It makes more sense for sure when you describe it that way.?ÿ
@rover83 I love how you word things. Your Assembly Line remark is spot on. ?ÿAnd its not always wrong it has its place we all want to be more proficient it??s just figuring out the balance between that and educational and mentoring and quality. I so wish I could use my limited vocabulary better you have to go and thank your English mentors. English matters and I am just poor at that.
There is absolutely no reason for a surveyor to calibrate because construction companies do. Even for the exact same control points.?ÿ
@mightymoe It all boils down to knowledge and understanding and at this time it??s all waited against the time clock. I worked on data till 130am last night because a fire came up right before Christmas and I am headed out of town for two days to help get data in the field. More work than workers is a lot of it right now. I know it takes less time to do it right the first time but it seems right now that everyone is just spinning their wheels. All i keep saying to my boss is we need to plan. He keeps saying no time to plan. I just repeat Winston Churchill and Benjamin Franklin. Failure to plan is planning to fail. Not exactly quoted just redneck shortened up a bit. But in times like these it rings truer than any other time for sure. ?ÿI have a site right now that I have slowly started getting the crews to get observations on on all project control. I am hoping to build the transformation over the holidays for that very purpose. But they barely have time to keep up with contractor much less go around the site and observe all mandated control and such that was done by another surveyor and miss quoted on the datum but I have to match it. We mostly use robot to keep everything relative from what contractor uses. They have a site calibration if i could get my hands on it could probably do the math easier and then just spot check. But again its that whole nad83 scaled from somewhere and ngvd29 vertical by a monument that is not listed. And I honestly don??t think its on ngvd29 from the sample shots and knowing the area its navd88 by some means some geoid or some bm no one knows where or what. So now its project control lol.
@mightymoe It all boils down to knowledge and understanding and at this time it??s all waited against the time clock. I worked on data till 130am last night because a fire came up right before Christmas and I am headed out of town for two days to help get data in the field. More work than workers is a lot of it right now. I know it takes less time to do it right the first time but it seems right now that everyone is just spinning their wheels. All i keep saying to my boss is we need to plan. He keeps saying no time to plan. I just repeat Winston Churchill and Benjamin Franklin. Failure to plan is planning to fail. Not exactly quoted just redneck shortened up a bit. But in times like these it rings truer than any other time for sure. ?ÿI have a site right now that I have slowly started getting the crews to get observations on on all project control. I am hoping to build the transformation over the holidays for that very purpose. But they barely have time to keep up with contractor much less go around the site and observe all mandated control and such that was done by another surveyor and miss quoted on the datum but I have to match it. We mostly use robot to keep everything relative from what contractor uses. They have a site calibration if i could get my hands on it could probably do the math easier and then just spot check. But again its that whole nad83 scaled from somewhere and ngvd29 vertical by a monument that is not listed. And I honestly don??t think its on ngvd29 from the sample shots and knowing the area its navd88 by some means some geoid or some bm no one knows where or what. So now its project control lol.
88 and 29 are relatable over small distances (a few miles) so 29 can be easily incorporated into a projection by either using a shift from 88 or attaching Geoid 18 to the ortho elevation. If Geoid 18 won't match the differences between monuments you've got levelling issues.
Normally it doesn't take too much to figure out what happened.
But still, any internally consistent control network (angles are accurate, distances are on the same surface) can have an LDP designed around it without too much effort. If it's calibrated then any error found between the GPS survey (Usually a button pushed RTK shot) and the given coordinates is imbedded in the file. Much better to at least have a constructed geographic model without "error" placed over the control and let the tiny "errors" show up when locating points.?ÿ
Surveyors are a funny bunch about calibration, agonize over adjustments, star net, least squares, tiny differences, then sit on a few control points of unknown origin and accept the numbers shown on the screen from a quick calibration without much of an understanding what those numbers are telling you.?ÿ
If you have a projection in Trimble, then you can analyze ground distances, internal angles, errors of the points, you will have a Geoid model which should track all the elevations and not be limited to the area between the points, you won't have a tilt, you won't have a plane that doesn't capture geoid contours inside your calibration area.?ÿ
If you have a Trimble calibrated file good luck figuring out accurate ground distances, ect.?ÿ
And if you really want a wake up call look at the Gobal Coordinates vs the Local Coordinates in the calibrated file.?ÿ
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@mightymoe yes sir. Well i do know this area has a county published sudo nad83 and sudo ngvd29 datum i have only surveyed this area for about a year off and on but no matter what our project required i kept myself a separate file of all raw data and did a little digging and asking the older folks at conferences at the watering hole what and the heck was up with that county. And i did come across in my bosses old office a few drawings and some old published values of the various networks even one traverse and all raw measurements and adjustments in paper form. I borrowed that and figured out what the issue was horizontally. ?ÿI have tied to several NGS monuments that they published as being held but they don??t match by feet. I tried everything international feet us ft etc but its even in the vertical. Literally 2 BM 500 feet from each other on two different level runs don??t match by .6 ft. And like you say surveyors are funny. My old ls said just calibrate and hold it lol. ?ÿCalibrate to the whole county hold every monument. ?ÿIts like photo control right. If i hold it its always good at that point never mind the wrinkles and distortion between them. ?ÿThis site i am on is not to bad because i can bypass all that and just build the transformation on the control itself. ?ÿIf i can get some time. For the future work. Right now i don??t have time to do much more than flip data back and forth to the field crew to keep them hopping. ?ÿI am new to this company and really enjoying the people and all just trying to get my bearings on how they do things and not be the bull in china cabinet which is not always easy for me. I am a lead follow or get the hell out of my way personality. I hate doing things i know are not correct and biting my lip because thats the way we always have done it mentality. This company is not so much like that as i was doing some testing as i learn more of how tbc operates and the big boss looked and said what are you doing. I showed him he said do that again and i did he said Uhmmm that is a time saver so he said keep it up let??s see more of that. Tbc the more i use it the more I figure out how many things are just so easy to do. I need more time to get productive with it for sure. I have never built a transformation in it from scratch or a LDP i did in other places and programs but that was for other reasons. I am sure i will mess up before i get it right. ?ÿBut hopefully i will get into that soon.
if it's not good control nothing you can do will work. There is no reason to force control, that's one danger of calibrations.?ÿ
@mightymoe yes in the area where my project is it??s pretty good relative to itself in the areas i have checked so far. I been reading some other things here on some ideas you posted in other links. I have never really had to compute a LDP because i wS always on a known datum. Now i have sudo did that back years ago in other countries so they were not the same as my coordinates. I think i have a decent understanding basic with my geodetic background and such to feel comfortable trying to create one is it possible to do this in TBC. ?ÿI have several projects starting next year that this method would be great for. And when using TBC and Trimble access I assume after you get it done its as easy as loading the new datum projection into Trimble access and the rtk or robot would and could all be used interchangeably just like i do now with choosing nad83 and correct zone . ?ÿWhich is much better than saving a site calibration and using it only for gps and then different for robot. ?ÿI wonder if Trimble has a power hour or video on the steps inside tbc to do this. Most of my experience was in transverse mercator projections so i have to always make my brain turn 90 on the scale factor changes on lambert of which i work in now lol. North south and east west changes. Also if i build a ldp can i set my civil3d up with same parameters somehow to have the imagery show up for the exhibits etc. the LDP if we are going to get closer to ground seems like the most logical for my brain i have just not wrapped my head around how it will work for my field crews staking and mapping back and forth. I prefer to stay on grid but can??t get the ls to do that yet. I took a traverse they ran on ground and hand entered all the same raw angles distances etc in Trimble access emulator on state plane and i showed him it was working it scares some people i guess. I would have been the same way if i didn??t have to do it in the government I guess who knows. ?ÿTo me working on known datum is easy now days and requires no extra time. We create more work on office and field side just keeping data seperated. So a tbc project for grid rtk and tbc project scale only then off to cad after scaling gps data. ?ÿTo me its insane lol.
But they barely have time to keep up with contractor much less go around the site and observe all mandated control and such that was done by another surveyor and miss quoted on the datum but I have to match it.
Two things: 1) If the initial surveyor isn't doing the construction staking, that may say something about them, the project, or the contractor(s); 2) I don't know any "follow-after-the-fact" construction surveyors that would not perform a control recovery and analysis, and be perfectly comfortable with the site before staking anything.
We mostly use robot to keep everything relative from what contractor uses.
That sounds like the best/easiest thing to do.
They have a site calibration if i could get my hands on it could probably do the math easier and then just spot check. But again its that whole nad83 scaled from somewhere and ngvd29 vertical by a monument that is not listed. And I honestly don??t think its on ngvd29 from the sample shots and knowing the area its navd88 by some means some geoid or some bm no one knows where or what.
This whole scenario you describe is a textbook example of why you should be doing your own site calibration and forget about reinventing the wheel.
88 and 29 are relatable over small distances (a few miles) so 29 can be easily incorporated into a projection by either using a shift from 88 or attaching Geoid 18 to the ortho elevation. If Geoid 18 won't match the differences between monuments you've got levelling issues.
This entire last passage has "issues".
But still, any internally consistent control network (angles are accurate, distances are on the same surface) can have an LDP designed around it without too much effort.
Fair point, but then you'd be adding another layer of complexity, while potentially logging unpaid effort. KISS: Keep It Simple Stupid!
If it's calibrated then any error found between the GPS survey (Usually a button pushed RTK shot) and the given coordinates is imbedded in the file. Much better to at least have a constructed geographic model without "error" placed over the control and let the tiny "errors" show up when locating points.?ÿ
A proper review of the site calibration point-pair residuals should lead the surveyor to "turn off" (not calibrate) to those points contributing too much error to the calibration.
If you have a projection in Trimble, then you can analyze ground distances, internal angles, errors of the points, you will have a Geoid model which should track all the elevations and not be limited to the area between the points, you won't have a tilt, you won't have a plane that doesn't capture geoid contours inside your calibration area.?ÿ
Sounds like you've not worked along the edge of two abutting projections, or into the adjoiner some distance when the bulk of the project was in the 1st mapping projection.
If you have a Trimble calibrated file good luck figuring out accurate ground distances, ect.?ÿ
If your field file has a site calibration applied, then the distances will be as accurate as the local control being calibrated to, and in that frame of reference/angle/distance basis.
And if you really want a wake up call look at the Gobal Coordinates vs the Local Coordinates in the calibrated file.
This is how all site calibrations/localizations work. (WGS84) Global Coordinates being "mapped" to (Local) Grid Coordinates.
if it's not good control nothing you can do will work. There is no reason to force control, that's one danger of calibrations.?ÿ
There are plenty of surveyors, engineers, and geospatial folks out there that start with a nice clean canvas, and instantly screw up their control, and then continue on that mucked up system to complete projects. Downstream 3rd party survyeors using a site calibration is quite an ingenious method of "unf@cking" work that might otherwise cause work stoppages.
Surveyors that struggle with site calibrations, state plane coordinates, grid-to-ground, etc. generally have no business in attempting to compute their own low distortion projections.
Heck look at all the work the NGS is doing to update NATRF2022 with LDPs, and many of them have PhD's?!
@michigan-left yes I understand site calibration and have reviewed a ton of them and had to tell fellow surveyors that its not good. Well i hit the points i held after good enough. I have witnessed those who only look at the residuals and not the scale and vice versa. I have no real issue with site calibrations i did them many times its when you can show the control has issues and some reason its like least squares well just adjusted it and make it work mentality that comes from those who should know better. That gets me. And as i know they have a place in certain instances for sure why is the question with today??s equipment it??s literally as easy as selecting what units you want or azimuth versus bearings setting. ?ÿ I have seen so many plats go out with a north arrow of nad83 spcXzone state. I know for a fact that there was assumed coords assumed north and site calibration done no one moved it back to nad83 so the north arrow was not even close. On the other side scaled nad83 spc and on north arrow even a few spots of the scaled values north and east. Next surveyor calls and sais I found your corner but miss your coordinates x amount. I said that??s understandable. Cad office manager guy sais they are wrong. I say nope thats about right watch. I unscale and show the shift. But he is always right because cad sais so. I said it??s not a cad function its not. He sais i need to learn land surveying and forget geodetic surveying. I laugh. ?ÿThe problem is not his fault he was taught that way. No big deal because the boundary was right the other surveyor was right. ?ÿBut it was a situation that was not necessary. ?ÿ I followed a survey of a surveyor we took over for because he passed away. ?ÿIt was sad. Large piece it took me literally 15 minutes of reading his plat to see what he did. ?ÿHe had nad83 2011 notes with metadata even a note that stated all distances are ground distances and coordinates are grid. I simply state grid cked the couple of corners cogo the boundary with ground distance to grid and hit everything on the site easily within tolerance. I simply finished the topo to his meta data to get my topo and mapping to match his from his meta data. The brought it into cad and I missed a bldg corner a tenth and a few curb and gutter shots about the same. I let them do it there way gave them the raw data and we all know what happened. Shift yes they translated and matched it all up. And they still didn??t have an answer of why. Goad I don??t work there anymore. ?ÿI do want to do this LDP thing theory wise i get it. Practical side workflow i need to see it done. I still believe every surveyor should have to go out west at 10000 foot elevation and get this down. In the east it is not as drastic in most areas that grid and ground would even be an issue but they still scale and or mix grid and ground. In Colorado in 90??s we had a coordinate sheet I believe it had two sets of coordinates for the big jobs dot I believe. Grid ground/project scale and meter to feet. All listed. ?ÿBut its been so long ago I can??t remember everything. But it was not a big deal for us then and our equipment could not do what this software today can so easily. ?ÿ Maybe the new datum and projection will help but i fear it will still be an issue for some. Why i don??t know. I understand that for layout of something designed on ground in certain areas can cause issues if not taken into consideration. But its not hard to figure out that either. I am know cad person but doesn??t all that software now handle grid and design on grid. I mean even boundary surveys you can do on grid and still retrace and retain the ground distance while being on grid. I have a lot to learn or re learn and un learn I guess. ?ÿ Always great reading your thoughts.
A proper review of the site calibration point-pair residuals should lead the surveyor to "turn off" (not calibrate) to those points contributing too much error to the calibration.
That??s what I do if I??m new to the site and need to get tied into site control. Locate all control points then check the report and throw out any that look way off. Sometimes they get disturbed and it shows in the report. This is all providing I already know the site control coordinates. If I??m filling in for someone else on site(out sick or something) ideally the job file would be nice.?ÿ
This was quite some time ago (haven't had the tsc3 in like a year) but I believe I ended up turning off the 0.026 and 0.020 points and then it improved all the residuals. If you have lots of points in a good location around the project you can experiment a little to see what works better.?ÿ
The new reference frames and SPCS2022 can't come soon enough. I suppose some will still insist on placing the cart before the horse by going backwards in order to use old data rather than bringing old data forward to use the new grid system thereby eliminating the need for local or Cali libations in the field. The posts here simply demonstrate the need for modernization. The Cali libation is the pouring out of a field process as an offering to the Trimble deity in Sunnyvale. The local libation is the pouring out of a field process as an offering to the rest of the local survey software deities across the fruited plane. I remember when our party chief made us tape a quarter mile to check the EDM. The old way was proven. The modern way was suspect. But, if nothing else, we learned how to tape adding more accuracy to our precision.
@norm?ÿ
What is the process to taking old data and making it work with a proper projection like UTM? I'm on the field side of this only and have a lot to learn still. However one thing this site has taught me is surveyors are very bulk headed and tend to assume that everyone elses situation is always exactly the same as theirs. It also seems like a lot of people assume everyone is in the states and should all be using state plane coordinates.?ÿ
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@on_point also depends on settings. Look at how much scaled or fixed scale can change just looking at residuals. ?ÿAnd the ppm on the tilt also depends on settings and how you apply the calibration. ?ÿEach manufacturer software handles these settings a little different. If you ran the traverse control or know about its quality prior to then the approach is a little easier. But when you don??t know how and the quality a little more being careful is needed. ?ÿI if it was unknown always observed everything and did a small sketch on note pad and compared it as i walked through it trying to get the best fit possible. ?ÿNow another thing i have seen is yes residuals point to a bad point but that bad point might not be in the control you are tying to but from a bad observation from the rtk itself. ?ÿMultipath etc. ?ÿThe other thing I have witnessed is and good residuals showed but the practice of tying down all the points that are somewhat in a straight line and then using that same calibration to stake or locate things outside the calibration held control. Holding everything hz an vt. I was called in once on a dot project in ga someone had held points along a route and still needed to do things perpendicular to the route and issue arrived between 2 surveyors and contractor all using different gps . Mostly this was a huge vertical issue. Every ones residuals looked good but only one had approached it correctly. ?ÿThat was he could show no vertical residuals because he understood that even if he had been close vertical on all thise points along the route once he went perpendicular any error in any measurements or the control itself would be amplified. He held one point in middle vertical and went perpendicular to Bench Marks one he had to set himself just a TBM because nothing existed. So residuals are good but not the whole picture sometimes.
What is the process to taking old data and making it work with a proper projection like UTM? I'm on the field side of this only and have a lot to learn still.?ÿ
If the project really needs to be in UTM, then toss the old values, the only option is to re-observe and tie to the proper geodetic datum. Maybe incorporate the raw measurements from the original survey, but good luck finding those (or getting the previous surveyor to hand them over).
If they want to hold to the local values of the points, but be able to relate them to UTM by way of a common geodetic basis, then the procedure is a little more complex. It still involves reobservation of everything (or as much as you are able to do), and then developing projection parameters that fit the existing control in a more rigorous mathematical way (as opposed to "warping" them to fit).
However one thing this site has taught me is surveyors are very bulk headed and tend to assume that everyone elses situation is always exactly the same as theirs. It also seems like a lot of people assume everyone is in the states and should all be using state plane coordinates.
As a US surveyor, I resent that remark.
We're nowhere near that cohesive. We can't even agree with the other surveyor that lives and works in the same town/city as us. Ask two US surveyors a surveying question and you'll get three opinions.
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The new reference frames and SPCS2022 can't come soon enough.
Amen.
Although there are quite a few states that failed to implement the final layer of LDPs for their proposed SPCS2022 parameters. Those of us working in those states are still going to see the same issues going forward.
Super happy about the shift to ITRF and ditching USFt, though.
@norm Yes on taping. I have 2 full sets and a partial set of chaining pins still. I remember setting hub & tacs and then turning around chaining between each one to check daily. If you showed up for work without a plumb bob drafting pencil and calculator you were not prepared and could get chewed out. I dropped my hp out of my shirt pocket more times than i can remember dipping manholes chaining a line in. I still have that hp 32sII it finally died but still have it. I finally bought shirts with a pocket big enough to button it up. Seems every crew chief i had back then had a pack of cigarettes calculator and pens and pencils stuffed in shirt pocket. I remember getting my first survey vest it was used handmedown but I still have that as well. Ended up hand sewing the shoulders back in while on a deployment in usmc. Still know the pls that gave that to me. I have the spread an outer disease now so even if it were not dry rotted it would not fit lol. ?ÿ
I hope the new datums are adopted as well. ?ÿ
What is the process to taking old data and making it work with a proper projection like UTM?
Here is one thing you NEVER want to do:
Calibrate to State Plane Coordinates / UTM while they are currently/previously linked to a mapping projection in the data collector.
If you MUST calibrate to SPC/UTM, be sure the "grid" coordinates are in the data collector in a job with a coordinate system as NO PROJECTION/SCALE ONLY. And make sure that scale is set to 1.000.
Then calibrate the observed WGS84 coordinates with the "dummy" grid coordinates.
If you try to perform a site calibration to coordinates on an existing mapping projection, everything gets twisted up because the data collector is mashing 2 projections together in an unholy alliance. It will yield crazy results, and you won't likely know it unless you use 3 points to calibrate. 2 for translation, rotation, and scale, and 1 as a check.
BTW, this technique will NOT fix a SPC grid-ground scaling problem either.
I've seen many instances of people thinking this is the case, but it is not.
@rover83?ÿ
I didn't mean to offend you, but I honestly see statements like "Why is anyone using anything but SPC" or to do with construction layout, comments that make it obvious that they have never done layout where there is a basement. I'm just saying people have a tendency to only see things from their own typical viewpoint or experiences and everything is always black or white.?ÿ
Anyway your comment helps me to understand why we frequently have local jobs or site calibrated jobs based on previous work, despite people trying to make it sound like there is absolutely no place for it. We don't have the time to "reinvent the wheel" on every project.?ÿ
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@Mi-Other-Left
A proper analysis of elevations before calibration with GPS begins with using the Geoid Model and inspecting the vertical relationship between control points, doesn't matter if they are 88, 29 or an arbitrary 100 at a building finished floor.?ÿ
Using residuals in the calibration reports to accept and reject control points has been one of the vexing issues concerning calibrations. How to know if the ones you're accepting are the good ones and the ones rejected are the bad ones, reapplying the calibration in a different sequence may reverse the numbers, it depends how the numbers are assigned. It's similar to monuments in a subdivision when errors are discovered, which ones are bad, the ones originally sat on and backsighted or the ones located. It's what leads to the notations of monuments being off .05'N, .12'E on a plat.?ÿ
Working near the edge of a zone is one reason a proper projection is superior.?ÿ
In a calibration (Trimble version) the ground distance inverse is lost, I want to know the relationship between ground and grid, not possible in a Trimble calibration, the ground distance is not correct once the calibration is applied.?ÿ
I don't know if you work with Trimble equipment, but if you do, you should understand that Local Coordinates are not grid coordinates. In any of my TBC files, the Gobal Coordinate and Local Coordinate values will be identical for each point (NAD83). In the case of a calibrated file only one point will have identical Coordinate values, all the others will have an "adjusted" Local Coordinate value after being put through the calibration and that point value will be used in calculated inverses.?ÿ
Also, I'm at least 95% confident that your files are not WGS84 based.?ÿ
Again, if you're working in a calibration using Trimble take a look at the Local vs Global Coordinate, if what you see is fine with you then calibration should be fine with you.?ÿ
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