System1200 27 TPS1200 Setup Methods En

BU Surveying Surveying & Engineering Division

System 1200 Newsletter – No. 27 TPS1200 Setup Methods

THE TPS1200 SETUP APPLICATION

In order to setup a TPS1200 instrument it is nec-essary to use the Setup application program. This may seem obvious, but the Setup applica-tion offers more options and benefits than may be apparent at first sight - there are different methods and functionalities available for different situations.

This is the first of a series of three newsletters that deal with the Setup application. This news-letter looks at the overall concept and focuses on the different setup methods used.

The next newsletter will go into more detail about the resection methods and the different methods of adjustment used to calculate the instrument’s position and orientation.

A third newsletter will cover some related special topics, such as mixing TPS and GPS measure-ments and how Setup can best be used to over-come potential problems.

GETTING STARTED

The Setup application program can be accessed in different ways.

Either start it from the Programs menu (either press the PROG button or choose 2. PROG… from the main menu) or directly access it from the Begin panel of any application (e.g. Survey or Stakeout)– just press F3(SETUP).

If you access the Setup application program from the Programs menu then the SETUP Station Setup Begin panel is accessed. Here you can select the active job (see Newsletter 6) and this is also the job to where the result of the setup will be stored).

If you access the Setup application program from the Begin panel of another application then the active job is selected in that Begin panel.

Either way, the SETUP Station Setup panel will be accessed and here it is possible to choose the Fixpoint job, the Method as to how to setup the instrument and also to select the source of the Station Coordinates.

It is also possible to configure some specific functionality of the setup application – press shift F2(CONF) to access the SETUP Configu-ration panel.

THE SETUP CONFIGURATION PANEL

Most configuration settings are relevant for spe-cific setup methods. Only the settings in the General page view of the SETUP Configuration panel are described below. The settings in the other page views are referred to throughout this newsletter or in the following newsletters.

Two Faces: This option allows two face meas-urements to be made to target points. This ap-plies to all setup methods except the Set Azi-muth and Known BS methods which only allow measurements in one face.

Use Scale: Allows a scale to be to automatically derive from the differences between measured distances and distances calculated from the coordinates of the target points and the setup point. This scale factor can then be used to automatically correct all following distance measurements from the same station point.

Set Angle Right: Sets an Angle Right value of 0° to the backsight point when using the Known BS Point method. The Angle Right (AR) display mask element can be configured to be used in display masks and consequently displays the angle difference between the backsight point and the current direction. This angle is only used for



display and has no effect on the orientation or the actual azimuth.

Auto Position is an option for all motorised in-struments. Choosing On means that the instru-ment will automatically turn to the next target point after each measurement made in Resec-tion methods.

JOB AND FIXPOINT JOB?

As already mentioned, the active Job will al-ready have been selected in the application’s begin panel.

The Fixpoint Job can be any job, but is normally a different job from the active job and, as the name suggests, may only contain coordinates of fixpoints (this job could also be thought of as a “control-job”). During the setup process, target points are selected from the fixpoint job, but no measurements are stored to it. Whenever a tar-get point out of the fixpoint job is used in the Setup application this point is copied to the ac-tive job. In this way all relevant data is stored in a single job while the fixpoint job is only used as a source for point coordinates.

However, if you do not want to use this function-ality you can always choose the fixpoint job to be the same as the active job. In this way all data is always taken from and stored to the same job.

THE DIFFERENT METHODS

This section describes the options that are avail-able at the Method prompt. Depending on what is chosen determines what panels are subse-quently shown during the setup procedure.

SET AZIMUTH

This method can be used when the coordinates of the station point are known and the azimuth to a remote target point is known. Alternatively, an “arbitrary” azimuth can be entered (e.g. 0°) to a specific target.

During the setup process, the instrument needs to be pointed at the target point, the azimuth entered and the known azimuth to be entered.

KNOWN BS POINT

This is very similar to the Set Azimuth method. The difference is that instead of typing in a known azimuth, a target point with known coor-dinates must be selected from the Fixpoint job. The Azimuth between the station point and tar-get point is automatically calculated.

A distance measurement to the known backsight point can be made, but is not necessary. How-ever the advantage of measuring a distance is that the measured distance can be compared to the theoretical with the difference being shown. Similarly, the measured and theoretical height differences are compared.

These differences can be checked against user definable tolerances and a warning is displayed if these are exceeded (e.g. if by accident you measured to the wrong point or had selected the wrong prism type). The tolerances are defined in the SETUP Configuration panel Checks page view.

ORI & HEIGHT TRANSFER

This method is basically the same as Known Backsight method (setting up over a known points and aiming at a target point in order to orientate the instrument).

But unlike the Known BS Point that is restricted to a single target point, the Ori & Height Trans-fer method allows measurements to made of up to 10 target points. The target points may be full 3D points (easting, northing, and height) or 2D (easting, northing) or even height-only points.

Measurements can be used to calculate the ori-entation of the instrument or to just derive the height of the station point, or both.

Note, although measurements to multiple points are possible, it may still be useful to use this method with only one backsight point. Although this then serves the same purpose as the Known Backsight method it maybe useful as it then allows to make use of some configuration settings that are only available in the Ori & Height Transfer method - such as two face measurements or the calculation of a scale fac-tor.

This method maybe especially useful when working with SmartStation and you wish to im-prove the height coordinate of your station. First determine the coordinates of your station using the GPS SmartAntenna and then improve the height by measuring to a target point with known height coordinate nearby.

RESECTION

In this method the instrument can be setup virtu-ally wherever is needed provided that at least two target points with known coordinates can be measured.



Station coordinates as well as orientation are derived from measurements to up to ten target points using a least squares adjustment algo-rithm that calculates the best fit between meas-urements and target point coordinates.

Before storing the setup result, it is possible to analyse the residuals of the measurements to the target points and to remove (or use as posi-tion or height only target points) in order to im-prove the resection.

RESECTION HELMERT

This method looks and “feels” exactly the same as the “regular” Resection method – panels are identical. The difference is in the way the results are calculated. “Regular” Resection uses a least squares adjustment algorithm to find a best fit between the measurements and the coordi-nates of the target points.

Resection Helmert is very similar but uses a Helmert coordinate transformation that finds the best fit between the coordinates of the target points and the coordinates of the measured points.

The resection methods will be covered in more detail in the next newsletters.

LOCAL RESECTION

Local Resection is a quick method for establish-ing a local coordinate system.

Unlike all other previous methods, no points with known coordinates are needed (either for the setup point or target points). A local “coordinate system” is defined by measuring to the first point which is assigned the coordinates 0,0. A second point then needs to be measured – this point then defines the direction of either the northing or easting axis (as defined in the Setup configu-ration panel).

The coordinates of the station point are calcu-lated in relation to this local coordinate system.

WHERE DO STATION COORDINATES COME FROM?

Broadly the setup methods can be divided in two groups:

The resection methods (Resection, Helmert Resection and Local Resection) use meas-urements to target points with known coordinates in order to derive the coordinates of the station point.

For these methods it is necessary to enter a Station ID – this is then the ID which is given to the computed station point.

All other methods require that the coordinates of the station point are defined before the target point measurements.

The station coordinates can come from one of the following different sources

FROM JOB

Choose a point from the active job (active job and not the Fixpoint job) which was selected in the application or setup panel and in which all measurements are stored.

FROM FIXPOINT JOB

Choose a point from the Fixpoint job as defined in the station setup panel. Remember that you can choose the fixpoint job to be the same as the active job. In this case this behaves in the same way as “From Job”.

RETAIN CURRENT

The point ID and coordinates of the last setup are always stored in the instrument’s system



RAM. In this way the instrument always remem-bers the last used station coordinates, even if the memory card is removed or replaced. Choosing “Retain current” for the station coordinates sim-ply recalls the last station coordinates that were set on the instrument.

FROM GPS

This option is only available for SmartStation. The station coordinates can then simply and quickly be measured by means of the attached GPS SmartAntenna.

SUMMARY

Setting up a TPS1200 is simple.

The different ways of determining or choosing the station coordinates and orientation are com-bined in a single application program that can be accessed conveniently from the begin panel of any application program.

Simply choose the method that best serves the situation at hand.

Documents

System1200 27 TPS1200 Setup Methods En