What am I missing here?

so you measured the distance... how did you get the bearing?

...Is that then, not good enough to have established the accurate position of the PK nail in state plane??ÿ

Like Peter I do not see how you have a bearing from the BM to the PK. And not just any bearing would do, it would have to be a grid bearing.?ÿ?ÿ

What you are missing is a bearing.

Depending on the Bench Mark there my also be one or more nearby?ÿAzimuth Marks. One of those may be sufficient to establish a bearing to the Bench Mark. What is missing is basic information. Alternatively SPC could be established on your PK via GPS and an azimuth could be calculated if you had corresponding Convergence values for your coordinate positions.

It is hard to respond to a simple question with a simple answer if we do not know how much else you may or may not know.

Paul in PA

One point gives you a starting point and a elevation.?ÿ Second point gives you a bearing and elevation check. Third and possibly more points give you bearing and elevation verification (assuming they are on the same coordinate system).?ÿ

Gentlemen, thanks for the replies.?ÿ I knew upfront that I was asking a "dumb" question but I'm trying to reconcile a few things in my head about this particular scenario.?ÿ Full disclosure: I'll save the boring details but I have been in and out of the surveying world for a number of years (life happens, I'll leave it at that).?ÿ I don't have a formal surveying education but am now at a point in life where I'm finally able to focus full time on surveying and attempt to carve a career out of it.

Back to the question at hand:

So even though the position of the BM is known, a shot to the BM from the PK nail doesn't provide a bearing because there is nothing being backsighted to create an angle.?ÿ Is that correct??ÿ In that case, I would need to set another PK on the far side of the property and use it as a backsight and THEN turn to the BM, yes??ÿ Can I just assume a 5000,5000 value for my intial PK and after shooting everything in, do a conversion in the office (using CorpsCon, etc.) to then establish their position on state plane??ÿ

Thanks again for your help and patience.

Dday,

The problem here is the 'Basis of the Bearings'. State Plane Systems are each a unique mathematical 'grid'. They distort directions, distances and relative locations differently at every point on the grid.

Thats a long way of saying you have to properly determine a direction in that State Plane system to compute a coordinate. You also need to compute the distortion of the distance you measured before computing the new location.

This math isnt incredibly hard, but it takes an investment of time and effort to become competent and efficient with it. Send an email to my profile and I will reply with a PDF of a manual that may help you with this.

Good luck and Happy New Year, Tom

You must include at least two known points, or a known point and a known bearing among your measurements in order to establish new SPC coords on anything.?ÿ

If you use only a local coordinate system you can arbitrarily pick what you call "known."

As Bill said, you must locate 2 points with ?ÿstate plane. One will give will give you a pivot point the other a grid bearing. It's the same as translating and rotating on to a plat or local control, but don't forget the combined ground to grid factor.?ÿ

Where are you located at? Just wondering if your on a Lambert or Transverse Mecator

Why not perform an astronomic (Solar or Polaris) observation (occupy the SPC/BM, Backsight the PK, turn to the Star)?

Solve the astro, apply the LaPlace and SPC Convergency, and get a?ÿbeer.

Loyal

Depending on the distance and accuracy required you will also have to apply a scale factor to the total station distance. For most surveys today, the only reason to use State Plane is surveyors' habit, and clients that don't know better.

....So even though the position of the BM is known, a shot to the BM from the PK nail doesn't provide a bearing because there is nothing being backsighted to create an angle.?ÿ Is that correct??ÿ In that case, I would need to set another PK on the far side of the property and use it as a backsight and THEN turn to the BM, yes??ÿ Can I just assume a 5000,5000 value for my intial PK and after shooting everything in, do a conversion in the office (using CorpsCon, etc.) to then establish their position on state plane....

Let's leave the state plane stuff out of it. Suppose you have established a 5000/5000 local coordinate system. And you want to tie into somebody else's 5000/5000 local system in the next block.?ÿ ?ÿYou are going to have to tie at least 2 points in that other system to your system in order to accomplish a transformation, right??ÿ

First and foremost state plane is just a coordinate system.

"First and foremost state plane is just a coordinate system"

True!

BUT, it is a formally defined, geodetically based Mapping Projection, WITH well defined parameters (as are properly designed and documented Low Distortion Projections and UTM).

Unlike the 5k/5k "nail on a hill," North = who knows,?ÿ"local" tangent plane (maybe) "system."?ÿ

Just say'n

Loyal