RADAR, post: 439330, member: 413 wrote: Isn't the entire state of Texas on a square grid; no East/West curved lines?
In 1836 all the greatest minds met, they said they would like to have the most tangled, disorganized cadastral system possible so future Texas Surveyors could claim to be the best, and they wanted to keep tinkering with the title records so the best Lawyers in the world, Texas Lawyers would perpetually have work disentangling the mess.
I see this True GPS North often here.
Surveyor (customer) insists that (yellow) box will deliver geodetic bearings at a site and that ALL bearings are 'GPS derived' and with respect to TrueNorth. "T has a special way to make this happen, only T has got it figured out." The reality is that the Salesman who taught the user how to setup a local projection was a salesman and not a geodesist.
Hard to convince these customers that the grid bearing = true at the random spot where the data collector places the Transverse Mercator LDP base with convergence to true everywhere else.
If you have the data collector file, or enough metadata (you won't because practioner has no idea what they did) then you can recreate the projection, with the correct scale factor and you will match the original job. Unfortunately, there is NEVER a clue as to the original projection because for some reason the Central Meridian and Lat of Origin are NOT disclosed. Typically the CM & LO are NOT at the base position either.
Button Pushers.
Many years ago, like 25 plus, I found a description that had apparently been prepared by a surveyor in the 1940's that started out with an assumed bearing for the east section line. It was something like North 00 degrees 14 minutes 12.43 seconds East. I had a reaction similar to what Tom mentioned above. In the 1940's, on a small rural tract. What the heck was that all about?!?!
If he had said it was assumed to be North (with no further clarification) it would have been fine. The attempt at placing such definition on a fairly crude line was asinine. No GPS. No total station. One end of the line may have been on a stone and the other on a car axle.
In PLSSia in general the goal was to have north-south lines that were fairly close to north and east-west lines that would be fairly close to east. Magnetic anomalies screwed that up somewhat in certain places. But, in general, a trip from the southwest section corner to the northwest section corner would be thought of as pretty darned close to north. Plenty of surveyors used such a line as a basis of bearings and simply called it north. Not geodetic north, magnetic north, solar north, true north................just north. Everything else fell into place from that. When convenient for the purposes of the survey, an east-west line, possibly the north section line, would be called out as the basis of bearings and labeled East or North 90 degrees East. Everything else fell into place from that. Yes, those were all "assumed" bearings but they got the job done because everyone knew what was intended.
Today we have people willing to demand a duel with pistols at 10 paces (29.034 feet) if one's black box doesn't produce the same numbers as someone else's black box.
Dave Karoly, post: 439333, member: 94 wrote: In 1836 all the greatest minds met, they said they would like to have the most tangled, disorganized cadastral system possible so future Texas Surveyors could claim to be the best, and they wanted to keep tinkering with the title records so the best Lawyers in the world, Texas Lawyers would perpetually have work disentangling the mess.
No, a proposal to sectionalize the public lands of the Republic of Texas was briefly entertained and rejected as impractical for the obvious reasons of cost and time. The actual situation that existed after the Texas Revolution was that there were extensive land grants that had already been made under the goverments of Spain and Mexico and those titles were to be recognized as valid.
One could argue with some basis that the Texas Independence movement was more about access to land than anything. The system followed in the various colonies in Texas adminstered by their commissioners as authorized by the Mexican authorities was orderly and resulted in a fairly regular tiling of land grants that was also adapted to topographic considerations. However, that system worked slowly and in any event the existing colonies only covered a fraction of the State.
What was adopted as a modification of that system was a dispersed organization that operated at the county level. As orginally conceived, the County Surveyor was to oversee the surveying of land grants within the boundaries of his jurisdiction and, if necessary, to appoint deputies to carry out surveys according to his instructions in specific parts of the county assigned to them.
That system began in 1837 with the opening of the Texas GLO. At that time, the greatest demand was in the vicinity of where other grants existed, including grants that were in progress at the time of the Declaration of Independence from Mexico, but to which no title had been issued. So, the obvious need was to fit new surveys of parts of the public lands to adjoin the existing grants and to update county maps to reflect both existing grants and unappropriated lands. Simply continuing the surveying of land within the county at variations chosen to follow earlier surveys made during the colonial period was an expedient solution that operated perfectly well at the time.
Fast forward more than 127 years from the exhaustion of the unappropriated public lands of Texas and what we have a a patchwork quilt that presents a level of complexity that is completely unlike that produced by the survey and subdivision of townships in the Western US. Just in something as elementary as research, the simplicity of the typical PLSS township should be striking compared to a metes and bounds system such as that which exists in Texas.
Mark Silver, post: 439335, member: 1087 wrote: I see this True GPS North often here.
Surveyor (customer) insists that (yellow) box will deliver geodetic bearings at a site and that ALL bearings are 'GPS derived' and with respect to TrueNorth. "T has a special way to make this happen, only T has got it figured out." The reality is that the Salesman who taught the user how to setup a local projection was a salesman and not a geodesist..
Yes, the other missing piece of "Bearing Basis = True North based upon GPS observations" is that there is absolutely no information provided as to the custom projection that was generated. I'd expect to find wacky scale errors throughout the survey that are an artifact of using the custom projection to generate rectangular coordinates of things located and staked out and just inversing between the coordinates to derive distances that are presented without any consideration of scale factors.
In college, we were first taught Plane Surveying Principles and were introduced to the different projections made to place all of our Earth to a flat map.
I am so happy to not having to muggle thru sections and all the PLSS style of surveying.
Also, I am happy that this area is Flat Land and the thought of what Geoid is on the menu for today never enters my mind, usually.
Working with metes and bounds is refreshing and not every Headright Survey have boundaries that extend across the county, region or state.
The original surveyors did not always run straight lines even when that was their goal. They did what they could with what they had and when we can find their footsteps we don't correct their failures now, 150+ years afterwards.
What is most important to provide is something on paper of what is on the ground that can be retraced with certainty.
To satisfy our BOR, we must do it within certain degrees of accuracy by using and stating certainties that actually exist and can be found and seen.
Realtors, Title Companies, Lawyers and many clients could care less if we do any of this. They just want the paperwork a.s.a.p to seal the deal.
I use WGS84, period. Once in a blue moon somebody requires something different and they usually get WGS84 and the opportunity to turn that into whatever they want.
When I come across the counties from miles away with control from any compas direction and arrive at my working points, the results are always within a tenth of a second of each other.
I then traverse with TS here and there and close into more located working points my distances fit and I adjust my directions accordingly with Crandal or DMD methods to fit the world.
Hopefully, all my directions are as close in relation with what WGS84 calls True North as possible.
Reading about the extents that most everyone else goes to in their 3D worlds makes me respect you guys very much and without doubt it keeps me within my element and working area.
:manhole:
I envision (I think envision is used incorrectly here) the original intent of the "basis of bearings" statement was to state whether the bearings are based on a magnetic north, or if the attempt was made to adjust them to geodetic north (or if something like a 'state plane grid' came along, if it was based on "that" north). The old GLO attempts to base everything on a "true" north basis adjusting angles to match the curvature displacement from "true". True in that sense does carry a precision differential. Today a lot of surveyors have decided that it is more important to state two of their monuments and what the bearing you used between them is. That's okay, but I don't think it reflects the original concept (per se).
Tom Adams, post: 439358, member: 7285 wrote: I envision (I think envision is used incorrectly here) the original intent of the "basis of bearings" statement was to state whether the bearings are based on a magnetic north, or if the attempt was made to adjust them to geodetic north (or if something like a 'state plane grid' came along, if it was based on "that" north). The old GLO attempts to base everything on a "true" north basis adjusting angles to match the curvature displacement from "true". True in that sense does carry a precision differential. Today a lot of surveyors have decided that it is more important to state two of their monuments and what the bearing you used between them is. That's okay, but I don't think it reflects the original concept (per se).
Since the example I quoted pertains to a survey made in Texas, I'm pretty sure that I know what the intention of the bearing basis note is. It is to describe how the exact direction of the line as reported may be established on the ground for the purposes of comparision with the bearing of the line as it actually exists, for the intercomparison of the bearings of lines as determined in relation to different bearing bases by different surveys, and for the purpose of guiding the reestablishment of such boundary markers as may be necessary in the future.
In practice, that means describing how the Y-axis of the system of rectangular coordinates used in computing the bearings of lines as reported was oriented. The basis of bearings is in one of two classes:
- those that are independently reproducible without depending upon specific boundary markers to define the North direction to which the Y-axis is oriented, and
- those that require the existence of specific boundary markers to define that "North" direction
Independently reproducible is best since by definition it will always be able to be reestablished. The second-class method of relying upon monumented points to determine some specific direction will fail if those monuments no longer exist, undisturbed.
However, while the monuments defining the "North" direction used as the basis of bearings exist, they do provide a means of determining the errors in any bearing of any line reported with respect to the coordinate system with a Y-axis oriented to the "North" direction consistent with the assumed bearing of the line between the monuments.
Kent McMillan, post: 439350, member: 3 wrote: No, a proposal to sectionalize the public lands of the Republic of Texas was briefly entertained and rejected as impractical for the obvious reasons of cost and time. The actual situation that existed after the Texas Revolution was that there were extensive land grants that had already been made under the goverments of Spain and Mexico and those titles were to be recognized as valid.
One could argue with some basis that the Texas Independence movement was more about access to land than anything. The system followed in the various colonies in Texas adminstered by their commissioners as authorized by the Mexican authorities was orderly and resulted in a fairly regular tiling of land grants that was also adapted to topographic considerations. However, that system worked slowly and in any event the existing colonies only covered a fraction of the State.
What was adopted as a modification of that system was a dispersed organization that operated at the county level. As orginally conceived, the County Surveyor was to oversee the surveying of land grants within the boundaries of his jurisdiction and, if necessary, to appoint deputies to carry out surveys according to his instructions in specific parts of the county assigned to them.
That system began in 1837 with the opening of the Texas GLO. At that time, the greatest demand was in the vicinity of where other grants existed, including grants that were in progress at the time of the Declaration of Independence from Mexico, but to which no title had been issued. So, the obvious need was to fit new surveys of parts of the public lands to adjoin the existing grants and to update county maps to reflect both existing grants and unappropriated lands. Simply continuing the surveying of land within the county at variations chosen to follow earlier surveys made during the colonial period was an expedient solution that operated perfectly well at the time.
Fast forward more than 127 years from the exhaustion of the unappropriated public lands of Texas and what we have a a patchwork quilt that presents a level of complexity that is completely unlike that produced by the survey and subdivision of townships in the Western US. Just in something as elementary as research, the simplicity of the typical PLSS township should be striking compared to a metes and bounds system such as that which exists in Texas.
Basically what you are saying is "you can pay me now or you can pay me later, a lot more later." Texas chose a lot more later but shortsightedness is part of the American condition.
A comment here. I was licensed for several years, before I DISCOVERED that 2 GPS receivers, placed out in the open, on AUTONOMOUS position would essentially YIELD the SAME brg and dist, day, after day, and so on, within a few tenths of a second.
That said, they will float around a bit, (Think translate) but, the rotation, and distance between will remain the same. Day, after day, after day, with any basic proper use of the equipment. (This was L-1 Static)
This basic fact is probably NOT a part of many surveyor's basic knowledge, and therefore, the idea of an objective Basis of Bearing essentially escapes them. Back on the old rpls.com, there was a guy, that used to use sun shots, and argue all about it.
GPS has largely replaced sun shots, for bearings. With good reason. Easy, to do, and hard to mess up...
So... with the advent of easy, and fairly cheap RTK GPS, and Static GPS, many practitioners, DON'T KNOW what their equipment can do, and what it cannot do.
N
Dave Karoly, post: 439362, member: 94 wrote: Basically what you are saying is "you can pay me now or you can pay me later, a lot more later." Texas chose a lot more later but shortsightedness is part of the American condition.
No, sectionalizing the Texas public lands would have been a completely unworkable scheme for the reason of the highly varied quality of the land and the quantities involved. In 1837, when the Texas GLO opened for business, the basic size of a land grant to which the residents of Texas were entitled who had not previously obtained land in Texas from Mexico was:
1a. A league and a labor (26,000,000 sq. varas in all) of land if they were heads of households, who had resided in Texas on the day of the Declaration of Independence from Mexico and had not left Texas to escape military service, or
1b. 1/3 of a league (8,333,333 sq. varas) of land if they were unmarried men above the age of 17.
Settlers in Texas who arrived after March 2, 1836, but before October 1, 1837 were entitled to :
2a, 1,280 acres of land if a married head of household or
2b. 640 acres of land if unmarried.
Settlers in Texas who arrived after October 1, 1837, but before January 1, 1840 were entitled to :
3a. 640 acres of land if a married head of household or
3b. 320 acres of land if unmarried.
The nature of these grants was in the form of a certificate that entitled the holder to have that quantity of land surveyed out of the public domain, which meant that the holders of the certificates could actually find lands that were suitable for the purposes they had in mind, whether farming, ranching, or operating a mill on a spring-fed creek.
It would have been an extremely wasteful exercise to have attempted to presurvey tracts of land scattered across the Republic in anticipation of the sizes and shapes that would actually be in demand in the locations where they would be. It was much more efficient to allow the holders of the certificates to to make those choices themselves, or even to see the certificate to someone else and use the funds to buy some previously surveyed land.
Kent McMillan, post: 439369, member: 3 wrote: No, sectionalizing the Texas public lands would have been a completely unworkable scheme for the reason of the highly varied quality of the land and the quantities involved. In 1837, when the Texas GLO opened for business, the basic size of a land grant to which the residents of Texas were entitled who had not previously obtained land in Texas from Mexico was:
1a. A league and a labor (26,000,000 sq. varas in all) of land if they were heads of households, who had resided in Texas on the day of the Declaration of Independence from Mexico and had not left Texas to escape military service, or
1b. 1/3 of a league (8,333,333 sq. varas) of land if they were unmarried men above the age of 17.
Settlers in Texas who arrived after March 2, 1836, but before October 1, 1837 were entitled to :
2a, 1,280 acres of land if a married head of household or
2b. 640 acres of land if unmarried.
Settlers in Texas who arrived after October 1, 1837, but before January 1, 1840 were entitled to :
3a. 640 acres of land if a married head of household or
3b. 320 acres of land if unmarried.
The nature of these grants was in the form of a certificate that entitled the holder to have that quantity of land surveyed out of the public domain, which meant that the holders of the certificates could actually find lands that were suitable for the purposes they had in mind, whether farming, ranching, or operating a mill on a spring-fed creek.
It would have been an extremely wasteful exercise to have attempted to presurvey tracts of land scattered across the Republic in anticipation of the sizes and shapes that would actually be in demand in the locations where they would be. It was much more efficient to allow the holders of the certificates to to make those choices themselves, or even to see the certificate to someone else and use the funds to buy some previously surveyed land.
So what you are saying is Texas has the smartest surveyors but they couldn't figure out how to lay out square miles? No wonder Texas is so screwed up. Texas sounds like weak lumber to me, California is far more diverse and we sectionalized everything, mountains, valley, plain, desert.
Kent McMillan, post: 439369, member: 3 wrote: a completely unworkable scheme for the reason of the highly varied quality of the land and the quantities
So Texas had cornered the market on quality and quantity of land?
[USER=3]@Kent McMillan[/USER]
Do you seriously think that Texas is the only state in the union that has a highly varied quality and vast quantity of land?
You don't get out of Texas much, do you...
Dave Karoly, post: 439374, member: 94 wrote: So what you are saying is Texas has the smartest surveyors but they couldn't figure out how to lay out square miles? No wonder Texas is so screwed up. Texas sounds like weak lumber to me, California is far more diverse and we sectionalized everything, mountains, valley, plain, desert.
No, what i'm pointing out is that if you look at the pattern of most desirable lands in Texas as reflected by the earliest locations of surveys, you'll find that a rectangular grid would have been a simple, but remarkably inefficient solution to actually getting those lands into the hands of settlers. In California, what the rectangular grid of the PLSS produced when overlaid upon the actual lands were loads of fraudulent townships where the good lands were actually surveyed and the remainder was simply located by the pen.
In Texas, the system functioned somewhat more transparently in that the private owners whose interests were being located were directly interested in the survey and could see what what done.. The system broke down in North and West Texas where great blocks of land scrip issued to various entities, typically railroad companies, were located on land where use as large ranches was the really the only one feasible. The land scrip had been sold as a commodity on the market and the owners of, say, 100 certificates issued to the Missouri, Kansas & Texas Extension Rwy. Co. might be investors who lived in Massachusetts and expected to make a fortune raising cattle in Texas.
So, in the cases of the West Texas railroad blocks, the survey typically amounted to locating the boundaries of the entire tract consisting of the 100 sections of land and the 100 alternating sections that were also required to have been located for the State to be sold as School Land. Many of those same blocks were later found to have extremely valuable minerals in the form of oil and gas under them and from that moment the real complexity of the system came to light, unlike the PLSS.
That's an oldie, don't see it much for surveys after the early 2000's, seemed to be the new early GPS users that put that one down. They were excited to get something that would get good north without solars and such.
No biggie, it was always way better than the government plats to the nearest minute and then the slop in solars that were done. I usually have good results with those maps when following them. Going in the assumption is they are actually grid.
MightyMoe, post: 439384, member: 700 wrote: Going in the assumption is they are actually grid.
I don't know enough about the projections that the Trimble salespeople convinced their customers to use, but I assume that they are typically Lambert projections tangent to the ellipsoid at one particular latitude that happens to be where either the base was set up or the first rover shot was taken.
Kent McMillan, post: 439387, member: 3 wrote: I don't know enough about the projections that the Trimble salespeople convinced their customers to use, but I assume that they are typically Lambert projections tangent to the ellipsoid at one particular latitude that happens to be where either the base was set up or the first rover shot was taken.
All of the FUGARWE Trimble "calibrations" that I have seen lately, are expressed as Transverse Mercator Projections. If you can get a copy of the "original" Data Collector (.dc) file, you can generally extract the projection parameters. That doesn't justify the use of such behind the curtain BS (IMO), especially when the USER has no clue what is going on behind said curtain.
Loyal
Tom Adams, post: 439306, member: 7285 wrote: No surveyor just walks up to a point with no orientation and just says "Hey, for the sake of discussion, let's assume this here line to be N18?§12'56.4"W. They got that bearing somehow, and the basis of bearings statement is designed to help someone get on the same bearing base (even if the points on the ground no longer exist)
I'm confused. Weren't the stars around, and their azimuth's measurable to within a few seconds or so, many years before State Plane Grids, GPS, the PLSS, or the Texas' unique equivalent thereof, existed? What's the problem here?:confused:
Kent McMillan, post: 439387, member: 3 wrote: I don't know enough about the projections that the Trimble salespeople convinced their customers to use, but I assume that they are typically Lambert projections tangent to the ellipsoid at one particular latitude that happens to be where either the base was set up or the first rover shot was taken.
You would assume wrongly
rfc, post: 439390, member: 8882 wrote: I'm confused. Weren't the stars around, and their azimuth's measurable to within a few seconds or so, many years before State Plane Grids, GPS, the PLSS, or the Texas' unique equivalent thereof, existed? What's the problem here?:confused:
Decidly not
