How to download DEM data # Lesson 8 (Part 1) of 29 # QGIS Tutorial

[Music] [Music] hi welcome to today's qgis tutorial lesson 8. in this video we'll learn how to download dm data and use it in qgis 3.14. if you haven't subscribed to my channel please do so so that you can get a notification when i upload the next lesson if you are new to my channel you can follow all my previous lessons from the links in the description below let's get started so we're going to learn how to download eem data so what is dm digital elevation model is a specialized database that represents the relief of a surface between points of known elevation so how can we use dem we can use dm by to generate contours uh hill slope hydrology erosion and drainage analysis watershed and groundwater flow engineering and structural design and also flight simulation two ways of downloading gm easily is by open topography and using a plug-in in qgis called the srtm downloader so we're going to cover both ways of downloading dm data so let's start by how to download data using the open topography we're going to go to our browser open click open a new tab and then you're going to just type on the search button there open topography.org then you're going to click on enter it will take us to the home page of the open topography so we want to download the dm data we will go to the data tab there is the home tab and then the data tab and we want to get this data from catalog so we're going to select from data catalog and then a new tab appears and under the new tab there's the ot high resolution topography the ot community contribute contributed usgs 3dp and then there is the global data and you can see there are three files in the in the global data so we're going to select the global data and it will get us three different kinds of rasta data that you're going to use now we are interested in the srtm which is the shattered topography mission srtm and they are also in three categories here so there is the srtm gl3 srtm gl1 srtm gl and ellipsoidal so let's look at srtm gl3 first and read the description so i'm going to click on that so that i can read the description about the tm gl3 and you can see this is global 90 meter resolution and has so much information down here that you can read on your own to better understand what this data is all about this is 90 meter resolution but i want a bit of a more accurate data so let me look at there now the srtm glt-1 and see what it has so i'll go to srtn gl1 now select that and you can see this is srtm gl1 which is global which is that in 30 meter resolution so i'm going to select this and use it in my in my my analysis to download my first data dm data so once you select the srtm tl1 which is global 30 meter resolution just scroll down and the first step you do which is select the area of the data to process so you're going to select the the area of the data that you want to process you can select any region in the world so you can first of all zoom in let me just zoom in zoom into an area maybe say i'm looking for let me go to ethiopia so i'll zoom into ethiopia and i want to zoom in and see maybe a region which is within the great river valley already some mountain some all over sort so i think i'm going to select this region here you can see they have very many rivers so after i was saying that this is the region i want to get the dem i come and click on select region then it will change the cursor and i can just select the region that i want to download there the dm data i select that the bigger the extent the bigger your the data will be so you can see for mine i have download the selection area is approximately 70 000 kilometers square so i'll just go down you can also manually enter coordinates if you want but you're not going to enter the coordinates manually we're just going to use the ones that we have selected from the canvas then the output data format is adjective it leave it at that then visualization you can decide to check these boxes if you want you can check these and this but it will make it take a longer time to give you the data but you can for just for visualization you can check the two but i will not check them for now then hydrological terrain product and leave it the way it is i just read the information and leave it global solar irrigation i'll leave it on that then down here they'll tell you to enter your job description so for my job description i'm going to just say gis yes analysts or anything you can write anything and at least the job description i just said gis my email address which is this then i'll click on submit and it will take me to another tab so thank you for the submission for your job and then you just wait it is querying you can see here it is querying and extracting the srtm raster data for your area interesting just wait a few minutes and you can see it has already queried and you can see here is actually trying to download my data here this is where i'm going to be able to download the data from so just give it a few minutes as it queries all my data and you can see now download job results are here you can see i have a raster srtm.r which is 77 mb and this is the visualization now when we talk about visual visualization how is it going to look like uh in your in your map canvas and that's how it's gonna be looking like so i'm going to download now there rasta this one this srtm result so i'm going to download this very small file 777 mb so i'm going to look for where to to save my data i'm going to go to my gis folder which is on the desktop uh gis data now we're dealing with rasa data so i'm going to create a new folder and call it raster data then within the folder i'm also going to create another new folder and because you're going to be working with different kinds of raster data so i'm going to just call this dm and then i'm going to save this as dm so i can leave it at that or i can change it to ethiopian rasta dna because i'm dealing with ethiopia so then i just download it and depending on how frustrated it is this is pretty much straightforward and to just download it very quickly perfect the download is completed so i'm going to open the folder and it's a zip file so i'm going to extract it and now i can open the folder and i have my output srtm data here so that is how you download srtm from open topography so now we want to load our our raster data that is the srtm data into qgis so we're going to first start by creating a new project by clicking we're going to create a new project and we'll create a new blank project here then we are going to load the layer now it's a raster layer so longer vector let's go into layer add layer and now we are adding a raster layer i'm going to select address the layer and then you're going to browse away or it's under file so we're going to browse for where our raster data is and it's on the desktop gis folder the data folder and we have we have the rasta data and then there is the dem and now we'll go to the folder which has the tiff right you can either just load it directly or you can just change it if you have so many other kinds of files you can just customize it here you can see there are very many there are very many file extensions here so these are jotif and i can even just select youtube and customize it to youtube and then select the the file then i'm going to add it in qgis but give it a few minutes and it has loaded here and then i click on close and this is our data you can see very nicely there's a river passing here and the other gray areas so the darker areas represent the lower areas and the lighter areas represents the higher area this is the elevation of the different regions in this so that's one way of now downloading the srtm data in in using open topography [Music] you

Channel: WiseGIS

Views: 1,140

Keywords: gis, opensourcesoftware, qgis, qgis 3.14, qgis 3.14 Pi, DEM, RASTERDATA, contours, Vector, vector data, qgis tutorial, qgis3, open data, foss, gis application, bigdata, training, education, how to download DEM, digital elevation model, up and running with qgis, open topography, srtm

Id: jKncv1E-2mw

Length: 11min 52sec (712 seconds)

Published: Tue Aug 11 2020