[Geowanking] RE: New coding schemes - geospatial metadata

brian grant hbgrant at voyager.net
Mon Jun 18 07:26:25 PDT 2007


it seems the thread is returned to its origin which for me is location
measurement metadata (optical attributes to an open view)

regarding the idea that attributing a location measurement to an area grid
is:

>a non-reversible transformation
> to your initial point data

is one way of seeing it but I prefer assigning what timestamped measurement
was taken by what instrument with what configuration. what's measured
encompasses more than the point of measurement; defining area of measurement
is very helpful.

so reversibility is not that important because the entire measurment event
is recorded with metadata.


>
> So either you have a point location, or a circular area, and you are
> applying a transformation to change that point, or circle, into a
> triangle.  And you can't reverse that transformation, plus you don't
> have any real certainty that your actual position is within the
> resulting triangle.


shape is less importatnt that minimum boudaries necessary to define area -
RF is a funny thing, ya know - our location fixes may or may not be GPS
which may or may not be circular


>You want to be able to analyze and present your data by
> defined areas...

yes and absolutely.


>But nor does your method of storing data need to be how you present the
data.

correct but a hierarchical scheme originating from a recursive function can
be very database friendly, open and easy to understand.

great thoughts, Rich - thanks


 - brian

> -----Original Message-----
> From: geowanking-bounces at lists.burri.to
> [mailto:geowanking-bounces at lists.burri.to]On Behalf Of Rich Gibson
> Sent: Friday, June 15, 2007 1:52 PM
> To: geowanking at lists.burri.to
> Subject: Re: New coding schemes -was [Geowanking] Open Street View
>
>
> On 6/15/07, brian grant <hbgrant at voyager.net> wrote:
> > > What is 'contemptible' about lat/lon?
> >
> > it's lousy for assigning attributes to an area; more than adequate for
> > determining what area is under measurement.
>
> It occurs to me that you are looking for an alternate system because
> you are not using tools that understand geometries.  Take a look at
> the PostGIS documentation dicusion of GIS objects:
> http://postgis.refractions.net/docs/ch04.html#RefObject
>
>
> > > I am still confused as to what is wrong with tracking the location of
> > > your sensor notes using lat/lon.  What is the problem with lat/lon?
> >
> > identifying their location with lat/lon is OK - it's storing
> the resulting
> > data attributable to a defined area where lat/lon becomes troublesome.
>
> I don't think you want to store your data 'attributable to a defined
> area.'  You want to be able to analyze and present your data by
> defined areas...
>
> >
> > > What is so attractive to you about losing resolution?
> >
> > I'm not losing resolution. in fact, I'm incorporating the
> precision of the
> > location measurement into the area defined.
>
> huh?  It looks like you are applying a non-reversible transformation
> to your initial point data.  Arguably, because of GPS accuracy, your
> original point data is really an area of probability-you have a 95%
> (or whatever) chance that your true position is within x meters of the
> GPS reported position...
>
> So either you have a point location, or a circular area, and you are
> applying a transformation to change that point, or circle, into a
> triangle.  And you can't reverse that transformation, plus you don't
> have any real certainty that your actual position is within the
> resulting triangle.
>
> >
> > also, the mesh I'm suggesting has a direct correlation to lat/lon.
> > it has to - it's how we measure location.
> >
> > my point is that our method for measurement doesn't have to be
> how we store
> > data.
>
> But nor does your method of storing data need to be how you
> present the data.
>
> cheers,
> Rich
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