SID File Data - Line Measurement Data and Ties to Survey Documents

Field Name

Datatype

CDCS name

NOTE:

Angle_err_est

Numeric

none

Allows angles to be calculated then used in the adjustment with an angle_err_est. Format for value is A DD.MMSSss, appended to Bearing_Type in SID file, Ex: BT:GA 0.0530.

Direction_correction

Numeric

none

Constant to be applied to each measurement to achieve truer representation of direction. This would be applied when the correction has been validated.

Format: DD.MMSSss

GMM example: BC:-0.0025 means move 25 seconds in counter-clockwise direction

Direction_err_est

Numeric

none

This is the estimate of the direction (bearing|azimuth) error. Seconds units.

Direction_type

String

units of measure link -> direction type

Basis of bearing or basis of azimuth.

GMM values: BT:M (mean), BT:F (forward), BT:G (grid), BT:C (compass/magnetic) or BT:L (local/assumed). CDCS values: Assumed, Astronomic North, Astronomic South, Geodetic North, Geodetic South, magnetic North, Magnetic South, free text, unkown

Distance_correction

String

none

Constant and ppm Multiplier to be applied to each measurement to achieve truer representation of distance. This would be applied to a surveyor is known to have used a short|long steel tape or out-of-adjustment EDM.

GMM example: DC:-.05 +1.03 means subtract .05 from distance then multiply result by 1.03.

Distance_err_est_constant

Numeric

none

This is the estimate of the distance error irrespective of line length, feet units

Distance_err_est_PPM

Numeric

none

This is the estimate of the distance error that is based on the line distance. Parts Per Million.

Distance_type

Char

units of measure link -> distance type

Describes reference surface for the distance.

Allowable GMM values: DT:G (ground), DT:E (ellipsoid), or DT:P (plane/grid)

Distance_unit

Numeric

units of measure link -> distance unit

In GMM, codes are F, I, M and C to represent survey feet, international feet, meters and chains. A more flexible system would store the divisor to convert current units to a baseline unit such as survey feet. Ex: survey feet = 1.0, chains = 66, and meters = 3.2808333.

Lat_measurement_err_est

Numeric

none

This field is irrelevant and has never been implemented.

Long_measurement_err_est

Numeric

none

This field is irrelevant and has never been implemented.

SID_code

Char

n/a

An "S" in the first column denotes a line with Survey_ID and error values.

A "C" in the first column denotes free text comments, although some lines contain standard formats.

SID_suffix

String

none, see notes.

Additional categorization of lines, appended to Survey_ID.

On alphanumeric Survey IDs, a hyphen delimits the ID with the suffix.

Standard values BLM-wide:

  • TIE used on non-boundary lines. Denotes invisibility in coverage. Connector Line
  • LC means Long Chord of curve. Denotes invisibility in coverage. None
  • RP follows Long Chord entry. Invisible line segment to Radius Point. None
  • PBLT Protracted Bearing Line True, an example of a line in an Amended Protraction Diagram. None

There are often arbitrary user-assigned values that separate out different areas within a survey that have differing reliabilities. Ex. 7123-A, 7123-B.

Note: In GMM nomenclature the "SID number" refers to both the Survey_ID and SID_suffix.

Survey_ID

String

source link

Unique alphanumeric identifier that identifies a particular source document for brg/dists There are only local standards for these values. There can be several values for any given survey.