Control Points are locations with known coordinates in a defined geodetic spatial reference system and reported at a known level of accuracy. A further distinction can be drawn between geodetic or government control monuments (whose co-ordinates and other properties are recorded in the Province’s MASCOT control database) versus various forms of Survey control point (which have coordinates derived by individual surveyors, as part of a specific project, and which are only tracked within the PMBC database).
The following table contains the Control Point attributes and descriptions.
| Attribute Name | Description |
|---|---|
| GlobalID |
Unique global identifier for the feature Values: System-generated |
| Name |
Unique identifier of a geodetic control monument or georeferenced point. Values: For geodetic control or vertical benchmarks, this is the GCM number from MASCOT. For control points received through surveyor submissions, it is a combination of Plan Number and a Description of the marker. Notes: Other types of control point (i.e. GeoBC or field cadastral ties) are generally identified with a standard prefix (‘P’, ‘F’, etc.) |
| TabletMarking |
Identifier of a geodetic control point or vertical benchmarks as stamped on cap in field and recorded in MASCOT. Values: Free text field (maybe NULL) Notes: This is the description recorded in a survey plan. |
| HorizontalClass |
The Horizontal Class field within the MASCOT Control database Values: Integrated Notes: More information can be found at MASCOT System Screen Generated Reports |
| Type |
Describes the control point subtype Values: See Control Type domain for more details. |
| PointID |
Corresponding fabric point ID if available
|
| SurveyDate |
The date the control point was surveyed/established. Values: DD/MM/YYYY Notes: Comes from source, either as the date of the last Coordinate revision (from the MASCOT database) or as the date a Field survey was completed. |
| Active |
True if control point is active Values: 0 (Inactive) or 1 (Active) Notes: If true, control point has been associated to the fabric point referenced in the Name field. A control point needs to be active to be used in the fabric adjustment. |
| E |
X-Coordinate of the point feature class in BC Albers Values: System-generated Notes: Spatial coordinates of the ArcGIS Point feature class, not the permanent coordinates of the Control Point itself. |
| N |
Y-coordinate of the point feature class in BC Albers Values: System-generated Notes: Spatial coordinates of the ArcGIS Point feature class, not the permanent coordinates of the Control Point itself. |
| Z |
Height of the fabric point in metres above mean sea level Notes: Refer to the ‘AccuracyZ’ and ‘ElevationClass’ fields to understand how the ‘Z’ value was derived and the absolute positional accuracy of the elevation. |
| EAccuracy |
Horizontal accuracy of the Control. A statistical estimate of the likelihood the reported coordinates are close to true location of the measured point. Values: E-coordinate accuracy at 95% confidence level in metres Notes: derived from the Standard Deviation in Longitude recorded in MASCOT; field only applies for geodetic control points. |
| NAccuracy |
Horizontal accuracy of the Control. A statistical estimate of the likelihood the reported coordinates are close to true location of the measured point. Values: N-coordinate accuracy at 95% confidence level in metres Notes: derived from the Standard Deviation in Latitude recorded in MASCOT, field only applies for geodetic control points. |
| ZAccuracy |
Z-coordinate (elevation) accuracy at 95% confidence level Values: in Metres Notes: Generally derived from metadata provided by a Surveyor during submission. A value of ‘10’ indicates that the elevation was estimated from a Digital Elevation Model and not surveyed. |
| OriginalSR |
Defines the Spatial Reference System used for the original coordinates. Values: See Original SR domain for more details. |
| OriginalRealization |
Defines the realization, datum, and version used for the original coordinates. Values: See Original Realization domain for more details. |
| SurveyMethod |
The type of survey used to measure original coordinates of a control point. Values: Free text field Notes: If the survey plan type = “Survey” this will be populated from metadata by a Surveyor during submission. It will be the same as the ‘Georeferencing Method’ field of the survey plan that created the control. |
| PlanNumber |
The name of the survey plan that created the control. Notes: If the survey plan type = “Survey” this will be populated from metadata by a Surveyor during submission. |
| CreatedDate |
Date when control point was entered in the fabric. Values: System-generated Notes: DD/MM/YYYY |
| ModifiedDate |
Last date the control point record was modified in PMBC. Values: System-generated Notes: DD/MM/YYYY |
| Condition |
Tracks the physical condition of a geodetic control point, as recorded in MASCOT. Values: GOOD, ANOMALOUS, DESTROYED Notes: ANOMALOUS indicates that the recorded coordinates are suspect and do not fit with the surrounding Control network. |
| OriginalX |
The X coordinate in the original Spatial Reference System. Values: Easting in a UTM NAD83 CSRS spatial reference Notes: Surveyed X-Coordinate (optional) provided by Land Surveyors during submissions or from published values in MASCOT. |
| OriginalY |
The Y coordinate in the original Spatial Reference System. Values: Northing in a UTM NAD83 CSRS spatial reference Notes: Surveyed Y-Coordinate (optional) provided by Land Surveyors during submissions or from published values in MASCOT. |
| OriginalZ |
The surveyed orthometric height (elevation) provided by Land Surveyors during submissions or from published values in MASCOT. Values: Metres above mean sea level Notes: The vertical datum is not tracked by PMBC. Please refer to source (MASCOT or survey plan) for more details on the vertical datum used. |
| QualityClass |
A record of the reliability of the published coordinates of a geodetic control point. From the MASCOT database. Values: A, B, C, D, and E. Notes: Class A is “very good”, Class B is “good”, Class C is “poor” and Class D is “very poor”. Class E means that the class is unknown, and it could be any of A to D. |
| OriginalEpoch |
Defines the epoch for the datum realization. Values: See Original Epoch domain for more details. Notes: The values are for current standard BC realizations. |
| CombinedScaleFactor |
Describes the ratio between Ground distances and projected UTM Grid Distances, at the control point location. Notes: For control points = “Survey” this is populated from the surveyor submission metadata and is an average value for the plan. |
| Description |
A general description of the physical location and/or appearance of a control point. Values: Free text field Notes: For geodetic control points or vertical benchmarks, this is the Marker Location record from MASCOT. For Survey control, a general description of marker type provided by the Surveyor. For CAD Tie, this identifies which parcel corner was tied by the surveyor. |
| Shape |
Contains geometry of the feature in the requested Spatial Reference. Values: Point geometry Notes: This is the geometry for the projected control point feature in the integrated parcel fabric and not the underlying component, ground based survey dimensions. |
| Error |
Horizontal accuracy of the Control - A statistical estimate of the likelihood the reported coordinates are close to true location of the measured point. Values: This is the semi-major axis of the error ellipse at a 95% confidence level (in metres). Notes: This field only applies for non-geodetic control points. Populated from the surveyor submission metadata. Surveyors calculate this value from GNSS observation. It is the same value labelled in a Survey Plan as ‘Estimated Horizontal Positional Accuracy’. |
| ErrorMinor |
Horizontal accuracy of the Control - A statistical estimate of the likelihood the reported coordinates are close to true location of the measured point. Values: This is the semi-minor axis of the error ellipse at a 95% confidence level (in metres). Notes: This field only applies for non-geodetic control points. Populated from the surveyor submission metadata. See Error field for details. |
| ErrorAngle |
Horizontal accuracy of the Control - A statistical estimate of the likelihood the reported coordinates are close to true location of the measured point. Values: Azimuth of semi-major axis of error ellipse Notes: This field only applies for non-geodetic control points. Populated from the surveyor submission metadata. See Error field for details. |
| SurveyType |
The survey methodology used to measure coordinates for a control point. Values: See Control Survey Type domain for more details. |