Creating 3D Building models in from OSM Data and Digital Surface Models + Visualization

hi there today I want to show you how we can use Open Street Map building footprints and a digital surface model to create accurate 3d models of building blocks for noise calculation the data that we working with today is Open Street Map building footprints that we have already downloaded a terrain model and a surface model let's have a look at the difference between the terrain model and the surface model first so the terrain model is a model of terrain as the name says and so it normally interpolates the surfaces beneath buildings and it doesn't include the information the height information about buildings and vegetation here you can see the terrain model and now we overlay the surface model here you see we already have the information of the buildings and the vegetation and if we take a look at the OpenStreetMap building footprints in particular in the attribute table we will find that there is no information about the building height and so this is what we want to add in this lecture the tool that we are going to use is called zonal statistics and we can find it in the processing toolbox if you haven't opened your processing toolbox yet go to processing and click on tool box then in the search field we type in so no statistics analysis we find the zonal statistics tool we double-click on it handled so what the zonal statistics tool does is it takes polygons and rosters and calculates statistics for the polygons from the Russell Russell a in our case we're interested in the maximum values because we want to get the the high data from the roofs so first we choose the raster layer and we choose the surface model and then we choose for the zone layer we use the OpenStreetMap buildings here in the line statistics to calculate we can click on this button and choose from a range of statistics that we want to calculate and for our purpose we just click all and run the tool once it has finished we can open the attribute table of our OpenStreetMap building footprint layer and scroll to the far right and there we see that we have quite a few statistical values calculated for each polygon okay now let's have a look how this looks and 3d to do that we are going to use the qg s to 3 j s plugin if you haven't downloaded it yet you can go to plugins manage and install plugins and then search for QGIS to three GS and here you have it and just download it if you haven't done so ok let's open the tool before we open it let's zoom into an area the thing is that these three modeling operations are quite computational heavy and so if you don't want to wait ages to compute large model zoom in and exclude some of the data go to web q james to 3 j s and click on the q GS to three.js exporter with preview off so when the exporter we first choose a reference surface which in our case is the terrain model and then we select the polygons the OpenStreetMap polygons that we want to have displayed above the terrain model click right on the OpenStreetMap layer and here we're going to set some attributes of all the legs layer first we want the object type to be extruded and in all case we are working with absolute values high value so we will leave absolute here and in style we're going to select one of the statistics that we have calculated and we're gone for maximum okay we can leave the rest click to apply and then here in the bottom right corner we click on preview and wait a second until the model is lowered okay there we are double click in the middle zoom in here and there we can see that our building footprints have no the Edit height values and so to check how these height values compared against a building model from the last survey I have downloaded also the building model from the dancer love it let's have a look how this looks in comparison okay so we have now loaded the Lancer very 3d model and this is a facade model only so it doesn't include the roofs now let's have a look at the differences you see that first of all there can be a difference in the XY coordinates of the building footprint our experience is that in general especially in heavy populated areas the OpenStreetMap data is more accurate than Survey data that is because it is often more up to date than the survey data and with regards to the height there are two different things to notice here so with flat roofs you get almost the the exact value as in the survey model which is only the the height of the facade and so if you have a flat roof but you get the perfect height but if you don't get a flat roof or if you have a tilted roof then there is an overestimation of the facet heart okay that's it for today thank you for watching and see you next time

Channel: Stapelfeldt

Views: 1,838

Keywords: LimAQ, Stapelfeldt, ODEN, Noise mapping, QGIS, DSM, OSM, Noise, Acoustic

Id: 5seGENRssDc

Length: 7min 53sec (473 seconds)

Published: Mon Apr 20 2020