[mapserver-users] distance search in PLSS

[Puneet Kishor]

Ed,

Here are some more assumptions...

> From: Ed McNierney [mailto:ed at topozone.com]
..
> How accurate do you need to be? 

not at all really... as long as I get a list of the contiguous trsq in all
directions... as I said, the selection would be "pass-through" (it could be
"contains" as well, but for now let's assume "pass-through"... even if it is
"contains" it doesn't have to be precise, for ex, if doing radius searches,
square qs won't fit completely inside a circle, etc.)


> The two issues I can think 
> of right off are that you don't know when the current 
> meridian runs out and you need to look at a new one, 

yes, that is a problem, but again, let's assume that my area of interest
lies completely within one...

> and the 
> fact that the grids aren't entirely regular and have many 
> hole in them, especially around Indian reservations and other 
> unsurveyed areas.  That is, if you start with T21, R10, S23, 
> the next section to its west will be  Section 22 - IF Section 
> 22 actually exists at all.

again, let's assume that I have a completely contiguous grid for my area of
interest.

fwiw, my area of interest is the Northern Illinois region, but that is
neither here nor there.

tia,

pk/




> 
> -----Original Message-----
> From: Puneet Kishor [mailto:pkishor at GeoAnalytics.com]
> Sent: Wednesday, August 28, 2002 11:23 AM
> To: mapserver-users at lists.gis.umn.edu
> Subject: [mapserver-users] distance search in PLSS
> 
> 
> not directly a mapserver question, but...
> 
> given a PLSS quarter-section, and a distance (let's assume, 
> in increments of
> 1/4 mile, since each qs is a quarter-mile square), I want to 
> return a list
> of all the quarter-sections and their parent sections, townships, and
> ranges. 
> 
> For example, if I choose T21, R10, S23, NW, what trsq values 
> would be around
> it within a radius of 1/2 mile.
> 
> Also, let's assume that I am interested in pass-through 
> selections. So,
> every 1/4 mi incremented radius will select the "next" outer 
> set of trsq.
> 
> The catch is, I don't want to do this spatially... instead, I 
> want to use a
> database... in other words, pure logic and math.
> 
> I have a table of PLSS values with fields for t, r, s, qs. 
> PLSS follows a
> set pattern. It is reasonable to assume that an algorithm 
> could be devised
> to do this on the fly.
> 
> Any ideas, anyone?
> 
> tia,
> 
> pk/
>