Topic: assumed coords to S.P.C.S.

[MSTG007]

Does anyone have a convertor which will take your assumed coordinates to state plane?

No luck finding one.

Thanks!

[Dent Cermak]

It doesn't work that way. You are wanting to take your N10,000 E10,000 system to a State Plane coordinate system. The converter is called a solar observation. Or GPS observation on TWO points in your survey or run from a known point on the State Plane coordinate system through two of your survey points in a closed loop traverse. Remember, you have to set State Plane Coordinates on TWO points to be on grid North. You cannot take of of ONE point and run a turned angle or azimuth and necessarily be on State Plane(that takes you off "Grid North" and puts you then on "Magnetic North". )Setting TWO points sets grid bearing.
You cannot convert. You CAN tie. We have gotten in the habit of using State Plane on most all projects. Makes it easier to put different projects together and now we have solid control points all over the place.



AFTERTHOUGHT: If someone asked you to find such conversion software, they are messing with you and are not to be trusted. If you came up with this idea on your own, don't tell anybody. 

[mjfarrell]

IF you can get me the KNOWN coordinates for the assumed control points
then it might be possible to do this.  Otherwise you are lost in space, so to speak.

[Dent Cermak]

Sure. Once the points are tied to the State Plane Coordinate System, moving everything is a 2 second operation.There just isn't any software that can provide, "Guess where I am and provide me with the correct State Plane Coordinates."

[MSTG007]

Dent, Guys

I Know its been awhile, But i do have SPCS system setup in my office. We use a set of control called HARN points. which the state regulates for IN. But now all our projects (new ones) are on SPCS and most the counties want them on it so they can drop it in there GIS.

Again. Anyone know how to use MAP???

thxs

[Dinosaur]

I have the similar chore in Kansas City.  So far, I have found no easy way to do this as these coordinates must also be in metric units.  For now we do it manually by copying our boundary with a known grid coordinate and converting it with the local scaling factor determined by our surveyor and then scale it down to metric.  We then just list the coordinates from this boundary and place a table on the plat.  This me hod is tedious at best, but it does yield the required results.

With Civil 3D, there appears to be a way to keep two coordinate systems for a project, but I am uncertain if this would work with one in feet and the other in metric.  I have  been forbidden to try this at work and while this has not stopped my in the past, but having also been cautioned against it by someone I respect, it remains untested.

[Dent Cermak]

This does not have to be done in MAP. You can use SPCS in LDD all day long. if your control is in meters all you need is a copy CORPSCOM a freeware program that will convert the SPCS metric values to feet quite handily. Then you will need at least 2 ponts in your drawing that have known SPCS values, either run in, GPS'ed or published. It's then a simple matter of moving the points to your state plane coordinates.
I do this everyday. We run GPS to all of our projects now and base our jobs on those points. If you cannot find CORPSCON send me a PM or email and I will send the *.exe file back to your email address.

Just dawned on me a link might help. DUH!!


http://crunch.tec.army.mil/software/corpscon/corpscon.html

[sinc]

You cannot convert. You CAN tie. We have gotten in the habit of using State Plane on most all projects. Makes it easier to put different projects together and now we have solid control points all over the place.

It's a little hard to tell from your posts, but I hope you are not designing projects in SPC....

You *ARE* using Project Coordinates, right?  They're just very close to SPC?  In other words, Project Coordinates * Project Scale Factor = SPC, right?

We recently got a project that was designed in SPC instead of project coordinates, and it caused some issues.  I believe that the REAL length of the 2-mile project was 0.7 feet longer than the plans indicated (or was it shorter? - I forget).  Once we figured out what was up, we were able to deal with it, but it meant none of the distances or quantities in the plans were quite in tune with reality...

[Dent Cermak]

Our clients and equipment require that a scale factor be applied to all projects. State plane coordinates are obtained fron GPS observation and the approprite scale factors are applied to each field book file. I've been doing this for 40 years now and have always used scale factors and/or combined factors in my work.
Usually the distances will be shorter because most areas have a scale factor of 0.9999*****. i have seen some areas where it's 1.******** though, but that's  outside the US generally.

[Swift]

Scale factor is a result of the map projection used. Each state has it's own projection(s) so that the data 'fits' the states terrain.

[Dent Cermak]

Yep, scale factor is a result of earth curvature. CORPSCON is an excellant source for the scale factor of your site. The Combined Factor is computed from the scale factor and the Z (elevation) variable for the site. We just had a job messed up because someone applied the combined factor for the site in LDD instead of the requested scale factor. An easy fix, bit very aggrivating if you are DEEP into the project.

[sinc]

We aren't sure what happened with the project we got.  They might have done the design survey with GPS and collected state plane coordinates without ever converting them to project coordinates.  Or they might have converted the design survey to state plane in order to combine it with other drawings, and then accidentally done all their engineering with the state plane version.  Or maybe they screwed it up some other way, like using the scale factor improperly in their GPS equipment.  Who knows.

We asked the engineer, and got the response "The project was designed in State Plane Coordinates.  Multiply all coordinates by <whatever it was> to get ground coordinates."  This also meant, of course, that all the distances on the plans were slightly wrong.   :ugly:

It was just a sewer line, though, so it wasn't a major headache.  More of an amusement.