Generate a DSM from a point cloud in QGIS using the LASTools plugin

hello this is hustle class senior lecturer at ITT dolphin Institute for water education in this video I'm going to show you how to convert a point cloud to a digital surface model we are going to use a point cloud data set from the Netherlands from the Ahn 3 data set and we're going to use the Loess tools plug-in in QGIS to read those data and to convert that to a digital surface model we're going to use the terrain shader plug-in to calculate some shades and we're going to add open data for the Netherlands aerial photographs to grip it over the digital surface model to see the result and we use the cutest 3d viewer to visualize the results so first we're going to download the point cloud data set from the aah and three data set find this on the P doc data set portal it's a date so that covers the whole of the Netherlands and if we go to download and we click of it on we can choose a title for which we want the point clouds and I'm gonna download out that for Rotterdam so gets the tile and then I can download it in the la that format that's a compressed loss point cloud file and I can read those files using the last tools you just plug in and before we can use the plug-in we have to download the last tools you can install the plug-in from the plug-in manager which also says that you first have to download the files from the Loess tools and you find it down in your tool box but you need to configure you go to providers and you find last tools and make sure that it points to the folder where you've saved the last tool software the first thing that we're going to do is to check the file I'm going to use last info I point to the file that I've downloaded it's a huge file see this also all these processing tasks will take a bit for the video of speed-up and here you see the results all the information about this point cloud file and they can also visualize it using last view it uses the visualization tool from last tools and when I run it it will launch that interface there it is in reality this is also much slower because this is the full tile which has many many points this is ten times the normal speed and it loads a point cloud for retina and this visualization tool has some options we can navigate a bit through it to see the points and it has also some filters so I can choose for example to only render the ground surface that's what we see here in the same way I can say to only render buildings so now we're going to split the data set because it's licensed software and there are limitations to one and a half million points so we're going to use the last split tool to split into tiles of 1 million points normally that takes a bit but I've cut it a bit for this video so now it has generated many different tiles of 1 million points for each tile and the next step is to make a rest are out of that using the last two dem pro 2 which can convert all the tiles in a folder to d apps so the cell size I'll put it on 0.5 because that's also the reported cell size that the authorities use with a H and 350 centimeter resolution you can see we can choose your all kinds of other settings but I'll keep the default now use the 64-bit executable I'm going to copy this generated split files to a folder so we can do in that double folder you have an extension of Loess and that should be okay and there write it to a DM folder normally that also takes a lot of time but here I've split it up a bit for the video I'm going to set the project to the projection of the Netherlands the DMS don't have the projection with them yet but if I drag them from the browser to the map canvas it will take the projection of the project there are loads and from the layers panel I can see them now and I'm going to build a virtual Ruster to merge all these styles into one layer select them on their 404 tiles I don't want them as balanced so and check that box and I save it to a virtual file that's more efficient in space because it will not generate one Big D file for example I'll run it and it's done so I can now remove the other layers that we don't need anymore because the virtual Rhea layer will be one big image which contains all the other tiles so while it's loading I'm going to open also the OpenStreetMap to see if it's really in the right position and we can see that is the case especially if we look at the river so now I'm gonna render it as a hill shade to look at the result there it is to set the projection and I'm going to zoom in and there it is we can even see the ripples on the river that's the center of Rotterdam zoom in a bit more and then to see some artifacts and we can smooth it a bit by changing some of the resampling settings there's a nice plugin to get more natural shades and it's not in the standard repository but we can download it from github it's the terrain shading plug-in and there are this I could simply download it as a zip file then in kuja's I can install it from a zip file after installing the plugin i find the terrain shading plugin in the processing toolbox i'm going to use this shadow depth function i load the elevation model i keep the defaults for now and i choose an output file i'll save it in this case as a tiff file let's call it terrain shade and i run it and there it is you can already see that it creates a lot of shades and there's nice Styles developed by the same developer as a tool which you can find in the style library in a repository you can download it also here from github set the projection and I can load the style files from the layer properties and there it is used 0 to 15 and let's try the others also so this is quite dominant in shade you want more subtle ones we can load one of the other ones we see more subtle one or this one let's have a closer look at this one in 3d so I open a new 3d viewer then the 3d viewer I need to point to the digital elevation model raster layer that's the DSM and I can change some of these parameters to get a higher resolution to play a bit with these values to get a good performance and a good resolution and it's of course quite challenging for your CPU and your memory and then you can see that it will render after a while and you can navigate through it and you can see the building so this is a dsm rendered from the point cloud and it's the center of rotterdam and we see the shade project it on top of @dm there's a nice plug in the p-doped plugin where we can download open data from the Netherlands and I want an aerial photograph now there's a little book well I can install it but I need to restart qgs then I can use the functionality that's only in this combination for some reason so I use the actual aerial photograph and add it here and then it will also render in the 3d view so here we see the centre of rotterdam but now in the RGB aerial photograph and now i'm just gonna show for fun some parts of rotterdam so here's the library and we see the cute buildings and the Markthalle we see the old harbor and williamsburg moves river norther island let me continue our route from the village birth to the Erasmus Bridge following the mass Bulevar and the monkeys and we make a turn to cross the bridge to the coffins out here it's a dinner finish rendering yet so we have less detail how come in a bit here we go back in the other direction we see the floating pavilion and the floating forest and we go back to the north side of the city field Samara parts is the museum park with museum boys from Berlin and hospital flyover the hospital and here we have some other views of the center this is the main shopping area we'll trade center and the Cocotte

Channel: Hans van der Kwast

Views: 16,784

Keywords: QGIS, LAS, LASTools, DSM, DEM, hillshade, terrain, PDOK, AHN, Rotterdam, 3D, LIDAR

Id: 9LUuMYzwjfI

Length: 14min 27sec (867 seconds)

Published: Mon May 11 2020