DECUMANUS_Antwerp_GreenRoofs_inverse SW/EMA Ecohuis BeschrijvingGreen roofs are building roofs partially or completely covered by vegetation. They are absorbing rainwater, providing thermal insulation and reducing air pollution. In this context, the identification of green roofs has great importance and represents the goal of the provided service. Furthermore, this task is carried out automatically - which is a great asset with respect to current approaches based on photointerpretation or even in situ surveys by experts – and allows easy and straightforward update once provided with new suitable imagery.Input dataVHR VIS+IR imagery [either airborne (preferably) or satellite], LOD2 model or DSM/Lidar data, building outlinesMethodologyGiven VHR satellite/airborne VIS+IR optical imagery, the building outlines and LIDAR/DSM height information, we estimate the percentage of vegetated areas on the building roofs by computing the NDVI index and determine where we are in the presence of a green roof.As concerns the current green roofs, finally we included all those roofs matching the above-mentioned constraint on the slope which are categorized as “hoofdgebouw” and exhibit a vegetation coverage greater than 5% of their surface. Based on a thorough visual check to exclude all the false detection due to intense tree coverage, we finally marked as green 1139 roofs. Here, it is worth pointing out that, since there is no agreed definition of what is to be considered as green roof, we applied our criteria following the directions that somehow were agreed in the Antwerp project meeting. In particular, in addition to those roofs where a grass layer or trees have been installed, we also included in the count all those roofs with a consistent presence of hedges or big potted plants (but we excluded those where – based on our experience – their coverage did not look significant enough). Indeed, they as well contribute to absorbing rainwater or reducing the urban heat island effect. Please also note that spontaneously vegetated roofs have been categorized as green roofs only in the cases where the vegetation layer looked significantly thick.ApplicationsMapping current green roofs has high support for a more accurate modeling of stormwater runoff and air pollution. Moreover, being the installation of a green roof usually supported by subsidies, a precise identification of their location will be of great help for planning in-situ survey of their actual status.
Creatiedatum: 2016-03-03T00:00:00
Publicatiedatum: 2016-11-28T00:00:00
Revisiedatum: 2016-11-28T00:00:00
Update frequentie: indien nodig
Beheer: Nora Danko
Contact: Nora.danko@stad.antwerpen.be
