3. Seminar Outline Regulatory Requirements Issues related to various survey methods

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1 Introduction & Seminar Outline 1. Welcome 2. Seminar Leader: Paul C. Wyman, O.L.S. Professional excellence through life-long learning 3. Seminar Outline Issues related to various survey methods 01

2 Introduction & Seminar Outline Paul C. Wyman, O.L.S. Licensed in 1973 as a Cadastral Surveyor in City of Kitchener Professional excellence through life-long learning. Established Private Practice in partnership with Gary Auer, OLS in 1980 Wyman & Auer merged with Brubacher, Campbell in 1989 Sold my interest in 1998 and worked as a consultant until 2001 Employed in Geomatics Public Works & Government Services Canada form 2001 to March 2014 March 2014 to present as a geomatics consultant focused on training Experience in nearly all types of cadastral survey except mining surveys, drainage act surveys and retracement of original township lot lines Undertaken peer competence reviews for SRD and Registrars Investigations Undertaken several horizontal and vertical control surveys using conventional survey equipment and GPS Undertaken a number of high precision optical alignment surveys inside factories to positions rollers and other machine parts Active in Association committees including several years as a Monitor for the AERC and on Council from 1988 to 1994 and was AOLS President in

3 Integrated Survey Regulation Ontario Regulation 216/10 under the Surveyors Act, Section 14 states: Integration 14. (1) When undertaking a survey for a plan to be registered or deposited in the registry system or land titles system, a licensed member shall integrate the survey with a coordinate system in accordance with sections 31 to 35 and determine the coordinates of every angle or corner on a line or boundary and all topographic information required under section 24. (2) The coordinates required under subsection (1) shall be accurate, at the 95% confidence level, to, (a) 0.05 metres in urban areas; (b) 0.2 metres in rural areas; or (c) one metre in remote areas. 03

4 Integrated Survey Regulation Sections 31 to 35 of Ontario Regulation 216/10 under the Surveyors Act provides details of the datum and projections that are to be used as follows: 31. If a survey is integrated with a coordinate system, (a) the system shall be referenced to the North American Datum 1983(Orig.) or the North American Datum 1983 (Canadian Spatial Reference System) realization; and (b) coordinates shall be expressed as grid coordinates in a Universal Transverse Mercator map projection or a Modified Transverse Mercator map projection that complies with sections 32 to

5 UTM & MTM Projections Sections 32 to 35, O. Reg. 216/10 05

6 AOLS Guide on Integration Factors to consider when assessing whether an area is urban, rural or remote: An area is urban if built-up or if there is a "specified control point" within 2 kilometres of the survey. A "built-up area" means land that is primarily used or zoned for residential, commercial or industrial purposes; per O.Reg. 525/91; An area is rural if there is a "specified control point" between 2 kilometres and 15 kilometres from the survey; An area is remote if there is no "specified control point" within 15 kilometres of the survey. When remote or rural land is being developed, surveyors should consider whether the area is becoming rural or urban. Registered plans should usually be treated as urban. 06

7 Total Survey Integration Section 14(1) of O.Reg.216/10 requires that you determine the coordinates of every angle or corner on a line or boundary and all topographic information required under section 24. The entire survey is to be integrated or able to be integrated from the information found on the survey plan. Specifically, the plan must publish: individual combined scale factors for each point or a site combined scale factor; plan bearings or azimuth must be UTM or MTM zone grid bearings in which the project is located or the plan should provide a rotation value between plan and grid bearings; grid coordinates for at least 2 points; statement of the accuracy (urban, rural, remote) of the integration Preferably information indicating how the integration was done such as ties to control monuments that were used, the RTN system used, etc. 07

8 Accuracy Section 14(2) of O.Reg.216/10 requires that The coordinates required under subsection (1) shall be accurate, at the 95 per cent confidence level. 1. The regulation and the AOLS Guidelines are silent as to the specifics of this accuracy specification. I presume that the regulation is referring to local accuracy rather than network accuracy. 2. Some survey methods used to integrate the survey provide better local integration and some better network integration and it varies somewhat as to the datum realization - NAD83(Original) or NAD83(CSRS) being used. 3. The only way you can determine if the coordinates meet this specification is with some type of statistical assessment such as using a least squares adjustment. 4. Coordinates for all points in the survey (not just those published on the plan) must meet the accuracy specification. 08

9 Horizontal Datums Section 31(1a) of O.Reg.216/10 requires that the system shall be referenced to the North American Datum 1983 (Original) or the North American Datum 1983 (Canadian Spatial Reference System) realization. As a brief refresher: A horizontal mapping datum is a mathematical model of the earth. The regular, mathematical shape that best defines the earth s surface is an ellipse. The surface of an ellipse is a one dimensional line but if we rotate the ellipse about its polar axis, then the two dimensional surface that is created by the rotation is a reasonable approximation of the earth s surface and is generally referred to as an ELLIPSOID or SPHEROID. 09

10 Modern Datums in Use in Canada Not Earth Centred Datum: 2015 Integrated Surveys Seminar Horizontal Datums North American Datum of 1927 (NAD27) North American Datum of 1983 (NAD83 Original) First Realization in 1980 s North American Datum of 1983 (NAD83 CSRS) Second Realization in 1990 s Earth Centred Datum: World Geodetic System of 1984 (WGS84) Datum Equatorial Semi-Major Axis (m) Polar Semi-Minor Axis (m) NAD27 (Clarke Ellipsoid 1866) 6,378, ,356,583.8 NAD83 (GRS80 Ellipsoid) 6,378,137 6,356, WGS84 6,378,137 6,356,

11 Horizontal Datums In Canada, we currently have two - NAD83 variants resulting from two different realizations of the NAD83 datum. Both NAD83(Original) and NAD83(CSRS) are essentially the same reference frame (different realizations) and both are non-geocentric by about 1.6 m, however the mathematical relationship between the GPS reference frame - WGS84 and NAD83(CSRS) is very accurately known and maintained, whereas the same is not true for NAD83(Original). Thus GPS survey data can be accurately and directly transformed into NAD83(CSRS) without occupation of control monuments (always better to use them if available). Accurate NAD83(Original) coordinates can only be derived through the occupation of control monuments with known NAD83(Original) coordinate values. 11

12 Horizontal Datums NAD83(CSRS) coordinates for the same point do change slowly over time. It is therefore important to note the epoch of the coordinates. The Government of Ontario coordinate monument data archive, COSINE provides NAD83(CSRS) coordinate data for the years 1997 and The following is the UTM Zone 17 coordinate data for the Conestoga Baseline Pillar No. 2 (Control Monument ): Epoch Easting Northing Change is approximately 2 mm per year 12

13 Horizontal Datum Section 31(1a) of O.Reg.216/10 requires that the system shall be referenced to the North American Datum 1983 (Original) or the North American Datum 1983 (Canadian Spatial Reference System) realization. NAD83(Original) and NAD83(CSRS) are the only systems that can be used for integration of surveys in Ontario. You cannot use NAD27, WGS84 or any other datum. I personally recommend using NAD83(CSRS) whenever possible as this realization of the NAD83 datum is much more accurate and has a well established, rigorous mathematical relationship to the WGS84 datum (GPS). NAD83(CSRS) Epoch 2010 coordinates are provided directly by Leica Smart-Net and Epoch 1997? by the Trimble Can-Net real time network system. Be aware of the Epoch when obtaining coordinates from NRCan or Ontario s COSINE. When using NAD83(Original) you should tie to the closest monuments to the project area at least for the 5 cm urban accuracy requirement- because the error remaining in the NAD83(Original) system may be larger than 5 cm. over large areas. 13

14 Horizontal Datum NRCan website: provides an application (TRX) that will convert NAD83(CSRS) coordinates between Epochs. Note also that this application calculates the combined scale factor at this location. 14

15 Projection Section 31(1b) of O.Reg.216/10 requires that coordinates shall be expressed as grid coordinates in a Universal Transverse Mercator map projection or a Modified Transverse Mercator map projection that complies with sections 32 to 35. A projection is the set of mathematical rules by which we represent (project) the irregular three-dimensional world onto a 2 dimensional surface. The Transverse Mercator projection is a cylindrical map projection developed by the Flemish geographer and cartographer Gerardus Mercator in The Mercator projection preserves angular relationships but distorts distances. To minimize the distortions, the projection is kept within geographic zones either 3 or 6 of longitude. The 6 zones are referred to as the UNIVERSAL TRANSVERSE MERCATOR (UTM) projection and the 3 zones are the MODIFIED TRANSVERSE MERCATOR (MTM) projection. 15

16 Projections Scale Factor (Two Step Process) Step 1 - ELEVATION SCALE FACTOR Projection of a distance on the Earth s surface to the Ellipsoid. Distances above ellipsoid (approximately sea level) are projected smaller on ellipsoid. Distances below ellipsoid are projected larger. 16

17 Projections Step 1 Elevation Scale Factor Elevation Scale Factor (ESF) = Ellipsoid Radius / (Height above Ellipsoid + Ellipsoid Radius). Using a mean Ontario Radius for the ellipsoid of 6,380,000 metres and an Ellipsoid Height accurate to about 5 m yields an Elevation Scale Factor (ESF) accurate to 5 or 6 decimal places. For a more precise ESF, it is necessary to have a more precise Ellipsoid Height and a more precise Radius. A more precise Radius Formula is: Ellipsoid Radius = c / {1 + e 2 [Cos(Latitude) 2 ]} where c = a 2 / b e 2 = (a 2 + b 2 ) / b 2 a = Equatorial semi-axis (metres) b = Polar semi-axis (metres) Using the precise radius noted above and an Ellipsoid Height accurate to about 0.1 m will yield an Elevation Scale Factor accurate to 8 decimal places. 17

18 Projections Step 1 Elevation Scale Factor To compute the elevation scale factor, the height above the ellipsoid (h) is required. If only the sea level elevation (H) is known then it is necessary to obtain the geoid height (N) to compute the ellipsoid height. The geoid height (N) at any location can be obtained on the NRCan website The Geoid Height N is negative when the Geoid is below the Ellipsoid. h = H + N Because N can be positive or negative (usually about -30 m to -40 m in southern Ontario) it is important to keep track of the algebraic signs to get the correct answers. 18

19 Projections Step 1 Elevation Scale Factor NRCan GPS-H 19

20 Projections Step 2 - Grid Scale Factor Step 2 - Projection of a distance on the Ellipsoid to the UTM Grid. (GRID SCALE FACTOR) Approx. Grid Scale Factor = k (1 + X 2 / 2R 2 ), k = Scale factor at Central Meridian ( for UTM or for MTM zones) X = Distance of point from central meridian in metres R = The Ellipsoid Radius - approximately 6,380,000 metres in Ontario This approximate formula and approximate Radius yield 5 to 6 decimals of precision for the Grid Scale factor. 20

21 Projections Scale Factor A more precise UTM or MTM Grid Scale Factor (GSF) is given by the following formula: GSF = k (1 + a 8 L 2 + a 10 L 4 ) where k = Scale factor at Central Meridian ( for UTM zones or for MTM zones) L = Radians(Longitude Central Meridian Longitude) a 8 = 1/2 [Cos(Latitude) 2 ] {1 + e 2 [Cos(Latitude) 2 ]} a 10 = 1/24 [Cos(Latitude) 2 ] {-4 + (9-28e 2 ) [Cos(Latitude) 2 ] + 42e 2 [Cos(Latitude) 4 ]} e 2 = (a 2 + b 2 ) / b 2 a = Equatorial semi-axis (metres) b = Polar semi-axis (metres) This formula is also an approximation but yields about 8 decimals of precision for the grid scale factor within a 6 Transverse Mercator zone (or smaller). The Combined Scale Factor (CSF) is obtained by multiplying the Elevation and Grid Scale Factors together: CSF = ESF x GSF. 21

22 Summary 1. All survey plans entering the LRO to be integrated 2. Three levels of accuracy urban (5 cm), rural (20 cm), remote (100 cm) Distance from existing control survey monuments may be defining factor Office research may be necessary to determine accuracy requirement 3. NAD83(Original) or NAD83(CSRS) datum 4. UTM (6 ) or MTM (3 ) projection Use Grid Bearings / Azimuth or show Rotation between Plan and Grid Show combined scale factor (individual or site) 5. Show how integration coordinates were obtained 22

23 Issues Related to Survey Methods Typical Methods 1. Conventional Survey Equipment Traverse from Existing Control Monuments 2. 2 Station GPS Traverse from Existing Control Monuments - static and rapid static post-processed data 3. 2 Station GPS Traverse from Existing Control Monuments - real time kinematic (RTK) 4. 1 Station GPS commercial Real Time Network (RTN) 5. 1 Station GPS Precise Point Positioning (PPP) ALL METHODS REQUIRE REDUNDANT MEASUREMENTS AND ERROR ANALYSIS TO CONFIRM ACCURACY REQUIREMENTS HAVE BEEN ACHIEVED 23

24 Issues Related to Survey Methods Conventional Survey Advantages: Well known technique by all staff (requires recording of set-up and target heights) No special equipment or training required May be best method in urban canyons Can generally provide sufficient accuracy Disadvantages: Requires Control Monument Research (Office and Field) Restricted to datum of Control Monuments Needs at least 2 inter-visible control monuments (4 preferred) Expensive for projects distant from control monuments 24

25 Issues Related to Survey Methods 2 Station GPS Traverse Static / Rapid Static Advantages: Highest accuracy survey - May be best method where high accuracy for other purposes is needed Can integrate survey from 1 control monument (2 or more recommended) Use the Can-Net or Smart-Net base stations (for a fee) Disadvantages: Requires Control Monument Research (Office and Field) unless using the Can- Net or Smart-Net base stations Requires staff training Restricted to datum of Control Monuments Requires post-processing of data Requires 2 survey quality GPS units 25

26 Issues Related to Survey Methods 2 Station GPS Traverse RTK Advantages: Can integrate survey from 1 control monument (2 or more recommended) Use the Can-Net or Smart-Net base stations (for a fee) Can generally provide sufficient accuracy Somewhat faster than rapid static Can provide high accuracy grid bearings Disadvantages: Requires Control Monument Research (Office and Field) using the Can-Net or Smart-Net base stations requires post-processing Requires staff training Restricted to datum of Control Monuments Requires 2 survey quality GPS units 26

27 Issues Related to Survey Methods 1 Station GPS Real Time Network (RTN) Advantages: For NAD83(CSRS) datum, no requirement to use existing control monuments (check against if available). For NAD83(Original) datum, you should integrate using local control monuments. Can generally provide sufficient accuracy Fast and only requires 1 GPS unit Disadvantages: Requires staff training Project must be within RTN service area Care required with regard to grid bearings (see slide 29) 27

28 Issues Related to Survey Methods 1 Station GPS Precise Point Positioning (PPP) Advantages: No requirement to use existing control monuments Can generally provide sufficient accuracy care needed for urban (5 cm) Only requires 1 GPS unit NRCan report provides accuracy estimate Disadvantages: Requires staff training Post-processing of data Requires long (3 hours +) occupation times Care required with regard to grid bearings (see slide 29) 28

29 Issues Related to Survey Methods Grid Bearing Issue Plan bearings or azimuth must be related to the UTM or MTM zone in which the project is located. The accuracy that you can determine a grid bearing for the project is dependent mainly on two issues how far apart the points are located and the technique used to integrate the survey. Simultaneous (differential) use of two GPS receivers (survey methods 2 and 3) will produce a very accurate (a few seconds of arc or better) azimuth between GPS antenna. Typical RTN accuracy is +/- 1 cm. If two points each have a horizontal positional error of +/- 1 cm, the two points need to be about 200 m apart to guarantee 20 seconds of bearing accuracy. Except for very long occupations (24 hours), typical Precise Point Positioning (PPP) accuracy is +/- 2.5 cm. If two points each have a horizontal positional error of +/- 2.5 cm, the two points need to be about 500 m apart to guarantee 20 seconds of bearing accuracy. 29

30 Issues Related to Survey Methods Grid Bearing Issue Plan bearings or azimuth must be related to the UTM or MTM zone in which the project is located. The accuracy that you can determine a grid bearing for the project is dependent mainly on two issues how far apart the points are located and the technique used to integrate the survey. Simultaneous (differential) use of two GPS receivers (survey methods 2 and 3) will produce a very accurate (a few seconds of arc or better) azimuth between GPS antenna. Typical RTN accuracy is +/- 1 cm. If two points each have a horizontal positional error of +/- 1 cm, the two points need to be about 200 m apart to guarantee 20 seconds of bearing accuracy. Except for very long occupations (24 hours), typical Precise Point Positioning (PPP) accuracy is +/- 2.5 cm. If two points each have a horizontal positional error of +/- 2.5 cm, the two points need to be about 500 m apart to guarantee 20 seconds of bearing accuracy. 30

31 Issues Related to Survey Methods Grid Bearing Issue Ratios: / to / to / to 6.5 Error at Rear SIB s with 2 cm error in Front SIB s: 1. 5 cm 2. 8 cm cm 31

32 Issues Related to Survey Methods Summary 1. The NAD83(CSRS) datum may be a better choice as NAD83(Original) is slowly being abandoned by government and CSRS has less inherent error. 2. Redundancy, Traverse Closures or some form of error analysis is necessary to confirm that you have met the integration accuracy requirements. 3. Care with respect to geometry should be exercised to ensure that an accurate Grid Bearing is determined for the project. This is less important if the entire project is measured using GPS. 4. Care should be exercised in determining a scale factor for the project. Scale factors change with east / west location and with elevation. 32

33 Seminar Conclusion General Discussion 33