Three-dimensional model of Riga’s territory terrain developed by “METRUM” will help prevent flood risks

The development of three-dimensional terrain model of Riga’s urban area was carried out by “METRUM” on request of Riga City Council City Development Department (RDPAD), acquiring the data of the capital territory terrain, buildings and vegetation or greenery by using airborne laser scanning. Riga’s terrain three-dimensional model is developed within the framework of the project “The assessment of water impact on Riga’s urban surface, prevention and improvement of the ecological situation”. The project is cofinanced by the Europian Union program LIFE+, and it is supposed to include a detailed hydrological process and the study of its impact on the territory of Riga, develop the flood risk management plan, as well as implement various other activities.“The primary goal of three-dimensional terrain model is to help identify the territories of Riga which are subject to flood risks. Our terrain, vegetation and building findings will be possible to combine with the flood modeling, as well as various visualization programs,” explains the production manager of “METRUM” Geographic information systems Artis Markots.When explaining the advantages of airborne laser scanning in comparison with the other data mining technologies, A.Markots puts an emphasis on the high accuracy: “When the laser beam transmitted from our airplane approaches the ground, it spreads out – a part of it is reflected from the foliage or branches of the trees, another part – from the lower-lying branches, while the rest part reaches the ground. From one signal we obtain a dense point cloud which reflects the land terrain, as well as the buildings and vegetation. Other data mining techniques which are used for aerial photography do not provide such accurate information, for instance, it is only partially possible to determine the land terrain beneath the bushy trees. By using airborne laser scanning it is possible to get very accurate data of land terrain also with wooded areas.”RDPAD emphasizes that „METRUM” findings regarding the buildings and vegetation will be possible to supplement and use in the creation of such three-dimensional model which will allow to see not only the terrain of urban area, but also buildings, streets and trees. In the future it will also be possible to implement and assess new building proposals, coordinated building projects and objects under construction, thus facilitating the decision making process.The development of three-dimensional area model has been so far carried out by “METRUM” both in Latvia and abroad by using laser scanning, as well as aerial photography. Three-dimensional terrain models are developed for urban planning needs of Liepaja, Ventspils, Saldus, while the flood modeling data are prepared for Liepaja, Jelgava, Kekava area. Currently the determination of water levels and flood areas is being carried out in Ozolnieku area.