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Data Distribution - Satellite Products 
Of the vast amount of satellite imagery now 
stored in archives, only a limited percentage 
is ever ordered by end-users. One of the 
reasons may be that the distributors provide 
only limited data alternatives to the user 
who generally needs a digital orthoimage and 
possibly an elevation model over a specific 
map section imaged in a specific timeslot. 
For satellite data to be used more broadly, 
distribution capabilities will need to be 
vastly improved. Multi-temporal digital 
datasets representing orthoimagery over 
standard map sheet areas in standard map 
projections will have to be offered at 
affordable prices. These datasets will need 
to be normalized to standard sensor, 
atmospheric and illumination characteristics, 
and updates will have to be available 
regularly and without delays. 
Until the user community can rely on a 
regular data supply of consistent quality at 
competitive prices it will continue to be 
hesitant to set up infrastructures which 
depend on this data. At present the primary 
commercial data distribution channels are 
EOSAT and SPOT-Image, both of which are 
directly aligned with a single satellite 
source (Landsat and SPOT respectively). 
Similar agencies are being set up in other 
countries as well. For example, in Canada, 
Radarsat International (RSI) will distribute 
processed Landsat and SPOT data and act as 
the primary commercial distribution channel 
for Radarsat data around the world. 
In addition to product distribution these 
agencies negotiate on behalf of their 
governments the data rights granted to 
individual ground reception stations. The 
stations then orchestrate further 
distribution in their region of interest. 
Generally however, distribution by 
groundstations is subsidized for the common 
good rather than being based on sound 
commercial principles, and is limited to the 
satellites handled by the ground station. 
From a user viewpoint, one would like to be 
able to approach a single agency or company 
and order the datasets of interest, 
regardless of satellite. The proliferation 
of satellites over the next few years will 
hopefully encourage governments and private 
industry around the globe to respond to this 
need and establish better distribution 
channels. In this regard it is encouraging 
to see that the intent of the EOSDIS program 
in the U.S. is to distribute data from a 
number of satellites (be it U.S. only). As 
well, companies such as Radarsat 
International will act as a single-source 
commercial distributor for imagery from 
multiple satellites. 
Data Distribution - Products 
The situation for airborne sensors is 
different to that of satellites in that 
distribution is generally carried out by the 
company flying the sensor and data is 
generally collected for a specific customer. 
However, it is similar in terms of the lack 
of availability of standardized map products 
offered by these companies. Here also the 
providers of the service will have to improve 
their offerings to reach the available market 
potential. In Canada this has been 
recognized by industry and government 
participants in the MEIS-III program. The 
commercialized system will output standard 
data products in the form of calibrated 
digital orthoimages. Providing data products 
at prices the market can bear is a major 
objective of this program. 
Data Extraction Tools 
Another factor contributing to the under 
utilization of remotely sensed imagery is the 
lack of integrated tools available to extract 
all embedded feature, elevation and thematic 
information from the imagery and to deposit 
it in the application oriented data bases 
with accurate geographic coordinates. 
Recent years have seen a tremendous growth in 
geographic information systems. Many of 
these systems started as a solution to a 
specific problem rather than being designed 
as a general tool, and consequently each one 
appears to be more suitable for certain 
applications than for others. Most systems 
are based on proprietary data structures, 
which has complicated the ability to exchange 
information between them. 
At the same time, a proliferation of image 
analysis systems has occurred, resulting in a 
spectrum which ranges from very simple PC- 
based solutions to multi-million dollar image 
mapping systems. While the simpler systems 
allow the imagery to be transformed in 
desired map projections through simple 
warping techniques, the complex ones achieve 
a much higher accuracy by geocoding the 
imagery using sensor position information, as 
well as providing sophisticated information 
extraction techniques. 
So far however, remote sensing systems and 
geographic information systems have developed 
along separate tracks and the potential 
remote sensing can offer as a reliable data 
source for geographic information systems has 
been largely untapped. While some suppliers 
have offered links between the two types of 
systems, few if any have offered integrated 
solutions that work. 
Realizing that effective use of remotely 
sensed data has been limited by the lack of 
integrated tools, Canadian Government and 
Canadian Industry have collectively funded 
the development of what is called a 
Geographic Information Extraction System 
(codename Geomate).