> The 1.7 degrees is mapping angle for the UTM system listed, and not the SPC. To find out SPC use a utility like corpscon or the online conversions on the NGS web site. The data sheet for the station probably has the SPC values too.
>
> I can probably help you if you want to send me an email maybe we can talk. I am up by Burlington, but might be able to help.
>
> - jerry
Thanks. Downloaded Corpscon and studying it. Don't see an email addy in your profile. You could send me one; I believe mine's in there.
>You could try using one scale for you whole traverse and your result may be decent but using a unique scale for each leg is the way it works by the book.
Thanks very much. The whole traverse comprises 400' difference in elevation, and 22 minutes of longitude. It's not that hard to enter a different scale factor for each leg, if I planned ahead and had them written down.
Scale factor also changes with Longitude, correct? Does that mean that the scale factor computed in Corpscon or other program is unique to each Lat/Long, taking known elevation into account? Is elevation more critical than Longitude? Or vice versa? If I can get Corpscon figured out, I could enter a dozen points along the traverse and see how the scale factor changes.
My first question is why? Why do you want to complicate your endeavor by working in State Plane or UTM on such a relatively small project area? Remember the intent behind the original development of the State Plane coordinate systems was to minimize distortion over long distances due to convergence. If your not working with GPS over considerable distances and your project is confined to a limited area, there is simply no reason to complicate things using Grid North and scale factors. If you were running and ten mile long traverse along a latitudinal arc, I could understand the need. The main advantage to using a State Plane or UTM projection is to be able to relate latitude and longitude to a Cartesian coordinate system while keeping the distortion to a minimum. On a 25 acre survey, the advantages are just not there. For all intents and purposes, your project area is as flat as piddle on a plate. 😉
Just because I'm paranoid, doesn't mean they aren't out to get me.
This is a good reason to book your shots. Don't try to field enter scale factors. If you book it you can play with the data in s variety of ways.
In general elevation matters more. It depends what kind of projection your coordinate system is to tell if latitude matters more than longitude. No change in lat has minimal effect of scale in lambert. Same with long in transverse Mercator.
> This is a good reason to book your shots. Don't try to field enter scale factors. If you book it you can play with the data in s variety of ways.
OK, so what I'm hearing is to not mess with this at all prior to the field work:
And then, just do it later (like when the snow starts flying).
:good:
Just because I'm paranoid, doesn't mean they aren't out to get me.
> My first question is why? Why do you want to complicate your endeavor by working in State Plane or UTM on such a relatively small project area?
My first thought was: I want to learn how to do it.
but after reading this entire thread again....I'm convinced. It's going to get in the way of the other stuff I'm learning. So for my forthcoming on property traverse(s), I'll just start at N1000, E1000 and Z1000, book all the angles and distances and leave it at that for now.
Have to admit though, the the thought of trying a 2 mile traverse was intriguing. Maybe I'll put it on the schedule for next spring. I want to get what I'm doing now done before the snow falls.
Thanks for all the input.
> So would you say that the survey done in 2013, calling out a "-0°03'" convergence angle, that he was just rounding, or could 27" of convergence be due to the difference in Longitude between the BM and the site (72°35'6", compared to 72°33'56"). I downloaded Corpscon but haven't figured out how to use it. Put it on the list.
The convergence angle for the control point described on the data sheet Loyal posted is -0°02' 43.5". So somewhere between there and your property the convergence angle is -0°03' exactly. >
> Lacking any better azimuth information, would it be safe just to use his measured angle?
Safe, yes.
Sadly, there are quite too many Professional Surveyors who don't know how to handle this.
Do Not Put A Grid Factor In For Practice Work
Do everything at 1.00000000 scale and adjust later. Once you are accomplished you may use a grid factor, if you risk it. But it is best to always do certain field work the same way so you someday do not have to wonder how you did it.
In any case that factor is only good at the point of the mark and not everywhere on your project.
Paul in PA
Also, How Many State Highway Compliant Cones Do You Have?
18"ers do not cut it.
Also you may have to comply with vehicle rules along the right of way.
Paul in PA
Not 1000, 1000, 1000
You wan your starting coordinates large enough to never go negative.
Paul in PA
Not 1000, 1000, 1000
5000
1000
100
Is my preferred one on small construction jobs. No confusion between xyz.
This ain't Texas!
Looked at in Google-super and I mean super easy traverse.
>22 minutes of longitude
Do you mean 22 seconds? Sounded like your project did not cover many miles.
Not 1000, 1000, 1000
> 5000
> 1000
> 100
>
> Is my preferred one on small construction jobs. No confusion between xyz.
That's an interesting idea, as is Paul's about choosing numbers that won't go negative.
I've got at least 2000' of Easting to cover, only about 1000, and the POB IS almost exactly 1000, which I'd like to keep to at least check elevation without too much math in the field. If there's no problem with the number of digits, I could use N5000, E10000, and Z1000.
> Sadly, there are quite too many Professional Surveyors who don't know how to handle this.
Long traverses, or tying to State Plane Grids?
I know The old timers certainly knew how to do traverses (with unbelievable results).
But your comment gave me a thought: I still want to learn it, and the need to is apparent for long traverses (which came up as a side issue in this thread regarding starting with good horizontal control).
Traversing such a distance (for the first time)from a known point to my project won't really do me much good (as a learning experience) because I won't know how good I did...I mean the pin I'm going to is not tied to anything much.
But what if I find TWO Benchmarks, both of excellent quality, perhaps both even accessible in the winter, and both with known State Plane Grid coordinates, a few miles apart? Other than the marks themselves, I don't even need to see the dirt...I'd be using prisms on tripods.
Traversing between them would likely tell me how good I did, would it not? I won't kid myself about possible results. This won't be any Yolo Baseline for sure, but it might be a start.:-)
5000, 5000, 1000 OR 10000, 10000, 1000
Using different starting N&E was useful in the days of handwritten coordinates due to coordinate swapping. but not really a problem with data collectors.
Paul in PA
5000, 5000, 1000 OR 10000, 10000, 1000
A new engineer on the project provides a point to stake out. He uses a different format then what the survey tech is used to, in the original project control design, which point range choice would be safer?
Point to stake
1020 1050 100
Or
5020 1050 100