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ARSF Data Processing

Introduction

The ARSF acquires an increasingly wide range of digital airborne remote sensing and atmospheric data from our unique instrument suite. The digital data acquired are Quality Checked immediately following each sortie. Data collected during a survey include:

To check the processing status of recently acquired datasets, please see the latest processing scheduleexternal link and questions concerning this schedule should be addressed to ARSF~Processing.

Remotely sensed data from passive sensors: AISA Eagle & Hawk

Data from each flight line and for each sensor (Eagle & Hawk) are supplied as individual Hierarchical Data Format (HDF)external link Level 1b files. The different levels of HDF are defined according to the standard NASA definition table, and the format is supported by most commercial image processing software.

Product Definition
Level 0 Raw "sensor format" data at original resolution
Level 1a Level 0 data reformatted to image files with ancillary files appended
Level 1b Level 1a data to which radiometric calibration algorithms have been applied, to produce radiance or irradiance, and to which location and navigational information has been appended.
Level 2 Geophysical or environmental parameters derived from Level 1a or 1b data, may include atmospheric correction.
Level 3a Level 1b or 2 data mapped to a geographic co-ordinate system using on-board attitude and positional information only.
Level 3b Level 1b or 2 data mapped to a geographic co-ordinate system using on-board attitude and positional information with additional ground control points.
Level 4 Multi-temporal/multi-sensor gridded data products.

The above NASA definitions have been implemented to provide a consistent framework for the data processing strategy and to provide a standard family of data products. The table shows the elements of a complete data processing chain taking raw data, acquired by a sensor (Level 0), through a series of standard processing steps. These steps include the production of radiometrically calibrated data (Level 1b), traceable to a national standard, and derived geophysical data products (Level 2), which may follow the application of an atmospheric correction. Finally a geometric rectification to a georeferenced co-ordinate system or map projection can be applied using either sensor attitude & position information alone (Level 3a) or augmented by user defined Ground Control Points (Level 3b). The spatially registered data set, containing the original sensor bands or, more generally, some derived data product (i.e. ocean chlorophyll distribution, vegetation red-edge parameter, or surface temperature) can then be combined with other spatially referenced information to former higher level products (Level 4) such as through time series analysis.

The ARSF understands that for most scientific applications, the data are required to be geocorrected (Level 3) but that some users must apply atmospheric corrections or other custom procedures prior to the geocorrection of the data (to produce Level 2 data). Therefore, the ARSF supplies the Level 1b data, along with the software necessary to geocorrect the Level 1b (or user-created Level 2) data and so produce a Level 3a product.

Digital camera data: Leica RCD105 39 megapixel digital camera

Images from the RCD105 digital camera are downloaded and processed with the pushbroom scanner data.

LiDAR data: Leica ALS50-II

Data from each flight are supplied as a quality-checked unclassified point cloud (ASCII and/or LAS formats). On request, the point cloud can be gridded to a DEM in azgcorr-compatible or other formats.

Licensing

ARSF licence the use of data and software within the terms and limits specified in the NERC Data Policy statement. Please consult the Policy section. The ARSF supply the datasets together with a customised Licence for the Use of Copyright Software and Data form which you must complete in full and return to Carl Joseph .