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(Rev. ed.)Series: Publication (Geodetic Survey of Canada) ; no. 23 // "This volume supplants two separately published first editions, namely: Precise Levelling in Alberta (No.23), issued by the Geodetic Survey of Canada in 1930, and Bench Marks in Alberta (No. 53), by the Topographical Surveys Branch, Department of the Interior, in 1924".

The geoid is used as a transformation linkage between ellipsoidal heights (h) determined from DGPS observations and orthometric heights (H). Widespread acceptability and adoption of GPS in local geospatial data acquisitions require the development of a local geoid model (N) for use to obtain orthometric heights in the absence of a national geoid model. Geoid model can be developed by gravimetric approach; global geopotential model (GGM); geometric technique among others. The conventional approach to GPS measurements is the use of one base reference station for field measurements. It has several drawbacks e.g. in signal range/coverage, accuracy degradation of results, etc. Based on Grashof's law of stability of triangles, this study was therefore based on dual reference base stations to improve on DGPS signal range and stability of results. Pro-online matrix solver was applied to the least squares observation equations of the two modelled FCT surfaces (multi - quadratic and bicubic) to determine polynomial coefficients. The geoid undulation was computed and orthometric height generated for production of a topographical plan at 1m contour interval for elevation data in surveying, engineering and environmental applications. Skill =1 and bias = 0 were computed to confirm the predictive capability of the models and that no bias/errors were introduced into the respective modelling exercise. Diagnostic test also confirmed the viability and feasibility of providing vertical datum surface for FCT by this approach. Standard deviation (σ) as accuracy indicator was computed and the multi-quadratic model with σ =11cm was the better geoid surface for modelling of orthometric height in the FCT by the geometric method.

The geoid is used as a transformation linkage between ellipsoidal heights (h) determined from DGPS observations and orthometric heights (H). Widespread acceptability and adoption of GPS in local geospatial data acquisitions require the development of a local geoid model (N) for use to obtain orthometric heights in the absence of a national geoid model. Geoid model can be developed by gravimetric approach; global geopotential model (GGM); geometric technique among others. The conventional approach to GPS measurements is the use of one base reference station for field measurements. It has several drawbacks e.g. in signal range/coverage, accuracy degradation of results, etc. Based on Grashof's law of stability of triangles, this study was therefore based on dual reference base stations to improve on DGPS signal range and stability of results. Pro-online matrix solver was applied to the least squares observation equations of the two modelled FCT surfaces (multi - quadratic and bicubic) to determine polynomial coefficients. The geoid undulation was computed and orthometric height generated for production of a topographical plan at 1m contour interval for elevation data in surveying, engineering and environmental applications. Skill =1 and bias = 0 were computed to confirm the predictive capability of the models and that no bias/errors were introduced into the respective modelling exercise. Diagnostic test also confirmed the viability and feasibility of providing vertical datum surface for FCT by this approach. Standard deviation (σ) as accuracy indicator was computed and the multi-quadratic model with σ =11cm was the better geoid surface for modelling of orthometric height in the FCT by the geometric method.

The geoid is used as a transformation linkage between ellipsoidal heights (h) determined from DGPS observations and orthometric heights (H). Widespread acceptability and adoption of GPS in local geospatial data acquisitions require the development of a local geoid model (N) for use to obtain orthometric heights in the absence of a national geoid model. Geoid model can be developed by gravimetric approach; global geopotential model (GGM); geometric technique among others. The conventional approach to GPS measurements is the use of one base reference station for field measurements. It has several drawbacks e.g. in signal range/coverage, accuracy degradation of results, etc. Based on Grashof's law of stability of triangles, this study was therefore based on dual reference base stations to improve on DGPS signal range and stability of results. Pro-online matrix solver was applied to the least squares observation equations of the two modelled FCT surfaces (multi - quadratic and bicubic) to determine polynomial coefficients. The geoid undulation was computed and orthometric height generated for production of a topographical plan at 1m contour interval for elevation data in surveying, engineering and environmental applications. Skill =1 and bias = 0 were computed to confirm the predictive capability of the models and that no bias/errors were introduced into the respective modelling exercise. Diagnostic test also confirmed the viability and feasibility of providing vertical datum surface for FCT by this approach. Standard deviation (σ) as accuracy indicator was computed and the multi-quadratic model with σ =11cm was the better geoid surface for modelling of orthometric height in the FCT by the geometric method.

The geoid is used as a transformation linkage between ellipsoidal heights (h) determined from DGPS observations and orthometric heights (H). Widespread acceptability and adoption of GPS in local geospatial data acquisitions require the development of a local geoid model (N) for use to obtain orthometric heights in the absence of a national geoid model. Geoid model can be developed by gravimetric approach; global geopotential model (GGM); geometric technique among others. The conventional approach to GPS measurements is the use of one base reference station for field measurements. It has several drawbacks e.g. in signal range/coverage, accuracy degradation of results, etc. Based on Grashof's law of stability of triangles, this study was therefore based on dual reference base stations to improve on DGPS signal range and stability of results. Pro-online matrix solver was applied to the least squares observation equations of the two modelled FCT surfaces (multi - quadratic and bicubic) to determine polynomial coefficients. The geoid undulation was computed and orthometric height generated for production of a topographical plan at 1m contour interval for elevation data in surveying, engineering and environmental applications. Skill =1 and bias = 0 were computed to confirm the predictive capability of the models and that no bias/errors were introduced into the respective modelling exercise. Diagnostic test also confirmed the viability and feasibility of providing vertical datum surface for FCT by this approach. Standard deviation (σ) as accuracy indicator was computed and the multi-quadratic model with σ =11cm was the better geoid surface for modelling of orthometric height in the FCT by the geometric method.

The geoid is used as a transformation linkage between ellipsoidal heights (h) determined from DGPS observations and orthometric heights (H). Widespread acceptability and adoption of GPS in local geospatial data acquisitions require the development of a local geoid model (N) for use to obtain orthometric heights in the absence of a national geoid model. Geoid model can be developed by gravimetric approach; global geopotential model (GGM); geometric technique among others. The conventional approach to GPS measurements is the use of one base reference station for field measurements. It has several drawbacks e.g. in signal range/coverage, accuracy degradation of results, etc. Based on Grashof's law of stability of triangles, this study was therefore based on dual reference base stations to improve on DGPS signal range and stability of results. Pro-online matrix solver was applied to the least squares observation equations of the two modelled FCT surfaces (multi - quadratic and bicubic) to determine polynomial coefficients. The geoid undulation was computed and orthometric height generated for production of a topographical plan at 1m contour interval for elevation data in surveying, engineering and environmental applications. Skill =1 and bias = 0 were computed to confirm the predictive capability of the models and that no bias/errors were introduced into the respective modelling exercise. Diagnostic test also confirmed the viability and feasibility of providing vertical datum surface for FCT by this approach. Standard deviation (σ) as accuracy indicator was computed and the multi-quadratic model with σ =11cm was the better geoid surface for modelling of orthometric height in the FCT by the geometric method.

Series: Publication (Geodetic Survey of Canada) ; no. 23 // "This volume supplants two separately published first editions, namely: Precise Levelling in Alberta (No.23), issued by the Geodetic Survey of Canada in 1930, and Bench Marks in Alberta (No. 53), by the Topographical Surveys Branch, Department of the Interior, in 1924". // Also published, rev. ed., Precise and secondary levelling in Alberta , Ottawa: Geodetic Survey of Canada, 1949. The revised edition also supersedes, James Wallace, Bench marks established along certain meridians, base lines and township outlines in Alberta , [Ottawa]: Topographical Survey of Canada, 1924.

The geoid is used as a transformation linkage between ellipsoidal heights (h) determined from DGPS observations and orthometric heights (H). Widespread acceptability and adoption of GPS in local geospatial data acquisitions require the development of a local geoid model (N) for use to obtain orthometric heights in the absence of a national geoid model. Geoid model can be developed by gravimetric approach; global geopotential model (GGM); geometric technique among others. The conventional approach to GPS measurements is the use of one base reference station for field measurements. It has several drawbacks e.g. in signal range/coverage, accuracy degradation of results, etc. Based on Grashof's law of stability of triangles, this study was therefore based on dual reference base stations to improve on DGPS signal range and stability of results. Pro-online matrix solver was applied to the least squares observation equations of the two modelled FCT surfaces (multi - quadratic and bicubic) to determine polynomial coefficients. The geoid undulation was computed and orthometric height generated for production of a topographical plan at 1m contour interval for elevation data in surveying, engineering and environmental applications. Skill =1 and bias = 0 were computed to confirm the predictive capability of the models and that no bias/errors were introduced into the respective modelling exercise. Diagnostic test also confirmed the viability and feasibility of providing vertical datum surface for FCT by this approach. Standard deviation (σ) as accuracy indicator was computed and the multi-quadratic model with σ =11cm was the better geoid surface for modelling of orthometric height in the FCT by the geometric method.

The geoid is used as a transformation linkage between ellipsoidal heights (h) determined from DGPS observations and orthometric heights (H). Widespread acceptability and adoption of GPS in local geospatial data acquisitions require the development of a local geoid model (N) for use to obtain orthometric heights in the absence of a national geoid model. Geoid model can be developed by gravimetric approach; global geopotential model (GGM); geometric technique among others. The conventional approach to GPS measurements is the use of one base reference station for field measurements. It has several drawbacks e.g. in signal range/coverage, accuracy degradation of results, etc. Based on Grashof's law of stability of triangles, this study was therefore based on dual reference base stations to improve on DGPS signal range and stability of results. Pro-online matrix solver was applied to the least squares observation equations of the two modelled FCT surfaces (multi - quadratic and bicubic) to determine polynomial coefficients. The geoid undulation was computed and orthometric height generated for production of a topographical plan at 1m contour interval for elevation data in surveying, engineering and environmental applications. Skill =1 and bias = 0 were computed to confirm the predictive capability of the models and that no bias/errors were introduced into the respective modelling exercise. Diagnostic test also confirmed the viability and feasibility of providing vertical datum surface for FCT by this approach. Standard deviation (σ) as accuracy indicator was computed and the multi-quadratic model with σ =11cm was the better geoid surface for modelling of orthometric height in the FCT by the geometric method.

The geoid is used as a transformation linkage between ellipsoidal heights (h) determined from DGPS observations and orthometric heights (H). Widespread acceptability and adoption of GPS in local geospatial data acquisitions require the development of a local geoid model (N) for use to obtain orthometric heights in the absence of a national geoid model. Geoid model can be developed by gravimetric approach; global geopotential model (GGM); geometric technique among others. The conventional approach to GPS measurements is the use of one base reference station for field measurements. It has several drawbacks e.g. in signal range/coverage, accuracy degradation of results, etc. Based on Grashof's law of stability of triangles, this study was therefore based on dual reference base stations to improve on DGPS signal range and stability of results. Pro-online matrix solver was applied to the least squares observation equations of the two modelled FCT surfaces (multi - quadratic and bicubic) to determine polynomial coefficients. The geoid undulation was computed and orthometric height generated for production of a topographical plan at 1m contour interval for elevation data in surveying, engineering and environmental applications. Skill =1 and bias = 0 were computed to confirm the predictive capability of the models and that no bias/errors were introduced into the respective modelling exercise. Diagnostic test also confirmed the viability and feasibility of providing vertical datum surface for FCT by this approach. Standard deviation (σ) as accuracy indicator was computed and the multi-quadratic model with σ =11cm was the better geoid surface for modelling of orthometric height in the FCT by the geometric method.

The geoid is used as a transformation linkage between ellipsoidal heights (h) determined from DGPS observations and orthometric heights (H). Widespread acceptability and adoption of GPS in local geospatial data acquisitions require the development of a local geoid model (N) for use to obtain orthometric heights in the absence of a national geoid model. Geoid model can be developed by gravimetric approach; global geopotential model (GGM); geometric technique among others. The conventional approach to GPS measurements is the use of one base reference station for field measurements. It has several drawbacks e.g. in signal range/coverage, accuracy degradation of results, etc. Based on Grashof's law of stability of triangles, this study was therefore based on dual reference base stations to improve on DGPS signal range and stability of results. Pro-online matrix solver was applied to the least squares observation equations of the two modelled FCT surfaces (multi - quadratic and bicubic) to determine polynomial coefficients. The geoid undulation was computed and orthometric height generated for production of a topographical plan at 1m contour interval for elevation data in surveying, engineering and environmental applications. Skill =1 and bias = 0 were computed to confirm the predictive capability of the models and that no bias/errors were introduced into the respective modelling exercise. Diagnostic test also confirmed the viability and feasibility of providing vertical datum surface for FCT by this approach. Standard deviation (σ) as accuracy indicator was computed and the multi-quadratic model with σ =11cm was the better geoid surface for modelling of orthometric height in the FCT by the geometric method.

The current design is a fixture for mounting digital indicator into MakerBot Replicator 2 for precise manual levelling of the table (I used this digital indicator https://www.ebay.co.uk/itm/0-001mm-0-12-7-Digital-Dial-Indicator-DTI-High-Precision-Measuring-Tools-401033/273847979676?hash=item3fc29c8e9c:g:oXAAAOSwzixc3KAb) The fixture sits on top of the 3D printer shafts and uses small clamps to stay stable. How to use it: 1. Run the table leveling procedure on MakerBot and come to the place where the head is positioned over the table. 2. Adjust the head to be perfectly leveled in this place (use 100um piece of paper to allow smooth insertion under the head) 3. Put some mark (pencil) around this place and switch off the printer 4. Move manually the head completely to the left side 5. Place the fixture on the shafts and clamp it with 3mm screws (insert the screws to tight the holder). 6. Insert the digital indicator inside the hole of the fixture, press it down until you get some non zero readings on the display 7. Move manually the digital indicator tip over the mark point (see step 3) 8. Press zero button on digital indicator to use this Z position as target height 9. Now you can move the fixture manually over different places of the platform and see the deviation from the target height, use the 3 screws on the bottom side of the platform to level it (the process is done on multiple passes until error becomes less than 10um)

The current design is a fixture for mounting digital indicator into MakerBot Replicator 2 for precise manual levelling of the table (I used this digital indicator https://www.ebay.co.uk/itm/0-001mm-0-12-7-Digital-Dial-Indicator-DTI-High-Precision-Measuring-Tools-401033/273847979676?hash=item3fc29c8e9c:g:oXAAAOSwzixc3KAb) The fixture sits on top of the 3D printer shafts and uses small clamps to stay stable. How to use it: 1. Run the table leveling procedure on MakerBot and come to the place where the head is positioned over the table. 2. Adjust the head to be perfectly leveled in this place (use 100um piece of paper to allow smooth insertion under the head) 3. Put some mark (pencil) around this place and switch off the printer 4. Move manually the head completely to the left side 5. Place the fixture on the shafts and clamp it with 3mm screws (insert the screws to tight the holder). 6. Insert the digital indicator inside the hole of the fixture, press it down until you get some non zero readings on the display 7. Move manually the digital indicator tip over the mark point (see step 3) 8. Press zero button on digital indicator to use this Z position as target height 9. Now you can move the fixture manually over different places of the platform and see the deviation from the target height, use the 3 screws on the bottom side of the platform to level it (the process is done on multiple passes until error becomes less than 10um)

The current design is a fixture for mounting digital indicator into MakerBot Replicator 2 for precise manual levelling of the table (I used this digital indicator https://www.ebay.co.uk/itm/0-001mm-0-12-7-Digital-Dial-Indicator-DTI-High-Precision-Measuring-Tools-401033/273847979676?hash=item3fc29c8e9c:g:oXAAAOSwzixc3KAb) The fixture sits on top of the 3D printer shafts and uses small clamps to stay stable. How to use it: 1. Run the table leveling procedure on MakerBot and come to the place where the head is positioned over the table. 2. Adjust the head to be perfectly leveled in this place (use 100um piece of paper to allow smooth insertion under the head) 3. Put some mark (pencil) around this place and switch off the printer 4. Move manually the head completely to the left side 5. Place the fixture on the shafts and clamp it with 3mm screws (insert the screws to tight the holder). 6. Insert the digital indicator inside the hole of the fixture, press it down until you get some non zero readings on the display 7. Move manually the digital indicator tip over the mark point (see step 3) 8. Press zero button on digital indicator to use this Z position as target height 9. Now you can move the fixture manually over different places of the platform and see the deviation from the target height, use the 3 screws on the bottom side of the platform to level it (the process is done on multiple passes until error becomes less than 10um)

The current design is a fixture for mounting digital indicator into MakerBot Replicator 2 for precise manual levelling of the table (I used this digital indicator https://www.ebay.co.uk/itm/0-001mm-0-12-7-Digital-Dial-Indicator-DTI-High-Precision-Measuring-Tools-401033/273847979676?hash=item3fc29c8e9c:g:oXAAAOSwzixc3KAb) The fixture sits on top of the 3D printer shafts and uses small clamps to stay stable. How to use it: 1. Run the table leveling procedure on MakerBot and come to the place where the head is positioned over the table. 2. Adjust the head to be perfectly leveled in this place (use 100um piece of paper to allow smooth insertion under the head) 3. Put some mark (pencil) around this place and switch off the printer 4. Move manually the head completely to the left side 5. Place the fixture on the shafts and clamp it with 3mm screws (insert the screws to tight the holder). 6. Insert the digital indicator inside the hole of the fixture, press it down until you get some non zero readings on the display 7. Move manually the digital indicator tip over the mark point (see step 3) 8. Press zero button on digital indicator to use this Z position as target height 9. Now you can move the fixture manually over different places of the platform and see the deviation from the target height, use the 3 screws on the bottom side of the platform to level it (the process is done on multiple passes until error becomes less than 10um)

The current design is a fixture for mounting digital indicator into MakerBot Replicator 2 for precise manual levelling of the table (I used this digital indicator https://www.ebay.co.uk/itm/0-001mm-0-12-7-Digital-Dial-Indicator-DTI-High-Precision-Measuring-Tools-401033/273847979676?hash=item3fc29c8e9c:g:oXAAAOSwzixc3KAb) The fixture sits on top of the 3D printer shafts and uses small clamps to stay stable. How to use it: 1. Run the table leveling procedure on MakerBot and come to the place where the head is positioned over the table. 2. Adjust the head to be perfectly leveled in this place (use 100um piece of paper to allow smooth insertion under the head) 3. Put some mark (pencil) around this place and switch off the printer 4. Move manually the head completely to the left side 5. Place the fixture on the shafts and clamp it with 3mm screws (insert the screws to tight the holder). 6. Insert the digital indicator inside the hole of the fixture, press it down until you get some non zero readings on the display 7. Move manually the digital indicator tip over the mark point (see step 3) 8. Press zero button on digital indicator to use this Z position as target height 9. Now you can move the fixture manually over different places of the platform and see the deviation from the target height, use the 3 screws on the bottom side of the platform to level it (the process is done on multiple passes until error becomes less than 10um)