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Copies navigation offsets from a source variable to destination variables in CoastWatch POES AVHRR CWF or HDF files in a list.
| Class: | CoastWatchAVHRR |
| Intended use: | Recommended for external callers |
| COM: | Exposed as the CopyNavigationOffsetsList method of COM class GeoEco.CoastWatchAVHRR |
| ArcGIS: | Not exposed as an ArcGIS geoprocessing tool |
| Method type: | Classmethod |
| CoastWatchAVHRR.CopyNavigationOffsetsList( | coastWatchFileList, sourceVariable[, destVariables[, basePath]]) |
| Python type: | list of unicode |
| Minimum length: | 0 |
List of CoastWatch POES AVHRR CWF or HDF files.
Navigation offsets will be extracted from the files in this list that contain the source variable and applied to the files that contain any of the destination variables, providing that the source file and destination file are for the same satellite image. If a file contains both the source variable and one or more destination variables, it will serve as both a source and destination file.
To determine of two given files are for the same satellite image, this function compares the image time, satellite, sensor, center coordinates, cell size, number of rows and columns, projection, and spheroid. If all are the same, the files are assumed to be for the same satellite image.
Only CoastWatch POES AVHRR files are supported. Other CoastWatch files, such as those for the GOES satellite series, will be skipped and a warning will be reported.
| Python type: | unicode |
| Minimum length: | 1 |
CoastWatch variable in the source file from which navigation offsets should be copied.
| Python type: | list of unicode |
| Default value: | [u'avhrr_ch1', u'avhrr_ch2', u'avhrr_ch3', u'avhrr_ch3a', u'avhrr_ch4', u'avhrr_ch5', u'cloud', u'cloudx', u'sst'] |
| Minimum length: | 1 |
CoastWatch variables in the destination file to which the navigation offsets should be applied. In general, navigation offsets should only be applied to variables that are derived from sensor data. At the time of this writing, the variables derived from sensor data included:
avhrr_ch1 avhrr_ch2 avhrr_ch3 avhrr_ch3a avhrr_ch4 avhrr_ch5 cloud cloudx sst
Peter Hollemans, one of the lead CoastWatch researchers at NOAA, suggested that navigation offsets should not be applied to the graphics, rel_azimuth, sat_zenith, and sun_zenith variables. With respect to the last three, he said:
"I've thought about it for a while and my inclination is to say don't correct the angle data. It's not a perfect solution -- ie: if we knew the satellite's position and orientation perfectly and recomputed the angle data, we would find very small discrepancies compared with the navigation-corrected version."
| Python type: | unicode or None |
| Default value: | None |
| Minimum length: | 1 |
| Maximum length: | 255 |
| Must exist: | No |
Base path to prepend to relative paths.
If any of the input paths (or output paths, if this method has outputs) contained in the lists are relative paths, they will be converted to absolute paths prior to processing, as follows:
The navigation offsets are the e and f coefficients of the navigation affine attribute of each variable (the HDF nav_affine attribute). Prior to setting the navigation offsets in the destination file, the entire navigation affine is reset by invoking the cwnavigate utility with the -R option.
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