Benchmark

1. What is a Benchmark?
2. Benchmark Types
3. NGS Datasheets
4. Benchmark Data Sources
5. Prepare Benchmark Database
6. Export Benchmarks as POI
7. Export Benchmarks as Waypoints
8. Export Benchmarks as Geocaches
9. Record Benchmark Visits
10. Benchmarking Apps

• Benchmarking Discussion Forum

1. What is a Benchmark?

• Benchmark Definition
  
  
  • 'Benchmark' is a generic term commonly used to reference geodetic control points.
  • A geodetic control point is a monumented or otherwise marked survey point established for the purpose of providing geodetic reference for mapping and charting activities as well as a wide variety of engineering and scientific applications.
  • Most geodetic control point positions have been recorded with a high level of accuracy well beyond consumer grade GPSr capabilities.
    
    

2. Benchmark Types

• Vertical Control Points
   
  • Markers that are known to have very precise elevation values.
  • This 'Vertical Control' is commonly referred to as a 'Bench Mark' by professional surveyors.
  • Bench Marks usually include the text 'BENCH MARK' near the outer edge of the disk.
  • May exist in many forms, including disks, bolts, rivets, chiseled squares and crosses, etc.
    
    
• Horizontal Control Points
   
  • Markers that are known to have very precise latitude and longitude values.
  • This 'Horizontal Control' is commonly referred to as a 'Station' or 'Mark' by professional surveyors.
  • Multiple types exist based on establishing control system and level of precision represented.
  • Most commonly marked with a disk, but can also take the form of bolts, rivets, chiseled crosses, etc.
    
    
• Intersection Stations
   
  • Intersection stations are a type of horizontal control mark.
  • Usually take the form of a prominent landmark, such as a water tower, radio tower, church spire, mountain top, or other object higher in the air than the surroundings, making it visible from many miles away.
  • Can be used to determine positions along the Earths surface when observed through a telescope.
    
    
• Triangulation Stations
   
  • Triangulation stations are a type of horizontal control mark.
  • Frequently take the form of a metal disk with a small triangle in the center.
  • Usually include the text 'TRIANGULATION STATION' near the outer edge of the disk.
  • Triangulation stations positions are determined by measuring distances and angles from other stations.
  • Typically associated with nearby reference mark disks and an azimuth mark disk.
    
    
• Reference Marks
   
  • Primarily used to prevent the location of a triangulation station from being lost.
  • Triangluation stations usually have two or more reference marks associated with them.
  • Reference marks have an arrow in their center pointing toward their associated triangulation station.
  • Not an actual geodetic control mark.
    
    
• Azimuth Marks
   
  • Used with its associated triangulation station to determine an accurate azimuth based on true north rather than magentic north.
  • Azimuth marks also have an arrow in their center pointing toward their associated triangulation station.
  • Not an actual geodetic control mark.
    
    
• Cadastral Marks
   
  • Primarily used to mark land boundaries.
  • Not an actual geodetic control mark.
    
    
• Additional types
   
  • Other types of horizontal control marks not associated with reference marks or azimuth marks include 'traverse stations', 'trilateration stations', and 'GPS stations', each frequently including those words printed near their outer edge.
    
    

3. NGS Datasheets

• Definition:
   
  • An NGS Datasheet is an ASCII text file consisting of rigorously formatted lines, each 80 columns wide.
  • Each datasheet includes information necessary to identify and locate a specific survey monument.
  • This unique datasheet format is commonly referred to as 'Digital Survey Data', or 'DSDATA'.
  • When multiple datasheets are combined into a single document, they are referred to as a 'DSDATA file'.
  • See NGS DSDATA Format to view additional detailed information.
     
• Format Overview:
  
  
  • Each NGS Datasheet will include most of the following information:
     
    • PID
       
      • This is a permanent identifier unique to each survey monument.
      • Always formatted as two letters followed by four numbers 'AB1234'.
        
        
    • Designation
       
      • This is the survey monuments name, and has no set format restrictions.
      • 'JONES', 'E 37 RESET', and 'WASHINGTON MONUMENT 1913' are all valid examples.
        
        
    • Coordinates
      
      
      • This is the survey monuments recorded position displayed in the DDD° MM' SS.S" coordinate format.
      • These coordinates are always accompanied by one of the following:
         
        • ADJUSTED - 'Location Adjusted' coordinates are the most stable, reliable, and accurate, as they are computed using advanced surveying techniques far more accurate than any consumer grade handheld GPSr.
        • SCALED - 'Location Scaled' coordinates are not very accurate, as they are manually derived by estimating their location using a scale (ruler) with a topographic map, and can be off by several hundred feet.
          
          
    • Box Score
      
      
      • Some NGS datasheets (usually triangulation stations) include data enclosed in a 'box' made of dashes '-' and vertical bars '|'.
      • Inside this box are the distances and azimuths from the PID to other stations, reference marks, or azimuth marks.
      • This information is useful for finding the main station from its reference marks or vice versa.
        
        
    • Station Description
      
      
      • This is a description of the station as written by the agency placing the survey monument, including:
      • Directions for locating the monument using local landmarks (valid when the monument was placed).
      • Distance and compass direction from local landmarks to the station.
        
        
    • Recovery Reports
      
      
      • Notes left by previous visitors that may include any of the following:
      • Satellite visibility and equipment used.
      • Recorded position (coordinates and brief description of location).
      • Mark condition (good, poor, not found, destroyed).
      • Photos (macro, wide angle, includes witness post and/or prominent landmarks).
        
        
• Sample Datasheets
  
  
  • Review these NGS Sample Datasheets to become more familiar with the information they provide.
    

4. Benchmark Data Sources

• United States
  
  
  • National Geodetic Survey
     
    • The mission of the National Geodetic Survey (NGS) is to define, maintain and provide access to the National Spatial Reference System (NSRS).
    • The NSRS provides a consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States and its territories.
      
      
    • Archived Datasheets
      
      
      • Download geodetic control point data for an entire state.
      • Archives for each state are updated monthly.
      • Recommended for users wanting to create a complete station database.
        
        
    • NGS Data Explorer
      
      
      • Search for geodetic control points on an interactive map.
      • Download individual datasheets for selected stations.
      • Recommended for users searching for stations in a specific geographic location.
        
        
    • NGS Database Search
      
      
      • Retreive individual geodetic control point datasheets by:
        
        
        • Station Name
        • Station PID
        • County
        • Radial Search
        • Rectangular Search
        • USGS Quad
        • Project Identifier
        • Load Date
        • CORS Site ID
    
    
    
  • Groundspeak  (Destroyed 04JAN23)
    
    
    • Groundspeak also provides access to a partial and incomplete benchmark database.
    • Created using data obtained from the NGS database in the year 2000.
    • Does not include updated recovery notes or information for newer and older benchmarks since added to the NGS databse.
    • Will include logs posted by geocachers that are not included in NGS datasheets.
    • Groundspeak benchmark downloads (*.loc) include only the station PID and coordinates with no additional information provided.
      
      
    • Groundspeak Database Search
      
      
      • Find benchmarks by Coordinates, Postal Code or Designation.
      • Results are displayed 25 per page, and can be downloaded in *.loc format individually or one page at a time.
      • Groundspeak *.loc files include only the station PID and coordinates with no additional information provided.
        
        
    • Near a Geocache
      
      
      • Each geocache page includes a link to find nearby benchmarks, located between the description and logged visits:
        
        
        
        
      • Results are displayed 25 per page, and can be downloaded in *.loc format individually or one page at a time.
      • Groundspeak *.loc files include only the station PID and coordinates with no additional information provided.
        
        
        
  • Waymarking
     
    • Select and download desired benchmarks in *.gpx format from the Waymarking categories below:
       
      • US Benchmarks
      • US Historic Survey Stones and Monuments
      • Azimuth Benchmarks
        
        
    • Import downloaded *.gpx files directly into GSAK.
      
      
      
      
• Canada
  
  
  • Waymarking
     
    • Select and download desired benchmarks in *.gpx format from the Waymarking categories below:
       
      • Canadian Benchmarks
        
        
    • Import downloaded *.gpx files directly into GSAK.
      
      
      
      
• Europe
  
  
  • Waymarking
     
    • Select and download desired benchmarks in *.gpx format from the Waymarking categories below:
       
      • Belgium Benchmarks
      • Czech Geodetic Points
      • Danish Benchmarks
      • Dutch Benchmarks
      • French Benchmarks
      • German Benchmarks
      • Portugal Geodetic Points
      • Spain Geodetic Vertices
      • UK and Ireland Trigpoints
      • European Historic Survey Stones, Monuments and Benchmarks
        
        
    • Import downloaded *.gpx files directly into GSAK.
      
      
      
      
• South America
  
  
  • Waymarking
     
    • Select and download desired benchmarks in *.gpx format from the Waymarking categories below:
       
      • Latin American Benchmarks
        
        
    • Import downloaded *.gpx files directly into GSAK.
      
      
      
      
• Africa
  
  
  • Waymarking
     
    • Select and download desired benchmarks in *.gpx format from the Waymarking categories below:
       
      • Southern African Trig Beacons
        
        
    • Import downloaded *.gpx files directly into GSAK.
      
      
      
      
• Australia & New Zealand
  
  
  • Waymarking
     
    • Select and download desired benchmarks in *.gpx format from the Waymarking categories below:
       
      • Australia/NZ Benchmarks
      • Australian Trig Points
        
        
    • Import downloaded *.gpx files directly into GSAK.
      
      
      
      
• World-Wide
  
  
  • Waymarking
     
    • Select and download desired benchmarks in *.gpx format from the Waymarking categories below:
       
      • Public Land Survey Marks
      • Greenwich Meridian Markers
      • Milestones
        
        
    • Import downloaded *.gpx files directly into GSAK.
      
      

5. Prepare Benchmark Database

• Benchmark data downloaded from the resources listed above must be processed before exporting to a GPSr.
• The example workflows provided below make use of the following Windows PC software titles:
  
  
  • GSAK: A powerful and popular geocache management tool (Direct Download)
  • NGS>GPX: A small utility for converting NGS datasheets into GPX files (Direct Download)
    
    
• Tip: If having difficulty achieving the desired results, carefully recheck all options for each step in the process.
  
  
  
• NGS Database Preparation
  
  
  • Create an empty working directory on your computer.
    
    
    
    
  • Download and copy data files to the working directory.
    
    
    
    
  • Unzip compressed folders when present.
    
    
    
    
  • Open the NGS>GPX program.
    
    
    
    
  • Select File > Settings > Defaults > Yes, then configure Processing > Output as shown below, and select OK.
    
    
    
    
  • Drag the *.txt file containing the NGS datasheets to the NGS>GPX window and release.
    
    
    
    
  •  Select Process.
    
    
    
    
  • NGS datasheets are read...
    
    
    
    
  • NGS datasheets are written to file...
    
    
    
    
  • Wait for NGS data conversion to complete, then select Close.
    
    
    
    
  • Repeat NGS>GPX Conversion process for each datasheet when working with multiple downloads.
    
    
  • Start GSAK program and open or create a Benchmark database.
    
    
  • Drag the *.gpx file to the GSAK window and release.
    
    
    
    
  • Configure GSAK import options as displayed below, and select OK.
    
    
    
    
  • The resulting GSAK database should appear similar to what you see below when using NGS>GPX:
  • (displayed columns and symbols may vary when using data downloaded from other sources)
    
    
    
    
  • Repeat GSAK database file import process for each datasheet or *.gpx file when working with multiple downloads.
    

6. Export Benchmarks as POI

• Recommended only for Garmin devices unable to use *.gpx or *.ggz file formats.
• Provides minimal benchmark information (Longitude, Latitude, PID and Designation).
• POI Benchmarks can not be searched, filtered or logged using the geocaching features available on your Garmin navigator.
• For additional detail and improved functionality, see Export Benchmarks as Geocaches.
  
  
• Open GSAK benchmark database prepared above.
  
  
  
  
• Select View > Add/Remove Columns..., and configure displayed columns precisely as shown:
  
  
  
  
• Select File > Export > CSV or TXT..., edit 'File Name', configure options as shown, then select Generate.
  
  
  
  
• Copy *.csv file created by GSAK to Create a Custom POI.
  
  
  
  
• A new benchmark *.gpi file will now be present in the [GPSr]\Garmin\POI\ directory:
  
  
  
  
• Restart the GPSr to view benchmarks displayed as POI:
  
  
  

 

 

7. Export Benchmarks as Waypoints

• Why?
  

 

 

8. Export Benchmarks as Geocaches

• Trick or Treat?
  
  
  • While modern Garmin devices do not currently support benchmarks, they do support many traditional geocache types.
  • A majority of these Garmin GPSr will also allow the user to Personalize Your Map with Custom Symbols.
  • Early navigators did not provide support for geocaches, which had to be loaded as simple waypoints without any additional information.
  • When geocaching support was first introduced, Garmin simply included two additional waypoint symbols, 'Geocache', and 'Geocache Found'.
  • Future models would add support for the more common geocache types, displaying each of them using their own unique symbols.
  • On these devices, the 'Geocache' symbol now only appears if/when an unsupported geocache type is encountered.
  • To enable Benchmarking, the Trick is to ensure that all unsupported geocache types loaded to our device are Benchmarks only.
  • And the Treat is the ability to search, view, hunt, and log Benchmarks on our Garmin GPSr just like geocaches!
    
  
  
  
  
• Export to GPX
  
  
  • Recommended for Garmin devices that do not support the *.ggz file format.
  • Limited by the maximum number of geocaches and *.gpx files specified for the device.
  • GPX Benchmarks can be searched, filtered and logged using the geocaching features available on your Garmin navigator.
  • Must copy desired benchmark symbol to [GPSr]\Garmin\CustomSymbols\Geocache.bmp.
  • Do not load *.gpx and *.ggz files that include duplicate benchmarks to the same device.
  • To improve device indexing speed and avoid *.gpx file limitations, see Export to GGZ.
    
    
  • Open GSAK benchmark database prepared above.
  • Select View > Add/Remove Columns..., and configure displayed columns as shown:
    
    
    
    
  • Select Database > Global Replace..., configure options as shown, and select Replace.
    
    
    
    
  • All benchmarks in database should now display 'Geocache' in 'Symbol' column:
    
    
    
    
  • Select File > Export > GPX/GGZ/LOC File..., edit 'File name to create', configure options as shown, then select Generate.
    
    
    
    
  • Copy *.gpx file created by GSAK to the [GPSr]\Garmin\GPX\ directory, or [microSD]\Garmin\GPX\ directory.
    
    
    
    
  • Restart the GPSr to view benchmarks displayed as geocaches:
    
    
    
  
  
  
  
  
• Export to GGZ
  
  
  • Recommended for all Garmin devices that support the *.ggz file format.
  • Allows the user to load an unlimited number of benchmarks and provides improved indexing performance.
  • GGZ Benchmarks can be searched, filtered and logged using the geocaching features available on your Garmin navigator.
  • Must copy desired benchmark symbol to [GPSr]\Garmin\CustomSymbols\Geocache.bmp.
  • Do not load *.ggz and *.gpx files that include duplicate benchmarks to the same device.
  • For devices that do not support the *.ggz file format, see Export to GPX.
    
    
  • Open GSAK benchmark database prepared above.
  • Select View > Add/Remove Columns..., and configure displayed columns as shown:
    
    
    
    
  • Select Database > Global Replace..., configure options as shown, and select Replace.
    
    
    
    
  • All benchmarks in database should now display 'Geocache' in 'Symbol' column:
    
    
    
    
  • Select File > Export > GPX/GGZ/LOC File..., edit 'File name to create', configure options as shown, then select Generate.
    
    
    
    
  • Copy *.ggz file created by GSAK to the [GPSr]\Garmin\GGZ\ directory, or [microSD]\Garmin\GGZ\ directory.
    
    
    
    
  • Restart the GPSr to view benchmarks displayed as geocaches:
    
    

 

 

9. Record Benchmark Visits

• Benchmark Logging Protocol
  
  
  • Consistent and reliable descriptions can help when appraising a mark's fitness for use and aid in station recovery.
  • Please include the following information when logging Benchmark finds (Groundspeak) and Survey Mark Recoveries (NGS).
    
    
    • Date: Include the date and time for the station observation, not the log entry.
      
      
    • Log Type:
      
      
      • Found - Must first verify the station PID, Designation and description all match the datasheet precisely.
      • Not Found - Unable to locate after significant effort with no evidence of station destruction present.
      • Destroyed - Only used when irrefutable evidence of destruction is present, otherwise report as 'Not Found'.
        
        
    • Mark Condition:
      
      
      • Good - No evidence of tampering, subsidence, frost heave, etc. Likely in original location and condition.
      • Poor - Obvious damage present or movement excessive for designated stability and/or accuracy.
      • Destroyed - Only used when irrefutable evidence of destruction is present. 'Missing' is not 'Destroyed'.
        
        
    • Description:
      
      
      • Provide a description of the marks appearance, general condition and surrounding area.
      • Include your GPSr averaged coordinates for 'Location Scaled' marks.
        
        
    • Photos:
      
      
      • Photos are very helpful for confirming station identification and condition and therefore highly encouraged!
        
        
        • Close Up - A full frame photo of the mark with all text and stampings clear, focused and legible.
        • Eye Level - Photo taken two or three meters from mark, showing immediate surrounding area.
        • Horizon - One or more photos demonstrating the mark's location in relation to area landmarks.
        • Equipment - One or more photos of the equipment used to locate and record mark location.
      
      
      
      
• National Geodetic Survey
  
  
  • In an effort to maintain updated records on more than 800,000 survey marks set around the country and its territories, the National Geodetic Survey encourages the public to submit their survey mark recovery information.
  • Open the Mark Recovery Dashboard to view station recoveries that have been submitted to NGS.
  • Visit the NGS Survey Mark Recovery Help page to view helpful survey mark observation guidelines.
    
    
    • NGS Mark Recovery Form
    
    
    
    
• Groundspeak (Destroyed 04JAN23)
  
  
  • The Groundspeak benchmark database has not been updated since it was originally created in the year 2000.
  • Will not include updated recovery notes or information for newer and older benchmarks since added to the NGS databse.
  • Benchmarks not found in the groundspeak database can (and should) still be logged at the National Geodetic Survey website.
  • Groundspeak benchmark pages can be located via:
    
    
    • Direct Link (add six digit station PID to end of link).
    • Database Search (enter station designation).

 

 

10. Benchmarking Apps

• Mobile phone apps that can enhance your Benchmark hunting experience!
  
  
  • Android
    
    
    • Benchmap - Search and view National Geodetic Survey (NGS) survey stations on an interactive map.
    • Benchmark Explorer - Search the National Geodetic Survey (NGS) database to discover benchmarks near your location.
      
      
  • iOS
    
    
    • (still looking)