Downloading SRTM DEM data using QGIS

hi guys welcome back to the channel in this video I'm going to show you how you can download srtm digital elevation model data for basically any region in the world using qgis now I have done a tutorial quite some time back showing how we can download srtm digital elevation data in raster format using USGS Earth Explorer web portal however the main advantage in the method that I'm going to show you in this tutorial when it comes to downloading srtm elevation data within qgis itself is that you're never going to have to leave your qgis workspace and you know spend time to search data in external platforms you could just do it with a click of a button while you are working on your project in qgis itself so for this we are going to have to use a plugin called srtm downloader and downloading plugins in qgis is actually quite easy now over here I have opened my qgis workspace so if you head over to plugins and go to manage and install plugins what you can do is simply search for the plugin called srtm downloader you can see the very first prompt and the only prompt is srdm downloader so to install the plugin we can just click over here and that will take care of the installation process and after that if you head over to plugins you can see that this new plugin called srtm downloaded has appeared over here so I'm going to click on that so when using srtm download what you can do is you can actually use your current canvas in order to specify the boundaries for which you would like to download your srtm data now when doing that it's actually always handy to have a base map so that we can use that base map as a guidance tool to navigate into the place that we would like to download the srtm data for so I'm going to download another plugin called quick map Services through which I would be able to install a free and open source base map called openstreetmap so I'm going to download this second plugin as well which is called quick map services I would have to search it over here quick map services and let's go ahead and install that plugin as well all right once the installation is done if you want to access the quick map Services plugin you have to head over to web instead of plugins because it actually gets installed or categorized on the web so right over here you can see the new plugin that we installed called quick map services and I'm going to select osm which stands for open street maps and I'm going to select osm standard alright guys now you can see that we have this open street map and the next thing that I would recommend you to do is to actually go over here and change the coordinate reference system of the data frame now after adding the openstreetmap you can see that the coordinate reference system has been changed to epsg 3857 however I would recommend you guys to set this back to eps g4326 which is the wgs 1984 geography coordinate reference system because when using the srtm downloader it's essential that we capture the coordinates in the proper coordinate reference system so that it can communicate with its source and extract the corresponding srtm tiles that you would require for your area of Interest so I'm going to click over here and and right over here you can see the epsg 4326 coordinate reference system so let's click on that and click ok and now all you have to do is just zoom into your area of Interest let's say for this particular tutorial I would like to download the DMS corresponding to this southern part of Italy so I'm just going to zoom into a random location like this all right assuming that this is the area for which I would like to have my digital elevation models downloaded all right once you have sort of navigated to your area of Interest what you can do is you can refine your extent using the zoom in tool and draw a rectangle like this making sure to Encompass all the areas for which you would like to have your srtn data downloaded so in my case it's going to be something like this all right now after that just make sure that you don't actually change your extent and in The Next Step I'm going to head over to plugins and open up this srtm downloader plugin and since you have already set the canvas extent all you have to do is just click right over here and it's going to automatically extract the western eastern northern and southern boundaries of your specified extent and it's going to grab all the Dem tiles that are actually available to fill that particular extent from the original data source and if this is not ticked you can actually uh put a tick over here load images to qgis because then all your all your DM files will be added to your working interface and finally all you have to do is just click over here on download now as soon as you do that you can see that before the downloading process starts it's asking me to enter a username and a password well before that you can see that it has actually identified four images that means for this area that I specified it'll be extracting four different srtm tiles because that's the number of tiles that it would require to actually fully cover this extent which I have specified and before it goes ahead and downloads these Styles it's actually asking me to enter a username and a password now from here you can see that the source from which it's going to download this data is actually going to be this NASA data web portal now if you're doing this process for the very first time it's essential that you actually click over here and head over to this portal and create a username and a password for yourself but once you have done that in every subsequent try you're not going to require a registration process anymore you can just directly use your username and password which you created the first time and if I click over here this is how the register for a data login profile web page is actually going to look like just scroll down and input the necessary information it's actually going to take only a couple of minutes and the process is quite self-explanatory once you register for a data login what you're going to get is basically a username and a password and for this tutorial I'm going to assume that you guys are actually able to do this step by yourself because it's not going to be complicated at all so once you have obtained your username and password you can enter your username over here and your password over here and just go ahead and click ok and with that you can see that it actually downloaded a sufficient amount of data to fully cover the area of Interest that I specified before using my zoom in tool and if I now go ahead and close this window you can see that these are the four tiles that I would actually require to fully cover my specified area of Interest now just as a side note if you would like to group or merge all of these tiles together into one single tile you can go to raster and the miscellaneous there is one tool called merge and if you click over here the input layers what you can do is you can just select all the input layers like this in this case it's going to be four different layers and click ok and after that just click run and once the processing is finished you can just untick these four different individual tiles and with that you will see that you will get one single raster file called merged right over here and that's basically a mosaic of the four different tiles that you had previously and guys this is a standard srtm digital elevation model file in the form of a raster so that means you can just if you click over here and go to properties you can do things like change the color scheme let's say if you go ahead with single band pseudo color you can actually assign a proper color ramp like this through which you would be able to identify the lower regions and the higher regions so in this color scale you can see that the higher region is actually given in this reddish colors and of course the lower regions are shown in this bluish colors and if you would like to save this digital elevation model into a separate file you can just right click over here go to export click save as and you can select the format over here and we can use geotiff as the file format and from here just navigate to the folder to which you would like to save this file and then you can give it a file name I'm just going to call this as Dem and click save and click ok and you can see that the extraction process is happening right over here and once it's done you will get a new file called Dem so what we can do is we can basically get rid of these other files that we do not really need so guys that's pretty much it if you would like to repeat the process for a completely different area well all you have to do is just zoom into your area of Interest again like this I'm just going to do a quick demo for you guys and once you are happy with the setting of your canvas extent go back to plugins srtm downloader set the canvas extent and simply click over here on download and in this case you can see that it's actually showing only one image one image is sufficient to cover this particular extent just click over here on OK after adding your username and password and just in a matter of few seconds it's going to download that srtm tile for you guys just like this so you guys can imagine how easy this process is actually going to be after you have set up a username and password using the NASA data web portal for the very first time you can download as many DMS as you need for any area basically on the globe without having to ever exit your qgis project alright guys so that brings us to the end of this tutorial if you did like this tutorial you can show your support by hitting that like button and if you do have any questions add a comment down below I'll see you guys again with another tutorial soon

Channel: GeoDelta Labs

Views: 51,414

Keywords: download dem data, download srtm dem data, digital elevation model, how to download DEM data, USGS EarthExplorer

Id: qKqgpZumMnM

Length: 11min 4sec (664 seconds)

Published: Sun Oct 02 2022