MASCOT NEWS  

Date of last update:  February 1, 2015

Download Data Field Choices Are Now Available - February 2015

Choice of fields (columns) is now possible before downloading MASCOT data. Field selections may be done to add optional fields to the download.

MASCOTW's URL has Changed - September 2012

Please note the new URL you see in your browser's address bar: http://a100.gov.bc.ca/pub/mascotw

The Method of Accessing MASCOT has Changed - March 2012

The method of accessing MASCOT has changed. A user is no longer required to apply for an account with a username/password. Instead MASCOT can be accessed by simply accepting a Disclaimer Page.

MASCOT's Query by Map, Graphics Based Access is now compatible with IE7 - April 2009

MASCOT's Query by Map, Graphics Based Access, presently is not compatible with IE7 - November 2006

Our web mapping infrastructure does not currently support IE7. The producers of the server software we use are currently conducting certification testing, however we have no ETA when a patch will be available. For more information, please browse the ESRI website

Since going back from IE7 to IE6 is not a realistic option, as a workaround I would suggest you run the current version of Mozilla Firefox which works fine with our web mapping applications.

Provincial Mainland & Vancouver Island Refresh Updates - March 2006

This notification is an update to previous notifications below (i.e. "Provincial and Vancouver Island Horizontal Adjustments).

These two adjustments are now published on MASCOT. BMGS has also provided the newly published geodetic control stations within the Integrated Survey Area (ISA) administrative boundaries for the Surveyor General Division of the Lands Titles and Survey Authority (LTSA). These, so-called, “ISA Listings” have also been published on their web site (see below).

To use the most up-to-date survey control and coordinates, please check the datum and / or time stamp in the horizontal and field of the MASCOT listing:

• The information related to the horizontal datum for the Provincial Mainland (other than the Greater Vancouver Regional District (GVRD)) must read,
  - Horizontal datum “NAD83(CSRS) 4.0.0.BC.1”
  - Date must be on or after 2006-03-21
• The information related to the horizontal datum for the Vancouver Island Plate (other than the Capital Regional District (CRD)) must read,
  - Horizontal datum “NAD83(CSRS) 3.0.0.BC.1.NVI”
  - Date must be on or after 2006-03-21
• Any questions and/or concerns, please contact Brad Hlasny at phone (250)356-0969 or email: Brad.Hlasny@gov.bc.ca.

New Integrated Survey Area (ISA) Listings for non-GVRD and non-CRD Municipalities

New official Integrated Survey Area (ISA) coordinate listings have been created for the following areas outside of the Greater Vancouver Regional District (GVRD) and the Capital Regional District (CRD):

Users may expect a small shift in horizontal co-ordinates for most municipalities (i.e. those having an on-going Municipal Geo-Spatial Reference or MGSR program in partnership with the Province). Two MGSR exceptions are Dawson Creek (at an expected 19 cm (approx.) shift) and Tumbler Ridge (at an expected 33 cm (approx.) shift). The following is a summary of shifts in all of the MGSR participating municipalities. The table below also shows (by way of a "yes" or "no") whether or not there are outstanding geodetic control surveys yet to be integrated and published. For those municipalities that have a "no" marked against them, this will indicate that there are no other control surveys to be integrated by the Province in that municipality at this time. Municipalities flagged by a [*], indicate that the average shifts are not precise and should Not Be Used for conversion from the previously 1998 published values to the current 2006 re-publishing. In these areas the average shift does not represent well the range and direction of the variable shifts in that municipality.

These listing have been created as a result of the adjustments described below. The official new coordinate listings supersede the previous listings. The official ISA Listings (in a non-printable format) are accessible via the Land Title and Survey Authority website at the following address: http://www.ltsa.ca/sgd_ispplans.htm .

NAD83 COORDINATE VERSION NUMBERING

With the recent re-publication of Geodetic Control Markers (GCM’s) in the Province of British Columbia, the MASCOT database presently holds coordinate versions from four different re-adjustments.

They are as follows:

1.) The Capital Regional District (CRD) Regional Re-Fresh of 2000

Version # NAD83(CSRS) 3.0.0.BC.1.CRD

2.) The Northern Vancouver Island (NVI) North of the CRD, Re-Fresh of 2005

Version # NAD83(CSRS) 3.0.0.BC.1.NVI

3.) The Greater Vancouver Regional District (GVRD) Regional Re-Fresh of 2005

Version # NAD83(CSRS) 4.0.0.BC.1.GVRD

4.) The Provincial Mainland Refresh of 2005, consisting of the remainder of the province with the exception of the GVRD and Vancouver Island.

Version # NAD83(CSRS) 4.0.0.BC.1

The following is an explanation of the version numbering scheme for the publication of NAD83 coordinates in Canada. The scheme is capable of tracking coordinates from different adjustments by different agencies or different adjustments of different networks/hierarchies by the same agency (e.g., CACS vs. regional CACS vs. CBN vs. GPS on Bench Marks vs. provincial vs. municipal). The scheme provides a means to uniquely define these different network adjustments.

Definition of acronyms used:

CACS Canadian Active Control System

CBN Canadian Base Network

GPS Global Positioning System

CSRS Canadian Spatial Reference System

ITRF International Terrestrial Reference Frame

NAD83 North American Datum of 1983

NAD83(Adopted) Original realization of NAD83 (primarily horizontal only)

NAD83(CSRS96) Realization of NAD83 based on preliminary transformation from ITRF96

NAD83(CSRS98) Realization of NAD83 based on adopted transformation from ITRF96

NAD83(CSRS) Equivalent to NAD83(CSRS98)

NMIP Network Maintenance Integration Project (1993)

SIHBA Secondary Integration Helmert Block Adjustment (1990)

GVRD Greater Vancouver Regional District

CRD Capital Regional District

NVI Northern Vancouver Island

The version numbering scheme is of the following form:

NAD83(CSRS) a.b.c.XX.d…

a = version number of the realization of the NAD83 reference frame:

0 = NAD83(Original) (e.g., used for NMIP and SHIBA adjustments)

1 = NAD83(CSRS96)/ITRF96 (e.g., CACS v1.0 used for CBN v1.x)

2 = NAD83(CSRS98)/ITRF96 (e.g., CACS v2.0 used for CBN v2.x)

3 = NAD83(CSRS98)/ITRF97 (e.g., CACS v3.0 used for CBN v3.x)

4 = NAD83(CSRS98)/ITRF2000 (e.g., CACS v4.0 to be used for CBN 4.0)

b = version number of national and regional CACS coordinates. A number 0 shall be used to denote coordinates directly from the transformed ITRF solution. Subsequent numbers shall be used to track further adjustments for regional CACS stations not in the ITRF or for updating CACS stations that have moved since the ITRF solution.

c = version number of CBN based on CACS version "a" (usually 0 or 1, as in CBN 3.0 and CBN 3.1).

XX = 2-character sub-network identifier, normally the provincial code for a provincial network; i.e., BC, AB, SK, MB, ON, QC, NB, PE, NS, NL, YT, NT, NU. Codes for other national networks besides the CBN shall also be used (e.g., "BM" for the GPS on Bench Marks network, "CHS" for Canadian Hydrographic Service networks, etc.).

d... = version numbering scheme of sub-network (provincial) adjustments and hierarchies which are based on the national adjustment version "a.b.c". The sub-network numbering scheme is left to the responsible provincial agency. In some cases it is only necessary to number the provincial network and thus only one decimal field is shown. For more hierarchies/networks, additional fields are used as needed. For consistency, only decimal points are used to separate the fields (e.g., "NAD83(CSRS) a.b.c.XX.d.CRD"). Note that all federal version numbering begins at 0 but provincial agencies begin at 1.

v v v  NOTICE   v v v

Provincial Mainland and Vancouver Island Horizontal Adjustments

Introduction

This notice outlines certain outcomes from ongoing maintenance of the geo-spatial reference in British Columbia.   The anticipated changes are described below.   Users of the geo-spatial reference system, particularly those concerned at the millimetre to sub-metre level, are advised to take note of the changes and contact BMGS for any further information required.

Details

1.     Provincial Mainland Horizontal Refresh Networks Adjustments

These are based on Natural Resource Canada’s, Geodetic Survey Division (GSD) datum of NAD83 (CSRS) v4.0.

The results of this new horizontal readjustment will be published in two phases:

a) GVRD - publication of the new horizontal coordinates occurred on April 5, 2005.

b) Remainder of Province - except for the Greater Vancouver Regional District, the remainder of the province will also be affected by a provincial refresh adjustment targeted for publication on March 31, 2006.

2.     Vancouver Island Horizontal Refresh Networks Adjustments

These are based on Natural Resource Canada’s, Geodetic Survey Division (GSD) datum of NAD83 (CSRS) v3.0.

The results of this new horizontal readjustment will be published in two phases:

a) CRD - publication of the horizontal coordinates occurred on November 17, 2000.

b) Remainder of the Island - except for the Capital Regional District, the remainder of the Vancouver Island plate will also be affected by a Vancouver Island refresh adjustment targeted for publication on March 31, 2006.

Please note that the coordinates in the Capital Regional District (CRD) will not be republished at this time - only those on Vancouver Island outside of the CRD will be republished.   This will bring the rest of Vancouver Island in line with the CRD, which was published after the 2000 adjustment.

A set of scientific coordinates for the Island, compatible with the mainland and based on the GSD datum of NAD83 (CSRS) v4.0 will be available at a later date.

Significant geophysical movements (i.e. plate tectonic movement of approximately 5-10mm/year) between Vancouver Island and the mainland will continue to affect the provincial coordinate system.   The issue of geophysical movements and time-varied coordinates will soon have to be addressed given the increasing use of GPS is identifying this problem more readily and will require a more advanced geo-spatial reference system (e.g. regional network RTK solutions, long GPS baselines, etc.).

Provincial Refresh Update - September 15, 2005

This notification is an update to a previous notification below (i.e. "Provincial Horizontal Adjustment and Regional Vertical Adjustment in the Greater Vancouver Regional District (GVRD)"). This is to inform provincial stakeholders and users that due to technical difficulties (i.e. data issues within some historic municipal data), Base Mapping and Geomatic Services is not in a position to publish the new provincial horizontal readjustment on the specified date of September 30, 2005.

It is expected that work on the readjustment can be completed by the end of the calendar year; however, to be able to provide a firm, reliable date, the publication date of March 31, 2006 has been selected. On this date the Surveyor General Division of the Lands Titles and Survey Authority (LTSA) would also be ready to publish the affected Integrated Survey Areas (ISAs) at the Land Titles Offices.

Other than the publication date, all other information in the notification below remains the same.

Any questions and/or concerns, please contact Brad Hlasny at phone (250)356-0969 or email: Brad.Hlasny@gov.bc.ca.

To MASCOT Users of Survey Control in the Greater Vancouver Regional District (GVRD)

Please be advised that some of the stations currently on MASCOT within the Greater Vancouver Regional District (GVRD) may not be on the newly published and adopted horizontal and/or vertical datum (i.e. adjustment version).  These points are not consistent with the new datum because the stations do not have survey connections to them within MASCOT.

To use the most up-to-date survey control, please check the datum and / or time stamp in the horizontal and vertical fields of the MASCOT listing:

• The information related to the horizontal datum must read
  - Horizontal datum must read  “NAD83(CSRS) 4.0.0.BC.1”
  - Date must read 2005-04-05
• The information related to the vertical datum must read
  - Vertical datum must read  “CVD28GVRD”
  - Date must read 2005-03-23

Please see the following example extracted from a MASCOT long listing:

BMGS is currently working on integrating (or retiring) the non-conforming survey control to ensure compatibility and consistency.  Further updates and communications will being published as progress is made.

We apologize for any confusion or inconvenience this may have caused.

New Integrated Survey Area (ISA) Listings for GVRD Municipalities

New official integrated survey area (ISA) coordinate listings have been created for the following fourteen areas within the Greater Vancouver Regional District (GVRD):

ISA No. 1        Surrey
ISA No. 13      Delta  
ISA No. 14      Coquitlam
ISA No. 16      North Vancouver District
ISA No. 18      Richmond
ISA No. 25      Burnaby
ISA No. 31      Vancouver
ISA No. 35      Port Moody
ISA No. 36      Maple Ridge
ISA No. 41      Langley Township
ISA No. 42      Whiterock
ISA No. 44      North Vancouver City
ISA No. 45      Langley City
ISA No. 49      New Westminster

These listing have been created as a result of an adjustment noted below. For other ISAs within the province; these will also be republished at a later date. The official new coordinate listings supersede the previous listings. The official listings are accessible via the land Title and Survey Authority website at the following address: http://www.ltsa.ca/sgd_ispplans.htm .

v v v   NOTICE   v v v

Provincial Horizontal Adjustment and

Regional Vertical Adjustment in the Greater Vancouver RegionalDistrict (GVRD)

Introduction

This notice outlines certain outcomes from ongoing maintenance of the geo-spatial reference in British Columbia.   The anticipated changes, starting mid-March 2005 and continuing throughout the year, are described below.   Users of the geo-spatial reference system, particularly those concerned at the millimetre to sub-metre level, are advised to take note of the changes and contact BMGS for any further information required.

Overview

From time to time, horizontal and vertical adjustments to the provincial coordinate system are effected in order to ensure compatibility of the system with the national and international systems and standards, including alignment with Global Navigation Satellite Systems.   In 2005, the following events are anticipated.  

1.      Provincial Horizontal Adjustment – A province-wide horizontal adjustment has just been completed.   The publication of the newly derived coordinates will occur in two phases:

a.      GreaterVancouver Regional District (GVRD) Publication - For the GVRD, the publication of new horizontal coordinates from the provincial adjustment will occur on March 15, 2005 .

b.      Publication for Remainder of Province - except for the Capital Regional District, the remainder of the province will also be affected by the provincial refresh adjustment scheduled for publication September 30, 2005 .

2.      Regional (GVRD) Vertical Adjustment –In concert with the horizontal adjustment, the vertical datum (providing"Mean Sea Level" or spirit level based elevations) for the GVRD has also been readjusted and will be published on March 15, 2005 .

3.      Regional (GVRD) Geoid – In concert with the vertical readjustment a new geoid and height corrector surface will also be republished on March 15, 2005 .

4.      Geodetic Control Monument Classification and “Retirement” Scheme – In keeping with the previously announced (2000) geodetic control monument classification and retirement scheme; BMGS continues to review the control monuments on the provincial database and "retire" monuments.   This scheme is now being rolled out province-wide starting in April 1, 2008 .

Details

1.   Provincial Horizontal Refresh Networks Adjustment

The 1998 provincial horizontal readjustment of the geodetic networks (i.e.physical monuments establishing the system of latitudes, longitudes and heights) in BC was performed to alleviate some of the problems left over from the NAD83 conversion exercise and to incorporate new precise and accurate GPS surveys that the federal government had conducted in order to move to the adjustment referred to as NAD83( CSRS).   In 2000, the Capital Regional District (CRD) and BMGS completed a regional precise GPS and levelling network (or High Precision Network - HPN), resulting in a readjustment of the networks on southern Vancouver Island.  

Since 1998 and 2000, a number of strategic, province-wide geodetic GPS surveys have been completed by, or in conjunction with, the Geodetic Survey Division (e.g. second-epoch surveys on the western Canadian Base Network (CBN) stations and GPS-on-BM surveys).   BMGS and the GVRD have also recently completed a significant regional High Precision Network that included a precise GPS and vertical control survey.   These events have necessitated a stand-alone Provincial horizontal readjustment in order to integrate all of the surveys undertaken over the last seven years.   The new adjusted coordinates are computed on the NAD83( CSRS) ellipsoid.

The Canadian Spatial Reference System (CSRS) is a national initiative designed to make NAD83 more consistent with global navigation satellite systems (such as GPS) and allow ease of convertibility with current and future global datums (i.e. the International Terrestrial Reference System or ITRF).   This system will therefore provide greater accuracy in absolute sense and a better compatibility with satellite-based surveys.   It should be noted that in a relative sense, i.e. across small distances in local areas, the changes in coordinates would generally not be significant to most users .   That is, distances and angles between immediate monuments will generally remain the same.

The results of the new horizontal readjustment will be published in two phases:

a)      GVRD - publication of the new horizontal coordinates will occur on March 15, 2005 .   This has been communicated and coordinated through the GVRD and its partner municipalities.

b)     Remainder of Province - except for the Capital Regional District, the remainder of the province will also be affected by the provincial refresh adjustment targeted for publication on September 30, 2005 .   As with the GVRD, BMGS anticipates holding more communications with stakeholder groups in order to prepare for this publication.  

Please note that the coordinates in the Capital Regional District (CRD) will not be republished at this time - only those on Vancouver Island outside of the CRD will be republished.   This will bring the rest of Vancouver Island in line with the CRD, which was published after the 2000 adjustment.  

Significant geophysical movements (i.e. plate tectonic movement of approximately 5-10mm/year) between Vancouver Island and the mainland will continue to affect the provincial coordinate system.   The issue of geophysical movements and time-varied coordinates will soon have to be addressed given the increasing use of GPS is identifying this problem more readily and will require a more advanced geo-spatial reference system (e.g. regional network RTK solutions, long GPS baselines, etc.).  

In summary, for the time being, Vancouver Island will be kept on one NAD83( CSRS) adjustment (epoch 2000 orNAD83(CSRS) ₂₀₀₀ ), and the rest of the province on another adjustment (epoch 2005 or NAD83(CSRS) ₂₀₀₅ ).   BMGS has kept the 2005 adjustment results for Vancouver Island internal to MASCOT as "scientific coordinates".

Users may expect a small shift in horizontal coordinates of less than 6 cm for most municipalities (i.e. those having an on-going Municipal Geo-Spatial Reference or MGSR program in partnership with the Province).   More municipality-specific information will be published in the next few months as BMGS completes the adjustment analysis.

For those interested in moving from one datum and/or adjustment to another(e.g. NAD27 ? NAD83( CSRS) ₂₀₀₀ ,etc.) BMGS will be producing a version of the National Transformation that allows one to transform from one datum/adjustment to another quite easily.

Note that the Surveyor General will also be issuing, for the purposes of Integrated Survey Areas ( ISAs ), new ISA Certificates for all so affected municipalities.   Please consult the Surveyor General Division, now part of the Land Title and Survey Authority ( http://www.lts a .ca/ ), for more details.

2.   GVRD Regional Vertical Adjustment

Similar to the HPN horizontal survey and adjustment conducted in the GVRD, a highly precise and accurate HPN first-order levelling control survey was conducted to improve the vertical datum and provide compatibility with GPS (RTK).    In the GVRD, the vertical adjustment will result in some significant vertical shifts in some municipalities (mm in West Vancouver to 0.15m in Aldergrove ).   However, the new vertical datum will essentially be "distortion free" and the precise first order levels completed under the HPN survey will not be deformed to fit the existing distorted BMs.

This will also create a vertical "bench" between the data in the GVRD's eastern border with the FVRD's western border i.e. between Langley/Abbotsford and Maple Ridge/Mission.  This may only be a temporary issue depending on discussions with the FVRD and its municipalities.   BMGS has also adjusted the vertical data in the FVRD and thus the new elevations for this area are available for regionally significant projects.

3.   New Geoid Model Publication– GVRD Region Only

A new and better Canadian geoid model became available in 2000 through Natural Resources Canada, Geodetic Survey Division(GSD) in Ottawa.   The new model is known as CGG2000.

Orthometric heights derived from GPS ellipsoidal heights and pure gravimetric geoid heights (i.e. CGG2000) are not equivalent to CGVD28 heights due to errors in the realization of both CGVD28 and the pure gravimetric geoid model, unless used with ellipsoidal heights at bench marks.   GSD has developed a Height Transformation based upon survey stations positioned across the GVRD using GPS and levelling observations.   The GPS-derived NAD83( CSRS) ellipsoidal heights and levelling-derived CGVD28 orthometric heights, in addition to a pure gravimetric geoid heights, provided the basis for establishing the Height Transformation.

The Height Transformation (HT) allows users to obtain GPS-derived orthometric heights compatible with the surrounding CGVD28 vertical control, without the need to occupy benchmarks during field operations.   In the GVRD,the overall accuracy of the Height Transformation is estimated as ? 1-2 centimetres (with 95% confidence).

For the GVRD, this "augmented" geoid , called “HT_GVRD_BC00”, will replace our current publication of HT97 on March 15, 2005 .   The new augmented model provides better accuracy for geoidal values undulation and deflections of vertical.   Note that the deflections of the vertical are true CGG2000 values and are not distorted by the height corrector model.   For further information on geoids, height corrector models and the GPS Ÿ H software, please see http://www.geod.nrcan.gc.ca/index_e/products_e/software_e/gpsht_e.html .

All geodetic control markers ( GCMs ) in the GVRD will have new "augmented" geoid values published on the MASCOT listings.   BMGS willalso be publishing this geoid model for the rest of the province by the September 30, 2005 target date.

4.   Classification and retirement of Geodetic Control Markers

As part of the proper management and maintenance of the geo-spatial reference in British Columbia, horizontal control monuments continue to be retired since the implementation of NAD83.   In 1990 and 1993, some 12,000 and 790 monument coordinates (horizontal only), respectively, were removed from the public record due to their unreliability or low accuracy (i.e. lower than 1 m accuracy).   This removal from MASCOT, primarily in the rural regions, reflects the greater availability of tools and methods (i.e. GPS) amongst geodetic surveyors to establish 1 metre or better control points in local areas with relative ease.   In continuing this trend, a further 2,600 monument records (horizontal only) were removed (June 1998) from the public record due to their unreliability or low accuracy.   In this case, a higher accuracy or lower tolerance for error and unreliability was used.   As a result of continued advances in available tools and methods (primarily GPS) the threshold of 0.4 m at standard deviation (or 1 m at 95% confidence) is being used to eliminate rural monuments with sub-standard coordinates and 0.2 m at standard deviation (or 0.5 m at 95% confidence) to eliminate urban monuments with substandard coordinates .

In order to outline a future path towards an orderly retirement of horizontal coordinates, each monument will be classified as to its permanency (horizontal coordinate only).   It is expected that in the next 5-10 years some 25,000 horizontal monument coordinates may be retired from the public record.   Significantly, more and more urban monuments will be retired as the availability of tools such as high precision GPS(enabling 1cm level real-time positioning) take a hold in many municipalities.

With the redefinition of the horizontal coordinate system in the Greater Vancouver Regional District (GVRD) coming to a close in the spring of 2005, a horizontal marker classification system is formally being implemented in the region.   This is the same marker classification system that was implemented in the CRD in the recent past (see past notices at mascot_news.html ).

Under the marker information retrieved from MASCOT, users in the region will now see a Class A, B, C or D shown against the 'HorizontalClass' field.   These classifications will aid users in deciding which markers to use for their geo-referencing and positioning requirements.   The classifications will also be used to "retire" horizontal coordinates of these markers and otherwise discourage the longer-term maintenance of the horizontal coordinates (see further explanation below).

The horizontal classifications for markers are defined as (1sigma):

Urban

Rural

¹ Precision refers to the statistically derived standard level confidence in the coordinates with respect to the NAD83 Datum, as realized through the Canadian Spatial Reference System (CSRS).

² Reliability refers to a measure of the confidence in the one-sided mathematical (Least Squares Adjustment) process used to derive the precision.   As well, reliability includes such aspects as marker stability or ability to support a certain level of position.   Normally, positioning accuracyis a summation of precision and reliability.   As such, one cannot ignore the impact of lower reliability on the accuracy of geodetic control markers.   The method used for deriving reliability in this case is empirical and is based on well-accepted rigorous evidence showing the correlation between number of observations and reliability.

³ In addition to precision and reliability considerations, Class A GCMs were selected on the basis of GPS sky view and satisfying the placement of an approximate one kilometre grid.   This sparser grid is necessary for proper long term high accuracy datum maintenance.

Previously, class D markers (both urban and rural) have been retired throughout the Province.   Efforts continue towards classification and retirement of more markers as per previous announcements.   After consulting users,it is the intent of Base Mapping and Geomatic Services (BMGS) to retire all class C markers in the GVRD on or before April 1, 2008.   Further information (i.e. proposed GCM classification maps and listings) will soon be available to municipal stakeholders.

Retirement of the marker is with respect to horizontal coordinates (and survey ties) only.   The horizontal aspects of the marker will no longer be maintained by BMGS.   However, unlike Class D markers, Class C markers will continue to form part of the public record, albeit the coordinates will not be maintained and will be “downgraded” through the classification system.   Future horizontal re-adjustment and/or integration to any subsequent Canadian Spatial Reference System (CSRS) version or any other adopted Reference System, Reference Frame or Datum, will no longer be performed for retired markers.   Due to the lower class and retirement, users must be mindful of the non-maintenance and the effects of being"out-of-sync" with the surrounding datum through the passage of time.

Vertical coordinates for a retired marker will remain on public record and be maintained by BMGS i.e. they will effectively become Bench Marks (BMs).

Summary

In summary, the following future changes and activities are presented above…

1.      Province-wide adjustment will change currently published horizontal coordinates by approximately 5 cm.

2.      Two realizations (i.e. adjustments) of NAD83(CSRS) will be in use in British Columbia:

i)      NAD83(CSRS) ₂₀₀₀ for Vancouver Island and

ii)     NAD83( CSRS) ₂₀₀₅ for the remainder of the province.

3.      Coordinates on Vancouver Island will be adjusted to the previous NAD83( CSRS) ₂₀₀₀ adjustment (conducted for the CRD regional adjustment).   This will effectively bring all of Vancouver Island onto one adjustment.

4.      The publication of the horizontal adjustment results will be rolled out in two phases:

i)      GVRDeffective March 15, 2005 .

ii)     Remainder of the province (except the CRD) effective September 30, 2005 .

5.      A regional GVRD vertical adjustment will be published on March 15, 2005 .   This will change all of the heights/elevations by typically 0.06m (but as much as 0.15 metres).

6.      A new geoid model/height corrector surface specific to the GVRD will be published on March 15, 2005 and be reflected to all MASCOT listings.

7.   Geodetic Control Monuments in the GVRD will eventually be classified and based on their classification some will be retired (horizontal only not vertical).

8.      The Surveyor General Division of the newly formed Land Titles and Survey Authority will take steps to file the Integrated Survey Area (ISA) co-ordinate listings for public access.

Important Notice To Users of Graphics Based MASCOT Access 

The new Internet Mapping Framework (IMF) system for Graphics Based Access has now replaced the old Query by Map (static gif file) system. The old system will remain available for one year, however has not been updated since June of 2000. The new IMF Query by Map system will be updated daily .

Notice

Classification of Geodetic Control Markers for Horizontal Datum Quality and Use And Retirement of class C markers within the Capital RegionalDistrict

With the redefinition of the horizontal coordinate system in the CRD coming to a close at the end of the year 2000, a new horizontal marker classification system is formally being implemented in the region.

Under the marker information retrieved from MASCOT, users in the region willnow see a Class A, B, C or D shown against the `HorizontalClass’ field. These classifications will aid users indeciding which markers to use for their geo -referencingand positioning requirements. The classifications will also be used to "retire" horizontal coordinates of these markers and otherwise discourage the longer term maintenance of the horizontal coordinates ( see further explanation below).

The horizontal classification for markers are defined as (1 sigma):

Urban

Rural

¹ Precision refers to the statistically derived standard level confidence in the coordinates with respect to the NAD83 Datum, as realized through the Canadian Spatial Reference System (CSRS) version 2000.

² Reliability refers to a measure of the confidence in the one-sided mathematical (Least Squares Adjustment) process used to derivethe precision. As well, reliability includes such aspects as marker stability or ability to support a certain level of position. Normally, positioning accuracy is a summation of precision and reliability . As such ,one cannot ignore the impact of lower reliability on the accuracy of geodetic control markers. The method used for deriving reliability in this case is empirical and is based onwell-accepted rigorous evidence showing the correlation between number of observations and reliability.

3. In addition to precision and reliability considerations, Class A GCMs were selected on the basis of GPS sky view and satisfying the placement of an approximate one kilometre grid. This sparser grid is necessary for a proper long term high accuracy datum maintenance.

Previously, class D markers (both urban and rural) have been retired throughout the Province. Efforts continue towards classification and retirement of more markers as per previous announcements. After consulting users, it is the intent of Base Mapping and Geomatic Services (BMGS) to retire all class C markers in the CRD on or before December 31, 2003 .

Retirement of the marker is with respect to horizontal co-ordinates ( and survey ties) only. The horizontal aspects of the marker will no longer be maintained by GDBC. However, unlike Class D markers, Class C markers will continue to form part of the public record, albeit the coordinates will not be maintained and will be downgraded through the classification system. Future horizontal re-adjustment and/or integration to any subsequent Canadian Spatial Reference System (CSRS) version or any other adopted Reference System, Reference Frame or Datum, will no longer be performed for retired markers. Due to the lower class and retirement, users should be mindful of the non-maintenance and the effects of being "out-of –sync" with the surrounding datum through the passage of time.

Vertical co-ordinates for a retired marker will remain on public record and be maintained by GDBC.

Important Notice To MASCOT Web Users

Users of the geo-spatial reference in British Columbia requiring sub- metre( and especially decimetre or better) level horizontal co-ordinates should read this important notice. All users should also read item 2 of this notice. As well, those concerned with orthometric heights (i.e."Mean Sea Level"or spirit level based elevations) and or ellipsoid heights should also read items 3 and 4 of this notice. This notice outlines maintenance changes being made to the geo-spatial reference in British Columbia. 

1. Provincial Horizontal Refresh Networks Adjustment

The 1993 horizontal readjustment of the geodetic networks (i.e. monuments establishing the system of latitudes, longitudes and heights) in BC was performed in conjunction with similar simultaneous readjustment in Alberta , Saskatchewan ,Manitoba, Northwest Territories and the Yukon. Since 1993 ,large quantities of geodetic survey data have been processed which includemany new GPS surveys connecting to municipal and rural networks. A new stand alone Provincial horizontal readjustment integrates all of these surveys done in the last 5 (or more) years. The new adjusted co- ordinates are computed on the NAD83 (CSRS) Ellipsoid. The Canadian Spatial Reference System (CSRS) is a national initiative designed to make NAD83 more consistent with global navigation satellite systems (such as GPS) and allow ease of convertibility with current and future global datum’s (i.e. the International Terrestrial Reference System or ITRF). This system will therefore provide greater accuracy in absolute sense and a better compatibility with satellite- based surveys . It should be noted that in a relative sense,i.e. across small distances in local areas, the changes in co-ordinates would generally not be significant to most users. That is, distances and angles between immediate monuments will generally remain the same.

The results of the new horizontal readjustment will replace the 1993 values on or about June 1, 1998 .Users may expect a small shift in horizontal co-ordinates of less than 10 cm for most municipalities ( i.e. those having an on-going Municipal Geo-Spatial Reference or MGSR program in partnership with the Province). Two MGSR exceptions are Dawson Creek ( at an expected 18 cm (approx.) shift ) and Nelson ( at an expected 15 cm (approx.) shift ). The following is a summary of preliminary shifts in all of the MGSR participating municipalities. For those using the National Transformation Version 2 (NTv2) to transform from NAD27 to NAD83, the following average (i.e. approximate only) shift for each municipality must be additionally applied to arrive at NAD83 (CSRS) co- ordinates. The table below also shows (by way of a "yes" or "no") whether or not there are outstanding geodetic control surveys yet to be integrated and published. These relate to the announced list of "ISA" projects that the Province committed to publish in its letter of Sept. 1st, 1997. For those municipalities that have a "no" marked against them, this will indicate that there are no other control surveys to be integrated by the Province in that municipality. All outstanding projects in the remaining municipalities are expected to be completed and published by September 30, 1998. Note that the Surveyor General will also be issuing new ISA Certificates for all affected municipalities. Please consult that Office for more details. Municipalities flaged by a[ * ], indicate thatthe average shifts are not precise and should Not Be Used for conversion to CSRS. In these areas the average shift does not represent well the range and direction of the variable shifts in that municipality.  

2. Staged Retirement of Control Monuments

As part of the proper management and maintenance of the geo- spatial reference in British Columbia, certain horizontal control monuments continue to be retired with the implementation of NAD83. In 1990 and 1993, some 12 ,000 and 790 monument co-ordinates (horizontal only), respectively, were removed from the public record due to their unreliability or low accuracy(i.e. lower than 1 m accuracy ). This removal, primarily in the rural regions , reflects the greater availability of tools and methods (primarily GPS) amongst geodetic surveyors to establish 1 m or better control points inlocal areas, with relative ease. In continuing this trend, a further 2,600 monument co-ordinates (horizontal only) are likely to be removed (on or about June 1, 1998) from the public record due to their unreliability or low accuracy. In this case, a higher accuracy or lower tolerance for error and unreliability is being used in 1998. As a result of continued advances in available tools and methods (primarily GPS) a new threshold of 0.4m at standard confidence (or 1 m at 95% confidence) is being used to eliminate rural monuments with sub-standard co-ordinates and 0.2 m at standard confidence (or 0.5 m at 95% confidence) to eliminate urban monuments with substandard co-ordinates .

In order to outline a future path towards an orderly retirement of horizontal co - ordinates, each monument will shortly be classified as to its ( horizontal co - ordinates) permanency. It is expected that in the next 5-10 years some 25 ,000 horizontal monument co-ordinates will be retired from the public record. Significantly, more and more urban monuments will be retired as the availability of tools such as high precision GPS - enabling 1 cm level real-time positioning - take a hold in many municipalities. Initiatives at the Capital Region District and the Greater Vancouver Regional District , in co-operation with the Province, are currently underway to implement Active Control Systems that will enable such systems to take effect in those regions.

More details will be posted later this year to explain the classification system .

3. New Geoid Model Publication.

All markers, on or about June 1, 1998, will have new " augmented"geoid values published on the MASCOT listings.

A new and better Canadian geoid model became available in 1995 through Geodetic Survey Division (GSD) in Ottawa. The new model is GSD95. More recently , a correction model called HRG97 has been developed by GSD to primarily model the general distortions in the vertical datum (CVD28). This was done by comparing the primary spirit levels network elevations to those derived from GPS based (CSRS) ellipsoidal heights, after applying the GSD95 geoid model. Since most users are concerned about deriving CVD28( "Mean Sea Level") based elevations, the effects of GSD95 and HRG97 have been combined so that GPS users may readily obtain orthometric heights by applying one correction only. This"augmented" geoid , called HT97, will replace our current publication of GSD95 on or about June 1, 1998. The new augmented model provides better accuracy for geoidal values undulation and deflections of vertical. Note that the deflections of the vertical are true GSD95values and are not distorted by HT97.

Accuracy of the augmented geoid (HT97) is thought to be about 1 to 2 m in absolute terms and 5 cm in relative terms, along primary level routes or southern regions. Relative accuracy across mountainous terrain and in remote or northern regions may amount to several decimetres.

4. Orthometric Heights ("Mean Sea Level"Elevations) Revisions.

With the new Geoid model, new elevations have been computed for markers that currently have orthometric heights based on GSD91 and GPS observations( i.e. have no direct geodetic spirit levelling connections). These 933 markers are distributed throughout the province and are primarily rural points . The new ID cards, published on or about June 1, 1998, show the GSD95 and HRG97 (i.e. GSD95 + HRG97 = HT97) based GPS elevations for these markers . The ID card (long form) also show the vertical shift (change in elevation ) resulting from the upgrade to the latest Geoid model (as augmented by HRG97). The vertical shifts range from 0.0002 metres to 6.5874 metres , averaging about 0.1582 metres.

For more details on any of the above, please contact Base Mapping and Geomatic Services .

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******* Access to Geodetic Survey Of Canada Bench Marks - May 21, 1997 *******

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Access to complete information on all the Geodetic Survey of Canada bench marks ( symbolized by solid red squares) is now available. You can download them in long or short forms, or tab delimitted format. Please contact us if you have any question.

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DATE: Nov 21, 1996
NEWS: GSRU Website Version 1.1 Goes Online

Version 1.1 of the Geo-Spatial Reference Website went into production service on Thursday, November 21, 1996.

The new framed version enhances the web site navigation.

The new introduction section gives a good overview of the site functions and also illustrates many of the web features using direct link examples.

One of the major site enhancements is the new survey utilities area. Users may access Free software that enables various computations on the ellipsoid, mapping plane computations transformations, observation reductions and magnetic declination calculations. You may also want to look at the new Feature Manipulation Engine BC (FMEBC - Free software) ,a smart translation routine that supports model to model transformations.

We would like to thank those users that have submitted monument reports using the on-line form and we also encourage all users to submit monument condition reports. These reports are updated to the online system regularly.

Please feel free to ask questions or provide feedback using the comments/ problems form .

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