Carlson Survey Coordinate Transformation Report - Translatio

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Carlson Survey Coordinate Transformation Report - Translatio

Postby JoeRoberts » Wed Dec 12, 2018 1:49 pm

Good morning,

One thing that I haven’t been able to nail down is what units are being represented in the report generated after performing a coordinate transformation (Helmert or Rigid Body) regarding the translation values. The scale and rotation units are straightforward, but I can not for the life of me figure out what translation units are being reported. We work within the metric system here in Canada and in New Brunswick we use NAD83 Double Stereographic NB.

We do a lot of coordinate transformations, and are required to keep detailed records so we can defend in court of law, or in an audit by the Association of New Brunswick Land Surveyors. I love the Carlson Survey coordinate transformation interface and the ability to perform a rigid body transformation (huge upgrade over the C&G function) for transforming to local survey evidence or between the older adjusted iteration of our control network and the more modern high precision control network.

I just can’t figure out what units are displayed in the report concerning the translation quantities. I also can’t figure out how to find the settings for any reporting (not just the coordinate transformation report) so that I can tailor them to our business’s needs. We switched to Carlson survey from C&G DOS about 5 years ago and I love the modern interfaces and Carlson commands over the C&G commands (despite how intuitive those are, being able to use Windows is nice, and frankly, more normal – the older gentleman around these office are still dragging their feet but, I digress). I’d like to be able to automate reports to become more efficient in our office procedures, and customizing these reports to automatically output what we need would be a time saver over the traditional “printer” files that we have been using since C&G DOS was introduced to our business years ago.

Are there any tutorials on reporting and customizing reports? I have searched the Carlson Manual but I’m not having much luck turning anything up. Any help would be greatly appreciated.


Thanks,


Joe
Joe Roberts
Geomatics Engineer
ANBLS S.I.T.
Kierstead Quigley and Roberts Ltd.
Saint John, NB
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Re: Carlson Survey Coordinate Transformation Report - Transl

Postby gskelhorn » Thu Jan 10, 2019 1:51 pm

Hi Joe,

A quick response about the rigid body transformation part of your question...

This is a three parameter transformation of one coordinate system onto another. That being said, the transformation parameters are related to the origin of the coordinate system. Since we typically solve the transformation parameters using a set of points with coordinate values much larger than the overall spatial extent of the point set, any rotation will cause the the solved translation values to be quite large.

The units of the translation parameters are the same as the units of your coordinates.

To maybe make it clearer, the expression for the transformation from src to dest coordinate spaces is:
E_dest = dE + E_src * cos(r) - N_src * sin(r)
N_dest = dN + E_src * sin(r) + N_src * cos(r)

so we are rotating the src coordinate system and translating to the src origin to the dest origin.
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Re: Carlson Survey Coordinate Transformation Report - Transl

Postby ocm3 » Thu Jan 06, 2022 5:04 pm

While the transformation expression is correct, and could also be expanded to include scale by adding the k value:
X = k X Cos θ – k Y Sin θ + Dx
Y = k X Sin θ + k Y Cos θ + Dy

The results of the Least Squares Local Transformation tool do not give the proper parameters that can be entered into the equations.
The results from the tool for Scale (k), Rotation (θ), Dx, and Dy are based on the first point in the Alignment Points list.

Likewise, if you use the Enter Transformation Parameters option and use the parameters obtained from the Least Squares tool, the Base North and Base East coordinates need to be the Destination Coordinates from the set of translation pairs.

It would be nice if Carlson would provide the correct parameters for the Transformation Equations to allow computations in other tools, e.g. Excel. Without knowing that first translation pair the parameters are not very useful.

Chuck
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