CDASTER

Description

Parameters

cdaster(filehd, file, cdic, tex1)

Parameter descriptions

FILEHD

Specifies the full path and file name of the header file on the CD.

FILE

Specifies the name of the PCIDSK file that will receive the processed data. This file will be created automatically and must not already exist.

CDIC

Specifies the list of channels or layers to read from the CD. Up to 16 channels can be specified.

For each channel, a corresponding channel is created in the output PCIDSK file. Duplicate channels are not allowed.

Store images of different resolutions and file size into separate files.

Ranges of channels or segments can be specified with negative values. For example, {1,-4,10} is internally expanded to {1,2,3,4,10}.

TEX1

Optionally specifies a line of text that describes the file. Typically, this contains information that identifies the location of the data and the CD reference number.

If TEX1 (File Description) is not specified, the File Header fields in the generated output PCIDSK image database hold the following information:

• FH5 receives the tape ID, satellite sensor, and satellite track
• FH7.1 receives the acquisition date and scene center (longitude and latitude, in decimal degrees)
• FH7.2 is empty

Return Value

Returns: execution status

Type:  PCI_INT

The return value is 0. This function returns only if it executes successfully; otherwise, it throws an exception.

Details

CDASTER is part of the satellite orthorectification component. It reads the ASTER HDF file format images from the CD when a satellite orthorectification is required. CDASTER automatically creates a PCIDSK file, reads all of the requested imagery channels from the CD, and saves the satellite path information in a segment. Output from CDASTER is used with SATMODEL and ORTHO2.

The USGS data center provides access to different levels of geodetic processing and product types. The following format is supported:

• 1A level in HDF format

CDASTER extracts from the CD the geographic coordinates of the scene center and the four corner points. The corner points are extracted only if they are UTM coordinates; otherwise, the LAT/LONG coordinates are used to calculate the equivalent UTM coordinates. The values are stored in the output orbit segment. These points can be used as ground control point (GCP) input for an approximate correction, which is useful when GCPs are unavailable for an area. Note, however, that using geographic coordinates may not produce very accurate results. To ensure an accurate calculation, a sufficient number of GCPs must be used for each scene or block of scenes.

The generated file is automatically created with the dimensions required to hold all of the requested data. Ensure that sufficient disk space is available before running CDASTER.

Example

Read in an ASTER file and create a PCIDSK file from it.

from pci.cdaster import cdaster

filehd = "pg-pr1a0000-2001020201_008_032.hdf"
file = "Imported_aster.pix"
cdic = [1]
tex1 = ""

cdaster(filehd, file, cdic, tex1)

References

Toutin, Th. "Analyse mathématique des possibilités cartographiques du système SPOT". Thèse de Docteur-Ingénieur en Sciences Géodésiques, ENSG, Paris, France, 1985. pp1 -163.

Toutin, Th. and Carbonneau Y. "La multi-stéréoscopie pour les corrections d'images SPOT-HRV", Canadian Journal of Remote Sensing, Vol. 15, No. 2 (September 1989) p110. (Also available in English from the Canada Centre for Remote Sensing.)