Index
Image Processing I A-Z Image Processing III
Enhancement

Image Processing II
Import of data

Raw data (which may denote already preprocessed data you retreive from a provider of satellite data) are often organized in the so-called BIL-format (= Band Interleaved by Line), a common way to store multispectral data. Here's an example for a 4-bands data file:

110 115 138 215 ... line 1 of spectral band 1
72 85 97 105 ...... line 1 of spectral band 2
218 172 160 35 .... line 1 of spectral band 3
156 134 129 92 .... line 1 of spectral band 4
111 115 142 210 ... line 2 of spectral band 1
69 83 96 104 ...... line 2 of spectral band 2
.....

In real the digital numbers (a measure for the spectral reflectance) are stored in a long sequence. So you must feed the BILIDRIS-routine with some knowledge about the nature of your raw data to be imported. That should not be a problem, as these data are delivered together with a header file, which might be directly included in the BIL-data or could be shipped as separate text file.

Have a taste of what that looks like from the following real sample file ( SSC Satellitbild, 1996), where the informations of immediate interest in the process of importing through BILIDRIS are colored red:

Parameter

IDENTIFIER
DATE
TIME
CENTER_LAT
CENTER_LON
NW_LAT
NW_LON
NE_LAT
NE_LON
SW_LAT
SW_LON
SE_LAT
SE_LON
PROD_BANDS
DEVICE
TRANSMISSION
MISSION
STATION
IMGFILE
NCOLS
NROWS
NBANDS
LAYOUT

Description

Unique name of standard product
Acquisition date, year/month/day
Acquisition start time (UTC), hour/minute
Scene Centre Latitude, degrees minutes
Scene Centre Longitude, degrees minutes
North-West Corner Latitude, degrees minutes
North-West Corner Longitude, degrees minutes
North-East Corner Latitude, degrees minutes
North-East Corner Longitude, degrees minutes
South-West Corner Latitude, degrees minutes
South-West Corner Longitude, degrees minutes
South-East Corner Latitude, degrees minutes
South-East Corner Longitude, degrees minutes
Image bands in the product (1-4 digits)
Instrument device number
Direct data dump or tape-recorder playback
Resurs-O1 mission
Ground station where data is received
Name of the file with image data
Number of columns in the image file
Number of lines in the image file
Number of bands in the image file
Organisation of bands in the image file

Example

SK950709N50E015
950709
0905
50 15
15 53
53 27
12 9
52 8
21 24
48 7
10 48
46 57
19 8
1234
SK1
DIRECT
3
Kiruna
AL191021.bil
4000
3750
4
BIL

The latitude, longitude coordinates must be expressed as decimal degrees. The SW_LON / NW_LON form the MinX / MaxX, the SE_LAT / NW_LAT the MinY / MaxY reference points. Reference system is 'latlong', reference units are 'Degrees'.

Results of the BILIDRIS-routine are 4 images, each of them 15 MB in size, representing 4 different spectral bands.

Besides the BILIDRIS import IDRISI has yet some more tools to get satellite data in:

- the import/export utilities
BIPIDRIS to import Band Interleaved by Pixel files
ERDIDRIS to convert to and from ERDAS *.gis and *.lan files (also mention the Palette conversion PALIDRIS)
- a binary file viewer
DUMP (or here)

Index
Image Processing I A-Z Image Processing III
Enhancement
last modified: | Comments to Eric J. LORUP

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