[mercury-users] rtree, time and constraints?

[doug.auclair at logicaltypes.com]

Dear all,

Thank you very much for adding the rtree module
to the standard library.  It directly addresses
an issue I'm working on which can be described
thusly (the following rather long example is
present to illustrate my questions):

-----
Let's say I'm an astronomer and am continuously
taking pictures of the sky (night and day). The
rtree gives me indexing into my archive very 
nicely, as it allows me to record the area of
coverage of the picture.  When I query for
images of an area of interest, rtree should give
me those images.
-----

I have not yet begun to use rtree to implement
this indexing system, but I have a question before
I may reinvent the wheel.  Does rtree give a
region that is spacial and temporal?  I.e. I 
wish to see visible spectrum images of, say, the 
Orion nebula because of recent activity in stellar 
formation.

Questions:

* Given that each image is time-stamped, is it
possible to narrow the search to not only that
region in space but also, say, within a 3 day
period of two weeks ago?  But only during the
nighttime?  Is this trivial? Instead, are there 
papers or other resources to assist me in 
understanding this data structure for this 
purpose?

* Would having a constraint system over the rtree 
make the implementation simpler or more concise?

* Where are good examples of end-to-end use (i.e.
establishing the store, constraining the 
variables and then reading out the results)
of a constraint system in the Mercury compiler
that wouldn't be to much of a stretch for me
to follow to look into using constraints for
purposes like these?

Thank you for your patience and help.

Sincerely,
Doug Auclair

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