Am I missing something?
I haven??t seen a single follow up from SapperPLS.
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We have provided SapperPLS with answers that require in depth research to begin a response. Moving from flat earth surveying to geodetic surveying is a steep learning curve. The numerous datums used and imperfect models of the earth they are based on only add to the confusion.
He traversed 1200 feet. And 800 ft. 4 setups. Total Station. Starting SPC XY, published NGS(reset), and he must have determined an azimuth, somehow. Even SF is on the data sheet. Not geodetic, SPC. It was on the exam.?ÿ
??I did stay up till 4 AM last night trying to find an answer and didn't find one.??
imo: he doesn??t have proper azimuth. He might??ve forgotten to subscribe to his own topic.
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he/she was logged on and viewing it an hour or two after the initial posting.
Waiting for moderation approval, I guess I'm too new?
I didn't take into account the convergence.?ÿ That was the issue.?ÿ I do appreciate everybody's in depth response.?ÿ I did reply, but I guess because I'm new my posts require moderator approval.?ÿ Hopefully it isn't long before you all see I did get your responses and tried to reply.
The 1:42k resection only means the two start point values related well with each other. If you have network adjustment software you should be able to push things around until you find the problem.
FWIW,
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I agree with other posters who encouraged you to provide more information.
I copy below extracts for a CT classically positioned monument for illustration as I do not know what monument you actually used. The source for the azimuth you used is also of interest. Unfortunately, azimuth marks for a monument do not in general include accurate distances making positioning impossible.
When dealing with classically positioned monuments, the data sheet will include a section known as the ??Box Score? that shows the geodetic azimuths and distances to the reference and azimuth marks for the main station. Use these values to position the reference monuments. The azimuths and distances are from the main station.
in addition, these monuments participated in the NAD83(1986) adjustment and fitted t0 the subsequent state-by-state HARN surveys.?ÿ
Sadly, I haven't looked at a data sheet in quite a while but don't they also list state plane coordinates for the monument and/or accessories?
But is this a SPC job? He needs grid azimuth, which i think is problem.
I assume, perhaps unrealistically, that a licensed surveyor would know how to transform a geodetic to a plane azimuth especially since the convergence angle is on the data sheet. The data sheet even shows both!
Convergence angle and SF is given on the data sheet. If he has geo azimuth, I know I always have to double check if I added or subtracted correctly ?ÿ
And I hope he isn??t using the azimuths to the RMs for azimuth. I haven??t seen a Box Score lately on current data sheets.?ÿ
And the Q is: how did he get azimuth? If he is using the ??27 and ??83 discs, then he??s off in the woods.
imo it??s an azimuth problem.?ÿ
All... thanks for all of the responses. ?ÿI did use the geodetic azimuth??s in the box score for the NGS point. ?ÿI totally blanked on the convergence. ?ÿOnce Larry Scott mentioned it, I adjusted for convergence and everything matched up perfectly. ?ÿFor the record, the point I used was titled Asylum in New London County. ?ÿIt sits atop Jail Hill in Norwich, CT about 500?? more or less NW of City Hall. ?ÿThanks again to everybody.
And yes, I do know how to convert geodetic to state plane etc, but it was a classic case of staring at my problem too long and if it had been a snake it would have bitten me. ?ÿKind of feel a little bit silly, but hey, that??s why I asked. ?ÿSometimes a second set of eyes is all it takes.
I figured it was azimuth right off because I mostly use geodetic, and in Starnet that goes poorly right away. (There??s a geo-grid azimuth option setting.)
It??s either forgetting convergence or misinterpreting the (+) (-). Been there done that, got the tote bag.?ÿ
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I got into a recent discussion about a First order NGS point in the middle of a boundary I was doing.
It is one of those points in a convenient location in a County Road ROW so all you need to do is pull up and park next to it to occupy it. For that reason I've used it for a number of jobs. A young engineer working with us, doing some environmental and permitting work sent me an email that he sees that the coordinates I have for the point are about .5' off.
He was using the datasheet numbers and I was using 83/93 from DOT and the local HARN position which are about .1' from the recent NAD83 Epoch.
Trying to explain to him why my number was correct and the datasheet was not was a frustrating experience, not as bad when I tried to explain to them why the landowner calling the sheriff on their environmental guys digging holes in his field was correct and the county GIS lines were not and the guys with their little handhelds and their GIS lines could end up in jail.
(The RMs for the NGS (reset) are not an accurate source of azimuth.)
Interesting.?ÿ I just assumed the azimuth's given are geodetic.?ÿ Certainly worth checking
No matter how good the reference mark azimuths are, they are usually under 100 ft from the station, so not good to project 2000 ft.
