As part of the subdivision platting requirements in Montgomery County, we are required to tie-in a corner of the subdivision to the nearest Survey Corner.
Everyplace (earthpoint, Texas land Survey) have different coordinates.
Is there a publication that shows these coordinates?
Thanks,
John
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Typically when I am surveying land I take the time to perform an on-the-ground survey so I can establish coordinates to any items I show on my survey. I don't even use another surveyor's coordinates, because depending on the base (origin) point used to establish his control his coordinates will differ from my own. What city are you platting in and what are you naming this subdivision?
Use the following link.
https://www.ngs.noaa.gov/NGSDataExplorer/
John,
I'm agree with Kevin.
Usually, the accuracy of GIS data is unknown or impossible to judge ("what is the data's source?" "how they are measured/computed/interpolated?" "they coresponding only to the nominal scale of GIS or have better accuracy?").
I suggest You, contact the nearest office of NGS.
In my Country (Italy), the IGMI (an Organization like NGS) sell datasheet of National Geodetic Point network; coordinates of cadastral point, in opposite, are freely available on website.
Bye!
Carlo Alberto
Just so everyone knows, I never suggested that a GIS or Google Earth "tie" was an acceptable means of accomplishing the county requirements. I second, third, and fourth the concept that GIS is inherently inaccurate. That said, my explanation for this requirement from the county is upon us as the most qualified professionals on the planet to provide the best datum reference and documentation of our surveys to their GIS department. The only way they can build a more accurate GIS database for their cadastral layer is by using surveyor's precise deliverables tied to a repeatable datum. I used to do just this in Montana by providing my state run Montana Cadastral group with my GPS ties to recovered section corners. This helped them geo-register their shape files to real measurements on a stone that hasn't been seen since it was planted in 1894 by the GLO. The help I gave them was returned 10-fold by surveyors like me doing the same, over time their database improved from 50' to sometimes 3'. For some projects, I would simply upload their shape file for my search coordinates for simplicity.
Hi John,
Sorry it took so long to get back to you. As far as I know there is no publication that shows these coordinates. If you find one let us know.
PS , To be clear state plane or geodectic coordinates for the abstract corners.
Best Regards,
Billy
John,
I'm a bit confused by your question. First, the coordinates of a mark are not the legal or controling location. That location is in fact the mark itself, be it an original stone or post from 1840's or a modern Harrison monument. It does not matter if the "record coordinate" is an assumed 5000,5000, a NAD27 or a WGD84 reference. What matters is what you say the relationship of your subdivision is to this nearest survey corner. (I'm assuming this is a section corner of some sort) by either a bearing & distance or by referencing coordinates in a common coordinate system - Montgomery Co., Texas has a CORS station _ TXCN - that is currently referenced in NAD 83(2011) and State Plane Coordinate Zone TX C.
Second, if you are attempting to tie your subdivision to a published corner by simply plotting a coordinate derived by some unknown source or method, well that's just wrong and could certainly be considered negligent or malpractice. Not cool.
Hope this helps and good luck,
Kevin
Thanks, Kevin
I referenced the the subdivision corners with Grid Coordinates based on NAD 83 (2011), State Pllane Coordinate Central Zone.
Its just that albeit the the red line from the County want a tie to the nearest Survey Corner.
I did that by getting as close a coordinate from the Texas Land Survey GIS, but was wondering if someone had published this data. I get different locations From Earthpoint.
Again, Thanks,
John
never, never..., please never - Dear God in Heaven - use any measurements or coordinates that you pull from any GIS system as a basis for your survey boundary work. GIS systems and their information are from ad-hoc sources, unknown quality, and you have no idea how reliable and consistent it was entered in the GIS system and maybe most importantly how any of this was adjusted to fit together to create the GIS map.
I will, however, use GIS as a research tool. I have used coordinates from GIS systems to help navigate to a remote corner to get within a few feet or meters of where a monument is supposed to be many, many times but I have NEVER EVER used a GIS distance, bearing or coordinate as a substitute for my own field measurements or computations.
From the "Montgomery County Subdivision Guidelines"
"The boundary of the subdivision and accurate dimensions, both linear and
angular, of the boundary, tied to a original survey corner, or street right of
way intersection."
I think you are reading more into this than is really required.
Quite a few jurisdictions have this requirement. The easiest thing to do is to measure a bearing and distance from a corner of the subdivision to a survey corner using Google Earth. We find Google Earth is a good way to develop coordinates fairly accurately or close enough for this task.
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