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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | RE: GISList: Imagery availability |
| Date: |
02/19/2003 06:55:34 AM |
| From: |
GS Rao |
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On the subject of online availability and ordering of satellite images.
Up until a few years ago, the National Remote Sensing Agency, based in
Hyderabad
was the single source for all satellite imagery in India.
Initially it used to supply Landsat data, followed by TM, SPOT and JERS, as
and when these
satellites became operational. Later of course, it provided data from the
IRS series of satellites.
The first major hindrance was the enormous amount of data being recorded
and archived
everyday. This was compounded by the fact that users demanded a "perfect"
image.
From the user's perspective a "perfect" image is one in which
The area of study is in the centre of the frame. This eliminates the
need for
paying for additional frames if the area happens to be along the edge
of adjacent frames.
The frame has 0% cloud cover.
Needless to say, these conditions were seldom fulfilled resulting in slew
of accusations, prominent
among which were allegations that the staff was not doing a "complete"
search.
To overcome this, NRSA came up with the Quick Look Imagery. These were 70
mm by 70 mm
diapositives which could be quickly visually checked. This mostly
benefitted the local firms
who could zip down and take a peek at them.
Later NRSA developed a software module, made freely available. The inputs
for this were the
bounding latitudes and longitudes of the area of interest. The module would
spew out the
path and row number, as well a set of dates of acquisition. ( A much more
user friendly version
of this was developed by an NGO, based in Ahmedabad, Gujarat).
All said and done, it seems to me, the major problem is the huge amount of
choices available,
and the user's desire to get maximum value for money spent. Not to mention,
a sense of
uneasiness lurking in the user's mind that despite all efforts he still
hasn't got what he
really wanted.
To further complicate the issue you could throw in additional twists -
minimum canopy cover for the
geologist versus maximum canopy cover for the forester.
Most agencies wait for the purchaser's cheque to be cleared before they
commence processing the
order. One way out of this is to set up an account. That is, you pay a
lumpsum upfront, and keep ordering
until the account runs out. This is viable for frequent purchasers only.
And that too if the bean counters
in finance can be wooed first.
Of late NRSA has also taken the beaten path. It has appointed several
re-sellers in major cities.
This makes for faster and more frequent contact between purchaser and
re-seller, but doesn't
necessarily speed up the process.
One of NRSA's major initiatives has been a two to three day Data Users Meet
held once every year.
I am told that the participation in this is steadily increasing and more
and more user problems are being
addressed and resolved.
I guess we are still a little ways off from online realtime purchase,
payment and delivery.
Warm regards
Dr G S Rao
Assistant General Manager - GIS
Larsen & Toubro Infotech Limited
Mumbai, India
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