CDALOS

Description

CDALOS reads ALOS imagery from a LGSOW-format CD when satellite orthorectification is required. CDALOS automatically creates a PCIDSK file, reads all of the requested imagery channels from CD, and saves the satellite path information to a segment. The output file from CDALOS is used as input to OrthoEngine.

Parameters

cdalos(filehd, filo, linkfile, cdic, tex1)

Name	Type	Caption	Length	Value range
FILEHD *	str	Header path and file name	1 -
FILO *	str	Output satellite CD layer(s)	1 -
LINKFILE	str	Create linked File (NO\|YES)	0 - 3	YES \| NO Default: NO
CDIC	List[int]	CD input channel(s)	0 - 16
TEX1	str	File description	0 -

* Required parameter

Parameter descriptions

FILEHD

The full path and file name of the ALOS PRISM/AVNIR volume file.

The volume file name typically includes a prefix; for example:

VOL-ALPSMB003062950-O1A____B
LED-ALPSMB003062950-O1A____B

FILO

The name of the PCIDSK file to receive data. This file will be created automatically and must not already exist.

LINKFILE

If specified as YES, instead of creating a new PCIDSK FILO to read the data from FILI, this parameter will create an output file in which the image channel is linked to the original imagery channel. The orbital segment will still be created in FILO. The default value is NO.

Note: With 1A and 1B1 data products that have more than one channel or tile, a link file is not supported.

CDIC

The list of channels or tiles to read from the CD.

With each channel, a corresponding channel is created in the output PCIDSK file except for PRISM Level 1A, 1B1 products. For these products, only a single channel is created since each image in the product relates to a swath of the overall image. If no value is specified for this parameter, all channels or tiles will be extracted.

Up to 16 channels or tiles can be specified. Duplicate channels or tiles are NOT allowed.

TEX1

A textual description of the file. Typically, the description identifies the location of the data and the CD reference number.

If no value is specified for this parameter, the file-header information in the generated output PCIDSK image includes the following:

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

This parameter is optional.

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

CDALOS reads ALOS PRISM- and AVNIR-format data when satellite orthorectification is required. CDALOS automatically creates a PCIDSK file, reads all of the requested imagery channels from CD, and saves the satellite path information to a segment. The leader and imagery files must exist in the same folder as the volume file. Output from CDALOS is used in CATALYST Professional OrthoEngine.

The following formats are supported:

AVNIR-2 Level 1A, 1B1, and 1B2R formats
PRISM Level 1A, 1B1, and 1B2R formats

CDALOS extracts from the CD the geographic coordinates of the scene center and the four corner points. 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.

When the value of the LINKFILE parameter is NO, the output file is automatically created with the dimensions required to hold all of the requested data. You should ensure that sufficient disk space is available before running CDALOS. When the value of the LINKFILE parameter is YES, the image channel is not created; instead, it is linked to the image channel of FILI. With stereo data, LINKFILE is ignored and a new file is always created because rotation is required for data reading.

With PRISM Level 1B1 in NITF format, when all tiles are specified, CDALOS will create the projection in the output file. For an example of the required structure of the source data, see the Examples section.

Example

The user has received a ALOS PRISM 1B2R product in LGSOWG data format and wants to perform orthorectification on the data. The user wants to extract channel 1 and store the data in the file prism.pix.

from pci.cdalos import cdalos

filehd	=	"VOL-ALPSMB003062950-O1B2R_UB"
filo	=	"prism.pix"	# output file name
linkfile	=	"NO"
cdic	=	[1]	# input channel
tex1	=	"Richmond Hill, Canada"	# file description

cdalos(filehd, filo, linkfile, cdic, tex1)

References

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

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

Environments	PYTHON :: EASI :: MODELER
Quick links	Description :: Parameters :: Parameter descriptions :: Return Value :: Details :: Example :: References