Good descriptions help surveyors appraise a mark's fitness for use and aids in mark recovery. To help you in writing good descriptions, the primary metadata elements are illustrated below.
A.
* via Mark Recovery B.
* via
DSWORLDC.
via
OPUSD.
via
WinDescvisibility ←
←from GPS
uses
all these,
& moreposition condition condition condition notes notes notes photos photos stamping stamping designation type type setting setting rod depths application magnetic magnetic stability stability equip. IDs
* use these only for marks already published.
Tools:
- Observer field log and other survey forms
- For details, see the Description Processing Handbook and datasheet metadata.
Geodetic control marks report accuracy bounds for each position value. These accuracies are estimated from the survey technique used and the coherence of the survey within the existing network. They describe a 95% confidence region surrounding the datum point. Separate local and network accuracies describe the tolerances to adjacent, directly connected marks and to the NSRS network as a whole, respectively. See FGDC accuracy standards for details.
YES, SUITABLE
it depends
UNSUITABLE
Survey marks should have a generally open view of satellites passing overhead, relatively clear of tall obstructions nearby (buildings, trees, wires.) Older marks, set before the satellite era, are often unsuitable.
Tools:
visibility obstruction diagram [optional]
Many older bench marks were positioned using only scaled map coordinates. If you have a more accurate position, report the latitude and longitude. Acceptable positions come from the following sources:
- ±10 m: GNSS handheld: e.g., consumer-grade GPS with or without WAAS correction.
- ± 1 m: GNSS survey: e.g., engineer-grade GPS with differential or kinematic correction.
GOOD
No evidence of tampering or movement (subsidence, frost heave, etc.)
NOT FOUND
Description insufficient or existance doubtful. Recovery unlikely without extraordinary effort.
DESTROYED
Irrefutable evidence of destruction. Absent such first-hand evidence, report as "not found"
NEW MARKS
Describe new marks by noting distances and directions to local witnesses (posts, trees, curbs, etc.) along with any other salient features (recommended approach, hazards, etc.). This will help future surveyors recover and assess the suitability of your mark.Example: The mark is at the highest point of a small hill, known locally as Hassler's hill, a 5 minute hike west from a parking lot at 1843 Bache St, Peirce City, MO.
Located in the SW corner of a 2 ft square concrete pad projecting 0.3 ft above ground, 3.3 ft S from S edge of sidewalk, 26.6 ft NE from a 15" oak tree, 9.9 ft W (bearing 282) from utility pole 123A.
PUBLISHED MARKS
Describe published marks by briefly updating the last description.Example: Recovered as described in 2010, except utility pole 123A is now gone. Mark is 32.1 ft south from centerline of gravel driveway accessible from 1874 Patterson Ave. Ownership is now Hilgard city park.
Example: Recovered as described.
Tools:
- Mark description / recovery forms [optional]
- Consider also other recovery note and photo archives, e.g., geocaching websites.
CLOSE-UP
highlight stamping with chalk,
use macro mode, oblique angle
to show mark condition, avoid
shadows
EYE-LEVEL
remove dirt & debris to show
monument extent, open the logo
cap, add a placard to identify
mark and demonstrate scale
HORIZON
align view to include witnesses
&/or visibility obstructions, show
equipment in use to document
setup and clarify mark location
Please only submit photos which add a unique and unambiguous view of a mark's location, condition, or utility for future surveys.
Tools:
For details, see photos for DSWORLD/WinDesc and contracting SOW.
Consider also other recovery note and photo archives, e.g., geocaching websites.
Stamping is the unique ID, if any, that the original marksetter struck into the tablet.
Example: "MEADES RANCH 1891" as shown at right.
Do not physically alter an existing mark unless you are conducting a formal mark reset.
Designation (aka "name") is a user-friendly identier, unique for the area and usually descriptive of the mark stamping &/or location.
Examples: MEADES RANCH, WASHINGTON MONUMENT, Q 132 RESET
Tools:
- Search our database by mark designation to ensure your proposed designation is unique.
- See bluebook annex D for historic naming conventions.
Knowing what to look for improves mark recovery and may explain stability problems.
Specific setting allows you to add comments about the setting. E.g., Setting = "Light structure", specific setting = "4x8 ft concrete storm drain". These improve mark recovery and may explain stability problems.
Survey marks should be stable, permanent, unique, recoverable, and safe-to-use. Avoid mark proliferation by finding & re-using existing marks whenever practicable.
Tools:
See mark setting guidelines at bench mark reset, NOAA Manual NOS NGS 1, and contract attachments T, U, and V.
Rod and sleeve depths refer to the lengths of material used to construct a rod mark, useful in judging stability and subsidence. Leave these blank unless you set the mark &/or have specific knowledge of the lengths.
Rods may flex during installation, actual "depth" may be less than the length.
PLSS CORNER
Cadastral boundary corner of the US Public Land Survey System
TIDAL MARK
A reference mark witnessing the tidal datum for a water level measuring gauge.
FAULT MONITORING
Established to monitor local or regional crustal instability.
We highlight just a few common uses, to aid in organization and search.
Cadastral surveyors occasionally include magnetic material in or alongside the setting to aid in mark recovery. This is generally avoided for geodetic marks.
Use a magnet to test.
Stability is your best estimate of the mark's ability to maintain a long-term, constant position relative to other local features. Consider the setting quality, soil type, threats from construction or traffic, etc.
Antenna Type: see OPUS.
Example: "TRM29659.00" above.
Antenna S/N: Serial number, usually on a label underneath the antenna. Example: "0220356892" above.
Receiver Model: the brand name.
Example: "GRX1200 PRO" above.
Receiver S/N: Serial number, usually on a label on the back of the unit. Example: "462886" above.
Reciever Firmware: usually within the receiver config. menu. Example: "7.28" above.
These identifiers could facilitate equipment tracking to isolate performance problems.
