Hyperspectral Data Delivery Contents
This page describes the file formats and delivery structure used in the hyperspectral data deliveries.
Delivery Structure
A standard delivery directory contains the following sub directories:
- dem - Contains a Digital Elevation Model suitable for use with APL
- doc - Contains a copy of the most recent data quality report
- flightlines - Contains the level-1 data
- fodis - Contains radiometrically calibrated FODIS data. This is only present for some Eagle flights.
- level1b - Contains radiometrically calibrated image data and mask files.
- line_information - Contains XML files (1 per flight line) describing the data and flight line information
- mapped - Contains radiometrically calibrated and mapped data, zipped to save space
- navigation - Contains post-processed synchronised navigation data
- logsheet - Contains a logsheet that gives a brief overview of the flown project
- project_information - Contains an XML file describing the project information
- screenshots - Contains JPEG files of level-3 processed data including mosaics.
- sensor_FOV_vectors - Contains field of view sensor vector files required for APL geocorrection
Digital Elevation Model
The format of the delivered Digital Elevation Model (DEM) is band Sequential (BSQ) ENVI format binary data. The projection is in WGS-84 latitude and longitude, with heights relative to the WGS-84 spheroid. There is an accompanying ASCII text header file containing the required information to read the binary data. In most cases, the DEM will have been created from ASTER data.
Fodis, Level1b and Navigation files
The files contained in the fodis, level1b and navigation directories are in band interleaved by line (BIL) ENVI format binary data. There is an accompanying ASCII text header file containing the required information to read the binary data. This data format is essentially a stream of binary data that is ordered thus. Suppose that the file is made of N lines of data from B bands, where each line contains M samples:
sample 1 of band 1 of line 1, sample 2 of band 1 of line 1 ... sample M of band 1 of line 1
sample 1 of band 2 of line 1, sample 2 of band 2 of line 1 ... sample M of band 2 of line 1
.......
sample 1 of band B of line 1, sample 2 of band B of line 1 ... sample M of band B of line 1
sample 1 of band 1 of line 2, sample 2 of band 1 of line 2 ... sample M of band 1 of line 2
sample 1 of band 2 of line 2, sample 2 of band 2 of line 2 ... sample M of band 2 of line 2
.......
sample 1 of band B of line M, sample 2 of band B of line N ... sample M of band B of line N
Alternatively this can be viewed as a large table such as:
Line 1 | ||
|---|---|---|
| ||
| ||
... | ||
|
Line 2 | ||
|---|---|---|
| ||
| ||
... | ||
|
...
Line N | ||
|---|---|---|
| ||
| ||
... | ||
|
Line and Project information
The files in the line_information and project_information directories are in XML format. XML is a markup language which contains specific tags that describe the contents. The ARSF delivered XML files conform to the ISO19115 standard, some basic information on these files can be found here.
Screenshot images
The screenshots are supplied as JPEG images. This is a type of compressed image format that can be opened by most image viewers. The supplied screenshots are one for each flight line for each sensor, and one mosaic for each sensor. If the flight is in the UK and one where Ordnance Survey licensing allows, the mosaic images will contain vector overlays to show the expected accuracy of the geocorrection.
Read-Me, Logsheet and Data quality report
The documents included with the delivery are in PDF. This is an open, platform independent standard for distribution of documentation, which allows graphical, text and tabular data to be included in the same file. Free viewers are available for displaying these documents. Please note that these documents will contain important information relating to your data set and should not be ignored.