Downloading Digital Elevation Data (SRTM) from USGS EarthExplorer

hello guys welcome to another tutorial in this tutorial i'm going to show you how to download srtm dem data absolutely for free from usgs earth explorer web portal now to access the usgs earth explorer web portal you can simply do a very basic google search something like this you can search srtm data usgs and right over here you can see that we can get the access to this uh explorer usgs web portal and if you're logging in for the first time this is how it's going to appear for you guys well you're not going to face any problems in navigating around even if you do not really have an account but just keep in mind that if you really need to download stuff from here you need you really need to have an account for yourself so i have already created an account for myself quite some time ago even if you want to create an account or even if you want to log in assuming that you do have an account you can simply go over here to login and as you can see over here i have already entered my username and password and all i have to do is simply click on sign in but but in your case if you haven't really created an account for yourself you can click right over here it's a it's a very simple process it's going to ask a couple of questions from you and after that you'll be having your account almost in no time so i'm just going to go ahead and click on this button to sign in all right now as you can see i have already signed into my account and since i'm interested in downloading the dem data for a part of uk first i'm going to use this window in order to navigate into or zoom into the to my area of interest and there are actually multiple ways of selecting or specifying your area of interest now one of the easiest ways of doing that would be simply by creating a polygon right now i have my mouse pointer changed into something that looks like a hand so if you click once over here you can see that it's it's actually going to put up a pin over there which specifies a certain latitude and longitude now that's just a point but if you if you would like to create a polygon all you have to do is just add more points and these points are basically going to add like the vertices of your polygon which eventually is going to form the polygon as well so you can see that right now i'm successful in in specifying my area of interest well this was done just randomly and that's not going to be my area of interest now let's say if you did some mistake and if you would like to get rid of this entire thing you can simply scroll down over here and select clear coordinates and after that you can maybe even pan your map into us into into a completely different place and you can start putting in the the pins like this which will basically form the polygon again all right that's one way of doing that i'm going to clear these coordinates out and if you come over here you have the option of specifying your area of interest through a kmz file or even through a shape file now i have already prepared a kmz file kmz file is basically the file format which is being read by google earth so if you have managed to create a polygon and if you have converted that into a kmz file using google earth you can simply open that up so i'm just going to open my kmz file like this and right over here you can see that i have a file called boundary which is a kmz file so that's going to be my boundary it's polygon and i'll simply open that up yeah now you can see that this was my area of interest so it's going to specify again it's going to specify the coordinates of these for these five points which are basically the vertices of that polygon and once you have done that you can click on these data sets and that will bring you to this data sets page and now what we are interested in is this digital elevation models that you can see over here and you can see a couple different types of digital elevation models and from this i'm going to select srtm you can see that we have actually a few few different types of srtm data now we have this white field srtm data and we have this non-white field and we have this one arc second global now i'm always going to go with either this white field or this one arc second i'm not really sure why someone would pick this non-white field over over these two because this white field basically means that they have actually used techniques like interpolation methods combined with other available uh elevation data from different sources in order to correct those uh those existing whites and this product is available at a horizontal resolution of 30 meters by 30 meters for us but for the other places in the globe it's going to be 90 meters by 90 meters but if you were to select this one arc second global it's going to be void filled plus it's going to be 30 meters by 30 meters for the entire globe so this is going to be a high resolution product for the entire globe compared to this this wide field product so i'm just going to go with this one because why wouldn't we have a high resolution product since my area of interest is in uk it's out of u.s so i prefer to have the 30 meters by 30 meters resolution product instead of having the 90 meters by 90 meters one all right so after i select this one i can simply click on this results and it's going to take a while and you can see that it actually gave me two different tiles now before you download any of these styles i think it would be handy to know where each of these styles would be located at isn't it so i'm going to zoom out my map view just a bit and you can see a footprint over here so this is a this is a quick and easy way to know where this style would get placed if you were to put it into the map so i'm going to click on this footprint and you can see that that tile itself is actually covering quite a huge area and if i click on this second footprint you can see that that's extending all the way up to up to the these northern parts as well as you can see my area of interest is actually covering majority from this style but just a little bit from this style and for this tutorial i'm just going to ignore this this style and i'm just going to download only this particular tile as you can see over here as it's covering a majority of my area of interest apart from this small parts over here and that's not going to be an issue for me for this tutorial and once you identify that that's the tile that you're going to go with you can simply go over here to this download options and you can simply click download in order for the download to begin now you can see that we have a couple of different download options and the product that i'm going to be interested in is this geotiff one arc second product so you can see that it's a it's a tiff raster which is also a geo reference that's why it's a geotiff and it's a one arc second product which basically means that it's uh having a resolution of 30 meters by 30 meters so i'm going to download this one and you can see that it's getting downloaded right over here and if you have a software like qgis you can simply use that to visualize the raster that you downloaded so if you have so right over here i have already saved that downloaded file into my into one of my folders so i'm just going to simply drag it and drop it over here and now you can see that how that tile looks and if you would like you can even change the symbology and assign a different color ram so that so that the variations of the elevation would be much more apparent to you guys so i will go over here to single band pseudo color and as a color ramp i'm going to select maybe a different color ramp maybe from here let's go with this bcyr and the mode i'm going to change it to quantile and i will assign let's say 20 different classes click on apply and click on ok and now you can see that how the elevation varies these red color areas actually show very high elevations you can see that the highest is 568 whereas these blue color areas correspond to low valuations so that's how basically you can download a srtm raster from the earth explorer usgs web portal so thanks a lot for watching guys take care

Channel: GeoDelta Labs

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Keywords: srtm dem 30m free download, srtm downloader qgis, download SRTM dem, how to download DEM data, srtm 30m, How to download a DEM file from USGS, How to download SRTM DEM data, digital elevation model, elevation data, arcGIS, qgis, elevation data download for free, digital terrain elevation data, digital terrain model, Download SRTM 30m Digital Elevation Models for Free

Id: yYWdxExabHo

Length: 8min 2sec (482 seconds)

Published: Fri May 28 2021