Carlson SurvPC7: How to set up a new job with a combined factor

[OleManRiver]

I wish I could help. I don’t have much experience with Carlson. I know they have a few different ways of dealing with combined factors. I guess what puzzles me is why if the have the datum information and the projection loaded into the system would you have to type in a factor at all. I mean if you tell it you are on nad 83 spc and zone whatever and have either a lat long ellipsoid height or a northing easting and elevation along with a geoid model it in theory should have everything it needs to reduce your ground distance to the grid. Now if you are running in 2d mode not carrying elevations then I could see the reason to input the combined factor. To do the reductions. Hopefully this will give you a bump for some of the more experienced Carlson users. I will be at a meeting this coming week and I know a guy that runs Carlson on grid with his total station and I will try and get you some information.

[shawn-billings]

I’m confused by the question.

If you are using State Plane Coordinates, then using the localization route will automatically scale measured distances from the total station by the either the user defined scale factor or by the computed scale factor of the occupation point (note this requires that elevations be valid for the computation to be correct). When using inverse, the grid distance is shown and the scaled horizontal surface distance is also given.

If you are using a custom projection, there should be no need to use a scale factor because the scale is handled by the design of the projection (provided that the projection has been designed to be “low-distortion” for the work area). The combined factor for points in a “low-distortion” projection will differ from 1 by such a small amount as to be negligible in most surveying applications.

I’m making assumptions here, and your case may fall outside of these two scenarios (1. working in true State Plane and using the localization/TS routine to scale measurements to grid for coordinate calculation and 2. working in a Low-Distortion custom projection). If you are working outside of those two, can you give more details? It might make it easier to make a recommendation.

[kjypls]

Shawn and OleManRiver, Thanks for the thoughtful replies.

I apologize for the confusion I may have caused by not explaining myself clearly. The job is not “run on grid”. It is essentially a localized project tied to grid via a pair of GPS points. All distances for the project are scaled by the combined factor determined by the pair of GPS points established for the project.

[rover83]

The job is not “run on grid”. It is essentially a localized project tied to grid via a pair of GPS points. All distances for the project are scaled by the combined factor determined by the pair of GPS points established for the project.

I think we need more information here

Is the project in ground (GNSS observations/points are scaled to ground) or is the project in grid (conventional observations are scaled to a defined projection)?

How is the orientation determined? Arbitrary azimuth between the point pair? Or an observed grid bearing from a specific projection (GNSS-derived)?

---

“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman

[kjypls]

The project map/description is representative of grid distances; conventional distance observations are scaled to the combined factor.

and,

The azimuth is GNSS derived; the bearings for the project are related to the pair of points established for the project.

• This reply was modified 5 months, 2 weeks ago by  kjypls.