Lawatan Prof Lichti

Lawatan oleh Prof Lichti dari U of Calgary. Beliau menyampaikan satu lecture tentang fotogrammetri terkini.

Pelawat dari U of Calgary

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Reiner Rummel at IUGG Prague 2015

Prof Reiner Rummel merupakan ahli geodesi yang menerajui perkembangan global geopotential model (GGM) khususnya yang dibangunkan dari satelit GOCE. Ringkasnya Rummel layak digelar sebagai 'the Father of GOCE'. Sebagai menghargai sumbangan besar beliau kepada GOCE dan juga GGM Prof Rummel telah dianugerah IAG Levallois Medal. Penganugerahan ini telah disempurnakan sempena IUGG General Assembley 2015  pada Jun lepas di Prague.

Rummel - Pemenang IAG Levallois Medal

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Eigen 6C4 GGM (2014)

There were a number of recent Global Geopotential Model produced in the last couple of years. Among them were Eigen 6C4 which was developed by a combination of teams from GFZ, CNES/GRGS and Kiel University. Papers on  the development of Eigen-6C4 were presented at a number of conference such as EGU General Assembly 2014 (read here) and Geodetic Week on Oct 2014 at Berlin (read here).

Look at the names behind Eigen-6C4

An evaluation of Eigen 6c4 was performed by Kostelecky et al  (2015) and can be read here - Evaluation of gravity field model EIGEN-6C4 by means of various functions of gravity potential, and by GNSS/levelling

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Geoid Talk - Series 3

Another series of talk on geoid computation was given this morning at Girg meeting room. It was attended by a number of grad students and I thank them for their patient in listening. Actually the talk was arranged ad-hoc and it is more of sort of repeating what was discussed in previous meetings.

Among the main points highlighted in the talk were the three input data required for geoid computation - terrestrial data, ggm contribution and DEM. Emphasis was also given on the development of current GGM and the role it plays in geoid computation. The concept and availability of various form of Stokes modification formulae was also highlighted. In the end a review of geoid development and revision in several countries around the World was mentioned.

Group photo with audience attended

Slides on geoid re-computation effort is attached for reference (jupem geoid review 1).

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Mesyuarat JK Latihan Industri 3Sghu

Mesyuarat diadakan pada 12 Nov yang antara lainnya membincangkan mengenai isu penempatan LI. Seramai 11 pelajar memohon untuk menjalani latihan di Girg dan diputuskan hanya 5 yang patut dicadang terima. Pada kali ini tiada yang menjalani latihan di pantai timur kecuali seorang yang memilih Kuantan. Kawasan utara juga kurang dengan hanya seorang di Kedah yang beberapa yang lain di Penang dan Ipoh. Selebihnya ramai di Selangor, KL, N9 dan Melaka. Majoriti adalah di Johor.

Tarikh lawatan LI telah diputuskan pada 20-27 Mac dan 2-9 Mei 2016.

Pembahagian tugas lawatan LI

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Lab1 Sghu 4863

Pelajar yang mengambil subjek elektif Sghu4863 perlu menyelesaikan Lab 1 mereka melibatkan pengukuran simulasi sebuah objek geometri. Lab ini biasanya dijalankan indoor dan mereka diminta untuk mengukur objek bentuk rectangle rel tangga di sekitar Blok C03.

Setiap kumpulan terdiri dari lima pelajar dan boleh menyiapkan Lab tersebut dalam tempoh 4 - 5 jam kerja lapangan masing-masing.

Pelajar 4 Sghu gembira setelah menyiapkan kerja ukur mereka

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Prof Hans-George Wenzel (1945-1999)

When talking about the stochastic approach of modification of Stokes for geoid computation two names always been quoted - Sjoberg and Wenzel. Prof Sjoberg is famous with his formulation described particularly in three journal papers (Sjoberg 1984, 1991 and 2003) while Wenzel has two both published in 1980's (Wenzel 1982, 1983). As mentioned in previous post Wenzel's work on stokes modification can only be found in these two papers. It seemed no follow-up and no taker continuing his work. This is understandable as a results of his demise in 1999 at the age of 54.
Wenzel in memoriam written by Torge in IAG Newsletter March 2000 can be read here.

Wenzel was born in 1945 and he studied geodesy at TU Hannover in 1968-1972. He then entered Institute of Theoretical Geodesy U of Hannover and he received the Doktor-Ingenieur degree with a thesis on the accuracy of gravimetric earth tides observations (1976), and his Dr.-Ing. habil. thesis dealt with high resolution spherical harmonic models for the gravitational potential of the earth (1985).

Wenzel two monumental papers on stochastic stokes modification were;

Wenzel H.G. (1982): Geoid computation by least-squares spectral combination using integration kernels. In Proceedings of IAG General Meeting, Tokyo. pp: 438-453
Weber, G & Wenzel H.G. (1983) Error covariance functions of sea gravity data and implication for geoid determination. Paper presented to IAG General Assembly, Tokyo. Marine Geodesy 7: 199-226

Another major publication of importance to geoid is;

Wenzel (1998) Ultra-high degree geopotential models GPM98A, B, and C to degree 1800. In Proc of the joint meeting of the International Gravity Commission and International Geoid Commission, Trieste Italy.

Late Prof Hans-George Wenzel

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Stochastic Stokes Modification - Sjoberg & Wenzel Works

In geoid computation method there were two types of Stokes modification (SM) been developed - the deterministic and the stochastic approach. Examples of the former include Molodenski et. al (1962), Wong & Gore (1969), Meissl (1971) , and Vanicek & Kleusberg (1987). As for the stochastic approach  there were only two researchers have ever ventured into it - Sjoberg (1984, 1991 and 2003) and Wenzel (1981, 1983). The main difference between the deterministic and stochastic Stokes modification approach is that in the former minimizing truncation error is the only aim while the latter concerns not only the truncation error but in addition errors in terrestrial gravity data and GGM-derived gravity anomalies were taken into account as well.

In comparing the two stochastic approaches  i.e., Sjoberg and Wenzel works, the former was further actively developed and eventually resulted with a complete geoid computation package known as KTH Geolab. Wenzel work was not pursued further other than the two papers published (Wenzel 1981, 1983). Professor Wenzel (b.1948) died in 1999 at age of 54 and that put sort of a full stop to his idea of stochastic approach of Stokes modification.

Photo taken during talk given on Stokes modification geoid

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Bulgaria Geoid - 2001 and 2004

Bulgaria geoid has been worked by Assoc Prof Elena Peneva of Geodesy Dept, U of Architecture, Civil Engineering and Geodesy, Sofia. Her work was submitted as a doctoral dissertation entitled "Gravimetric Geoid Determination for the Territory of Bulgaria" (in Bulgarian) at the same department in 2001. It was later published as a journal paper "A preliminary gravimetric geoid model for the territory of Bulgaria" in AVN 10/2004. The Bulgaria geoid was computed by remove restore technique employing FFT method using Gravsoft geoid package. She later evaluated this geoid with gps-levelling data and the results were then published in 2006.

Prof Peneva website can be reached here; her paper in AVN journal can be downloaded here; the gps-levelling comparison can be read here.

Her class on geoid computation is here - link.

Prof Elena Peneva (researchgate)

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Kuliah Jemputan LS Prof Wan Aziz

Pada pagi ini satu kuliah jemputan telah diadakan kepada pelajar 1Sghu. Kuliah disampaikan oleh penceramah undangan Prof Dr Wan Abdul Aziz yang juga merupakan mantan pensyarah FGHT.  ProfWan  kini adalah seorang Juruukur Berlesen yang membuka firma sendiri di Taman Melawati KL. Tajuk ceramah yang disampaikan ialah "A Professional Licensed Surveyor: Benefits and Challenges". Kandungan ceramah menjurus kepada prosidur dan syarat bagi graduan Geomatik untuk diterima sebagai Juruukur Berlesen.

Sebahagian yang hadir kuliah jemputan LS Dr Wan Aziz

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