Ocean Color Forum - Not logged in
I have a subscription for nrt MODIS Aqua scenes (1278).
Day-time scenes for the area 60N-62N, 7W-3W are requested.
The subscription yields the following scenes for 10 June 2012: A2012162010000, A2012162024000, A2012162042000, A2012162055500, A2012162090500, A2012162122000, and A2012162140000.
The Level 1 and 2 browser yields the following Modis Aqua day-time scenes for the same day: A2012162024000, A2012162042000, A2012162122000, and A2012162140000.
Can someone explain why my subscription yields 7 scenes and the L1/L2 browser just 4 scenes?
Please see the following page from the browser Help.http://oceancolor.gsfc.nasa.gov/BROWSE_HELP/quadsphere.html
I haven't checked the scenes that you mention, but I
suspect that this is what is going on in your case. If
you think that is not the explanation, then I can
Your answer suggests that the subscription service uses courser quad-sphere bins than the Level 1/2 browser,
i.e. the subscription service uses level-6 bins and the Level 1/2 browser uses level-7 bins.
Can you confirm this.
I believe the subscription service uses the two
latitude and two longitude extrema of the scene
(our subscription coders can correct me if this is
not so). The browse code uses level-6 quadsphere
Have another look at this figure.http://oceancolor.gsfc.nasa.gov/BROWSE_HELP/other_search_implementations.png
(The browser used to use level-7 bins many years ago,
but we sacrificed the finer search resolution in favor
of a smaller database implementation.)
The search engine implemented for the subscription service produces
more results than the L1/L2 browser.
These extra hits are not useful (to me) and result in download of more images than needed.
Are there plans to improve the search engine for the subscription service,
for example by implementing the same search mechanism as used by the L1/L2 browser?
Unfortunately, such a modification to the subscription
service is not a trivial undertaking, and it is not high
on the current list of priorities of our relatively small
Pitty, no modification of the search engine.
It was worth a try.
Anyhow thanks for your very quick answers.