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Uploading/Downloading using a Leica data recorder

Communications for the Leica TPS1100 instrument

The communications for the TPS1100 instrument are made using the Leica GeoCOM communications interface. Communications for the GRE3, GRE4, GIF10 and TPS1000 are made directly and do not use GeoCOM. The communications for all the instruments are described in detail below.

Communications Settings on the Computer

For the GRE3 and GRE4 data recorders use the following parameters set via the Data Recorders Configuration function described previously.

I/O Port : user selectable
Baud Rate : 2400
Parity : even
Data Bits : 7
Stop Bits : 1
Flow Control : software
Timeout : 5

For the GIF10 and TPS1000 data recorders use the following parameters set via the Data Recorders Configuration function described previously.

I/O Port : user selectable
Baud Rate : 9600
Parity : none
Data Bits : 8
Stop Bits : 1
Flow Control : software
Timeout : 5

For the TPS1100 data recorder use the following parameters set via the Data Recorders Configuration function described previously.

I/O Port : user selectable
Baud Rate : 9600

For the TPS1100 the recommended Baud Rate is 9600. But the interface also supports the following Baud Rates: 2400, 4800, 19200 or 38400. The Parity, Data Bits, Stop Bits, Flow Control and Timeout parameters are not used by the TPS1100 interface and so are not important.

Communications Settings on the Instrument

The required communications settings for the GRE3 and GRE4 are as follows:

Baud rate: 2400
Parity : even
Protocol : ACK/NACK
Last characters of data block : CR/LF
Last characters after ACK/NACK : ACK/NACK

Set these parameters using the following instructions.

1. Set baud rate of 2400bps by entering: SET MODE 70 RUN 2400 RUN RUN
2. Set even parity by entering: SET MODE 71 RUN 2 RUN RUN
3. Set ACK/NACK protocol by entering: SET MODE 72 RUN 1 RUN RUN
4. Set last data block characters by entering: SET MODE 73 RUN 1 RUN RUN
5. Set ACK/NACK characters by entering: SET MODE 74 RUN 1 RUN RUN

The required communications settings for the GIF10 are as follows:

Baud : 9600
Parity : none
Comm Protocol : ACK/NACK
Comm Stopbit : 1
Comm EndMark : CR/LF
Comm Connected as : DCE
Flow Control : software

To set these parameters select the COMM menu and press the Run button. Scroll through the COMM menu using the left/right arrows and select values using the up/down arrows. When you have selected the appropriate values press the Run button to return to the main menu.

The required communications settings for the TPS1000 are as follows:

Baud Rate : 9600
Protocol : None
Parity : none
Terminator : CR/LF
Data Bits : 8
Stop bit : 1

The following instructions describe how to set these communications settings.

1. Press the F3 key from the main menu to select CONF.
2. Select GSI communications param with the cursor arrow keys and press the Enter key.
3. Scroll through the Communications menu using the left/right arrows and select values using the F6 LIST key.
4. When you have selected the appropriate values press the CONT button to return to the main menu.

For the TPS1100, the settings are controlled automatically by Surpac via the GeoCOM interface. So you do not have to change any settings yourself on the instrument.

Downloading Data from the Instrument

To download data from a GRE3 or GRE4 follow the instructions below:

1. Ready the software to receive the data as described in Data Recorders Down Load To File
2. Press DATA GOTO 1 RUN SEND RUN
3. Press APPLY in the software to accept the data

The GIF10 responds to remote commands from the computer. There are no required actions on the GIF10 to initiate a download. The download process is controlled from the software. You only need to enter the job number in the software to download it.

To download data from a TPS1000 follow the instructions below:

1. Ready the software to receive the data as described in Data Recorders Down Load To File
2. Select Send and Receive GSI data from the main menu and press the Enter key.
3. Press the shift key followed by the F2 key to select CONF.
4. The Configuration screen is now displayed. Make sure the following settings are active.

Send Proto : ACK/NACK
Recv Proto : ACK/NACK
End Transf : ETX
Time delay : 10 msec

5. Press the CONT key to continue
6. Select the job you wish to download by pressing the F6 LIST key. Highlight the job you want to download using the arrow keys and then press Enter
7. Press the F3 SEND key to initiate the data transfer
8. Press APPLY in the software to accept the data

For the TPS1100 instrument you have two choices when downloading data. You can either turn the instrument off and let Surpac (via the GeoCOM interface) automatically prepare the instrument (this is the recommended option). Or you can leave the instrument on and prepare it yourself by putting it in GeoCOM On-Line mode. These two options are described in detail below.

To download data from a TPS1100 with the instrument turned off follow the instructions below:

1. Ready the software to receive the data as described in Data Recorders Down Load To File. On the LeicaTPS1100 Data Recorder form, fill in the Job/Area name field with the name of the file on the instrument that you want to download, but leave off the .GSI extension. For example, if you want to download "work.gsi" from the instrument then enter "work" in the Job/Area name field. Then press APPLY in the software to receive the data. No other action is required. Surpac will automatically turn the instrument on and put it into GeoCOM On-Line mode and download the data.
2. When the data has been downloaded the instrument will be left in GeoCOM On-Line mode. Press the EXIT (F6) key to leave GeoCOM On-Line mode and continue using the instrument.

To download data from a TPS1100 with the instrument turned on follow the instructions below:

1. If the instrument is already switched on you must put it into GeoCOM On-Line mode yourself before doing the download. If the instrument is on but not in GeoCOM On-Line mode the download will not work. To go into GeoCOM On-Line mode do the following:
   1. In the Main menu choose option 5 "Configuration".
   2. In the Configuration menu choose option 2 "Communication mode".
   3. In the Communication mode menu choose option 3 "GeoCOM On-Line mode".
   4. You will then be asked if you want to switch to GeoCOM On-Line mode. Press the YES (F4) button. This will display a message on the instrument saying that GeoCOM On-Line mode is now active.
2. Now ready the software to receive the data as described in Data Recorders Down Load To File. On the LeicaTPS1100 Data Recorder form, fill in the Job/Area name field with the name of the file on the instrument that you want to download, but leave off the .GSI extension. For example, if you want to download "work.gsi" from the instrument then enter "work" in the Job/Area name field. Then press APPLY in the software to receive the data.
3. When the data has been downloaded the instrument will be left in GeoCOM On-Line mode. Press the EXIT (F6) key to leave GeoCOM On-Line mode and continue using the instrument.

Note: While downloading data from a TPS1100 instrument, if a GeoCOM message box is displayed saying "Unable to find a GeoCOM device at the common settings. Do you wish to try all possible settings?", select the "no" button. The most likely reason for this error is that you have attached the instrument cable to the wrong I/O Port of the computer (eg com1 instead of com2). The I/O Port may be checked via the Data Recorders Configuration function described previously. Other possibilities include:

• The instrument is switched on but not in "GeoCOM On-Line mode".
• The instrument is in RCS mode.
• If the machine is set up so that at 'power on' the levelling screen is displayed, this problem may also occur.

If any of these cases occur you are advised to manually put the instrument in "GeoCOM On-Line mode". See above for instructions on how to do this.

Uploading Setout Points to the Instrument

To upload data to a GRE3 or GRE4 make sure the instrument is displaying the RDY symbol in the instruments status window. Next process your point data ready for uploading as described in Data Recorders Upload Coordinates and then press apply in the software.

The GIF10 responds to remote commands from the computer. There are no required actions on the GIF10 to initiate an upload. The upload process is controlled from the software. You only need to enter the job number to which you want to load the data via the software.

If you wish to load the data into a new job area in the GIF10 then you must create the job on the data recorder before you can load data into it. Do this with the CREATE menu option on the GIF10.

To upload data to a TPS1000 follow the instructions below:

1. Process your point data ready for uploading as described in Data Recorders Upload Coordinates
2. Select Send and Receive GSI data from the main menu and press the Enter key.
3. Press the shift key followed by the F2 key to select CONF.
4. The Configuration screen is now displayed. Make sure the following settings are active.

Send Proto : ACK/NACK
Recv Proto : ACK/NACK
End Transf : ETX
Time delay : 10 msec

5. Press the CONT key to continue
6. Select the job area that you wish to upload into by pressing the F6 LIST key. Highlight the job you want using the arrow keys and then press Enter
7. Press the F5 RECEIVE key to ready the instrument to receive data
8. Press APPLY in the software to accept the data

For the TPS1100 instrument you have two choices when uploading data. You can either turn the instrument off and let Surpac (via the GeoCOM interface) automatically prepare the instrument (this is the recommended option). Or you can leave the instrument on and prepare it yourself by putting it in GeoCOM On-Line mode. These two options are described in detail below.

To upload data to a TPS1100 with the instrument turned off follow the instructions below:

1. Ready the software to send the data as described in Data Recorders Upload Coordinates. On the LeicaTPS1100 Data Recorder form, fill in the Job/Area name field with the name of the file on the instrument that you want to upload to, but leave off the .GSI extension. For example, if you want to upload to "work.gsi" on the instrument then enter "work" in the Job/Area name field. Then press APPLY in the software to receive the data. No other action is required. Surpac will automatically turn the instrument on and put it into GeoCOM On-Line mode and upload the data.
2. When the data has been uploaded the instrument will be left in GeoCOM On-Line mode. Press the EXIT (F6) key to leave GeoCOM On-Line mode and continue using the instrument.

To upload data to a TPS1100 with the instrument turned on follow the instructions below:

1. If the instrument is already switched on you must put it into GeoCOM On-Line mode yourself before doing the upload. If the instrument is on but not in GeoCOM On-Line mode the upload will not work. To go into GeoCOM On-Line mode do the following:
   1. In the Main menu choose option 5 "Configuration".
   2. In the Configuration menu choose option 2 "Communication mode".
   3. In the Communication mode menu choose option 3 "GeoCOM On-Line mode".
   4. You will then be asked if you want to switch to GeoCOM On-Line mode. Press the YES (F4) button. This will display a message on the instrument saying that GeoCOM On-Line mode is now active.
2. Now ready the software to send the data as described in Data Recorders Upload Coordinates. On the LeicaTPS1100 Data Recorder form, fill in the Job/Area name field with the name of the file on the instrument that you want to upload to, but leave off the .GSI extension. For example, if you want to upload to "work.gsi" on the instrument then enter "work" in the Job/Area name field. Then press APPLY in the software to send the data.
3. When the data has been uploaded the instrument will be left in GeoCOM On-Line mode. Press the EXIT (F6) key to leave GeoCOM On-Line mode and continue using the instrument.

Note: While uploading data from a TPS1100 instrument, if a GeoCOM message box is displayed saying "Unable to find a GeoCOM device at the common settings. Do you wish to try all possible settings?", select the "no" button. The most likely reason for this error is that you have attached the instrument cable to the wrong I/O Port of the computer (eg com1 instead of com2). The I/O Port may be checked via the Data Recorders Configuration function described previously. Other possibilities include:

• The instrument is switched on but not in "GeoCOM On-Line mode".
• The instrument is in RCS mode.
• If the machine is set up so that at 'power on' the levelling screen is displayed, this problem may also occur.

If any of these cases occur you are advised to manually put the instrument in "GeoCOM On-Line mode". See above for instructions on how to do this.

Data Format Notes

Leica data recorders have code blocks and measurement blocks and with alpha capabilities for all but the GRE3 data recorder. Apart from the lack of alpha capabilities, the GRE3, GRE4 and GIF10 formats are identical. The TPS1000, TPS1100 format is identical in style with the difference being that the fields for recording data items are 16 characters long instead of the 8 characters in the GRE3, GRE4 and GIF10.

To store the relevant information in the data recorder it is necessary to use a numerical coding system.

To indicate the start of a job a code block with a code value of 0 is used.

To store the reference station number (no alpha capabilities) a code block with a code value of 1 is used. The second code word in the record contains the number of the backsight station. The next record in the data recorder must be a measurement line with the reference angle to the backsight. If this is not the case then you are prompted to enter the reference angle (default of 0.0000).

To store the instrument station number a code block with a code value of 2 is used. The second code word contains the station number and the third code word contains the height of instrument axis in millimetres since it is not possible to enter a decimal point.

Target height is stored using a first code block with a value of 3. The second code block contains the target height in millimetres. Every time target height changes this sequence should be entered.

To indicate the start of a string a code block with a code value of 4 is used. The second code word in the record contains the string number.

The measurement block contains, a point number, horizontal angle, vertical angle and slope distance in that order. The measurement block may also contain XYZ co-ordinates which will be saved to the string file if they are present. The co-ordinates are scaled down by 1000 as the values are stored to the millimetre in the data recorder file. If a measurement block contains angles, distances and co-ordinates, the co-ordinates will be discarded and the raw observations will be used to calculate the co-ordinates of the points.

Code blocks and measurement blocks may be interspersed in any order in the data collector. It is your responsibility to make sure that the data recorded is in a logical and orderly fashion for further processing.

A typical GRE3, GRE4, GIF10 file follows:

410001+00000000                                     <-- start of job
410002+00000001 42....+00000092                     <-- backsight station
110003+00000092 21.102+35955400 22.102+09124010  31..00+00000000  <-- reference station
410004+00000002 42....+00000091 43....+00001530     <-- setup station and height of instrument
410005+00000003 42....+00001470                     <-- target height
410006+00000004 42....+00000001                     <-- string number
110006+00000092 21.102+35959540 22.102+09140000 31..00+00836682   <--measurement
410004+00000007 42....+00001234 43....-00005678 44....+00009012
110006+00000092 21.102+35959540 22.102+09140000 31..00+00836682 51....+0030+000

A typical TPS1000, TPS1100 extended format file follows. The "*" character in column 1 defines that the data is in the extended 16 byte format. Note that leading zeros are stripped from all point identifiers.

*410001+0000000000000000                                     <-- start of job *410002+0000000000000001 42....+0000000000000092             <-- backsight station *110003+0000000000000092 21.102+0000000035955400 22.102+0000000009124010  31..00+0000000000000000  <-- reference station *410004+0000000000000002 42....+0000000000000091 43....+0000000000001530     <-- setup station and height of instrument *410005+0000000000000003 42....+0000000000001470              <---- target height *410006+0000000000000004 42....+0000000000000001              <-- string number *110001+00000000000000B1 84..10+0000000012312120 85..10+0000000000000000 86..10+0000000000000000 87..10+0000000000001300 88..10+0000000000001234 79....+00000000000000B2 *110002+00000000000000B2 21.024+0000000035959560 22.024+0000000008209220 31..00+0000000000000000 51..1.+000000000000+000 81..00+0000000000000000 82..00+0000000000000000 83..00+0000000000000000 87..10+0000000000001300 *410003+0000000000000555 
*110004+0000000000000001 21.024+0000000004152590 22.024+0000000008153450 31..00+0000000000009217 51..1.+000000000000+000 81..00+0000000000006092 82..00+0000000000006793 83..00+0000000000001233 87..10+0000000000001300 
*110005+0000000000000002 21.024+0000000004153010 22.024+0000000008153450 31..00+0000000000009216 51..1.+000000000000+000 81..00+0000000000006092 82..00+0000000000006793 83..00+0000000000001233 87..10+0000000000001300 
*110006+0000000000000003 21.024+0000000004153020 22.024+0000000008153450 31..00+0000000000009216 51..1.+000000000000+000 81..00+0000000000006091 82..00+0000000000006793 83..00+0000000000001233 87..10+0000000000001300 

All the special coding features described here can be used by all Leica data recorders, even the extended format. Examples of the GRE3 format only are shown however.

Point Descriptions

The values for the point descriptions in the string file that is created from an input file are obtained by concatenating the value from the point number field (word index 11) and the values from any REM words (word indices 71 to 79 inclusive) and separating the individual values with commas. All items that are used in the construction of the point description have leading zeros removed.

110006+00000092 21.102+35959540 22.102+09140000 31..00+00836682 51....+0030+000 71....+0000post

The observation line shown above will create a point description that is post,93 in the string file. The value 92 is obtained from the first item on the line, the point number, and the value post is obtained from the last item. The point number is always placed after the last description field value obtained from the available REM words.

Offset Codes

The offsets are defined by a code block with the offset information which the next observation that follows this code block will use. The offset data are then `forgotten'. This means that you MUST define and record offset information before you record the observations to the point.

Shown below are 2 lines from a data recorder file. The first line is the code block that contains the offset data and the second line is the observation to which the offsets apply.

410004+00000007 42....+00001234 43....-00005678 44....+00009012
110006+00000092 21.102+35959540 22.102+09140000 31..00+00836682 51....+0030+000

The code block consists of a number of parts and these are explained below.

410004+00000007 = code value 7 for offsets 42....+00001234 = perpendicular offset + to the right - to the left
43....-00005678 = distance offset + for longer - for shorter
44....+00009012 = vertical offset + for higher - for lower

If any of the perpendicular, distance or vertical offsets are missing they are assumed to be zero.

Single Face Pointings To New Stations

Surveyed points may be stored as new stations in the survey database. To identify a surveyed point as a new station use the following code. Precede the observation to the new station with a code block. The first word in the code block must have a value of 5 to indicate that a new control station observation follows. The ID of the new station is taken from the point number field and leading zeros are removed before using it as the station ID.

If you are surveying a new station underground and want to store the height from the floor to the target, enter the height in millimetres as the second code word following the first code word of 5 in the code block preceding the observation. For example,

410006+00000005 42....+00002537
110006+00001236 21.102+35959540 22.102+09140000 31..00+00836682

You are given some options regarding the creation of the new station. This is done via the Options for New Station form, see here for more details.

Use of station errors table: If a station errors table exists in the survey database, information regarding the order of the new station may be displayed. See here for more details.

Multiple Face Pointings To New Stations

The Leica data recorders support multiple face pointings to a new foresight station. This is when a number of angles and distances to a backsight and foresight station are read and the mean value is used to determine the coordinates of the new station. Before multiple face pointings can be read the backsight/setup stations must be identified and the instrument/target heights must be specified. To indicate that multiple face pointings have commenced, a code block with a value of 20 in the first code word must be stored. The number of the new station MUST be in the second word of the code block. Leading zeros are removed from the station number before it is used as the station ID. To indicate multiple face pointings are finished, a code block with a code value of 21 must be stored.

If you are surveying a new station underground and want to store the height from the floor to the target, enter the height in millimetres as the third code word following the new station number in the second code word of the code block with a value of `20' in the first code word.

On reading the end of multiple face observations code the angles and distances observed will be meaned, the coordinates of the new station will be stored and the results will be written to a `.txt' file with the location and ID the same as the `.obs' file which is being created.

Between the 2 code blocks previously mentioned, measurement blocks MUST exist in pairs. The first measurement block in a pair MUST be an observation to the defined backsight station and the second measurement block MUST be an observation to the new foresight station. The turned angles are calculated and totalled and then meaned when all observations have been found. It is not necessary to measurement a distance on each observation to the new station as any distance of ZERO will not be included in the mean distance.

You are given some options regarding the creation of the new station. This is done via the Options for New Station form, see here for more details.

Below is a brief example of some multiface observations:

410001+00000000                   <-- start of job code 410002+00000001 42....+00000092   <-- backsight
110003+00000092 21.102+35959540 22.102+09124010 31..00+00000000  <-- ref angle to backsight
410004+00000002 42....+00000091 43....-00001720   <-- Inst and HI
410005+00000003 42....-00000000                   <-- Target height
410006+00000004 42....+00000001                   <-- String number
410006+00000020 42....+00001111 43.....00002537   <-- Height to floor & new station 1111
110006+00000100 21.102+25217440 22.102+09122020 31..00+00000000  <-- BS observation
110006+00000100 21.102+01424380 22.102+08749240 31..00+00036535  <-- FS Observation
110920+00000102 21.104+05442000 22.104+08938300 31..00+00000000  <-- BS observation
110920+00000102 21.104+17649050 22.104+27210420 31..00+00000000  <-- FS observation
410006+00000021                   <-- End multi-face

Below is the report which is produced from the above observations by using the LEICA GRE3 function.

Use of station errors table: If a station errors table exists in the survey database, information regarding the order of the new station may be displayed. See here for more details.

Drill Hole Surveys By Extended Rod Method

The GRE3 data collector supports codes for the observation of drill holes using the EXTENDED ROD METHOD. The surveyor observes two points on a rod which protrudes from a drill hole. The first observed point MUST be closest to the hole collar. The distance of the first observed point from the collar (along the rod), the distance between the two observed points (along the rod), the dip of the rod (measured by clinometer) and the hole ID are items which must be stored in the data collector along with the observations to the two points on the rod.

The dip of the rod and the distance between the 2 points are included as check measurements and have no effect on the results of the calculations. The distance from the first point to the hole collar is essential as it is used to determine the collar position in case the first observed point is offset from the collar position.

Below is an example of observations on a drill hole using this method.

410001+00000000                   <-- start of job 410002+00000001 42....+00000092   <-- backsight station
110003+00000092 21.102+35959540 22.102+09124010 31..00+00000000   <-- ref angle to backsight
410004+00000002 42....+00000091 43....-00001720     <-- Instrument and HI
410005+00000003 42....-00000000                     <-- Target height must be 0
410006+00000004 42....+00000001                     <-- String number
410006+00000006 42....+00002020 43....+00001400 44....-00006000   <-- Drill hole code
110006+00000100 21.102+10157570 22.102+09122020 31..00+00010908   <-- First rod point
110006+00000100 21.102+10357560 22.102+08514390 31..00+00011529   <-- second rod point

As the points are typically observed on the rod the Height of Target should be zero to give the correct results. A drill hole survey is indicated by a code block with a code value of 6. Code word 1= Distance from hole collar to first observed point. Measured along the rod and entered in millimetres. Code word 2= Distance between the 2 observed points on the rod. Measured along the rod and entered in millimetres. Code word 3= Dip of the rod. Measured by clinometer and entered as DDDMM. Where DDD are degrees and MM are minutes. The hole ID MUST be in the point number field of the observations.

Below is an example of the report produced from the above survey. This report in a `.htm' file format. You can select the format of the report file (htm, rtf, not, csv).

Backsight Station Check

When processing the input file the system may be forced to perform a check on the quality of the backsight station that has been identified in the input file. The backsight station check is very useful in underground surveying applications as confusion regarding station marks and station identification is much easier than for surface surveying.

Normally the backsight station is identified by 2 lines in the input file. These lines identify the name of the backsight station in a code block and the orientation of the horizontal circle to the backsight station in a measurement block. The table below shows two lines that demonstrate this.

410002+00000001 42....+00000092                     <-- backsight station
110003+00000092 21.102+35955400 22.102+09124010  31..00+00000000  <-- reference station

In this example the backsight station is 92 and the measurement block records the vertical (not so important) and horizontal (very important) angles observed to the backsight station. This is the minimum requirement for the backsight station information. The measurement block is used to orientate the horizontal circle.

A check on the backsight station can be made by recording information about the height of the target at the backsight station and by recording meaningful slope distance and vertical angle information from the setup station to the backsight station in the measurement block. This is best shown by example.

410002+00000001 42....+00000092 43....+00001625     <-- backsight station with target height
110003+00000092 21.102+35955400 22.102+09124010  31..00+00532846  <-- reference station

In the example shown here, the backsight station is 92 and the height of the target at the backsight station is 1.625. This is obtained by dividing the value in code word 43 by 1000. Recording the height of the target at the backsight station causes the backsight station check to be performed.

With the height of target present, the vertical angle and slope distance observed to the backsight station are used to calculate the horizontal distance and vertical distance from the setup station to the backsight station. The height of the instrument at the setup station and the height of the target at the backsight station are used to compute the difference in height between the two stations.

These observed values are compared to the known values, as determined by the coordinates stored in the station database. If the difference between the known and observed values differ by greater than .005, for either the horizontal or vertical distance, the BACKSIGHT STATION CHECK form is displayed showing the measured, known and error values.

You may continue processing the survey if the errors are acceptable by choosing the Apply button.

If the errors are unacceptable the most likely reason is incorrect identification of the backsight station name in the input file. It is conceivable though that the station mark may have been moved. In either case the backsight station check has identified a problem with the survey that can only be rectified either by correcting the backsight station name or resurveying the job. You may choose the Cancel button to skip to the next survey in the input file until the problem can be identified and rectified.

RESECTION

Resection is a method for determining the unknown 3D position of an occupied station by measuring angles and distances to stations whose 3D coordinates are known. Surpac allows you to enter observations to multiple known stations, and uses a least squares solver to find the best coords for the unknown station based on all the data. The least squares solver uses several parameters related to the instrument accuracy of the particular data recorder (measured angle standard deviations etc). These parameters are set using the Data Recorders Configuration function described previously.

The Leica GRE3, GRE4, GIF10, TPS1000 and TPS1100 data recorders support resection in Surpac.

Note on the use of Resection: Resection is a form of triangulation. Therefore for optimum results, points for observation (i.e. the resected point and the known stations to be used for the resection observations) should be selected to give strong geometric figures. That is, for the resection observations you should avoid features such as very acute turned angles between known stations, and having the new resection point and two or more of the known stations being used for the resection being in (approximately) a straight line. Another well documented limitation of the Resection method is that if you are performing a resection without recording any slope distances (i.e. you only record horizontal and vertical angles), then the resection point itself and the first three known stations used in the resection observations must not all lie on the same circle.

The implementation of resection for the Leica data recorders is best illustrated by examples from raw data files (NB these examples use the TPS1000/TPS1100 format but the methodology for the GRE3/GRE4/GIF10 format is similar). There are in fact three ways that a resection block can appear in a raw data file. The first method is designed to be used by clients who have the current (as of the Surpac V5.0 release) version of the Surpac menus installed on their Leica instrument. The second method has been implemented for a future version of the Surpac menus on the Leica instrument (when an explicit Surpac Resection option will be available). The third method has been implemented for clients who do not have Surpac menus programmed on their instrument and so must enter the codes directly into their instrument keyboard without using a menu. These three methods are now described below:

Method 1:

This method is designed for users who have the current (as of the Surpac V5.0 release) version of the Surpac menus installed on their Leica instrument. It is envisaged that this will be the most common method for the majority of the Surpac community. The example below shows how a resection block will appear in the raw data file for the first method:

*410001+0000000000000000                                                 <-- start of job
*410002+0000000000000002 42....+000000LEICASTAT1 43....+0000000000000000 <-- name of resection station and instrument height
*410003+0000000000000003 42....+0000000000000000                         <-- target height
*410004+0000000000000001 42....+000000000000STN1                         <-- backsight station
*110005+0000000000000001 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000000000 <-- backsight reference angle
*410006+0000000000000004 42....+00000000000RSTN1                         <-- a resection observation follows, to station STN1
*110007+0000000000000002 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000039028 <--resection observation  
*410008+0000000000000004 42....+00000000000RSTN2                         <-- a resection observation follows, to station STN2
*110009+0000000000000003 21.324+0000000035132560 22.324+0000000008836150 31..00+0000000000016234 <--resection observation
*410010+0000000000000004 42....+00000000000RSTN3                         <-- a resection observation follows, to station STN3
*110011+0000000000000004 21.324+0000000000501360 22.324+0000000008942300 31..00+0000000000005678 <--resection observation
*410012+0000000000000004 42....+00000000000RSTN4                         <-- a resection observation follows, to station STN4
*110013+0000000000000005 21.324+0000000009236410 22.324+0000000009015080 31..00+0000000000009650 <--resection observation
*410014+0000000000000004 42....+0000000000000001                         <-- new string number
*110015+0000000000001001 21.324+0000000023817380 22.324+0000000009251030 31..00+0000000000038967 <--normal observation
*110016+0000000000001002 21.324+0000000019515320 22.324+0000000008756430 31..00+0000000000010677 <--normal observation

In the example above we have set up our instrument at an unknown station called LEICASTAT1 (which currently does not exist in the database). The backsight station is a known station STN1 (which must currently exist in the database). We then take a reading to set the backsight reference angle (as we would with a normal setup). We then take resection observations (horizontal angle, vertical angle and slope distance) to 4 known stations STN1, STN2, STN3 and STN4 (these four stations must currently be in the database). These MUST be in clockwise order. The first of these observations MUST be to the station that we nominated as the backsight station (STN1 in this case). An observation is identified as a resection observation by the appearance of the 'New String Number' code (i.e. code 4) just before the observation. For normal use, the new string number would be an integer, but if it has the following form then Surpac will identify the immediate next observation as a resection observation:

RSTN1

If the first character 'New String Number' field is 'R' then the next observation is taken to be a resection observation, and the characters following the 'R' are taken as the known station to which that observation is made. Each resection observation must have its own 'New String Number' code. Surpac identifies the resection observations as ending either when an integer 'New String Number' code is entered, or simply an observation appears that does not have a 'New String Number' code immediately before it. When the resection observations cease all the resection observations are put into a least squares solver and the coordinates of the unknown station are calculated. At this point you are given the option of putting the new resected station into the database as a permanent record, or just using the calculated coordinates temporarily. Now you can continue taking readings as though the resected station is a KNOWN instrument station, and the backsight station used is the one that you nominated for the resection observations. So in the example above, by the time we get to point 1001, the station LEICASTAT1 is now a known station and it is used as the instrument station for point 1001, and STN1 is used as the backsight station. Point 1001 is now surveyed as a normal point and its coordinates are calculated and put in the string file. NOTE: New code 3 target height lines can be entered at any time, so you can vary the target height as you make resection observations.

*410001+0000000000000000                                                 <-- start of job
*410002+0000000000000002 42....+000000LEICASTAT1 43....+0000000000000000 <-- name of resection station and instrument height
*410003+0000000000000003 42....+0000000000000000                         <-- target height
*410004+0000000000000001 42....+000000000000STN1                         <-- backsight station
*110005+0000000000000001 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000000000 <-- backsight reference angle

at this stage the user invokes the Leica free-station menu
now enter the resection observations in surpac-code form:
*410006+0000000000000004 42....+00000000000RSTN1                         <-- a resection observation follows, to station STN1
*110007+0000000000000002 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000039028 <--resection observation  
*410008+0000000000000004 42....+00000000000RSTN2                         <-- a resection observation follows, to station STN2
*110009+0000000000000003 21.324+0000000035132560 22.324+0000000008836150 31..00+0000000000016234 <--resection observation
*410010+0000000000000004 42....+00000000000RSTN3                         <-- a resection observation follows, to station STN3
*110011+0000000000000004 21.324+0000000000501360 22.324+0000000008942300 31..00+0000000000005678 <--resection observation
*410012+0000000000000004 42....+00000000000RSTN4                         <-- a resection observation follows, to station STN4
*110013+0000000000000005 21.324+0000000009236410 22.324+0000000009015080 31..00+0000000000009650 <--resection observation

Surpac also supports double face resection (for face left and face right observation pairs). Here the face left observation must come first (and the face left observation must have a vertical angle between 0 and 180 degrees), and the face right observation to the same station second. The readings pairs are meaned before being used in the least squares solver. Note: You cannot mix single face and double face observations in the same resection calculation.

Below is an example of a double face resection for the first method:

*410001+0000000000000000                                                 <-- start of job
*410003+0000000000000002 42....+000000LEICASTAT1 43....+0000000000000000 <-- name of resection station and instrument height
*410004+0000000000000003 42....+0000000000000000                         <-- target height
*410005+0000000000000001 42....+000000000000STN1                         <-- backsight station
*110006+0000000000000001 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000000000 <-- backsight reference angle
*410007+0000000000000004 42....+00000000000RSTN1                         <-- a resection observation follows, to station STN1
*110008+0000000000000002 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000039028 <-- resection observation (face left)
*410009+0000000000000004 42....+00000000000RSTN1                         <-- a resection observation follows, to station STN1
*110010+0000000000000003 21.324+0000000012918310 22.324+0000000027212520 31..00+0000000000039028 <-- resection observation (face right)
*410011+0000000000000004 42....+00000000000RSTN2                         <-- a resection observation follows, to station STN2
*110012+0000000000000004 21.324+0000000035132560 22.324+0000000008836150 31..00+0000000000016234 <-- resection observation (face left)
*410013+0000000000000004 42....+00000000000RSTN2                         <-- a resection observation follows, to station STN2
*110014+0000000000000005 21.324+0000000017132560 22.324+0000000027123450 31..00+0000000000016234 <-- resection observation (face right)
*410015+0000000000000004 42....+00000000000RSTN3                         <-- a resection observation follows, to station STN3
*110016+0000000000000006 21.324+0000000000501360 22.324+0000000008942300 31..00+0000000000005678 <-- resection observation (face left)
*410017+0000000000000004 42....+00000000000RSTN3                         <-- a resection observation follows, to station STN3
*110018+0000000000000007 21.324+0000000018501360 22.324+0000000027017300 31..00+0000000000005678 <-- resection observation (face right)
*410023+0000000000000004 42....+0000000000000001                         <-- new string number
*110024+0000000000001001 21.324+0000000023817380 22.324+0000000009251030 31..00+0000000000038967 <--normal observation 
*110025+0000000000001002 21.324+0000000019515320 22.324+0000000008756430 31..00+0000000000010677 <--normal observation 

Method 2:

The second method has been implemented for a future version of the Surpac menus on the Leica instrument (when an explicit Surpac Resection option will be available). NOTE: the 'Surpac Resection' option is not to be confused with the instruments own resection menu items which are programmed by the manufacturer and allow the instrument to do its own internal resection calculations.

The first below shows how a resection block will appear in the raw data file for the second method:

*410002+0000000000000040      <-- start of resection
*110003+000000000000STN1 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000039028 87..10+0000000000000000 <-- resection observation and target height 
*110005+000000000000STN2 21.324+0000000035132560 22.324+0000000008836150 31..00+0000000000016234 87..10+0000000000000000 <-- resection observation and target height 
*110007+000000000000STN3 21.324+0000000000501360 22.324+0000000008942300 31..00+0000000000005678 87..10+0000000000000000 <-- resection observation and target height 
*110007+000000000000STN4 21.324+0000000009236410 22.324+0000000009015080 31..00+0000000000009650 87..10+0000000000000000 <-- resection observation and target height 
*410009+0000000000000011 42....+000000LEICASTAT1 88..10+0000000000000000  <-- name of resection station and instrument height
*110012+0000000000001001 21.324+0000000023817380 22.324+0000000009251030 31..00+0000000000038967  <--normal observation

Code 40 is used as a start of resection marker and code 11 is used as an end of resection marker. Again we have resection observations to 4 known stations STN1, STN2, STN3, STN4. In this method the station to which the resection observation is made is stored in the 'Point Number' of the observation. Also, for this method, the target height must appear on the resection observation line. The observations MUST be in clockwise order. Surpac will use the FIRST of these stations as the backsight station for any surveyed points that follow the resection block. On the same line as the code 11, must appear the name of the resection station (which currently will not be in the database), and the instrument height. So as in Method 1, by the time we get to point 1001 in the example above, the station LEICASTAT1 is now a known station and it is used as the instrument station for point 1001, and STN1 is used as the backsight station. Point 1001 is now surveyed as a normal point and its coordinates are calculated and put in the string file.

Below is an example of a double face resection for the second method:

*410002+0000000000000040      <-- start of resection
*110003+000000000000STN1 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000039028 87..10+0000000000000000 <-- resection observation (face left) and target height 
*110003+000000000000STN1 21.324+0000000012918310 22.324+0000000027212520 31..00+0000000000039028 87..10+0000000000000000 <-- resection observation (face right) and target height
*110005+000000000000STN2 21.324+0000000035132560 22.324+0000000008836150 31..00+0000000000016234 87..10+0000000000000000 <-- resection observation (face left) and target height
*110005+000000000000STN2 21.324+0000000017132560 22.324+0000000027123450 31..00+0000000000016234 87..10+0000000000000000 <-- resection observation (face right) and target height
*110007+000000000000STN3 21.324+0000000000501360 22.324+0000000008942300 31..00+0000000000005678 87..10+0000000000000000 <-- resection observation (face left) and target height
*110007+000000000000STN3 21.324+0000000018501360 22.324+0000000027017300 31..00+0000000000005678 87..10+0000000000000000 <-- resection observation (face right) and target height
*410009+0000000000000011 42....+000000LEICASTAT1 88..10+0000000000000000  <-- name of resection station and instrument height
*110012+0000000000001001 21.324+0000000023817380 22.324+0000000009251030 31..00+0000000000038967 <--normal observation

Method 3:

The third method has been implemented for clients who do not have Surpac menus programmed on their instrument and so must enter the codes directly into their instrument keyboard without using a menu. Method 3 is similar to method 2 except:

• the target heights must be entered as separate code 3 lines in the resection block, they do not appear on the resection observation line (but code 3 target height lines can be entered at any time in the resection block, so you can vary the target height as you make resection observations)
• the name of the resected station, and the instrument height, must appear in their own code 2 line at the start of the resection block

The example below shows how a resection block will appear in the raw data file for the third method:

*410002+0000000000000040      <-- start of resection
*410002+0000000000000002 42....+000000LEICASTAT1 43....+0000000000000000 <-- name of resection station and instrument height
*410002+0000000000000003 42....+0000000000000000 <-- target height
*110003+000000000000STN1 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000039028 <-- resection observation 
*110005+000000000000STN2 21.324+0000000035132560 22.324+0000000008836150 31..00+0000000000016234 <-- resection observation
*110007+000000000000STN3 21.324+0000000000501360 22.324+0000000008942300 31..00+0000000000005678 <-- resection observation
*110007+000000000000STN4 21.324+0000000009236410 22.324+0000000009015080 31..00+0000000000009650 <-- resection observation
*410009+0000000000000011      <--end of resection
*110012+0000000000001001 21.324+0000000023817380 22.324+0000000009251030 31..00+0000000000038967 <--normal observation

Below is an example of a double face resection for the third method:

*410002+0000000000000040      <-- start of resection
*410002+0000000000000002 42....+000000LEICASTAT1 43....+0000000000000000 <-- name of resection station and instrument height
*410002+0000000000000003 42....+0000000000000000 <-- target height
*110003+000000000000STN1 21.324+0000000030918310 22.324+0000000008747080 31..00+0000000000039028 <-- resection observation (face left) 
*110003+000000000000STN1 21.324+0000000012918310 22.324+0000000027212520 31..00+0000000000039028 <-- resection observation (face right)
*110005+000000000000STN2 21.324+0000000035132560 22.324+0000000008836150 31..00+0000000000016234 <-- resection observation (face left)
*110005+000000000000STN2 21.324+0000000017132560 22.324+0000000027123450 31..00+0000000000016234 <-- resection observation (face right)
*110007+000000000000STN3 21.324+0000000000501360 22.324+0000000008942300 31..00+0000000000005678 <-- resection observation (face left)
*110007+000000000000STN3 21.324+0000000018501360 22.324+0000000027017300 31..00+0000000000005678 <-- resection observation (face right)
*410009+0000000000000011      <--end of resection
*110012+0000000000001001 21.324+0000000023817380 22.324+0000000009251030 31..00+0000000000038967 <--normal observation

You are given some options regarding the creation of the resected station. This is done via the Options for Resected Station form, see here for more details.

Use of station errors table: If a station errors table exists in the survey database, information regarding the order of the new resected station may be displayed. See here for more details.

Summary of important points for resection (for all three methods):

• The station defined in the first resection observation will be used as the backsight station in all subsequent normal observations until another backsight station is entered;
• The resection observations must be to stations taken in clockwise order;
• You are allowed a maximum of 20 resection observations to calculate the coords of a resection station, or 20 pairs of readings for double face observations;
• You must have horizontal angle and vertical angle readings for resection observations, but the slope distances are optional. If the slope distances do not appear or are set to 0.0 in the raw data file then only the angles will be used in the least squares solver for the resection station coordinates. You can have some resection observations with and some without slope distances in the same resection calculation. For double face resection you can also have face left with a slope distance and face right without a slope distance (or vice versa). Note that slope distances are still required for all conventional point surveys.
• If angles and slope distances are present then resection observations to a minimum of two known stations are required. If only angles are present then resection observations to a minimum of three known stations are required;
• If an underground database is used and the new resected station is stored in the database, then the station defined in the first resection observation is stored as the 'station from' and the reverse bearing from the new station to the station defined in the first resection observation is stored as the 'reverse bearing'.

Below is an example of the report created when resections are encountered.

RESECTION REPORT

Purpose : Testing purpose

UNADJUSTED OBSERVATIONS

INSTRUMENT ACCURACIES

Results

Station LEICASTAT1 has been inserted into the database.

OBSERVATION ADJUSTMENTS

Note: The Observation Adjustments are tabulated above to help highlight any erroneous observations.

Note on "Standard deviations" in the RESULTS section of the RESECTION REPORT file: In general the more stations that you take readings to for the resection, the better these values become as a measure of the accuracy of the coordinates of the unknown station. This is because the more readings that exist the more "redundant" information there is. Redundant information is important in a least squares adjustment as it helps to show the consistency of the observations used to calculate the coordinates. However, even if you only take resection observations to the minimum of two fixed stations there is still some redundant information, that is one slope distance and one vertical angle, so the standard deviations are still meaningful even in this most simple case.