Land Lot corner positions

I have been working on real estate mapping software for quite some
time, but this problem has always vexed me. Most legal descriptions
and survey drawings I've come across use Land Lot corners as an
original point of reference, but in order to combine this information
with other maps, I need an absolute position of these corners. Short
of trying to locate them physically with a GPS receiver (and hoping
the reading is accurate enough), is there any place this information
is cataloged?

twobits@gmail.com wrote:


Yes -- consumer GPS receivers can be off by 45 feet or more... usually
much less, but....

County recorder offices would have survey descriptions of boundaries,
but usually with respect to references.... not detailed lat/long in
a given datum.

The land lots are on county tax maps...but just by scale of drawing.

And a commercial atlas where one page is just a couple of miles square is
likely from tax maps...but only showing roads and land lots and not showing
all property lines like the tax maps.

twobits@gmail.com wrote:

They are always referenced in a chain of points from other points. If you
are looking at a single parcel, you probably need to back off to a section,
in order to gain any absolute reference.

Or, you can check with the local county, to see if they have geo-referenced
maps online. Once you locate the county web site, you could do a google
search like this one, looking for gis
        gis site:lake.ca.us
The maps provided don't have any discernible coordinates, but I can
visualize the parcel map of my property, compared to the same view in
Google Earth or ExpertGPS, and put in a few markers that are close to
the right places. It's not survey quality.

--
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5

On Mar 6, 1:18 am, d...@85.usenet.us.com wrote:

My county's gis department sells cad files of their "gis layers",
which typically includes roads and other features (which appear to be
derived from census TIGER/Line data). They also have a "parcels"
layer, showing property outlines, which I've so far been using to try
to find common polygon vertices and derive the land lot line positions
from those (the layers are in state plane, thankfully.) But most of
those polygons don't come particularly close close enough to the
polygons constructed from the boundary surveys at all, so I don't
really trust them for what I'm working on.