Convert GeoTiff (Bathymetry and Topography) to XYZ using QGIS

hi today i'm going to start to talk about how to extract data um the topographic data or best symmetry data if we have the the dual reference uh t file there are there are a couple of uh global relief data available for them one of them is e201 and they're usually offered in different type of data so for example here you can see it has the net cdf or you have that your reference active data here today i'm going to say that you how we are going to extract um the xyz xyz data if you have this geotiff data in uh uh to use it in any programming language that we want to use for for our purpose today um i will use the uh are the qgis which is the open source uh software um for gis and this the process is the same if you have any other software like rgrs so uh for the today purpose i've gone i used this one the eu topo one bedrock and the grid registered one so basically this is the file i downloaded and i'll show you how we can extract the part of the data on the entire data set as the xyz if we need so i downloaded and i will go ahead in the qgis server first thing go that i need to open that duotif filesaw i go to the layer and then add layer and add raster layer here you just go ahead wherever you save that you have your t file click on that and then open that g file and add it to your um the qgis and then close it after you added we have to set the reference for the file if it's not detected so go there properties and then on the source and we need to choose the what projection we are using so to find that again if i go back in this website i go down there it says the horizontal datum is uh wgs84 so i have to go there and just set it to was 84 so i will go back here and choose the wgs 84 and then click okay so now that my reference is set now if i want the entire if i want the entire um to extract data from entirety if we can just escape the next step i'm going to say uh but assume we don't want the entire uh different one on the part of that map to be extracted if you want to part of that map you can go ahead click on direct raster extraction and then click last here for example i want to extract the gulf of mexico and then you gonna put the longitude and the latitude here the the extent the minimum the maximum and then it's gonna extract four so i know for example for gulf of mexico is gonna be from negative 100 to negative 80 and then 16 in the latitude to 32. so you just put x min x max y min y max that the area that you want and um select here because we have only one layer so i want to clear from this area and um open that and i i will run it and it will clip that part for me that porter itself now if i come here if i you cannot maybe see it but if i turn it off you can see that part is already clipped out here so you can see it is clipped out here and now if i zoom there so this is the part that i just clipped and now assume i want to export the this part as the xyz if i want to export it as a xyz file what i would do is that again we'll go to the raster then disarm to the conversion and click on the translate or convert format and choose the this clipped version so this one if you want the other one you can if you want the entire t-file you can select the other one but because it's going to be really huge so i click on this one then the projection i got is the wg as a 84 and you probably need you can ignore their rest and and then you can um solve it but if you want to get it as is what you can hear and it says save to temporary file click on that save to file and when you save to file it gives you different options different types of file that you can choose from them so you can choose any of these files depending on what type of file you want so one of them is just there as you can see as you can see one of them is the dot xyz file so i'll just click on that and um just give it any any name that you want so i would just name it x xyz and click save and then when after that you'll just click run and it's gonna um save the file as the x y z uh to the to the hard drive so it's already saved there in that folder that you i defined as xyz um if i want it to be exported as a csv file the other way that i can do that comes here the you see the processing toolbox if it's not there go to processing tab and click on toolbox and here just simply type xyz and you will see that this gdap to xyz or click on that and it will ask you from what layer do you want so this is the layer we want is the clip layer so this is what we want and then when it comes here again click on that save to file and this time it's going to ask you to save to the csv file so you can put it as x y z um dot c and when you save is going to be saved as ac csv so click on that and then you run it and it's going to say with the xyz data as csv file for you so depend on which one unit this is this is how we um we can actually export the t values um to xyz or any other ascii format remember that in this case it when we clip it or when we choose it for example we clip it and then say we export the data in this area it export the entire data set for this area or any of these if you choose it to export it for example if i choose the entire map uh to be exported so it's going to export the entire data set to that ascii file or csv for xyz for any type of file that we want so that's how we do that

Channel: Arash Karimpour

Views: 5,754

Keywords:

Id: VlUg1lQJhms

Length: 8min 8sec (488 seconds)

Published: Mon Sep 14 2020