Three computer programs have been developed for ground processing of Enhanced Thematic Mapper Plus (ETM+) data from Landsat 7. The three programs and their functions are the following:
- The Landsat Processing System (LPS) program processes the Landsat 7 ETM+ data received by the Landsat ground station into an archival data product.
- The Image Assessment System (IAS) program assess the quality of ETM+ data and performs calibration of the ETM+.
- The Level 1 Product Generation System (LPGS) program generates level-1 ETM+ digital image data products (this means that LPGS performs radiometric and geometric corrections of ETM+ digital image data).
This software differs from the software used to process data from older satellites of the Landsat series. The content and format of the Landsat 7 wide-band (X-band) data stream are unique to the Landsat 7 system. While the data acquired by the Thematic Mapper sensors aboard the Landsat 4 and Landsat 5 satellites are similar to the ETM+ data, the ETM+ data stream received at the ground station is significantly different, such that the ground data-processing software developed for the older Landsat satellites cannot be used for ground processing of Landsat 7 data. Hence, it was necessary to develop the present three programs to handle the Landsat 7 ETM+ data.
A major difference between Landsat 7 and the older Landsat satellites is that Landsat 7 incorporates new radiometric calibration sources. The IAS program, in particular, implements new procedures for exploiting ETM+ observations of these sources for radiometric calibration.
The IAS source code is original. Large portions of the IAS source code were reused in developing the LPGS program.
The IAS program includes commercial-off-the-shelf software [Oracle for a data base and IDL for some digital image analyses], but these commercial programs are not embedded in the version of the IAS source code that the authors intend to distribute.
The software consists of lines of source code written principally in the C programming language and accompanied by descriptive documentation. The software is designed exclusively to run on the computer systems of the U.S. Landsat 7 ground data processing system, developed under management of the NASA Goddard Space Flight Center and delivered to the Earth Resources Observation System (EROS) Data Center of the U. S. Geological Survey for use during operations in orbit.
The Landsat 7 satellite is expected to transmit ETM+ data to a number (circa 10) of ground stations distributed around the globe. The stations are expected to be operated by international cooperators (foreign governments or government consortia) that will pay license fees to the U.S. Geological Survey. The LPS, IAS, and LPGS source code will be of greatest interest to those involved in the development of the ground data processing systems for international cooperators. Other organizations interested in creating data products derived from ETM+ data for their customers may also be interested in this software.
This work was done by Robert J. Menrad of Goddard Space Flight Center, Mina Samii of Computer Sciences Corp., and R. J. Thompson of the U. S. Geological Survey. GSC-14244