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Welcome to the homepage of Micro-Laboratory of Atmospheric Research and Geomatics Engineering (Micro-LARGE)


Recently updated (This page was last updated on August 29, 2016)


[August 29, 2016] The “What’s New” page is update. Click here to view.


[August 29, 2016] 2017 Hong Kong PhD Fellowship (Annually available)


Starting from 2009, a new program for PhD students “Hong Kong PhD Fellowship Scheme” is introduced by the Hong Kong Research Grants Council. The Fellowship Scheme aims to attract the outstanding students in the

World (including those from Hong Kong and Mainland China) to pursue their PhD degree programs in Hong Kong.


The Fellowship will provide an annual stipend of HK$240,000 (approximately US$30,000) and a conference and research-related travel allowance of HK$10,000 (approximately US$1,300) per year for a maximum period of 36-month. Nearly 150 PhD Fellowships are awarded each year.


Please contact Dr. Liu ( for more information about this PhD Fellowship. More information about this PhD Fellowship Scheme can also be found @


Please note that, at all time, all kinds (MSc, MPhil or PhD including the Hong Kong PhD Fellowship) of applicants to PolyU are required to submit their application package through


[Note to prospective MSc/MPhil/PhD Students, Visiting Students, Postdoc Fellows]

The Micro-LARGE group always (year-round) looks for top excellent, self-motivated students and researchers who are striving for pursuing a post-graduate degree (MSc., MPhil, or PhD) to join the group.

Premium full scholarships will be offered to those successful applicants.

Please always contact Dr. Liu ( if you want more information or have questions.


We are more concerned with the following quality of applicants: Academic background, Publication records, Computer language skills (e.g. C++, Matlab, Fortran), English language skills, Inter-person communication skills.

For MSc/MPhil/PhD students to register a degree at PolyU, the minimum English requirement is:

Applicants who have not obtained a degree from an English-teaching university, the minimum English requirement is one of the following:

(1)         an IELTS (International English Language Testing System) >=6.5 (writing component >=6.0), or,

(2)         a regular TOEFL (Test of English as a Foreign Language) score of >=575, or,

(3)         a computer-based TOEFL (after 1998) score of >=232, or,

(4)         an internet-based TOEFL score of >=90, or,

(5)         other acceptable English test results, such as GRE (Graduate Record Examination) or GMAT (Graduate Management Admission Test).


All English language test scores (TOEFL, IELTS or others) are considered valid for five years after the date of the test.

For the Visiting Students and Postdoc Fellows, it is ideal to meet the PolyU’s minimum English requirement.



George joined the Department of Land Surveying & Geo-Informatics (LSGI), Faculty of Construction and Environment (FCE), The Hong Kong Polytechnic University(PolyU) on June 24, 2009. He and his family arrived at Hong Kong on June 23, 2009 from Calgary, Canada after George had lived, worked, and studied in Calgary for nearly 10 years.


Hong Kong is a quite dynamic city and is quite different from Calgary. One most distinct difference is the weather.


We welcome all kinds of collaborations to achieve our destinations. If you have any interests, please don’t hesitate to contact Dr. George Liu.


We are a group of scientists and engineers dedicated to the Research, Innovation, Development (RID) in the area of atmosphere and geomatics, using multiple techniques, such as Global Positioning System (GPS), Global Navigation Satellite System (GNSS), remote sensing satellites and other instruments.


The Micro-LARGE Lab is equipped with the world’s state-of-art instruments, software, datasets and algorithms to support the innovation work conducted daily by our researchers.


The excellence, impact and quality (EIP) of research outcomes are our ultimate pursuit, while quantity is our secondary condition. We, the Micro-LARGE, are striving to the highest level of excellence in teaching, research, and community service. It is our destination goal to research and use the modern Geomatics technologies to improve the living experience of the world’s people.


The Micro-LARGE Lab has a large number of research grants to support its RID activities. The Micro-LARGE Lab has established a large network of international collaborations with scientists from USA, Canada, Australia, Greece, UK and Mainland China. We always look for students (undergraduate, MSc. and Master of Philosophy (MPhil), PhD) and Research Assistant (with a Master degree), Research Associate (with a PhD degree) and Visiting Scholars to join this innovative, dynamic group. Please contact Dr. George Zhizhao Liu: for any inquiries.



We are very pleased to announce that one full-time PhD Scholarship is available at the Micro-LARGE group. 

PhD Scholarship Available

Department of Land Surveying&Geo-Informatics

The HongKong Polytechnic University

Applications are called for one PhD scholarship available at the Department of Land Surveying & Geo-Informatics (LSGI), The Hong Kong Polytechnic University (PolyU), Hong Kong, China. This position will be open until the successful applicant is identified.


The successful applicant will be funded to study in a PhD program for three years (3 years) since early 2012 at PolyU and be working on the 3D tomographic modeling of the water vapor in the greater China region. Specifically the candidate will be responsible for the project “3D Water Vapor Tomographic Modeling by Assimilating Multiple Sensors to Support Extreme Weather Forecasting in Hong Kong and Mainland China” funded by the Hong Kong Research Grants Council (RGC).


This project is technically supported by a team of international researchers. The successful applicant will work with scientists from Hong Kong Observatory, China Meteorological Administration (Beijing), The University of Calgary (Canada), and The RMIT University (Australia). The candidate will have the opportunity to physically visit and work with the international collaborators when project progresses.


Applicants are invited to send the CV and publication samples to Dr. George Zhizhao Liu, who can be contacted via no. (852)2766 5961, fax no. (852) 2330 2994 for further information. Only selected applicants will be contacted for interview. More information about the LSGI Department can be found at


Remuneration: Highly competitive salary will be offered to the successful applicant.

Advertisement Date:11 September 2011


Geomatics, an incredibly critical technology in this information era!


In this world, scientists, engineers, researchers, and actually many people are working hard every day to try to answer the following 6 most fundamental questions more correctly and more precisely:

1) When 2)Where 3) Who 4)What 5)Why 6)How

At present, we can easily answer “When” in a completely numerical way because our time has been digitalized, for instance: the UTC time at this point of writing is:2010-01-19 15:22:20. The numerical expression of time is an important progress in human being history and it is essential in this information era. So how about the other 4W1H questions? Can you also use numbers to answer the remaining 4W1H questions? Answer is yes or no. If you use Geomatics technology, you can answer the Where numerically too. Without geomatics, you can’t. Why? The answer is simple. For example, Hong Kong’s latitude and longitude is: 22°20North,      114°11 East. So you can see the location of Hong Kong can be easily described in numeric numbers. How to get these numbers? It is a part of geomatics technology – using Global Positioning System (GPS). With GPS, you may locate anywhere in the world numerically and display it on your computer screen. This is the power and beauty of geomatics technology – answering one of the world’s most fundamental questions “WHERE” in a numerical way, a way people have never thought of and away that is so critical in today’s information era.


With GPS technology, now any objects in our 4-dimensional space-time domain can be completely digitalized and numerically stamped. This is the contribution our geomaticians are making to the society.


[May 26, 2013] Recently, a paper was coauthored by Zhizhao Liu, Rui Xu, Yu Morton, Jisheng Xu, Wouter Pelgrum, Steve Taylor, Wu Chen and Xiaoli Ding.


[May. 22, 2013] We are very pleased to announce that Dr. Liu is to receive the Excellent Paper Award from the 2013 4th Chinese Satellite Navigation Conference (CSNC 2013) in Wuhan, China.


In the recent 2013 China Satellite Navigation Conference (CSNC) held May 15-17 in Wuhan, Dr. George Zhizhao Liu from the Department of Land Surveying & Geo-Informatics (LSGI) received the Excellent Paper Award for his paper “The First PPP-based GPS Water Vapor Real-Time Monitoring System in Pearl-River-Delta Region, China” co-authored with Research Associate Dr. Min Li. This paper presents their research findings of developing the first atmospheric water vapor real-time monitoring system for the Pearl-River-Delta (PRD) region using the latest Global Positioning System (GPS) Precise Point Positioning (PPP) technique. Based on their technique, now the amount of water vapor in the atmosphere over the PRD region can be quickly and accurately computed from GPS satellite signals. Since April 2012, the PolyU researchers have been supplying their atmospheric water vapor data to the meteorological agencies around the PRD region to support their daily services and research, including Hong Kong Observatory, Macao Meteorological and Geophysical Bureau, Guangdong Meteorological Bureau and Shenzhen Meteorological Bureau.


This year is the first time for CSNC to have the Excellent Paper Award. Dr. Liu was one of the nine award recipients out of 629 paper submissions (success rate: 1.43%). This research work was supported by the General Research Fund (GRF) of Hong Kong Research Grants Council (RGC).


[May. 11, 2013] We are very pleased to announce that Dr. George Zhizhao Liu was given an

honor of Individual Award of Shenzhen Virtual University Park for National Research Project, by the Shenzhen

Municipal Science and Technology Innovation Council December 2012.


[Dec. 12, 2012] The Inaugural Early Career Award Recipient (首届杰出青年学者奖”), Hong Kong Research Grants Council (RGC), Hong Kong Special Administrative Region (HKSAR). Dr. Liu was one of the 19 recipients out of 334 applicants across all the universities in Hong Kong in 2012 (success rate: 5.69%). He is also one of only 3 recipients in PolyU and one of 6 recipients in the Engineering Panel under Hong Kong RGC.


[July 23, 2012] We are pleased to share with you that our research project “Innovative Real-Time Cycle Slip Detection and Rectification for High Precision GPS Positioning” led by Dr. George Zhizhao Liu is funded by the Early Career Scheme (ECS), Hong Kong Research Grants Council (RGC), Hong Kong SAR Government. This project, together with 19 other projects across all the universities in Hong Kong, will be recognized with an “Early Career Award” (ECA), which is the first time to give ECA in the history of Hong Kong RGC.  For this project, one PhD student will be funded for three (3) years. Interested applications are welcome to contact Dr. Liu.


[July 23, 2012] We are pleased to share with you that our paper “Cycle slip detection and repair for undifferenced GPS observations under high ionospheric activity” co-authored by Changsheng Cai • Zhizhao Liu • Pengfei Xia • Wujiao Dai is published online @ GPS Solutions 4 July 2012. As of 23 July 2012 (20 days after the online publication), this paper has been downloaded 174 times, ranked 2nd in the list of most downloaded papers in the 30-days category. This paper can be downloaded @



 [14-15May 2012, Hong Kong]We are very pleased to announce theGNSSSchool(click for announcement) will be held attheDepartment ofLSGI,Hong Kong PolytechnicUniversity, 14-15 May 2012. Five distinguishedresearchers will give lectures for the GNSS School. The registration fee isonly HK$200 (approx. US$25).

Dr. Jade Morton: How GNSS Signal ProcessingAlters Signal Parameters: A Cautionary Tale in Using GNSS for Remote SensingApplications

Dr. PeterTeunissen: Carrier-Phase GNSS Attitude Determination

Dr. Maorong Ge: PPP Algorithms
Dr. Peng Fang:Global and Regional Reference Frame: Establishment, Maintenance, and Application
Dr. Danan Dong:Dig out signals from deep interior of the Earth using GPS measurements


[14 May 2012, HongKong]Dr. Jens Wickert, Acting headof section 1.1 “GPS/Galileo Earth Observation”

German Research Center for Geosciences GFZ, Potsdam,Germany is invited to give a talkonGPS/Galileo Earth Observation at GFZ: Recent activities and results” attheHong Kong PolytechnicUniversity.


[22 March 2012, Hong Kong] Dr.George Liu was invited to give a talk at theCivilEngineering and Development Department, Hong Kong Special Administrative Region(HK SAR) GovernmentonMonitoring Equatorial andLow-latitude Ionospheric Scintillation and Assessing Scintillation Impact onSatRef Network and GPS Applications in Hong Kong”.


[13 March 2012, Hong Kong] Weare very glad that our paper “A multi-sensor study of watervapour from radiosonde, MODIS and AERONET: a case study of Hong Kong” was published atINTERNATIONAL JOURNAL OF CLIMATOLOGY in December 2011. This paper wascoauthored by

Zhizhao Liu, Man Sing Wong,Janet Nichol and P. W. Chan. The citation is:Zhizhao Liu, Man Sing Wong,Janet Nichol and P. W. Chan (2011),Amulti-sensor study of water vapour from radiosonde, MODIS and AERONET: a case studyof Hong Kong,Int. J. Climatol.DOI: 10.1002/joc.3412.



[09 March 2012, Hong Kong] Dr.George Liu was invited to give a talk at theBeijingUniversity of Aeronautics and Astronautics (BUAA)onAn innovative approach for successful cycle slip detection and fixeven with arbitrarily large pseudorange errors”.


[08 March 2012, Hong Kong] Dr.George Liu was invited to present the Compass (Beidou) receiver evaluationresults at the Unicore Communications Inc. Beijing with a title “Preliminary Quality Analysis of the Pseudorange and Carrier PhaseData from Unicore Compass+GPS Receiver”.


[17 February 2012, Hong Kong]Dr. George Liu was invited to give a talk at the Chinese University of HongKong on “Water Vapor Observation in HongKong by Radiosonde, AERONET and MODIS”.


[17 January 2012, Hong Kong]Dr. George Liu is glad to receive fund support for the research “Improving the GPS SurveyingProductivity in Construction by Modeling the Localized Errors in the GPSNetwork—Case Study with Hong Kong’s SatRef Network” from Construction Industry Institute Hong Kong /PolyU Innovation Fund Governing Council. Thank youConstruction Industry InstituteHong Kong / PolyUInnovation Fund Governing Council!


[05 January 2012, Hong Kong]Dr. Jade Morton, Professor atthe Department of Electricaland Computer Engineering,Miami U, USA,was invited to give a talk atthe Department ofLSGI,Hong Kong PolytechnicUniversity on the topic “Ionosphere Effects and other GNSS and RF Navigation Research atMiami”.


[03 January 2012, Hong Kong]Dr. George Liu was invited to give a talk at the Hong Kong Observatory (HKO) on“Preliminary Investigation of Real Time PWV Monitoring in Hong Kong”.


[20 November 2011, Hong Kong]Dr. George Liu was invited to give a talk at the Wuhan University, China on “Evaluating Water Vapor Observed by Radiosonde, AERONET and MODIS inHong Kong”.


[11 October 2011, Hong Kong]Dr. Naser El-Sheimy, Professor at theDepartment of Geomatics Engineering, U of Calgary, Canada,was invited to give a talk atthe Department ofLSGI,Hong Kong PolytechnicUniversity on the topic “EmergingMEMS Sensors and Its Impact on Mapping and Navigation Applications”.



Last updated


[24September 2011, Hong Kong] We are very pleased to announce thatmultiple MSc level projects are available for thenew MSc students. The interested students are welcome tocontact Dr. George Liu by a visit HJ728 or an a call 27665961.


[24September 2011, Hong Kong]


[24September 2011, Hong Kong] We are very pleased to announce that ourGeneral Research Fund(GRF) application tothe Hong Kong ResearchGrants Council (RGC)was successfully fundedafter a fierce competition.Thetitle of this project is “3D Water Vapor TomographicModeling by Assimilating Multiple Sensors to Support Extreme WeatherForecasting in Hong Kong and Mainland China.


[24September 2011, Hong Kong] Our publication was reported in“Science Letter”on 7 June2011.



[24September 2011, Hong Kong]As of 23Feb. 2011our paper(link here)wasranked 3rdin the most downloaded papersin Journal of Geodesy based on the downloads in the past 90 days since itsfirst day of online publication, one of the internationally well recognizedjournals in Geomatics.

90days_download_Feb23_2011(after publish 90 days).png


As of 10 Feb. 2011ourpaper(linkhere)is ranked one of the 5 most downloaded papers in Journal of Geodesybased on the downloads in the past 77 days since its first day of onlinepublication, one of the internationally well recognized journals in Geomatics.

This paper developed afully automated cycle slip detection and repair algorithm for dual-frequencyGPS carrier phase measurements. It can be safely said that the cycle slipproblem that have been hanging over the GPS community as long as the GPShistory itself (~30 years) is well resolved.


This algorithm is extremelyeffective for high rate GPS data like 1Hz or higher. Virtually any size ofcycle slips can be detected and repaired.


For low rate GPS data (like30 sec data interval or larger) this algorithm can work for many cycle slipcases but it might be a little difficulty for small cycle slips.


This method has beenextensively tested and examined in many scenarios such as:

o  High dynamics (space-borne GPS receiver payload on COSMICsatellite)

o  Highly disturbed ionosphere (daily Kp index =7.6 on 31 March2001, the 4thhighest daily Kp value in the past 30 years)


We look forward to hearingyour feedback and your comments/suggestions are always welcome.



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