SAMPLE=1 the output cube would contain samples 1, 3, 5, 7, and so on. Note that this reduces the size of the output cube as specified by NSAMPLES. That is, if NSAMPLES=200 and SINC=2, the output cube will have 100 samples.
This is the starting line of the area to extract. It must be inside the cube.
This defines how many lines will be extracted from the input cube, if LINC is 1. Otherwise, the number of lines actually extracted from the input cube is NLINES/LINC.
|Internal Default||All lines|
This specifies the line increment to use when extracting from the input cube. This effectively skips lines when the value is greater than 1. For example if LINC=2 and LINE=5 the output cube would contain lines 5, 7, 9, 11, and so on. Note that this reduces the size of the output cube as specified by NLINES. That is, if NLINES=200 and LINC=2, the output cube will have 100 lines.
This specifies whether or not to propagate the SPICE Kernels group to the output file for a Level 1 image. If this parameter is set to "False," then there will be no camera model available to compute geometric and photometric information using the cropped cube.
Extract a 200x300 sub-area
This is a screenshot of crop. The GUI shows the parameters filled to extract a 200x300 pixel sub-area from the input image.
This is the full size input image. The area (200x300) to be "cropped" is outlined in red.
Cropped output image
This is the cropped output image that is 200x300, samples and lines respectively.
|Jim Mathews||1994-04-20||Original version|
|Jeff Anderson||2002-08-05||Converted to Isis 3.0|
|K Teal Thompson||2002-11-18||Added examples|
|Jeff Anderson||2003-01-28||Removed crop from the Utility category|
|K Teal Thompson||2003-02-03||Make images smaller|
|K Teal Thompson||2003-02-04||Added red rectangle to input image of example to illustrate crop area.|
|K Teal Thompson||2003-03-19||Moved images to /assets/image directory and thumbnails to /assets/thumb directory.|
|Stuart Sides||2003-04-04||Fixed problem with isiscvs not checking in the thumb and image directories.|
|Stuart Sides||2003-04-25||Added extraction labels|
|Stuart Sides||2003-05-16||Modified schema location from astrogeology... to isis.astrogeology..."|
|Stuart Sides||2003-07-29||Modified filename parameters to be cube parameters where necessary|
|Jeff Anderson||2004-02-16||Replaced extraction group with AlphaCube group and propagated other labels.|
|Jeff Anderson||2004-02-16||Added LINC and SINC parameters and set defaults for all parameters|
|Brendan George||2006-12-29||Fixed to allow input band selection|
|Elizabeth Miller||2007-02-01||Modified to adjust the upper left corner x and y values in the mapping group of the output cube if the input cube is projected|
|Steven Lambright||2008-05-13||Removed references to CubeInfo|
|Steven Lambright||2008-08-04||Added spice propagation option PROPSPICE. Fixed description of NLINES, NSAMPLES and now line associated and sample associated tables are modified when crop is run.|
|Steven Lambright||2008-08-06||Changed default of PROPSPICE to true. Sample/Line associated tables are no longer modified due to conflicts with other programs, such as pad, which doesn't know what data values to add to the tables.|
|Steven Lambright||2009-06-30||When an invalid projection exists the proper error should now be thrown.|
|Janet Barrett||2009-10-21||Now uses the SubArea class to produce output cube labels with corrected Mapping, Instrument, and AlphaCube groups.|
|Tracie Sucharski||2012-12-06||Removed unnecessary include of Projection.h. References #775|
|Stuart Sides||2013-06-23||Modified the calculations for number of lines and samples to use double precision math and then round up instead of integer math with truncation. When the number of lines or samples does not divide evenly by the linc or sinc values there will be one additional line or sample in the output cube.|
|Janet Barrett||2014-02-10||Delete input cube between successive runs of the program. This makes sure that the projection information is initialized each time the program is run in the GUI. Fixes #1500.|
|Ella Mae Lee||2014-04-02||Updated the documentation, fixes #1622 and #1688.|