Reference no: EM133034337
LSGI 2224 Geo-Referencing Systems
Question 1. Multiple choices (one or more options are correct).
(1) If you are using your smartphone to output the coordinates of one point on the campus of PolyU in November 2021. Which reference frame are your coordinates in:
(A) WGS84
(B) WGS 84 (G730)
(C) WGS 84 (G873) (D) WGS 84 (G1150) (E) WGS 84 (G1674) (F) WGS 84 (G1762) (G) WGS 84 (G2139)
(2) German company Geo++ GmbH has developed an Android smartphone App "Geo++ Rinex Logger", which can record the raw GNSS measurements of the smartphone in a RINEX format file. The RINEX format file can then be processed by high precision GNSS software to get a more accurate GNSS positioning result than the one from smartphone. Assume that you download RINEX format file from your Android smartphone and then upload it to online platform - the Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP) online service to determine the precise position of your smartphone. You used the precise GNSS orbit data produced by the International GNSS Service (IGS) during your GNSS data processing. The IGS precise orbit data are in the IGb14, which is aligned with the International Terrestrial Reference Frame 2014. So your final GNSS positioning coordinates for your smartphone will in the reference frame of:
(A) WGS84
(B) WGS 84 (G730)
(C) WGS 84 (G873) (D) WGS 84 (G1150) (E) WGS 84 (G1674) (F) WGS 84 (G1762) (G) WGS 84 (G2139)
(H) ITRF2014
(I) IGb2014
(3) Assume that you are one Land Surveyor employed by the AECOM Asia Company Limited located in Shatin, Hong Kong. You need to obtain very high precision coordinate for your control surveying points. So you deployed your receivers on your points and collected GNSS data on those points for a continuous two months from 1 January 2021 to 28 February 2021. You processed the two month data in the ITRF14 reference frame. Which epoch do your coordinates refer to?
(A) 2021.00
(B) 2021.08
(C) 2021.10
(D) 2021.12
(E) 2021.14
(F) 2021.16
(4) According to the results obtained by the Hong Kong Observatory, the horizontal movement of GPS stations in Hong Kong is approximately 33 mm/year in the East-southeast direction while the vertical movement is insignificant. Assume that you are a Land Surveying Graduate (LSG) working for the Survey and Mapping Office, Lands Department, HKSAR Government. For one slope deformation monitoring project, your colleagues surveyed the points using GNSS technology on 1 May 2020 and the coordinates in the latest ITRF frame ITRF14. One 1 November 2021, you surveyed those points again using GNSS again and also in ITRF14 reference frame. Assume that those surveying points did not undergo any artificial movements. Compared to your colleagues' ITRF14 solution, your coordinates will
(A) be nearly same with acceptable difference (at most a few mm) due to measurement noises
(B) be impossible to tell because the GNSS software used to process GNSS data may be different
(C) be different by about three centimeters
(D) be different by about five centimeters
(E) be exactly the same as both are under the same ITRF14 reference frame
Question 2. According to the results obtained by the Hong Kong Observatory, the horizontal movement of GPS stations in Hong Kong is approximately 33 mm/year in the East-southeast direction while the vertical movement is insignificant. Assume that you are one Land Surveyor employed by the EGS (Asia) Ltd located in North Point, Hong Kong. One benchmark was surveyed and used by EGS (Asia) Ltd in 1990 and coordinates in the Hong Kong 1980 geodetic datum were available. In the year 2021, your manager asked you to complete one surveying project, which required the use of that benchmark. It was unfortunate for you to find that the benchmark had been destroyed during a construction project.
You now have to use modern GNSS technologies to re-survey that benchmark. You used GNSS data processing method such as the Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP) online service to determine the precise position of this benchmark. You used the precise GNSS orbit data produced by the International GNSS Service (IGS) during your GNSS data processing. The IGS precise orbit data are in the IGb14, which is aligned with the International Terrestrial Reference Frame 2014. So your final GNSS positioning coordinates for the benchmark are also in the International Terrestrial Reference Frame 2014.
As the International Terrestrial Reference Frame 2014 is different from the Hong Kong 1980 geodetic datum. Assume that you can use Helmert transformation to transform your newly obtained GNSS coordinate to the Hong Kong 1980 geodetic datum. In your data quality check stage, you examine your new coordinates in Hong Kong 1980 geodetic datum by comparing them with the historical log sheet of that benchmark.
Will your new coordinates surveyed in 2021 be same as or approximately close to the ones in 1990? Please justify your answer. If not, how much difference will you expect to see?
Question 3. One station in Hong Kong has geodetic coordinates (22° 19' 19.81950"N, 114° 08' 28.27667"E, 20.2386 m) in the ITRF96 (reference epoch 1998:121).
(3a) What are the cartesian Coordinates in ITRF96 (reference epoch 1998:121)?
(3b) What are the cartesian Coordinates in HK80 reference frame?
(3c) What are the geodetic Coordinates in HK80 reference frame?
(3d) What are the grid coordinates (Northing, Easting) in HK80 reference frame?
Attachment:- Geo-Referencing Systems.rar