Trees 2D arrays
Fig. 1 Transputer networks
Researchers from the british ALVEY MM I project 'Real-Time 2.5D Vision Systems' (COLLINS et al.
1987) were the first to introduce transputer arrays into the photogrammetric community. They
discussed performance and software engineering aspects of different stereo algorithms on re-
configurable transputer arrays which »appear to offer the best solution to problems of building
future real-time stereo matchers« (MULLER et al. 1988). OTTO & CHAU (1989) have implemented
a 'region-growing' matching algorithm which on a SUN network gave a speed-up nearly linear
over the number of processors (up to 15 were used) and were confident to obtain similar results
on a transputer network. Recent developments at the University College London are based on
a PARSYS SuperNode system with 32 T800 processors (COLLINS 1990, DOWMAN 1990).
Transputers are also favoured by KERN Co. who presented the first digital stereoplotter. The
DSP1, exhibited at the ISPRS Congress in Kyoto, is equipped with additional transputer hard
ware to speed up the system mainly with respect to on-line correlation (COGAN et al. 1988).
KOELBL et al. (1990) reported on testing a dynamic programming algorithm on their KERN
DSR15 analytical plotter which is equipped with a pVAX 3200 host and some transputers. Three
T800 transputers working in parallel were 2.84 times faster than just one alone.
Current Hardware environment
At the Technical University of Berlin the ADSS is designed around a 12 MIPS SUN 4/330. This
RISC workstation provides a standardized graphical user interface based on X-windows, thus
permitting comfortable programming and operating. The workstation is extended with a
PARACOM MultiCluster-1 consisting of 14 INMOS T800 transputers in the basic configuration.
The imagery is stored in a bank of SCSI Winchester disks, 630 MB for each drive. Each hard disk
has a transputer based Mass Storage Controller (MSC) that can transfer data at up to 4
MB/second from or to the disk. The MSCs transfer the data in parallel to the adjacent proces
sors. The data can be routed to Graphics Display System (GDS-2) modules, based on the INMOS
G300 video controller, which allow the display on a high resolution stereo monitor.
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