IE60646B1 - Method and apparatus for survey datalogging - Google Patents

Abstract

The invention provides a method and apparatus for survey datalogging. The system includes a hand held computer which comprises an automatic datalogger, a check plotter, a free station/resection unit, a design setting out and monitoring unit, a traverse unit and a unit for computing areas and volumes.

Description

The present invention relates to a method and apparatus for survey datalogging and in particular a method and apparatus for survey datalogging for use in land surveying, mapping, civil engineering and construction applications.

The present invention provides apparatus for survey datalogging including a hand held computer, the apparatus comprising one or more of the following means? namely automatic datalogging means; check plot means; free station/resection means; design setting out and monitorin means; traverse means and areas and volumes computation means.

Preferably the automatic datalogging means includes means for effecting a topographic survey of one to a plurality of observations with a plurality of error checks, defaults and editing facilities? means for on sit draughting with an output/plot-code facility? means for providing a data output to a portable disc? a printer and means for computing raw data and polar and rectangular co ordinates in various formats suitable for major drafting and design systems • Preferably the check plot means includes means for - 3 obtaining an on site check plot which reads a co-ordinate file created by any of the automatic datalogging means; \ free station/resection means, traverse means, or design 1?.. setting-out and monitoring means, output means to a plurality of plotters in which a plurality of points may be plotted.

Preferably the check plot means includes means for stringing, scaling and calibration, means for selecting choice of pen colours and line types and means for storing the plot data on a portable disc or computer.

Preferably the free station/resection means includes means for determining instrument station coordinates using the horizontal angles and/or angles and distances to at least three known control points; means for displaying a least squares control point; means for deletion/replaeement of observations and recomputation; means for calculating residuals of arcs and deletion/replaeement of arcs after the final arc computation has been completed and means for storing observed orientations for direct use by the automatic datalogging means, traverse means or design setting out and monitoring means after co-ordinate determination.

Preferably the design setting out and monitoring fc means comprises means for setting out design co-ordinates by angle and distance or by X and Y differences, means for automatic downloading of design points, means for zenith angle determination for setting out of heights, means for remote heighting and means for co-ordinate monitoring which stores the computed design and dx, dy dz coordinates of up to one hundred and fifty points which may be output to the printer or computer.

Preferably the traverse means includes means for effecting a basic traverse function; means for computing provisional co-ordinates in real time having check and review facilities so as to monitor and flag a user on observation quality, in particular face left/face right horizontal angle differences and hacksight/foresight difference in distances between stations, means for establishing shadow or side traverses from any station; means for performing a bowditch adjustment, means for performing a two dimensional transformation to block shift and for re-orientating the primary and any secondary traverses, and means for effecting least squares adjustment.

Preferably the areas and volumes computation means includes means for calculating land areas, cross-sections and volumes for any group of points; means for obtaining check plot output display figures for confirmation of suitability and means for computing volumes from the areas by either the end areas or prismoidal rule,.

Advantageously, the invention provides a method for survey datalogging using the above apparatus„ The invention will hereinafter be more particularly described with reference to the accompanying drawings which show by way of example only a first embodiment of a system incorporating the method and apparatus of the invention.

The system known as GRAD consists of six application programs for use in the field on a hand held computer, as follows; (1) Traverse (GTS) (2) Automatic datalogger (GDS) (3) Check-plot (GDP) (4) Design setting-out a monitoring (GSO) (5) Free station/Resection (GFS) (6) Areas and volumes computation (GAV) In the drawings: Figure 1 is a lowchart of a toggle menu for the system? Figure 2 is system? Figure 3 is the program? Figure 4 is a flowchart of a pull-down menu for the a flowchart of the main menu options of a series of flowcharts for the input/output applications of which: Figure 4a is a flowchart for the communications and disc operations options? Figure 4b in conjunction with Figure 4a is a flow chart for the file operations options? Figure 4c in conjunction with Figure 4a is a flowchart for the data output options? Figure 4d in conjunction with Figure 4a is a flowchart for the control file? Figure 5 is a flowchart of the control coordinates file? Figures 5a to 5e illustrate the flowchart of the traverse program? Figure 7 is a flowchart of the observations entry sheet? Figure 8 is a flowchart of the automatic datalogger program.

Figure 9 is a flowchart of the check-plot program of which: Figure 9a is a subroutine for loading data to plot- ready form? Figure 9b is a subroutine for reviewing editing and plotting dat a? Figure 10 is a flowchart of the desing setting out and monitoring program of which: Figure 10a is a flowchart of the input and check of reference orientation (RO) details, , Figure 10b is a flowchart of the set-out option? and * Figure 10c is a flowchart of the monitoring option? Figures Ila and 11b illustrate a flowchart of the free station/resection program? and Figure 12 is a flowchart of the read-in from theodolite program.

In the drawings three function keys are central to the use of all the GRAD programss ENTER, ESC (escape) and MNU (menu)„ The ENTER key is a positive, forward movement key used to confirm or accept necessary data or use of program options where choice is presented» ESCAPS is a negative, backward movement key to reject an option, break out of a routine or return to the main menu.

The MENU key is used to access options/features particular to a specific working area of the programs.

This simplifies the accessing and use of many features available and avoids the need for the user to go to another section of the program to use a feature relevant to the areas in which they were working. The menu may be a toggle menu or a pulldown menu. Flow charts for these ' menus are detailed in Figures 1 and 2 respectively,., As . described in Figure 1, operation of the toggle menu is executed using the enter, escape or 81 any key keys. When the desired option is displayed, it may be activated via the enter key. The user may move through the options available by toggling any key. The escape key allows the user to escape back to the first option of the menu he is working within, or the main menu. The pull down menu (Figure 2) is operated via the MNU key in a similar fashion to the toggle menu, with the difference that all options within the menu are simultaneously displayed on screen and the desired option is chosen by placing the cursor, by means of f and keys on that option. The option is then activated by means of the enter key.

Both of these types of menus may appear automatically, prompting the user to perform an operation thus reducing key presses and the need for the user to know when an option should be used.

The main menu is central to, and appears in, each of the GRAD programs. Four choices of action are possible from the main menu in any GRAD programs 1. JOB IDENTITY DATA PROCESSING 3.

INPUT / OUTPUT ERASE CURRENT DATA Data relevant to the job is logged, output and erased - 9 in these areas in a format similar to that which the surveyor or engineer is already familiar with The GRAD main menu is detailed in the flow chart given in Figure 3. The GRAD option program may be accessed from a sign on position, or directly from any other of the GRAD programs. The toggle option may be used to access any other GRAD program... Alternately, any one of the four options of the main menu may be activated. With reference to Figure 3, these are: 3.i, the job identity option, which details the surveyors name, job title, client name and job date? 3.ii, the data processing option which gives access to all of the six GRAD programs (see below for detailed flow charts). 3.iii, the input/output option which provides for electronic information flow to and from the present computer (see below for detailed flow charts). 3.iv is a CLEAR option which may be used to erase data from the computer.

The input/output options outlined in Figure 3.iii are detailed in Figure 4. An overview of the program is depicted in Figure 4a. Route 4ai, the communications option, provide a means of checking data formats in the computer and allows choice of parameters necessary to * interface the computer with another device (e.g. a , personal computer or a data plotter). Option 4aii, the file operations option, is detailed in Figure 4b. As shown in this figure, it consists itself of a nest of four options which are used to load or erase control files, create new files for output or load information from the GFS program for output. Option 4aiii, detailed in Figure 4c, provides a means by which data may be transferred to an interfacing device. The disc operations option flow chart as depicted in Figure 4aiv provides a means by which data may be saved, loaded, deleted or formatted before being sent to an interfacing device. Figure 4av, the control file option, is detailed in Figure 4d and comprises a routine for entering known control coordinates or converting co-ordinates derived from GSO into control co-ordinates for a following step in GSO.

Other GRAD programs may be accessed and run from the main menu of any other GRAD program. When this is done, the data is reduced to a form compatible with the plotting program (GDP) and saved. If the user then runs the plot program GDP' this data file is automatically loaded. If any other program is run, another data file (Control Coordinates upon which all data captured is processed), is loaded.

If the user is starting a job for the first time, he must log-on in the Job Identity before logging and/or - 11 “ processing of data may commence, if he tries to enter DATA PROCESSING or INPUT/OUTPUT he will be prompted to sign-on first.

The user may log the job I.D. number, title, surveyor’s name and client. The program he is in will then automatically set a starting date for the job which may not be altered. It is automatically reset when the job is erased.

When the user runs another GRAD program, the JOB I„D,, is automatically transferred.

In option 2, data is logged and procedures implicit in a particular program may be carried out. These are primarily: 1. Station occupied 2. Height instrument on that station above ground point 3a„ The RO (Relative Orientation) target for that set-up or 3b. The detail feature's name (being observed) recorded, plotted or set-out 4. The height of that part of the object being recorded from the ground . The horizontal angle to that point 6. The zenith angle to that point 7. The slope distance to that point „ 8,. A comment/remark about the point.

Data may be transferred either into or out of a particular program.. The communication parameters necessary to do this may be set here. Files may be managed, loaded, saved, erased. Data may be saved to disk, as well.

To erase a job the user is asked to confirm the choice by pressing ENTER. If they do they are then asked to enter a code to ensure no accidental erasure or loss of data occurs. If the code is entered correctly then the data is erased.

GTS (Traverse) This program is used to establish the X, g, % coordinates of new control points (stations) on the ground from which further survey work may be carried out.

The pull-down menu for the GTS program comprises 12 options. These are: Observations set-up Overwrite Review tests New station R.O. check Last station Atmospherics Scale factor Point rile Close and check Theodolite entry type Traverse adjustment.

When first entering DATA PROCESSING in GTS a check is made as to whether the station occupied is a new setup or not. If it is not then the current station, instrument height and last four observations are displayed; the user then being prompted to input the next or perform some other function.

If it is a new station, then the new station's name and instrument height are displayed (if known); the user being prompted to ENTER or confirm them.

Upon entry/confirmation of the station the user is presented with the X, Y, Z co-ordinates of that point if they exist. If they do not exist, then the user is required to input them. If the maximum allowable number of co-ordinates on file is reached, the user is told this and not allowed to enter any more co-ordinates.

The instrument height is then ENTERED/confirmed and checked to ensure it’s within the proper range. If its not, the user must enter a correct value to proceed.

A check is then made as to whether the observation sequence has been set-up yet. This states how the observations will be input and used from that station. It is accessed in the pulldown menu but if the user fails to set it up by this stage the menu appears automatically.

The user cannot proceed until this is done.

The user now moves to the main section of the data logging spreadsheet. If this is the first station then 'RO’ is displayed as the 'REF3, if not, '3S' appears. The user confirms this and then enters/confirms the RO/BS target.

The user is then prompted to ENTER/confirm the coordinates of the RO/BS target or the bearing from the station to the target by a toggle menu. The co-ordinates are entered same as with the station. Range checks are carried out to ensure values are in the correct format.

The target height is then ENTERED/confirmed and the observations enter/received (horizontal angle, zenith/vertical angle, slope distance). These may be manually entered or received from an electronic edm and/or theodolite.

To carry out a traverse adjustment a series of checks are then made on the observations to ensure they are valid, that the maximum number has not been exceeded and what the next prompt/observation should be.

At least three stations must have been occupied, the program now prompting for the 4th or greater. If the closing station is the same as the starting station then it is a loop traverse so only one group of co-ordinates need be entered/confirmed. If not a loop traverse, then the closing station must be defined and the co-ordinates ft entered/confirmed for it.

The starting bearing between the starting station and the first RO is then reentered/confirmed. The user is allowed to alter this to determine a new orientation for the traverse. The closing bearing is then confirmed and the angles adjusted. If it is a loop traverse then the error is determined and corrected from the traverse angles, or else the error is determined by the difference between the computed closing bearing and the one entered/confirmed.

The co-ordinate error is then computed and displayed.

Finally, all occupied stations and then polar shots from those stations are adjusted by the amount of error displayed.

There are three possible outputs in GTS., The first is the observations with reduced angles and bearings from the traverse. Second is the control co-ordinate file.

Finally, the co-ordinate misclosure and the corrections applied to each co-ordinate may be output once the adjustment has been made.

, . . . A The flow charts of the programs utilised xn GTS are shown in Figure 6. The step are as follows: - 16 Figure 6ai identifies whether a new station is to be set up, or a previously known station is to be used; 6aii enters and confirms co-ordinates? Saiii enters height of instrument, checks this entry against the tolerance heights and checks that the sequence in which the observations will be made has been set up? 6bi establishes a new target and enters/confirms the co-ordinates or bearing for that target? 6bii enters the height of this new target and checks this against the tolerance range? 6c illustrate how the traverse adjustment checks are performed? 6d illustrates how the traverse adjustment is performed? 6e illustrates how the computation is performed? Figure 7 is the flow sheet for the ^observations entry sheet” referred to in Figure 6biii and Sc.

This provides a means of entering and recording data derived from the theodolite regarding height, vertical and horizontal angles and slope distances for successive measured points in a traverse.

GPS (Automatic datalogger) This program is used to determine the co-ordinates of topographical features for mapping, analysis, etc.

The pull down-menu for the GDS program comprises ten options. These are: Compute X, Y, S Overwrite Find point Feature review Mew station 1st point Review R.O.

Theodolite entry type Co-ordinates - N/Y Default ON/OFF When first entering DATA PROCESSING (GDS) a check is made as to whether this is a new set-up or not. If it is, then an RO is to be observed and checked, or else the user is prompted to continue logging detail points.

Entry of the station I„D„, co-ordinates and the observations are the same as with GTS except that no observation set-up need be stated before observing the ROy only one RO is observed. A check is then made to determine the quality of the RO target and observation.

If satisfied, the user may then proceed with the detail points, otherwise he can redo the RO.

For every detail point, there is a point number, the name/description of the feature being recorded, the rod height, the two angles and slope distance then a remark for every point. The remark has a text editor so that the user may press the left or right arrow keys to move through the text and then insert or delete characters.

The observations and their reduced co-ordinates may be output or the co-ordinate file may be output™ The detailed flow chart for the GDS program is given in Figure 8» With reference to this figure, 8i provides a means whereby, if necessary, a new station is entered, using the same procedure as described for GTS (and shown in Figure 6a). In the Figure 8ii, the newly established RO is checked, confirmed and edited if necessary, following which the detail points (rod height, horizontal angles and slope distance) are entered as shown in 8iii by means of the observations data sheet previously described (Figure 7). In this program, previously established stations are routed directly into the section described by 8iii of the program.

GDP (Check-plot) This program will provide an on-site check plot of a survey to establish that the work has been satisfactorily completed before leaving the site.

Two pull-down menus exist for the GDP. Menu 1 comprises seven options. These are: Grid type Line type Pen choice Plot calibration Initial plot Point to point Sort data Menu 2 also comprises seven options, which are: Border ON/OFF Grid ON/OFF Point number ON/OFF Height ON/OFF Lines ON/OFF Symbols ON/OFF Annotate ON/OFF GDP takes the data from other programs and loads it in a form ready for plotting, DATA PROCESSING then allows this data to be reviewed and/or edited. No other functions are performed in this area.

The plot data may be output from here. In addition all plotting is carried out in this area.

The user enters/confirms/computes the plotting scale, the plot's page number, the minimum and maximum coordinates in which the plot will be made and the grid interval for the plot. After the grid interval is confirmed the plotting may commence. Pressing the ‘BRK* key will halt the plotting if necessary.

Figure 9 outlines the flow chart of the GDP program.

The function performed by the routine in 9a is retrieval of information from other programs of the GRAD suite and reduction of this to a form suitable for output to plotting» Section 9b of the chart then processes this data, by means of the input/output functions and finally sends the data to the interfacing plotter» GSO (Design Setting-Out and Monitoring) GSO is used to locate and mark design points on the ground to show where pipelines, buildings, etc. should be constructed. The work can also be monitored for accuracy as well.

The GSO pull-down menu offers five options. These are: Theodolite entry type RO check Setting-out Monitoring Mew station Input of station information and RO details are the same as per GTS & GDS except that no observation set-up is made nor may a bearing be input for the RO» The user must enter/confirm co-ordinates of each RO target.

All further facilities are accessible in the pulldown menu but only after the RO Check has been completed. The user may use the Set-out option or Monitoring or make NSW Station set-up.

Design points may be set-out one by one (Single Points) or an automatic default sequence may be established to automatically bring up and compute the setting-out information for each point.

Having chosen a point, its design co-ordinates are entered/confirmed and the setting-out information computed and displayed. The user may then further utilize the information to reach a point by computing the x and y coordinates to it (dx, dy. Fix), by computing the angle left or right and the distance to it (Radial Fix) or the user can compute the zenith/vertical angle of the design point to set-out the height.

Observations are entered in a fashion similar to the other programs.

In monitoring the user may compare the observed coordinates of a point to its design values on file to ensure it is set-out in the correct place. The differences between these two determinations may then be stored on file and output later.

The user may also determine the height of an inaccessible point and store that point in the design file.

The design point file or the control co-ordinate file may be output, plus the results of monitoring checks that were stored.

The flow charts relevant to the GSO program functions are shown in Figure 10. The flow chart of Figure 10a defines the means by which station information and RO points are entered and the RO point check is executed. In the program section of Figure 10bi, the checked RO point is entered and its co-ordinates computed. From this derived data, the succeeding design points can be calculated iteratively by means of the program in Figure lObii. Monitoring in GSO is performed by means of the program depicted in Figure 10c. In Figure lOci a loop is provided whereby the height of a point may be calculated and stored. Figure lOcii provides the means by which calculated setting-out date may be compared with actual measurement, and any deviation recorded.

GFS (Free Station Resection) The pull-down menu for the GFS program comprises four options, as follows: Observation set-up Comp (ute) station Print find Theodolite entry type In GFS the initial station set-up is different from - 23 ™ all the other GRAD programs in that no co-ordinates are entered for the name of the station as that is what will be determined in the program.

After the station name and instrument height the user must establish the observation sequence as in GTS. Having completed this, they may now begin logging the observations and computing the X, Y, 2 co-ordinates of the station occupied.

After each target has been observed once in a sweep of the targets from start to finish, provisional coordinates of the station are computed from that group of observations. Checks are also made to indicate the quality of that group of observations.

Once satisfied the user then proceed with the next set of observations to the known targets and computes again. When the desired number of sets has been reached and computed, the provisional values are used to compute the final values which are extensively error checked, as well.

The observations and/or control co-ordinate files may be output.

The user may review/reset the communication parameters to enable the computer to communicate with another device.

Figure 11 details the flow charts of the programs for the GFS option,, The steps outlined in Figure 11a are those of naming the new station to be created, entering its height, defining the sequence of the observations to be made, followed by entry of the observations. The co5 ordinates of the new station are then calculated by means of the routine shown in Figure 11b. Initially, a set of provisional co-ordinates of the targets is calculated and a check is made to ensure that these lie within the allowed tolerance levels.

File Operations allows the user to reload the control file as it existed when he first began running the current program. He may erase the control co-ordinates held on file. He may create a file ready for plotting using the program raw (unprocessed) data. The last observation in GFS may also be used as the RO in any other program when the user continues with another survey function having established the co-ordinates of their station in GFS.

Disk operation allows the user to save or load a job onto a disk or back into the program.

The Control Co-ordinates section allows the user to edit the control file (and the design co-ordinate file in GSO).

The system has been prepared with the following objects in minds Optimizing the user’s time in the field? Minimization of errors; Information that may be easily interpreted by a third party; Review and editing techniques resemble familiar 'field book6 methods; Facility for alpha-numeric characters in the remarks for every point logged allows easy coding and identification of features surveyed.

The program’s communications facility provides easy storage or printing of observations (and reduced polar and rectangular co-ordinate form where possible) for many peripheral devices, suitable for manual plotting by orthogonal scaling (or protractor and scale rule), on a grid system or accessed by the GRAD GDP plot program.

Thus, data may be plotted in a site-office or stored in another device and work proceed unhindered.

Data may be recorded in a manual or automatic mode. Thus, the logger may be used for keying-in data read from an EDM and optical theodolite, or directly recorded by automatic data transfer from a 'total station instrument. The program depicted in the flow chart detailed in Figure 12 provides a means by which data retrieved from a theodolite is accessed to the GRAD suite programs. The program sets up the communication link for entry of data from the theodolite and allows the reading of horizontal angles, vertical angles and slope distance from the theodolite.

Data security is ensured when the logger is used for automatic raw data acquisition from a ’total station8.

The program may also be used as an off-line office terminal for loading data abstracted from a field book.

The second embodiment will now be described. The second embodiment includes the features of the first embodiment described above together with the following additional features. 8 Supervisor 8 This module allows the user to set certain parameters which effect the entire survey datalogging system, these parameters can be variable or constants used in the computations, also provided is a facility for a person of authority to control the quality of work done.

The latter is achieved by the person of authority accessing the Supervisor’ module, setting restricting parameters which define the required quality of work and then removing the Supervisor module from the hand held computer thereby removing the possibility of resetting these parameters (the 'Supervisor' can be replaced if desired,„ The common parameters are: Scroll Delay s Speed of screen movement Bearing : Whole Circle or Quadrant Vet. Circle s Zenith or Nadir Distance Unit : Meters or Feet Angle Unit s Degrees or Gons Primary Axis s North or South Secondary Axis : East or West Axis Display : Display Primary / Secondary / Vertical Axis or Secondary / Primary / Vertical Axis on screen and printouts The constant parameters are Scale Factor Radius of Earth Point Number Prefix : alpha / numeric Block Shifts s to relate local co-ordinates to geographical co-ordinates The quality control parameters are Distance Accumulator : allowed difference between two or more measurements of the same distance., BS - FS Height Diff : allowed deviation between computed difference in height between the same two points.

Horizontal Angle Checks allowed difference between two or more measurements of the same horizontal angle.

Zenith/Vert Angle Checks allowed difference between two or more measurements of the same zenith/vertical angle. zVangle Index Error s allowed amount of index error allowed in a theodolite/total station (can be ascertained from repeated measurements) Also included in the 'Supervisor' module is a facility to record plotter dimensions i.e. length of top margin, bottom margin and one side. If the plotter is knocked out of adjustment the actual dimensions can be recorded and during the plotting process adjustments are made (by means of a transformation) to correct Additional Features in GDS (Automatic Datalogging) program.

The following is a description of additional functions/facilities provided in the automatic datalogging program. Each function is accessed via the MENU key as in the first embodiment. a) Line of Sight When a point is recorded in the hand held computer additional measurements can be recorded (distances along line of sight and left or right of line of sight) to locate a point which is not visible from the occupied station. ~ 29 ·’ b) Taped Measurements The sides of a regular object can be recorded such that the user can locate one point on the object (by recording angles and a distance from the occupied station) and from that point record distances (left or right) to define the size and shape of the object. c) Feature Offset Having located a point on an object (by recording angles and a distance from the occupied station) the user can record another point on a different object by recording a distance (+ or -) and the new object name d) Cross Check This function allows the user to check the quality of data being recorded. A measurement is recorded from the occupied station, which has a known position, to another station which also has a known position. The calculated position of the second station should agree with the known position of this point thereby providing a check. e) Orthogonal Feature This allows the user to record the location of two points and one distance to define a rectangular object. f) Radius & Centre This allows the user to record the location of one point and a distance (radius) to define a circular object. g) Point & Centre This allows the user to record the location of two points to define a circular object. The first point is the centre and the second point is on the circumference h) 2 Point Circle This allows the user to record the location of two points to define a circular object. Both points are on the circumference. i) 3 Point Circle This allows the user to record the location of three points to define a circular object. All points are on the circumference. j) Tag Codes When a measurement is recorded an item called a 'tag’ is also recorded, this item will determine what type of line will be between this point and the next pont on the same object. The possibilities ares 1. Gap 2. Straight line 3. Curved line 4. Link back to the first point on the object by straight or curved line . This measurement is a duplication of the last measurement o. This point is a Tangent Point The user will type in a one letter code to define the tag. A help menu is provided to explain exactly what each code means. k) DTM Codes DTM means ’Digital Terrain Model8 (a representation of the terrain using digital data). When the user records a measurement a DTM code is also recorded. The DTM code defines the status of the point within the Digital Terrain Model. The codes are as followsϊ Y - Include point in DTM I - Exclude point from DTM N - Mull level X - Calculate a level but do not include it in the DTM A help menu is provided to explain exactly what each code means.

Claims (10)

1„ Apparatus for survey datalogging including a hand held computer, the apparatus comprising one or more of the following means? namely automatic datalogging means? check plot means? free station/resection means? design setting out and monitoring aieans; traverse means and areas and volumes computation means,

2. Apparatus for survey datalogging as claimed in Claim 1 in which the automatic datalogging means includes means for effecting a topographic survey of one to a plurality of observations with a plurality of error checks, defaults and editing facilities? means for on site draughting with an output/plot-code facility? means for providing a data output to a portable disc? a printer and means for computing raw data and polar and rectangular co-ordinates in various formats suitable for major drafting and design systems,

3. , Apparatus as claimed in Claim 1 or Claim 2 in which the check plot means includes means for obtaining an on site check plot which reads a co-ordinate file created by any of the automatic datalogging means? free station/resection means, traverse means, or design setting-out and monitoring means, output means to a plurality of plotters in which a plurality of points may be plotted. - 33

4. Apparatus as claimed in Claim 3 in which the check plot means includes means for stringing, scaling and calibration, means for selecting choice of pen colours and line types and means for storing the plot data on a portable disc or computer.

5. Apparatus as claimed in any one of the preceding claims in which the free station/resection means includes means for determining instrument station co-ordinates using the horizontal angles and/or angles and distances to at least three known control points? means for displaying a least squares control point? means for deletion/replacement of observations and recomputation? means for calculating residuals of arcs and deletion/replacement of arcs after the final arc computation has been completed and means for storing observed orientations for direct use by the automatic datalogging means, traverse means or design setting out and monitoring means after co-ordinate determination.

6. Apparatus as claimed in any one of the preceding claims in which the design setting out and monitoring means comprises means for setting out design co-ordinates by angle and distance or by X and Y differences, means for automatic downloading of design points, means for zenith angle determination for setting out of heights, means for remote heighting and means for co-ordinate monitoring <— J*, which stores the computed design and dx, dy ds coordinates of up to one hundred and fifty points which may be output to the printer or computer.

7. Apparatus as claimed in any one of the preceding claims in which the traverse means includes means for effecting a basic traverse function; means for computingprovisional co-ordinates in real time having check and review facilities so as to monitor and flag a user on observation quality, in particular face left/face right horizontal angle differences and backsight/foresight difference in distances between stations, means for establishing shadow or side traverses from any station; means for performing a bowditch adjustment, means for recomputing all side traverses after adjustment; means for performing a two dimensional transformation to block shift and for re-orientating the primary and any secondary traverses, and means for effecting least squares adjustment.

8. Apparatus as claimed in any one of the preceding claims in which the areas and volumes computation means includes means for calculating land areas, cross-sections and volumes for any group of points; means for obtaining check plot output display figures for confirmation of suitability and means for computing volumes from the areas by either the end areas or prismoidal rule. ·< - 35

9. Apparatus as claimed in any one of the preceding claims substantially as herein described.

10. A method for survey datalogging using apparatus as claimed in any one of the preceding claims.