CORS-: Updating Maps in Real-Time

by Konrad Saal maps, as well as in integrating collected GIS data into the common nationwide GIS database. In the past few years the State of Qatar, a pen- insula on the Arabian Gulf, has experienced CGIS setup the CORS network to help achieve coun- extensive infrastructure development. More try-wide, homogenous horizontal and vertical accu- than twenty years ago the results of a user racy and to ensure the availability of RTK corrections needs assessment carried out by the govern- for all survey and mapping communities in Qatar. ment clearly indicated an enormous need for Many agencies can now log on to the CORS network a fully integrated nationwide GIS. The govern- to carry out their tasks without needing to setup ment then established the Centre for GIS (CGIS) single base stations. The new CORS-Qatar network as a department of the Ministry of Municipal- consists of nine reference stations and helps many ity & Urban Planning. It is based in the capital organizations using RTK and GIS rovers receive dif- and became the official mapping agency ferential corrections for their day-to-day activities. of the State of Qatar. Since the end of October 2009, many public and private survey and map- All reference stations are homogenously distributed ping communities have been benefiting from a throughout the country and were established at Al nationwide Continuously Operating Reference Shamal, Al Thakhira, Al Jumailiya, , Al Khara- Station (CORS) network. nah, Abu Samra, Mesaieed and Sawda Natheel, and finally, at the Qatar University in Doha. Each of the The CORS network was set up with receivers, anten- nine reference stations is equipped with future proof nas, high-precision tilt sensors, and GNSS Spider Leica GRX1200+ GNSS receivers and highly accurate software from Leica Geosystems. Delivering highly Leica AR25 choke ring antennas. Due to the high accurate data and comprehensive customer servic- temperatures in Qatar, the receivers are installed in es, the CORS network now plays a major role in all air-conditioned indoor and outdoor cabinets. The geodetic and topographic surveys to update Qatar’s control center of the CORS-Qatar network is located

22 | Reporter at the Urban Planning sector building in Doha. CGIS decided in favor of Leica Geosystems equipment because of its high quality, outstanding customer service, ease of use, and product durability. In the meantime, the system has already passed durability tests in the Middle Eastern summer temperatures.

Reliable GNSS Data and Comprehensive Service The physical stability of the antennas fixed on rig- id masts is monitored to ensure the CORS network delivers reliable and precise data. They are moni- tored by Leica Nivel220 dual-axis high-precision tilt sensors that deliver an accuracy of 3 mm @ 1,000 m. The data is continuously streamed to check stability. Tilt measurements at the Al Thakhira site for test- ing purposes had proven that the position of the Leica AR25 is very stable at 0.45 mm. Additionally, the stability of the climatization inside the cabinets is monitored by meteo sensors measuring temperature and humidity.

The CORS-Qatar network is managed by CGIS. With Leica GNSS Spider, CGIS provides correction data for precise measurements for RTK surveys through TCP/IP, network processing, raw data streaming status, and Many public and private survey and mapping satellite tracking for its customers 24/7. Leica Spider communities now have access to CORS-Qatar. Web is used for the convenient distribution of GNSS data sets for public or internal access via standard Points were automatically recorded at regular inter- web browsers. The software allows keeping track vals of 5 m. No office processing of the data was of data, downloads, users, and costs while provid- required and the data could be quickly integrated ing additional services such as automatic coordinate into the common CGIS database via GISnet high- computation and a constant overview of file avail- speed network. Qatar is the first country to imple- ability and data quality. Registered clients can simply ment a comprehensive nationwide GIS and is inter- upload their GNSS raw data. SpiderWeb then uses nationally recognized as having one of the finest GIS one or more nearest reference stations to calculate implementations in the world. the coordinates of their data sets. Leica GNSS Spi- der with SpiderNet software then processes the raw The CORS network is now constantly in use for GIS data to issue correction information to the users in and GNSS surveys to keep Qatar’s maps up-to-date. the field. The network and the services of CGIS bring The network is also used for hydrographic surveys, numerous benefits to users of RTK for land surveys. offshore and ocean navigation. The system operates without downtime and since its establishment has routinely been used by land In the years to come, as Qatar’s infrastructure devel- surveyors and GIS professionals to position them- ops further, many of the organizations working with selves with high accuracy anywhere within Qatar. GNSS will benefit from the homogenous CORS net- Leica Geosystems Spider Business Center makes it work that provides consistent, high accuracy 24/7. All easy to manage and track customers’ access to the installed Leica Geosystems receivers and antennas RTK network services. are ready for future signals.

Quick and Accurate Update of Maps More information about the Centre for GIS in the After the installation of the CORS network, agen- State of Qatar at: www.gisqatar.org.qa cies began mapping Qatar’s main roads in real-time.

The Global Magazine of Leica Geosystems | 23