Tools Menu

Inverse Buttons - The 'Inverse' button is found on the main window (the button with the icon that shows a line with points at each end). You can also select the Tools->Inverse menu option. This feature is only active after a network has been processed successfully. This option can be used to obtain the bearing and distance between any two points in the network. Additionally the standard deviation of the bearing and distance between the two points is displayed.

The Relative Error Ellipse Inverse button is found on the main window (the button with the icon that shows a line with an ellipse in the middle). You can also select the Tools > Relative Error Ellipse menu option. This feature is only active after a network has been processed successfully. This option can be used to obtain the relative error ellipse between two points. It shows the semi-major and semi-minor axis and the azimuth of the error ellipse, computed to a user-define confidence interval. This information can also be used to determine the relative precision between any two points in the network. It is the relative error ellipse calculation that is the basis for the ALTA tolerance reporting. If the 'Enable sideshots for relative error ellipses' toggle is checked then all points in the project can be used to compute relative error ellipses. The trade-off is that with large projects processing time will be increased.

If you need to certify as to the "Positional Tolerances" of your monuments, as per the ALTA Standards, use the Relative Error Ellipse inverse routine to determine these values, or use the specific ALTA tolerance reporting function as explained later in the manual.

For example, if you must certify that all monuments have a positional tolerance of no more than 0.07 feet with 50 PPM at a 95 percent confidence interval. First set the confidence interval to 95 percent in the Settings/Adjustment screen. Then process the raw data. Then you may inverse between points in as many combinations as you deem necessary and make note of the semi-major axis error values. If none of them are larger than 0.07 feet + (50PPM*distance), you have met the standards. It is however more convenient to create a Relative Error Points File containing the points you wish to check and include the ALTA tolerance report. This report takes into account the PPM and directly tells you if the positional tolerance between the selected points meets the ALTA standards.

Convert GPS/Total Station Files

The purpose of this option is to convert GPS vector files that are in the manufacturers' binary or ASCII format into the StarNet ASCII file format. The advantage of creating an ASCII file is that the ASCII file can be edited using a standard text editor. Being able to edit the vector file may be necessary in order to edit point numbers so that the point numbers in the GPS file match the point numbers in the total station file.

There is also a tool to convert Trimble Data Exchange total station data to either the Carlson RW5 format or the C&G CGR format.

The following dialog box is displayed after choosing this option.

First choose the file format of the GPS vector file to be converted. Next use the 'Select' button to navigate to the vector file to be converted. If you are converting a Thales file you have the option to remove the leading 0's from Thales point numbers. Next, use the second 'Select' button to select the name of the new ASCII GPS vector file to be created. Choose the 'Convert' button to initiate the file conversion. Press the 'Cancel' button when you have completed the conversions. The file created will have an extension of .GPS. Following are the different GPS formats that can be converted to ASCII.

Ashtech/Thales 'O' files: Typically have .obn extensions and are binary files. Notice that you have the option to remove the leading 0's from Thales point numbers, by checking the "Remove leading 0's from Thales point numbers" check box.

LandXML (.XML): The landXML format is an industry standard format. Currently SurvNet will only import LandXML survey point records. The conversion will not import LandXML vectors.

Leica: The Leica vector file is an ASCII format typically created with the Leica SKI software. This format is created by Leica when baseline vectors are required for input into 3rd party adjustment software such as SurvNet. The SKI ASCII Baseline Vector format is an extension of the SKI ASCII Point Coordinate format.

NGS G-File: National Geodetic Survey format.

NGS G-File from OPUS report: National Geodetic Survey format as used in the OPUS report

Topcon (.TVF): The Topcon Vector File is in ASCII format and typically has an extension of .TVF

Topcon (.XML): The Topcon XML file is an ASCII file. It contains the GPS vectors in an XML format. This format is not equivalent to LandXML format.

Trimble Data Exchange Format (.ASC): The Trimble TDEF format is an ASCII file. It is typically output by Trimble's office software as a means to output GPS vectors for use by 3rd party software.

Trimble Data Collection (.dc): The Trimble .dc format is an ASCII file. It is typically output by Trimble's data collector. It contains a variety of measurements including GPS vectors. This option only converts GPS vectors found in the .DC file.

Trimble LandXML, (*.jxl): This is Trimble's Land XML format.

The Trimble Data Collection (.dc) and Trimble LandXML (.jxl) formats allow you to bring in both GPS vectors (creating a .GPS file) and Total Station data (creating a .RW5 file) at the same time.

Convert Level Files

The purpose of this option is to convert differential level files from digital levels into C&G/Carlson differential level file format. At present the only level file format that can be converted are the level files downloaded from the Topcon digital levels.

However, the Level Editor has several IMPORT options which expands the types of files you can convert:

EDM Calibration

The EDM Calibration program allows a surveyor to enter and process the raw data collected on an EDM calibration baseline. The purpose of an EDM calibration is to determine if the EDM is measuring within standards. The program performs a statistical analysis of that data as outlined in "Use of Calibration Base Lines", by Charles J. Fronczek, NOAA Technical Memorandum NOS NGS-10. The NGS document can be downloaded from the NGS website. NGS maintains a webpage on EDM Calibration Base Lines. The manual and other information on EDM calibrations can be found at http://geodesy.noaa.gov/CBLINES/calibration.shtm. Following is the main EDM Calibration dialog box. NGS publishes the EDM calibration data in metric units. SurvNet's EDM calibration program currently expects the data to be collected in meters.

The basic flow of this program is to first fill out the lower portion of the dialog box which contains different text fields, EDM constant values, and the optional Atmospheric Corrections settings. Next, fill out the grid in the upper portion of the dialog box. This grid contains the field data collected and also the published distances between monuments of the baseline. After this information has been filled out use the 'Compute' button The program will then display the result of the calibration in the window in the lower portion of the dialog box as follows.

After the file is processed the results can be stored as an ASCII text file. Use the 'Save Output' or the menu option "File/Save Results File As...". to save the results. First, you will be prompted for an output file name. The input data can also be stored. Once stored it can be opened and processed again.

Following is the entire output with a brief explanation of the results. Comments about the results are inserted in bold.

The above section shows the input. The input consists of the observed slope distances and the measured HI's. The from and To elevations are published data from the data sheet from NGS on the particular baseline being observed. The published distances are also published data from the data sheet from NGS. In this example atmospheric pressure was turned off so the temperature and Pressure fields are irrelevant.

If the scale error and the EDM constant are 0.0 then the edm is without error. So the purpose of the statistical test is to test how close to 0.0 are the results.

The two above lines show the values for the computed scale error and constant error.

The two above lines show the values for the computed standard errors of the scale error and constant error.

The above lines show the final results of the statistical test. Since the test determined that we cannot reject the null hypothesis, this edm is in good working order.

EDM Calibrations and Atmospheric Corrections

The atmospheric correction algorithms used in the edm calibration are from the NGS manual. To use this method both dry-bulb and wet-bulb temperature needs to be measured, or the vapor pressure, e, and the dry bulb temperature needs to be measured. Refer to the NGS documentation for a detailed explanation of the atmospheric corrections that they use.

It is probably most common to turn atmospheric correction off in the calibration program, and turn atmospheric correction ON on the EDM (total station). When atmospheric correction is turned off in the calibration program the user does not need to enter the temperature into the grid or any of the other atmospheric values. If atmospheric corrections are turned OFF then the grid input columns 'Temp.(dry bulb)', 'Pressure, (mm of Hg)', and 'Temp. (wet bulb)' will not be displayed since they are not needed.

Constants can be entered for both the EDM and the reflector. These values are added to the observed distances during processing. Typically they are set to 0.0.

The following text fields have no effect on any computations and are simply comments that can be used to document the calibration.

Entering Data Into the EDM Calibration Grid

Blank data records are inserted into or deleted from the grid using the following tool bar.

The first button deletes the current highlighted record. The second button inserts a new blank record before the current highlighted record. The third button inserts a new blank record after the current highlighted record. Alternately the 'Edit' menu options could be used to delete and insert new data records.

Following is a brief explanation of the fields that make up the grid.

From Sta. - This field represents the station name where the EDM is located. Any name can be used, but you must be consistent and used the same name whenever you occupy or measure a distance to the station.

From HI. - This field represents the height of instrument of the from station. It should be in the same units as the measurements. If horizontal distances are being entered into the grid then all the HI fields should be set to a constant value such as 0.0.

From Elev. - This field represents the elevation of the station. This value is published as part of the baseline calibration sheets obtained from NGS. If horizontal
distances then all the Elevation fields should be set to a constant.

To Sta. - This field represents the station name where the prism is located. Any name can be used, but you must be consistent and used the same name whenever you occupy or measure a distance to the station.

To HI. - This field represents the height of instrument of the to station. It should be in the same units as the distance measurements. If horizontal distances are being entered into the grid then all the HI fields can be set to a constant value such as 0.0.

To Elev. - This field represents the elevation of the station where the prism is located. This value is published as part of the baseline calibration sheets obtained from NGS. If horizontal distances then all the Elevation fields should be set to a constant.

Observed S. Dist. This is the measured slope distance. This can be a measured horizontal distance. If it is a horizontal distance then all the HI's and elevations should be set to a constant value.

Published Dist. This field represents the published distance between the From and To station. This value is published as part of the baseline calibration data obtained from NGS for the particular baseline being observed.

Temp. (dry bulb) This field is only present if atmospheric corrections are turned on.

Temp. (wet bulb) This field is only present if atmospheric corrections are turned on.

Pressure. (mm of Hg) This field is only present if atmospheric corrections are turned on.

Edit Output Files

You can edit any of the output files created by SurvNET processing:
    Report File (.RPT)
    NEZ File (.NEZ - ASCII coordinate file)
    Formatted NEZ File (.OUT - ASCII coordinate file)
    Error File (.ERR) - file containing list of processing errors).
SurvNET will use Microsoft Notepad as the editor.