Cloud Compare tips

hey this is sleepers and Stantec I am chief pilot for drone operations here in New Zealand and a geotechnical engineer based out of Denis this is an example on how we treat our point cloud surfaces to make them a little bit more manageable the example we're looking at here is the deep stream Creek pipeline discover problem we had a survey that we did for the Dunedin City Council to look at an exposed pipeline crossing the deep stream you can see here it's quite a nice resolution photography this was taken about 70 meters flight altitude we took the drawer essentially to give us a good bird's-eye view of what the problem was but also to allow us to to do some cross-section analyses and to look further afield you can see that the crossing is post at this point and it also has a second crossing cross car the vanilla I think it's Flagstaff Creek here what we'll see here is we don't just have the plan imagery on x40 model we also have the 3d imagery this is incredibly is for for visualizing the site and going through consultation processes with the client to see how we want to them address a solution in this instance I think we we were simply enough wrapping in and around the pipe to to stop any further student-student degradation at that point but but the job was interesting there's only so much you can use as pictographic a model for it doesn't have an awful lot of ability to cross cross sections you can see the vegetation is quite present it's not true digital terrain model so what we do is we we explore this information there's a whole bunch of output options one of the options that we have from the process model is a point so I'm gonna do now is pop across to our point of view which have opened in cloud compare and we have this model here which is the fill point cloud it looks like a 3d mesh model but actually if you start to zoom in close enough you start to see that these are actually individual points that are getting spotted by the photogrammetry processing software so in this instance what we've done is we have used the sugar almond taran we've used the fill point cloud we've used a plug-in within cloud compare which is called surface filter so you highlight the layer that you'd like to check I tend to choose Steve's book with slope processing there's a class resolution I like to think the cloth under tension and a certain resolution the smaller that you make the cloth resolution and higher the processing blood of the computer but the less likely it is to cut off crests on slopes and things like that the classification threshold is a distance of the the clause where it will count points I tend to leave it at about 0.5 meters but I have gone down as low as point two meters or point three meters but I have a very low altitude flight with a high resolution information on grasses even that I'm looking to get rid of so here we go for about point five meter plot resolution and 0.5 are not uncomfortable sure the processing here it takes a little bit of time but not a huge amount of time hopefully you'll be able to see that process getting done and at the end of it you end up with yeah this model here which is looks exactly the same but it's now in separate into growing points which I can disappear and leave us with ostensibly vegetation or or higher points this vegetation is nice to have from a reference perspective but it's not terribly useful and it's not a useful part of the DTM so you end up with ground points if you take away the vegetation you can see some holes left in our survey so there are ways to get this information into quite useful terms for our carrot guys this is several billion points at the moment which can be a little bit too much for our cat or predators to process but obviously the point plate it's nicely in terms also with the underlying also imagery that we get from cloud compare so if I turn this off for a second what I have done is I've run this screw tool here which is called projection and rasterize at the moment I'm choosing quite coarse resolution because this is a reasonably large scale model um if you made this step too small then for contouring passive purposes that can be quite quite a horrible looking contour model so anyway so what we do is we said is that looking for the minimum height I don't want to resample the input glide out I want real points I'm choosing to interpolate wherever there's holes in the model if you don't interpret it then you end up with essentially the process either leaving holes or or diving down to the bottom of the model yeah so what we do is we upgrade to the grid and we end up with something that looks like this now I can here I've actually got in tablet let me try it if I leave it empty and update the grid you will see that it's actually probably a little bit more pretty in terms of the model because you've got three points being modelled only but you do end up with holes those holes get to be a little bit interesting if we do a contour plot so if I do a contour plot of that information and I may there's something sensible within the zone of the model and I generate a contra model it would a little let me turn off everything except and let me turn this so it's a plan view so that model is actually that's pretty interesting because that's all those points some model you can see the high points of the trees it's quitter it's quite a good model there will also be excuse me the boundary conditions are are not terribly useful it just typed at the bottom oblong but but you can see we have quite a nice-looking contour plot there if however I take just the ground points [Music] yep with the holes in the model if I was to do the same thing with with that groin point and create exactly the same contour let's do that tools projection updated red so that we are essentially leaving emt's we've got quite a few holes in model if I go to the contour plot again put the same parameters and generate a section and it report annotation what we will see if I turn off that three pictures that we've got quell of holes so these holes are know to reflect in the holes the model but we don't actually have holes in the ground there so the contour plot starts to give us a huge damaged contour model so what I tend to do in those instances is I kill that I go back to my content my Dremel used tools projection and again have exactly the same parameters but instead of leaving empty I enter plate on these holes it's probably good to tell your client so that's what you're doing so they're not to align too much on this but it does make it much better model so we lose the b2 who go all the way from 0 up to the top the model list was less pretty if I go to my contour plot and I just limit it to something similar to what we had before generate that contra pot and explore that contour plot we should hopefully yeah now we have a model which is at least flatly interpolating between the boundaries of those holes so when I turn off the drone model you can see we now have quite a a good looking model where we were consider law points associated streams and if I start flicking between that and the contour from the including vegetation you can see how it's actually no closer to having a DTM rather than true in model assuming that we've got trees as ground so this is essentially a one meter contour plot this particular job we can under leave the original imagery again and now I get to something along the lines of of what my CAD guys are delighted to use

Channel: LeeFluff

Views: 21,042

Keywords: cloud compare, pix4d, drone, model, photogrammetry, stantec, new zealand

Id: OgIk15vMTG4

Length: 9min 45sec (585 seconds)

Published: Mon Feb 19 2018