Extracting and visualising Roof Data in QGIS

and this video I'll be talking about and demonstrating how to extract roof space or roof information losing curious so we will be using different data sources such as they mentioned data or TSM and the building footprint and based on these people expect key information about the buildings so in order to be able to construct better looking 3d visualizations and do some analysis so if we at the end of the video it should have something that goes like this so basically we have edited some of the buildings to create our details so using some the roof information to split up our buildings but we have buildings for a flat part and the steep part and so on and also I have classified the buildings of colors here according to the building's height so this is the end visualization qgs but this base is also far MIT but to be used in all tools such as Sketchup or C the engine or of this type of more 3d visualization - so the page states that we're going to start with is our altar photo I know also folks are not really good for defining footprints so the blue is the footprint here we see that all the photos always have some Spooner's I'm angling so therefore we can see this side of building enough that plane has been somewhere up here and there all the picture was taken that makes it difficult to identify the footprints if we look at this image which is the surface data you see that as much clearer some consistency between their surface data and the footprint laser and down here in this one I have added the or calculated the angle data so the slope but we can have the beam is flat then this movi color is a sum is between 10 and 50 degrees and this is between 50 and 75 so that's this is probably if you can see a em months at or a gamble a roof as you as it's called in America but your typical inside so we have this with too steep edges and to not so steep at the top of flat in this case here same again steep steep and a flat top so we have different variations of this men Zagreb are a flat topping or a not so steep Tony and then we have the red which is the edge of the building so angles larger than 10 to 5 I have classified as red in this case so that's our basic input data we will need to talk about what we want to generate so most important for us is to get these two measurements of the eave height and the ridge high so these are two indications of the roof so the building or the roof starts at the eave and ends at the beach our house consider some of those different types of building roofs rehab and they are almost local variation so you really need to know your roofs before doing this so we've talked about they have this gamble roof pitch screen normally we'll call them and sod in Europe and you can have RB boom bass more angle or you can have a dick as in this case you have a hip roof that be typically for fine on bond family buildings Europe and we have flat boots also lots of different types of roofs what you want to classify them depends on how you want to work book the date of birth getting to identified these rooftops based on our surface data is a bit tricky it will be a course classification and it's going to be a long journey to get that so I've written some steps that we'll go through but basically we will start with out here's them you'll filter using this our neighbors so this this is a neighborhood of focal analysis your truck movement to the video about different types of pasta alkylations so we have neighborhood and we take a five by five matrix and calculate the median that basically evens out all the small variations at B most of them will be mobile phone antenna and so live you'll do a calculation the slope all in brackets they are the qgs commands you'll reclassify our slope based on the V class by Table two so I said zero to ten percent that's flat one ten to fifteen to able we can call these from men shot and so these are the edges we will call these four men shot set 50% five and more than 75% I'll call it edge and we'll use in its information so our filter than this to to visually investigation of our buildings see the any buildings and need to be split in order to do a reasonable fee the visualization of it what's all of that is done we will take and our filter the SM and then football evened out and then fills out so we don't want our steep inches because if we want to calculate the evite that would be typically the minimum of the roof and if you have these steep edges that might give us quite a lot of wrong day to that so we'll get rid of the steep edges we will have to do some trestle formation of zeros to no data in order to do our calculations and we will create a new mask yes M this data will be used for aggregated to our building so we will find out what is the maximum one is the minimum in the building we will also use this new to the soul histogram okay to look at how large percentage of each of the classes we made here of our different classes our larger percentage of those were in each of our buildings and finally we will use that information to do a classification of our move times so a long journey and let's see how it goes in queue gets so we basic [Music] so in cookus we have our yes so we have a am this one anymore that a raster dates and buildings yes no so 1 & 0 you have a DTM you have a DSM the service model and we have it also frozen these are the basic data we'll be using to maybe have a course a bullet building footprints again in a single polygon version because we know that is a problem and in the 3d login and using multi packet so we will use a single word drama too emotional yeah yeah so first of all if we remember from our steps our first step was to filter out the SM so we use this our neighbor our neighbor and we run it on our DSM our dude on a five by five pixel window and what I want is a median Hey so I'll do that calculation and what that's finished so probably a good idea to be a bit cautious names so let's rename this to es M it's moved oh yeah smooth yes a say me Adam smooth okay we will once we got this one they use that to calculate our slope on so this is a really easy so there's this the tool called slope I use the one from Gao and I'll do it on my yes ma a.m. I slipped I smoothed out yes M I know I got this layer have you got the hi the white one as the steep edges I mean you can see this lat oh yeah boom it edges around for specification later I would do a classification of this data set also so in order to have a class from flat roofs semi steep so 10 to 50 50 to 75 and so on so in order to do that I will use the reclass - maybe you should this term that's called slope that's fine so I have this reclassification by table so what it does is that I'm here I can enter a table and down here I specify what my div name how this table should be read so the first column is my minimum the values are strictly larger than minimum and smaller than or equal to the third column of a second column my max I'll be specifying you see yeah yeah in this table I will add a new row of this first row I will write from minus 1 to 10 because I know there's no - slopes well that's because it has to be strictly larger so if I put in a 0 C Rose won't be classified so now if I use a minor so that would be my class 1 and I'll add a row I owe and more so this class will go from 10 so make me larger than 10 smaller than or equal to 50 and I'll call them for 2 and this one I will save 50 to 75 and call them free and the last class that's going to be the edges and Swedish seldom again it should be 75 or 80 it [Music] depends on your area you know so this is as lots of working backwards and form for this what I decided maybe seven to five is maybe I should go for you I don't know let's stick with this so I've created these one two three four classes for these values on my tool there is it maybe I should now call this one he named it so this is my eye slope me class I might as well just give it to following so unique values massive power that's fine so we have the edges which are our edges of the buildings wave so may have been state someone sent if I've said yeah these very things which is this typical man side effect so here we have it made it to be steep roof is also basically no so where's there we have them inside this is a less steep and steep okay move a flat top see this standard hip buildings they have this less steep roof well we have this very characteristic coming Paris many places we have a steep edge and a flat top so using this data set I now turn on my buildings and mean to the next color let's make them blue and maybe I'm at it sir good so what we're looking for now is buildings where we have red inches inside our building so that indicates ways that we have some steep cuts changes in elevation inside the building that is something that we might also hear inside this building there's something going on here we can maybe also see on the unclassified slope or even on the DSMB Z that's something we're all here and there's a something really low down there there's some bill later but basically we can use the DSM the slope and densified slope so visually go through our buildings to see how many buildings that need this one here's Panos it has some strange room in that building that should be edited and split splitting drama trees is a bit of a trick you have to learn so let's look at how to do that in order to do my editing find something to start let's start with this church here and I will typically need some extra tool buzz I normally use my advanced this is a session - and my snapping - these are the two tools I'll be using for this I'll take my buildings set them into edit mode and then there's different approaches for this building here I would like to make a island in this one or it this the tower might even make make - there's a steep edge and that goes up so if that's the case so it's something that is inside a building that you want to manipulate you'll use this tool that's called field ring so you can use fill ring and you basically disk into just roll your your ring inside your existing building that splits a building into two - and I work to Billings I might want to split this one right into a well so now these I got three buildings this one corner here is not a internal part so instead of putting a ring I will split my building do that using the split tool here but this one it is that you have to start outside the building or pray for you sometimes you can get along with this snapping and you're going to the building and here my snapping is important what I've done here is I said I'm stepping to my active layer and I'm stabbing both two segments and vertex and so if there's a vertice it will use that there you know place a pot there who are there outside the building and then right-click and now this one is at individual building by whose it's electrode and see this part has a building this is a bill so I let's find enough place to do it on ah there's lots that needs to be done this one up here is also interesting so we have this big building here is selected so but it clearly there is some parts that could be looks likes it's terraced we can if you look at our auto photo you can see area there is a series of terraces so what I would like to do here is again just use my split tool so coming from inside this building go into the corner there exact corner bring out ending inside this building part I ending Oh because I now have a selected object that was not part of the what I was doing it doesn't have to be selected but if there is something that is selected and it will only work under select so be careful there so and finally this one now so later so I have to clear my selection and then I can go and say and spit it or I shouldn't select that tell me that now that one is split into several parts this one is also a really annoying building so again this using this fitting - there's nothing selected so I'm me go and play how in here there's something strange going on there [Music] this type of might be a good idea to see what buildings I have if I select this building okay so run top head difficulty bones under that um and if I look at my snow beta or my oh this might be the clearest so we have this low area so again use my tip - I'm from outside don't get sick for that one in a sec say say outside myopic now and it's chaos one on this time so again this time and that exactly which Lee is the best to use yes difficult say this time I might want to select I saying this is a building one two in it make sure I don't do anything run and then say I'm coming from outside I'm just stepping there and I'll be into this building with outside so now I have a new building there ah let's make that one it's so annoying all these small buildings are not split um also this variation if you look in here as lots of slopes that's because this is a roof garden so there's always problems that you have to face so outside this building that they're that they're that they're outside the building so I think you understand in school there's some that are pitiful this one is really annoying building so if we look here we have a flat part and then the steep part and a very steep part and again hole down there if you look at the elevation data you can see I even higher and then something that this surface so this is probably a garage system and yeah so what I want you to do is I want to make one building here I'm building this part and then put it down here I have this going to be really difficult because this is a little hole in that I want to make holes but I can't make a hole round a hole so in order to do this I'll have to get rid of that one first so I'll start out by using my delete ring that one and pinging here let deleted that ring then I can use my head ring to my filming here it's okay I wanted one part for be up here and maybe this is best to do this tool on it that means he is going to be a bit dirty because that we have many different variations I'm innovation here I'll probably not be a really clean cut and knowing it's going to be here this and this time I will use a not a film ring on a ring and this is not is inner part it's not our building as such so some cases you'll have to delete hold and then build it up again so now I have in this case building up here a building here and a building here and a holder so editing the data checking around looking for things where you have hitches or looking at all the dates to see if you can find places that need is Inc publishers have done some and superbly on this building up here but I think you've got the principle so [Music] save the data I've been a bit stupid here don't know what because I'm editing my original data set that was a bit of a blunder I don't know if I can do the same as you know let's here see what this would do [Music] okay buildings 1c that's before after the edges have been committed yeah is that so not might remember - if before you do this copy your dataset I'll just save my now I have a beep I have a backup no problem so what you should have done before doing this budget it would be a good idea look on and said and save features as so you had a copy that come work on safely well thanks again pick up so I'll judge for not saying this first it's think we got that we made our buildings what should we do more so we have done as we've done our visual interpolation now we need to take our DSMB made remember we made this our yes MSN mail our smooth but it still has beta under steep edges so and it still has so these values for the steep that still part of it and it's all still ahead or says it dates outside the buildings we want to get rid of those what we want to do is that we want to have only data where our slope class is not equal for and where we don't have any buildings so this can be done in our raster calculator using this trick of quantification so if I use my calculator am i raster calculator raster your calculator raster calculator here and I think I want to use that one I remember the same yes well I want to say if my slope so if slope is different I use this one it's not equal 200 this one will return I can put back around it and this bracket here will return 1 if my announce mom by the way this is my reclassified slope on to do it so that one if my reclassified slope the ones were the classes in ah 1 2 or 3 this will return a 1 if it's fall it will turn 0 if I multiply that by my buildings which have one where the public sewer where there's no billing so if there's no building everything will be 0 this a building and it's not classified as or then it will be u 1 it is classified for fire as for and is a building it'll be 0 so there's always no trick to get the hang of these logics in the calculations once you got it is a powerful tool so and I'll use my filter DSM thing that one has my face for my calculation and run it and closes so yeah I have a none of my alkylation I have my one so it's white fair I have buildings and you can see it's it zero where I have the Steve matches or way I have outside my building the next thing I need to do is a this has a zero there and I'm going to use this for my innovation calculations so I need to not have a silver because silver is illegal elevation and we could have building heights of zero so we'll need to do some calculations on this and in order to avoid this problem with zero but have no data so I can distinguish between zero building height and is zero and no data I'll need to convert this simmer to no data the tool for this is on translate so I'll use this translate to announce it my this one so we'll get the big that's a vector version or the raster version there and I'm taking my mask so this output here should've given another name on my master calculator this let's let's do that so we have this output here let's call that mask zero so now we know that one and this was this tool here I use math word zero and what I'll do is I'll sit this column it says assign a specific no data value so sue won't be now considers my no data value and while I'm down here I might as well just change it to white because I've only got one 2 and 0 now so that's the efficient storage of this and run this so that's very quick true and it's this one converted I basically don't need that one anymore my converter tool here as black in there and you can see I can see at the moment I'm see if I turn this on you can see I'm seeing the underlying layers outside it it has noticed that she's wrong here in the classification I can if I want always if you have strange numbers on a Ledge in here you always go in and just choose your value and then apply what I want to do is I this one stick this is unique values mess if I and hey now you see I've only got class one here so this is right now so now I know I only want to have the building heights inside these the next step I'll have to look at is so what I need to do now is that I need calculate my elevation data so my building high so the buildings are the height of the buildings is my DSM and is to have a little M cap issue here so I have to calculate my building height which is my surface model - addition so the buildings are the height of the detail the surface - the detail and then I will need to use my converted here my mask to blend the tardis on that one mask Oh I'll use this one to Moscow so I only got moving the building the maratha calculator I will do a he SM and I should use my filtered one of course so that's that one and I will multiple tracked no subtract my DTM and then all of this so that's one part of my operation and put that in bracket because then I'll multiply with my mask motive by my mask and what happened yeah - yeah so my PSM - a DTM x my mask so that won't remove anything that's outside the building and I will just basically use my ESM as my base for this calculation and on that so now I have this layer well my output layer it says building use this get rid of my underlying information so let's see my author photo we're happy so I've only got you can see I only got elevation data for the buildings and I've only caught it where I don't have the steep edges so this one is my building height by building height layer that contains my clean building height if you wish information of my buildings and our basic code generated at last the information on e so I have my building height this one area I can use to extract what is the maximum what is the minimum height we need building and I have my slope classes that are masks so these are the difference so I can see which ours are flat what I now need is I need to aggregate this data to my buildings so now let's do that I can whatever what I do it and doesn't matter [Music] that these meant last type of fast operations is so know where my buildings are sones it does statistics different types inside these zones but this is the ones I'm going to use that to and I need here is some statistics I can use that on my building height to get the maximum height the minimum height million and I can use some histogram to calculate how many percentage of each of the different types of slope that are in my buildings so let's start off so more so I'll take my buildings so this is the one I'll do the calculation done this one my buildings should have made a copy is the one that I'm going to store my data in and you're going to create a new attribute that start up the name hist and then what the number of the of the cost the attribute so I run this and what our good is I've got a new layer so this output zones and inside this layer I have information and you can see I have this hist one is 2 is 3 it just how many cells and I in this building of each of my categories I Linden also do my solo statistics on my pasta layer is going to be my bill being Heights which is building height and I'm going to use my soon which is my output zones this one line is braided and it's going to make some new Wonder has an underscore and in minimum maximum so on and the statistics I want to calculate is down here yeah I can see I want don't want the Sun that does make sense I want to have the cup that's how many cells are there I want I don't need the mean I might well I probably want the median and I'm at the minimum and the maximum the median is always a good way of getting rid of the last noise in and so on so we can use these [Music] and okay and run my money so now these buildings have lots of information that I can use to do my classification on Sunday I know how many Dow each type I know how many there are in total so I can do a percentage and I know the minimum and maximum so I know what to do my classification or building or roof types I would create a new attribute I'll take this layer and properties and feels bring into edit mode great a new attribute old move class and that's going to be a text ring me into own and let's start by sitting into too difficult to spell quickly so unclassified okay so now I have one attribute unclassified move the value unclassified all of them and I can start giving it values for different types of buildings so and this is this there's a bit of an art to this because the order that you do things in will matter and depends on what you want to do so you probably have to tinker bit this but the basic principle is that you select some buildings so let's say I want all of them that have a steep side so these little blue comments item was more than it's a 8% inch steep and sad type but the edge type so to do that I'll go and say I'm using this up here too late by expression and I'll say that my feels around to build menus and say if my so those 75 50 to 75 percent they are in this case it yeah / total comp which is the count dog basically so that what count is the sum of 1 2 & 3 and we have excluded fall so if that is larger then 0.08 that's more than 8 percent that why I want to do not really as I said how much should it be before now it says more than one percent of the steeps I'll call it a steep room I can do select C okay most of them had that so that probably was not as that's a noise and let's see what five percent does no popping noise maybe I should stick when they say yeah this thing was a sit so if there's more than 8% bears I'll call them steep yep but they are now selected I will normally use when going to edit things our use of calculator in in the attribute table this so this could see there's the tool down here on that will create a new layer and or get bit strained so open attribute table and you shouldn't really do that if that's not what's but this is okay and we can see they all the select one they all unclassified a moment I will use a classifier and say these are steep place deep and I want to update my roof mass and now all of these have been given this majesty I could also say if my last two so if my class - that's those from 10 to 50 percent if they more than 40% of the roof see what that gives that we could call them to call them hip BAPS so our fate my pasture field for these hip but now they will be classified as if there's lots of no Dayton nuns here because they outside our the essential they have no dates in them that's fine I might just want to say that if there's more than let's say 50% that's flat and I'll call it a flat roof so I could do that also I'll go back to my selection and back that type one and that is more than 50% that that does that though like this it looks fine I will now call these flat update and move baths good so probably still have someone classified somewhere but this is approximate a good stuff and the video is getting really long so let's stop this and I'll save my changes put my pencil but and say save - let's finish off with visualization then we can see some of these change to be made so I don't remember that and I'm going to take this into my 3d visualization again I need to get rid of those with no data I just have to filter this things at first so we'll turn this dataset basically take any of these down here pound has to be larger than zero good so hopefully but these are my seam now so these my buildings most will classify my buildings now the properties and symbology and classified on my so every x' and use my rooftops there's a fire Ron I've got by different rooftops maybe we bought our flat to be bean cuz being put green roofs on them okay so we have our different time zone and we can now go let's also put our also for the victim visualization here we have our building times we have our classifications and we have an auto photo and we have calculated these different values into our buildings and we should be good to go the van Gogh my bed and again and say I want to use my DTM as my base that's so hopefully display my data relatively flat area then I want to exclude my polygons so these I want to do those is that I want to exclude them and they're going to be relative to my DTM that one on the DTM and I want to exclude them by and it's typically I could use max Oh million depending on what I want they should be that's up to you what looks best I use I use a million so it's not quite the top of the roof so be but there's a lot of noise especially around these green roofs that I want to a while so this and you can see our elements so we have on in church that we created you can see idyllic corn I created before I cut into the corner here in this little corner my two levels of my tower he can see this building over here this was the one we also have you moved the ring but it has a garage down here and then it has a terrace up here and also we worked with this building over here so here we had that mate they made this tower and we had these is extra elements in so these are these buildings we added to this yeah and we can see how our edits have changed our visualizations model here so basically we have finished we have got flour almost 1 hour video and basically demonstrating the process of enriching our polygon data of elevation data and move shape information so you can use for classification visualization in Kyrgyz with a bit more detail than it did in our original visualization and we can also use this information to work in Sketchup or hachi is Aria goes through the ArcGIS but I will probably be looking at how to do this in city engine so hope that you stayed on to the end and that you got through all these different elements of creating I enriched pretty model and I hope you liked it and hope to see you in another video bye

Channel: Geoinformatics

Views: 4,513

Keywords:

Id: fitQGrrthH0

Length: 53min 21sec (3201 seconds)

Published: Mon Apr 27 2020