Shanker KCGeodetic Survey Division (GSD) · Survey Department (SD)
Shanker KC
Master of Engineering
will update this soon ...
About
10
Publications
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Introduction
ME in Geodesy and Survey Engineering Student at LIESMARS, Wuhan University.
Key Technical Member of Sagarmatha Height Measurement Secretariat (SHMP).
Survey Officer at Geodetic Survey Division, Nepal. (*what I did till now? What I aim to do in next 10 yrs?)
Publications
Publications (10)
The geodetic infrastructure such as terrestrial reference frames and Continuously Operating Reference Station (CORS) infrastructure is fundamental to build and support climate responsive land governance and disaster resilience. Similarly, the surveying and mapping information from modern surveying methods such as Real Time Kinematic (RTK), Light De...
Heterogeneous measurements from various surveying methods need to be integrated to accomplish any survey project. The use of Global Navigation Satellite System (GNSS) and Total Station (TS) to establish a control framework along with utilizing existing national grid controls, for any survey project has been the standard practice. However, the succe...
By looking into the advancement of geodesy from past to present- theories and technologies of geodesy can be distinctly divided into classical and modern geodesy. Modern geodesy stands upon the achievements/foundations of classical geodesy however, modern geodesy has come very far away at present and classical geodesy has become almost obsolete. Th...
Orthometric height is the generally adopted type of height worldwide and in geomatics community. Precise levelling has been the method of obtaining orthometric height in past for most of the country, so as the Nepal. However, due to wide usage of Global Navigation Satellite System (GNSS), the alternative approach of combining GNSS derived ellipsoid...
Gravimetry implies to the measurement of gravity, which may be relative or absolute. It aids in geotechnical, archeological, geophysical,
geodetic etc. studies. Nepal initiated gravity survey in the 1970s when gravity transfer was made from Bangkok to Kathmandu and surveys
were carried out for mineral exploration by the Department of Mines and Geol...
![Snap of 1”:4 miles topographic map [16].](publication/355946023/figure/fig2/AS:11431281212155528@1702552286627/Snap-of-14-miles-topographic-map-16_Q320.jpg)
![Triangulation network Everest height measurement 1952–1954 [6].](publication/355946023/figure/fig4/AS:11431281212130156@1702552287613/Triangulation-network-Everest-height-measurement-1952-1954-6_Q320.jpg)
From celestial objects to every feature on Earth, geodesy provides a reference frame and is the foundation for surveying, mapping, and other geoscience activities. In Nepal, geodesy was officially introduced after 1924 to prepare the topographic map series. Although the previous geodetic project took place with foreign assistance, Nepal is utilizin...
The height measurement of the highest peak of the world "Sagarmatha" was conducted by Nepal for the first time. The methodology for the measurement was finalized from the workshop held in Kathmandu with the constructive comments from national and international experts. Trignometrical levelling, precise levelling, GNSS survey and gravity survey was...
Gravity plays very crucial role in geodetic issues as gravity field determines the shape of the earth. This paper reviews – beginning from defining the gravity, various applications of gravity in geodesy and in other fields, nature of gravity field of our terrain, instruments of gravity measurement, and techniques of gravity survey. This paper firs...
Gravimetric geoid plays the important role in the process of local/regional geoidal undulation determination. This approach uses the residual gravity anomalies determined by the surface gravity measurement using the gravimeter together with best fit geopotential model, with the geoid undulations over the oceans determined from the method of satelli...
Questions
Questions (72)
It seems it is common to combine basic observations to create new observable, which are then used for PPP and other applications. Basic observations such as pseudorange and carrier-phase observations are real measurement from GNSS. These real observations are combined to create entirely new observable which is not direct, physical, and real. Amazingly, these new observable solves the real problem such as PPP (e.g. Ionosphere -free combination).
- What is the theory behind this?
- Any similar approach like this in other scientific field or any simple analogous explanation?
- You could direct me to resources such as videos, or literature.
I have 3D position of few of GNSS stations obtained from AUSPOS service in ITRF2014 frame. I have 3D position of same stations from CSRS-PPP service in ITRF2020 reference frame. I want to transform ITRF2014 position into ITRF2020 position to compare the results. I came to know the transformation parameters to move from ITRF2014 to ITRF2020 are available in IERS website. However, I needed an explanation on how to achieve this such as brief theoretical overview, softwares or scripts that does this job, any walk-through resources e.g. document or videos that streamlined this process.
A gravity gradient is different than an absolute gravity value.
What is the interpretation of horizontal and vertical gravity gradient?
Below I have added EGM2008 gravity anomaly plot. The gravity anomaly switch its direction from negative in north of India to positive in Himalayas and Tibetan plateau.
Why is this happening?
What it says about geology of this region?
What it says about underlying crust and density in this region?
Could you please explain it really well - connecting ideas (cause and effect)?
How do I obtain gridded data points from discrete data points as shown in following figure?
Long-wavelength, medium-wavelength, and short-wavelength information of gravity field, what are these? What part of earth give rise to such different wavelength information?
I am having difficulty understanding the polar motion of the Earth. I am trying to understand terrestrial coordinate systems in geodesy. Then, there is idea of Conventional International Origin (CIO) and Greenwich mean astronomic meridian. Could anyone explain polar motion of the earth: its causes, and how it is measured.
How to understand the following polar motion plot?
In IGS website, only GPS precise orbit is available. I want to perform PPP analysis with multi-GNSS combination which requires precise orbit of other constellations along with GPS orbits. How can I get precise orbit for GALILEO, GLONASS, BDS etc?
We are trying to perform PPP analysis for 1h observation period. Is 1h of data sufficient for doing PPP analysis?
I have got rinex observation file of rinex version 3.04. But I needed to convert it to rinex 3.02 so that rtklib can take it as input. I checked the website of rtklib, it seems, rtklib can only support up to 3.02.
What does vertical datum refer to? Is it Mean Sea Level (MSL)? Is it a zero mark in the tide gauge? Is it some other height value than zero, far from the tide gauge? Is it one reference benchmark? Is it all the benchmarks in the levelling network? Is it the combination of all these?
Geoid: there are infinitely many level surfaces (equipotential surfaces) and the one which coincides with MSL is called a geoid. But what is the quasigeoid?
