[Xastir-Dev] Re: Xastir SAR feature added

[Owen DeLong]

I think it depends on what you're looking for.  If you're looking for
a person believed lost on foot, that's one thing, and I would think
circles would be best (Cdir=180), and voila.  If you're looking for
someone in a vehicle (OK, this starts to get outside of SAR, but,
I know there have been times when we've been trying to find people
in vehicles) or, say a package of instruments on a balloon platform
(yes, this is a relatively specific application, but, I know a bunch
of users that are involved with it at http://www.stratofox.org) or
something like that.

So, for SAR, I guess it's true, Cdir=180 hard coded would probably do what
they want.  However, I suspect it's not that hard to allow for Cdir<90 in
the code and draw arcs instead of circles and have the arc move over time.
One option would be start with making the code capable of everything, then,
dumb-down the UI if it's too confusing.  Hide the advanced possibilities
elsewhere.

Owen


--On Friday, September 19, 2003 11:32 AM -0700 "Curt Mills, WE7U" 
<hacker at tc.fluke.com> wrote:

> On Fri, 19 Sep 2003, Owen DeLong wrote:
>
>> What about a form that takes PLS, Vmin, Vmax, and TLS, Pdir, Cdir and
>> then tracks the probability arcs expanding/contracting them appropriately
>> with time.
>>
>> Example/Explanation:
>>
>> PLS	=	Point Last Seen
>> Vmin	=	Minimum anticipated speed
>> Vmax	=	Maximum anticipated speed
>> TLS	=	Time Last Seen (to compute likely position now from PLS
>> Pdir	=	Probable Direction of Travel
>> Cdir	=	Confidence in Pdir (expressed as degrees).  Larger number
>> 		wider arc.  180 = full circle (+/- 180 degrees from Pdir)
>>
>> This would allow you to input the above data about the subject, then,
>> Xaster could maintain a "track" on the possible/probable position of the
>> subject based on (Vmin+Vmax)/2 and draw a shaded search target area
>> which would update in real time.  The search target area would be
>> bounded by the Vmin arc, the Vmax arc, and straight lines between the
>> corresponding edges of the two arcs.  A third arc (the "likely position"
>> arc) would be drawn in the middle.  This way, the search area will grow
>> (as it needs to) with time, and, also move with the likely direction of
>> travel of the subject.
>>
>> The only real problem I see with this is that it would involve the
>> assumption
>> that whatever direction the subject was moving they kept moving in that
>> direction.  It wouldn't allow, for example, for a subject wandering in
>> circles.
>>
>> I think the behavior would be adequate for that with a 180 Cdir, but,
>> it would need some testing and such.  I am not a SAR expert, but, this
>> at least sounds like a good idea t me.
>
> I'm no expert either, but am trying to learn fast.  I'm going to try
> to take some of the multi-day courses regarding search management
> theory over the next year or two.
>
> The idea you listed above is similar to what I first wanted to do,
> at least regarding the circle that continuously expands based on
> time last seen and the current time/max anticipated speed.  I hadn't
> thought about trying to do anything regarding probably direction of
> travel, but I think that part might be problematic.
>
> When I discussed my idea with people in-the-know, they didn't like
> it.  What they wanted was fixed circles at 25% and 75% sizes based
> on the probability that the subject might be in that area based on
> collected statistics on lost people.
>
> I've been looking into these stats and now have data for 10% through
> 100% circles for both U.S. and England/Northern Ireland.  There may
> be data for Australia available soon as well.
>
> I'll try to add this stuff in, but might have to have checkboxes for
> which circles to display, as displaying 10 circles gets kind of
> cluttered.
>
> There are much more advanced search techniques as well.  This is
> just the first step.  As I learn about them I'll try to add them to
> Xastir.
>
> --
> Curt Mills, WE7U                    hacker_NO_SPAM_ at tc.fluke.com
> Senior Methods Engineer/SysAdmin
> "Lotto:    A tax on people who are bad at math!"
> "Windows:  Microsoft's tax on computer illiterates!" -- WE7U
> "The world DOES revolve around me:  I picked the coordinate system!"
>