TUTORIAL Agisoft Metashape - orthophoto and DSM generation (with GCPs)

in this short tutorial I will show you how from the beginning to the end generate TSM and orthophoto from the US data in our G soft metal shape professional so we start with the entity window here's where our model it's gonna show up and here are our two tabs reference tab and workspace tab first we're going to start with loading her photos and I would like you to see like we work right now in the local coordinate system we don't want that for the aerial data we want one work in some kind of the known reference system maybe latitude longitude altitude you can track change it here for wgs84 which is a lot longitude latitude altitude or you can search for the reference system that your data is it so we start workflow is something that we're going to be pressing a lot so here is our step step by step what we're gonna do first we're gonna add photos from the folder and I think all of them this photos out down sampled so the processing will go faster you can see here that the positions of the cameras are not loaded also you can't see the cameras here it's because this type of you is that was flown it's a tremble who is it does not save the information about the Patrol authorization in the exit file it does save it in the separate log file so I need to log it from the log I'm double-checking latitude longitude altitude yes and I have the rotation I want to see to load it with the rotation in this and right now we can see their grid here or our photos are located somewhere in within the reference system so this is the center of the photo the next step is to align those photos so the generic per selection takes much more time because it looks for example for this photo for tight points in all the photos the reference preselection has a preference for the photos that are in the vicinity so around it's looking more locally so we can use the if we have grant control points to optimize the alignment we can use lower alignment or a medium one like in my case i'm gonna be using medium it's gonna take some time depending on the resolution of your photos and also the number of the photos and of course on the on your computer performance so in my case because the photos we have just 70 photos 78 and there are down sampled so it's just took a couple seconds so we can see all our photos are aligned don't worry about the bounding box color it's it can be changed it's just my preference to have a bounding box is to indicate what array are what points you can see here the sparse point cloud what points will be taken into consideration in further processing so I wanted to move rotate here you can rotate region move the region so I want to rotate it a little bit with the bowl so it will just have all the photos okay you can see here it what's important there red is the bottom so it'll read supposed to be underground the base we can see here that other photos the old our points are often within the bounding box okay so the next step is to load our ground control points and in this case I have tab here I have just latitude longitude latitude of course there is no rotation and go for the grab control points I have just three for this white it is optimal to have at least five but this is just for display so I will do it faster and you also can do it faster in on your computers just with sample data here I press yes to all because I want them to be and now there is a time I have a separate video on how to locate the ground control points so I'm gonna pause it here and I'm gonna indicate it on all the photo so I'm just going to show you how I'm gonna do a filter photos by marker I will start with the sixth one and I'm gonna move this little flame I think it's a flame to the center of my growth control point and I'm gonna do it with all the photos that I have so I'm done with locating old my grand control points you can see here I've located them on over 20 pictures each because we had a really significant overlap but I think 80 percent site overlap and forward overlap too so my next step would be for optimizing alignment you hit you have here this magic wand here so what I do I check all of the boxes there are different coefficients associated with the optics of the camera and I press ok and now our o the whole point cloud this parts protocol is adjusted based on these grand cultural points you could you can see how it changed here I was showing you before the error was about like for 30-40 meters and here we have 0.001 so it's like less than centimeter so what's our next step remember not to realign the photos after you optimize the alignment next step is usually the most time-consuming step so you need to make sure that you don't ever ever use the ultra high setting it because it's just going to crash for you we're gonna use the manual settings in this case here you have the depth filtering mild is for for the models or for the text for some very complicated textures you don't want to filter all the outliers we're going to just do the moderate and we definitely want to calculate the point color so I'm gonna click OK and it's gonna take me probably a minute some we'll be right back I'm done with the processing and here I can activate and see my spice spice boy sparse pork line changing into dance point one so this is a sparse one this is a dance one our next step with the workflow is to connect all these points that we created into triangles so create build a mesh a triangulated network we want to use as a source data the dense cloud surface type we want a high field because we are working with our low data if we want to be working with a model we would use the 3d and that takes much much much longer and here is the face count I like to have a really beautiful model so I like to keep the face count high so I would do even the custom maybe five millions but in I want to have the enabled interpolation and of course calculate the very vertex colors I click OK and it's gonna take a little bit less time I'm gonna post below what's what are the parameters of my computer that it works so quickly on my computer and this is ready so this is active now I can see a model here let's look you can see how the the trees look like towers because all the only data we have is about the surface of the crowns we don't have any data from below because we have flown just so high so the next step is to build the texture the mapping I want to create all the photo or an adaptive water photo so I'm going to click that one adaptive ortho photo takes the flat surfaces and applies different algorithm to the flat surfaces into the nearly vertical surfaces so I'm gonna click OK and it's all gonna take probably couple seconds so the texture is ready and what is left now is go to the demon bird Ultimo's a ik if you're working in the demo mode you don't have license it's not going to be active because you are you need to be able to save files in order to build 3d em in order mosaic so I am choosing my own coordinate system under in North Carolina so this is three three five eight the epsg and you need to remember that whatever coordinate system you use for your dsm the same coordinate system it will need to be used for the other photo and our resolution is here 25 centimeters so about an interest generated again it's going to take probably couple seconds ready next I love your daughter mosaic as you can see I have no option to change the coordinate system because the only only what I have is what I've chosen for the DSM so yes the surface is that yeah and the mosaic and I just click OK it's gonna probably take a little tiny bit longer than for the for the DSM because the resolution is higher and now in my work space panel I can see the generated results so this is the D DM and the Ultimo's I equal the seam lines that I created and the next part what I want to do is export all the files so you go to file export and here you can expand then export the point cloud the model that we've built previously that you can also upload it to one of the what one of the online web servers that store your maps I use sketchfab so I want to export and export or the mosaic exported chain and save it as whatever whatever extension you need what's really really cool about the mecha-shiva general is you the processing report it's really great to have it this is like with our sample and you will see it will create the PDF that will tell us a lot about our processing so this is my report shows the overview of the orthophoto shows what was the overlap how many camera stations how many how many pictures were aligned the camera calibration report the camera locations with errors camera orientation the grant control points here with also with the error you just had three it's really not advisable to have it like but we had in one line it's best to have them on near the corners of the area and then one in the middle and it also shows us the digital elevation model and our processing parameters with the times for processing so fortunately it was not very long if you have a lot of photos and your computer's not as fast it can take you hours and hours so as I said I hope you enjoyed it and good luck with working with algae soft mega shape you

Channel: Justyna Jeziorska

Views: 71,231

Rating: 4.90625 out of 5

Keywords: Agisoft Metashape, UAS, drone, orthophoto, DEM, DSM, GCP, Metashape, Agisoft, tutorial

Id: O--J8JrAB7M

Length: 14min 8sec (848 seconds)

Published: Tue Jun 04 2019