CDMODIS

Description

Parameters

cdmodis(filehd, file, dbiclist, tex1)

Parameter descriptions

FILEHD

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

FILE

Specifies the name of the output file that will receive the processed data. The output file is created automatically and must not already exist.

DBICLIST

Specifies the list of channels or layers to read from the CD. A maximum of 16 channels can be read.

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

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

CDMODIS is part of the satellite orthorectification component. It reads the MODIS format CD when satellite orthorectification is required. CDMODIS automatically creates a PCIDSK file, reads all the requested image channels from CD, and saves the satellite path information in a segment.

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

Example

For a MODIS 1B product, perform an orthorectification on the data, extract channel 1, and store it in the file "modis.pix".

from pci.cdmodis import cdmodis

fili = "MOD02QKM.A2000355.1850.002.2001009110735.hdf"	# input image file
file = "modis.pix" 	# output image file
dbiclist = "1" 	# channel number 1
tex1 = "Richmond Hill, Canada"

cdmodis (fili, file, dbiclist, 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.)