China Remote Sensing satellite ground station and its research and development
Functional upgrade in the past years
In response to the practical needs and user's requests, the station did some functional upgrade:
- TM and MSS non-AP geometric correction.
It serves as a backup to AP geometric correction.
- Line shift alignment radiometrically corrected AA product.
This method of processing alleviates the back scan misalignment of TM data and makes AA product usable for various purposes.
- TM fast geodetic correction (1) (2)
Due to the high fidelity of TM PS products, a method of rigid shift correction is proposed with resulting accuracy very similar to that of PG products.
- Large area TM mosaicaking (2)
A first order polynomial transformation model is used for conducting precision correction and mosaicking of many scenes. Its cosmetic processing such as cloud removal may also be used for other purposes.
- Geocoded products
The original system products only WRS framed products. A new algorithm is developed to produce geocoded product. This leads to frame TM data in international mapping system and also TM data for each administrative region. An Atlas of Beijing from these two TM imagery products is under printing.
- Digitally zoomed TM products (3)
Algorithms for digital zooming together with photo enlarging are used for generation of Photoproducts up to scale of 1:50,000. They are widely used in resource inventory, planning and environment monitoring.
- Technique of quantitative photo color composite and multiespectral color composite.
By effective control of quantitative transmission, optimum color composite scheme in accord with user's request can be proposed. It can be used for quantitative color composite considering different spectral densities for different ground objects. This technique is used for color composite using up to all TM seven bands.
SPOT preprocessing system
It is a pipeline hardware oriented preprocessing system. In the first stage the system was jointly developed by our station and a American company. In 1987, due to problems of that company, we began to develop the system solely by our own effort. The system consists of: HDDT ingest, frame synchronizer, QL processing, 1A any 1B processing, CCT generation and image color display. A micro VAX 2 is used for system control and management, while the Motorola-68000 based hardwired blocks are responsible for various functional processing. 1B processing is performed by the micro VAX 2 with nearest neighbor resampling. The QL is carried out in real time at 9 seconds per frame. The annotated framed QL image is displayed on a 1k x 1k monitor. Look-up tables are used for 1A production at 2.5 min. per scene, while 1B product is generated at 10 min. per scene.
While SPOT preprocessing system is functionally completed, it cannot be used as an operational system, due to lack of spare parts of hardwired functional modules. The same reason causes 1B processing performed on micro VAX 2 machine.
Airborne multispectral data preprocessing system
This is a fast real time system with front end and back processing subsystems. The former is a hardwire-oriented system, using hardwired functional blocks and multimicroprocessor parallel processing to perform high capacity optical disk playback, frame synchronizing, decommutation, radiometric and geometric tangent correction, CCT and floppy disk product generation. The latter is a micro VAX 2 based general image analysis system with 1k x 1k color display. A comprehensive set of remote sensing image processing software and airborne multispectral preprocessing software is integrated in the system.
