Lecture 13

[Music] hello everyone so in our last lecture we have shown you that how we can Geor reference different kind of satellite images with the help of qgi software so we have give you a demonstration on uh how we can GE reference a topo sheet and uh we can GE reference a image with the help of bual map service so in this lecture we will show you that how we can do the uh merging and mosaicing of different uh satellite images on the qgi software and then we will uh give you a uh demonstration on the shape file generation and uh we will also uh show you that how you can uh use the attribute table of different shap files and you can generate different kind of information of those shap files so when you will open your qgi software and you have to load the uh satellite data uh which you want to merge or moac so I have opened here the uh the satellite data of srtm this is the srtm Dem so I have opened the five images and I will will show you that how you can um first I will uh uh show you that how you can mosac of two images to moac uh two image you have to first select that which two image you want to mosac so here you can see in your layer panel here five images has been opened and you can see this uh this is a uh image which is uh slightly little bit away from this four image so to mosac you have to choose two image which are uh which are nonadjacent images and to merge uh you have to choose two adjacent images so first I will uh show you the uh moosing part for that you have to choose two image which are not adjacent to each other so for uh this exercise uh I will choose two image so uh to do the mosing first you have to go to the raster option because these are all the uh raster image and all the algorithm which you will use to uh do the moing that is in the raster option you will find this options uh this uh plugins in the raser options so in the rter option here you can see there is uh certain plugins are given here in miscellenous option you will see that here uh few more options are given such as build bu virtual roster roster information and merge so in uh with the help of this buil virtual roster plugin you can moac to different image when you will open this build virtual roster uh option then you will see such type of window will open and here in the input layer you have to select the images which you want to mosac so I suppose I want to mosac uh two images for example this uh 30° and 78° longitude and uh 28 and 80 uh 28° uh latitude and 80° longitude image so for this uh I have selected this two image and here you can see uh you have there is uh some more information that you have to uh give the uh uh uh uh for example the resolution that resolution you have to select that the average high or lowest so by default you will see that this is uh set on the average and the another option is the virtual roster so you have to save your file where you want to save by default if you are not saving your file a virtual roster file will uh uh save in the qgs platform only but if you will set a directory then on the directory your file will be saved so uh to save your file you can uh click on this option and here you will see that two options you can uh see over here the save to a temporary file that means this your temporary file will be generated and that file will be save in your qjs platform only but when you will uh close your qgis and on that time your file will be you you will lost your file and if you want to permanently save your fi save your file so you have to set a directory for that you have to go to save to the file option and you can give to the directory and on that directory your file will be saved for now I will uh create a temporary file and you can uh once you have selected all the criteria then you can just click on the run so here you can see your virtual file has been generated on your layer panel and here you can see that if suppose I uh close this file and this this two file has been moac now you can see this is your single file has been generated and on this single file your two file is attached or this two file is moac so similarly you can moac many kind of files whatever uh based on your interest so you can uh also moac multiple files so now I will show you that how you can merge two images as I told you that to merge you have to choose you have to choose uh those images which are adjacent to each other so uh simil uh again you have to go to the roster option and in this ra roster option uh miscellaneous you can see the merge option with the help of this merge plug-in you can merge your images so here you have to uh uh select the input layer uh which uh for which you want to uh merge your images so here I these four Images are adjacent to each other so I will merge this four Images so first you have to select this four images and then you have here you can see the uh again you have to save the file to save the file you can give the directory for now I will uh save as a temporary file so and then you have to click on the Run option so your algorithm will run and you can see your virtual file has been generated so this is this is your merge image earlier you can see that this was the four image this four these four are s uh four different files which are adjacent to each other but once we have merged these images so one single file has been generated and the single file you can see over here so in uh as I also told you in one of our earlier lecture that how you can because this is a DM digital elevation model of srtm data so you can uh this is a uh black and white image you can fill color in this image and you can also generate the hillshade to get more uh information from your Dam so to generate uh the hillshade and give the color you have to go to the property so once you uh you will once you are in property option uh then you can see go to this single band shudo color first first you can generate the hillshade so from the hillshade option you can uh you choose the hillshade and here you have to uh give the Jed value you assign the J factor and then simply apply so here you can see the your uh merge hillshade of the four srtm image which we have um merge and we have uh generated the hill Shed from the from that uh merge file now to assign the color you have to Simply go to the property and choose the single band shudo color from the single band shudo color you have to select the color Ram whichever color you are uh uh you will assign that will apply to your D and you have to just apply so here you can see color has been assigned and if you want to generate a hill shed uh color map app for that you have to first generate the hill shade and then you have to give the color on that hillshade you just uh apply the jet Factor now make a copy of this file duplicate the layer and you just just assign color to this duplicate layer single Bend shudo color and the color and from the blending color blending option you choose the multiply so this will simply apply Color on the hill shed also so here you can see your color has been applied the over the hill shed map so this this exercise I although I already explained in one of our earlier lecture so this was just a kind of revision so now we will move uh little bit further and we will show you how we can uh generate different kind of shape files on this qgs platform this will help you during the mapping part in our coming lecture we will also show you that how we can map different kind of geomorphological features with the help of this uh DM or the digital surface model images so we will go to the so we will show you that how we can generate the shape files so to generate the shave file you first have to go to the layer option and you there is one option is the create layer so in this uh create layer option you will see that new J package layer this is uh your default uh format of the qgis only and the another option is the new shave file layer so you can choose this new shave file layer so that will generate your shave file but if you are choosing this new Geo package layer this this will also generate a shave file layer but those shavee file you can only uh open in the qjs platform only but this uh if you are generating the shave file with the help of this uh SS uh SSP format so that format you can open uh on the GIS as well as the qgis so we will uh uh create the shape file with the help of this SHP format so when you are opening this uh uh shap file option so here you can see some information you have to provide to generate the shap files so first you have to few points uh you have to keep in mind that the shap files are the vector files so Vector files means uh either it is a Point cloud or it is a line which are connected with the points or a polygon which are connected with the uh lines so these are all the shave files so uh here uh to generate a shave file first I will start with the point so point you can uh Point shape file you can use during the uh uh labeling of certain uh places for example if you want to uh uh label your map and you you want to add the uh location name in that in that case you have to uh choose the uh Point shap file so uh to generate the point shape file first you have to give the name file name and that you have to save uh uh in a directory to save a directory you just choose the directory and you just give the name of the file so uh I I'm just writing the point and you save uh uh the file name and then from the geometry type you have to assign that which which kind of uh shape file you want to generate either it is point multi-point line or polygon so first I will start with the point and then you have to give the other information for example the reference system for which coordinate system you want to uh apply on this uh point shape file so I will choose the wgs84 because this is the uh this is widely used coordinate reference system so I'm choosing this one you can uh based on your uh Regional location or based on your base map you can choose different kind of coordinate reference system which whichever suit whichever is suitable to your uh uh area or your map so now I will just click on okay okay and here in the uh layer panel you can see a new file has been generated with the name of point so when you will uh click on the uh uh when you right click over this point here you can see another option is is two option has been added one is open attribute table and another is toal editing and this togal editing you can also see over your uh qgis platform so here you can see one pen shape uh has been generated over here and with this pen shape this is also a togal editing uh option you can enable this uh Point shape file the another option is the open attribute table so your attribute table is the all the information which has been uh associated with this uh shavee file that would be Sav in your attribute table so in uh in uh coming uh few minutes I will uh explain you that how you can generate your uh you can build your uh attribute table or with the help of attribute table how you can extract information regarding your uh respective shape files so here uh all these uh information regarding your shavee file will be save so to uh generate the uh shave file for the point Cloud you have to just enable the togle editing mode so you just simply click on the togal editing option and this will enable a few uh symbols and here with this symbols you can simply add the points so here you can see one option is ADD Point feature so with this add Point feature you can simply Mark the point for example if I want to add a location on this map uh suppose this is uh this is a reason called halani so if I want to uh give a name on this particular reason so I have to just click over this uh uh location and once you are clicking over this location a new popup window will open and this will ask you to give the ID so you can start with the one and this is random number you can assign any number these numbers are basically associated with this uh with this uh Point shavee file which you have just generated so I am uh giving one and you can click okay and here you can see one point has been marked over here and with the help of your uh attribute table you can see that in your attribute table one point has been generated with the ID one and if suppose you want to give a name on this uh uh point so you have to Simply add a new field here uh you can see that only ID is present right now but you have to generate a new field on this attribute table to give a location name for that here you can see on this uh attribute table option certain uh certain features are given and with this help uh with this feature you can uh simply select deselect delete copy paste of uh your shave files and you can also generate a or add a new field here in this with this help of new field you can add a new field so you have to uh give the uh name of the field so suppose I want to just uh add the location so you have to give the location and then type which type of information you want to add on this field so that you have to choose with this type so suppose I want to give a text text type of information on this location because your location would be your uh kind of name right then in that on that case you have to choose the text suppose you want to uh assign a numerical number on that case you either choose the whole number or decimal number or suppose you want to assign a certain kind of uh uh information which is related to date so on that case you can choose the date option from this uh type menu so for this uh this case I will choose the text because I want to assign the location name and you can also give the length of the length of your text so you can uh Keep It Whatever uh uh length you want to assign on your name so you can accordingly choose the length of the text now click on okay and here you can see a new field has been added on your attribute table and you can assign a name to this attribute table simply you write a name and that that will add a name to your location you save your attribute table so you simply click on the save option and now you can see your uh location name has been added on the point so s likewise you can add more point you wherever you want to uh add a point you can simply click over there and a popup will open and that that will ask you to provide some information so now because we have added a new field location so now you can see location is also showing uh on this popup option now I will I can give it this to ID number two and location is for example this is Ram nagar so I will just assign Ram nagar so here you can see two point has been added and suppose you want to label the location on your map so you have to Simply go to the properties option and with this property option you can see that there is one option label just below the symbology so you can click over there and now it is by now by default it is on the No Label option you have to change this No Label to the single label and when you click uh on the symbol label now you have to assign the you have to choose the location from the uh drop down menu and once you have selected the location and simply apply so now you can see your your map has been labeled you can see over here if you can also change the color from the uh label menu here you can see the text and you can see the color option from the color option you can simply change the color whichever is suitable lab to your map so you can assign the color now you can see RAM nagar and hanani is labeled on your map so with the help of this uh Point cloud or the point shape file option you can generate the uh Point shape file or you as well as you can uh uh with this attribute table you can label your uh location in case you want to add location on your map now we will uh we will go to the uh uh second exercise of generation the line shape file to generate the line shape file you have to go to the uh layer option and create layer again you have to generate a new shape file earlier we have chosen the uh point from the geometry type now we have to choose the line first you have to assign the file name so I will just give the name line and from the geometry type you have to choose the line option and uh you have to also choose the coordinate reference system which is wgs84 4326 projection code and you just click on okay so now on the layer panel you can see that one layer has been added that is line and with this uh toggle editing mode you can enable this enable this uh line and here you can see One op with this uh add line feature you can simply draw the line so line would we use during the uh suppose in in case you want to uh draw the fults or you want to uh draw the roads or uh any kind of linear feature if you want to draw over your map so you this line uh uh linear Vector file you have to use this uh linear Vector file so suppose I want to just uh add a simple line so to draw the line you have to just first uh uh once you enable this tole editing mode so here you can see one uh symbol which is used to draw the line has been showing o over your map panel so you just simply click with the help of your mouse so because the uh uh default color is red so I just uh disable this map Dem now you can see this with the uh with the help of your mouse you can simply draw the line so to stop the uh line or uh drawing option you have to right click on your mouse once you right click so your popup will come and it will ask you to enter the ID so you can simply put one and here uh so this uh line has been draw and you can see uh this information on the attribute table so you have to open the attribute table here you can see one feature has been added and you can also add another field for example I want to just get a length for this line so you simply add a field name length and then you choose the type because length is a numerical number so I will choose the whole number from the type option and I will just click on okay so here you can see length has been added and you can simply calculate uh the length of this line with the help help of field calculator so in uh uh here in uh attribute table one option is ADD uh uh field calculator and when you will open the field calculator here you can see so two options are given one is create new field and update existing field so with this uh help of field calculator you can create a new field and you can generate the information for example I want to uh get the length for my uh my uh shap file so you can uh directly create your shape file uh directly create a new field called length over here or you uh as we did we first created the uh added the new field and then we will calculate the length so for our case we will choose the update existing field so on this update existing field from the drop down menu here you can see two options are given one is ID or another is length because our attribute table is uh only two field which is ID and length so I want to get the length for my shape file so I have to choose the length option and once you have chosen the length option here you can see the row number certain uh options are given from the geometry you will see the uh area and you will also see the length so you have to go to the uh here you can see the length once you you are double clicking over on the length here at the bottom left corner you can see the preview option here your length has been calculated so once you are clicking on okay so uh your length will be added on the on your attribute table so here you can see this is your length so now you have to save this attribute table from the uh save icon you minimize this and similarly you can draw multiple lines or whatever uh you want to do you can create any kind of linear features so that you can do with this linear shape file so you have to uh uh save this shave file whichever you have generated now we will um we will generate a vector F or uh now we will generate a polygon so to generate a polygon again you have to go to the create layer and then new shape file and you have to assign the name so I have chosen the name and then you have to choose the geometry type that would be your polygon and the coordinate system is wgs84 and and click on okay so polygon you to create a polygon here we you can see on the layer panel we have just added a new layer which is called a polygon so you just right click or you can simply go to the tole editing mode or enable your polygon option once you enabled your polygon option here you can see add polygon feature is enabled and with the help of this add polygon feature you can simply draw polygon so polygons are basically connected with the lines so to draw your polygon you use your mouse and you just simply click and here you can see whatever shape you want to generate that you can generate with the help of polygon and to once you are done with your uh mapping or you want to stop your polygon digitization so you have to just right click and once you are right clicking a popup will come and that will ask you to ID so you just give any random number so here you can see by default it is filled with a yellowish color but you can change your color with the help of property option once you are going to the property here you can see whichever color you want to assign in your map you that would be you can do with the help of property so you can see your color has been changed so suppose you you you can add different polygon with this uh with the help of this feature now suppose I have generated this two polygon and you want to do certain kind of things with this polygon feature that you you will see this is a vector option because all the files which we have generated either it is point it is line or polygon these all files are vector files so whatever whatever Al algorithm you want to assign or whatever shapes you want to create with the help of this Vector file that you that the plugins you will see on the VOR option so in this VOR option here you can see on uh the Geo processing tool and this Geo processing tool has been consist with the uh some uh more options for example if you want to dissolve this to uh Vector file so you can do uh this simply clicking with this uh with the help of this dissolve function so once you are clicking over this dissolve function here you can see you have to assign the input layer so that would be your polygon and you can simply uh dissolve your this two image now here you can see a new file has been added name dissolve and you can see this two file has been dissolved earlier this these was the two different kind different file and you can simply select this two file with the help of this uh this option select feature by area or single click once you are uh enabling this option and you simply click over your file so you can see this file has is selected so how you will know that your file is selected you can see this uh cross in each corner of your file these are basically note points and each note points are showing in a cross and your shape is filled with yellow color so this that means your file is selected so you can also select different shape file with the help of this option so so these these was the two different shave file once you dissolve this this is a single shavee file so it is converted to a single shap file similarly few more options are given here you can use this option and you can see what uh you can generate any kind of shapes according to your interest for example there is another option Union so that what it will do it will just create a union with uh Union uh of the this two it will create a union of this two different shape file so you can click on the union option and you can simply click on run and here you can see this is this is your union of for this to shave file so this was for the uh VOR layers now you can also use this roster option you can explore this roster option and here you will also see many uh different kind of options which you can use to create your uh Maps or get the more information for example suppose I want to get a uh particular set of uh for example I want to get a uh small portion of this map for my use or my uh uh research or interest so that you can use uh you can get this uh portion of map by the clipping of this area so how you can do that you can simply you can simply use this shave file you you have to uh use this roster option and here you can see from the extraction you can clip your map so in extraction there is two option one is uh click roster y extend that means you have to when you are enabling this option you will get you have to assign the input layer so I want to get file from my my merged file so this this is my file from where I want to get a uh fraction of map and in clipping extent you can use three options are given one is calculate layer calculate from layer another is use map canvas that will use your entire map and another is draw on canvas so you can simply draw that which fraction of map you want to use for your interest so I want to just get this much of map so here you can see your latitude and longitude has been assigned over your input image and you can once you are clicking on run so you can see this map has been generated so if I just disable this map so now you can see this map has been generated by the clipping method so this is also a DM but this DM is a small fraction of the map which we have merged and the another option was suppose this was our map and you want to get a uh uh you want to get a uh fraction from this map so that you you can use uh that you can get from the shap file so for example I have to just create a polygon so to create a polygon you have to Simply go to the polygon option and enable the polygon and you draw whichever fraction you want to get so once I draw you just give a random number and click and you select this polygon once you selected and now you go to the roster option and extraction and the first we extracted the map with the help of clip roster y extent now we will show you that how you can clip your map with the help of mask layer that is that is your vector layer so once you open open this you have to choose your input layer and now polygon so you can see here I have drawn several polygons so I want to just get a fraction for this my selected layer so you have to enable this selected feature only and you have to just assign the no data value zero and you click on the run here you can see your map has been generated so with the help of this clipping option you can get a particular set of map from your regon of Interest so we will stop here and in Le next lecture we will show you how we can generate the anac with the help of CET images thank [Music] you [Music] [Music] [Music]