Cloud Compare - Point cloud orientation with "Leve Tool"

have you ever received a point cloud which was completely I mean disoriented and have you ever received a point cloud where you expect it to have a flat XY plane in a certain position in the 3d model but you add the XY plane the real XY plane in another different position in this video I'd like to show you a very interesting tool inside the software the open software open source software cloud compare which is called level tool level tool allows you to pick three point generate a new plane inside the point cloud and that plane becomes the new XY plane in the workspace area of cloud compare this is a point cloud that I made after photogrammetric structure from motion process I shot some pictures from a camera that was lifted up three meters from the ground aim down angle down 45 degrees and there were no geotag pictures and I didn't put inside the software of the process the coordinates of this target in order to have a point cloud that was disoriented as I said in the very beginning if I choose the top view instead cloud compare I see this but I think that it's much more clear how this point cloud is bad oriented if I switch to I think the left side view all right and of course it's not as I was expected to be because this is a parking lot and I I expected to have the the XY plane the was I mean coincident with the flat surface of the parking lot but it's not like that so I have to edit this point cloud in order to have the XY plane put kind of a correct way relatively to the real life to the real object that I that I photographed that I surveyed in the field so the tool is here it's called level 2 if you leave the arrows if you leave the mouse still over the icon there's a new label that pops up and it says pick three points to make a cloud or mesh level so you have to select the point cloud you can even have a multiple selection but that just one point cloud and before doing that a lot just to clone the point cloud and I'll show you after a while why I choosing to clone the point cloud before launching this product is process so to clone the point cloud just go here there's a little icon with two ships and clone the selected entities a new point cloud is made inside the DB tree so I make this point cloud the original point cloud hidden and just and just left this point cloud with the flag on it left click on this point cloud left-click on the level tool so now I have to choose three points because three points are able to define a plane a unique plane the first point is the center of rotation because this cloud will be rotated I try I choose to - to pick this point here this is the center of rotation second point that I'm gonna choose define with the very first one the x-axis so I'm gonna I'd like to have this as a new exit x-axis so I will follow this stripe here and left click here for defining the second point that I have to define the third point it doesn't have to be orthogonal to the x-axis because once I have the x-axis and once have the center of rotation the Third Point allows the software to define the plane so I can click whatever I want maybe here and after I clicked the software rotated the point cloud and now the point cloud is oriented correctly I can see it just by moving through these views if I click the top view I see clearly the top view as I was expected to be when I imported the pipe loaded the point cloud at the very first step of this video if I move to the left view I see that now I see now that the point cloud is much more oriented than the original one if we flag here on the original cloud I make it visible and I you will see immediately what I was trying to to explaining you in term of orientation right this is the point cloud that I uploaded inside cloud compared at the very first step and this is the point cloud that has been rotated in order to put the new XY plane correctly in relationship with the XY plane that is in real life in the parking lot that I have surveyed with photogrammetry what happened here in this point cloud is that the coordinates of the cloud that I have just rotated what the software did the coordinates changed so this this tool is kind of a destructive tool so if I hadn't clone this point cloud what I will have at the end of the process is a new point cloud where the coordinate has been completely changed and so cloud compare doesn't have a kind of a undo comment so there is no that to step back and redo what you just did so it's always a good idea to make a copy of your original data before launching a destructive process so this is a destructive process but I'd like to show you another thing that if you somehow forgot about cloning the original data you can go back using the transformation matrix that is inside cloud compares and tracks every movement that the had been applied to the point cloud from the very beginning so I'm gonna delete this point cloud the the the rotated one after the level tool has been applied and I'm back to this one now I'm going to apply it again the level tool so left click on the point cloud left click on the level tool left click on the first point the rotation Center define the excesses axis and then the Third Point define the plane so this this cloud has been rotated what if I what if I want you to go back to the original cloud to the original coordinates of the point cloud of the points of the cloud go back go down here you have to scroll down here in the properties window if you scroll down here you go you reach the transformation history transformation history yes yes the story of the transformation applied to the point cloud from the very beginning so here's the matrix the transformation matrix if I had shown you this matrix before rotating before transforming this point cloud we would have some one in the jack diagonal and zero in all the other cells of this matrix but now things are changed there are numbers here and these numbers are the history of the rotation that have been applied to the to the point cloud I can apply a reverse matrix transformation in order to go back to the original coordinates of the cloud how can I do that I just to click Add to click here in export and there's a tool here which allows you to export annachi txt files left click here I just name the matrix you have to name this is the the matrix that have just saved before it's safe and then you have your transformation matrix stored in your drive then you have to apply it in a reverse way so you gotta go here select the point cloud go to edit and go here to apply transformation here's there's a matrix transformation that added I applied just before recording this video this is not correct I have to apply the reverse matrix transformation that I've just saved a couple of minutes ago so you gotta go here Ashi file scout flow your matrix which is this one open then here are the the numbers of the transformation in story matrix and then you have to go here and flag apply inverse transformation if you do not flag this apply inverse transformation a new transformation will be added to the transformation that had been headed to the point cloud before but I have to go back so apply inverse transformation click OK and what happens is that the point cloud is now again rotated and brought back to the original position in terms of coordinates of its point if I click on the cloud go down here now I see that the transformation in story the matrix of the transformation transformation in story is now filled with one and this way in the diagonal way the diagonal direction and zero or in all other cells that means that the the point cloud has been brought back to its original coordinates that were the original coordinates where that had the point cloud at the very first step where I uploaded inside software so I hope that this video has been useful I think that being able to manage a point cloud in order to correct kind of a kind of correct the orientation is really a useful tool generally speaking point cloud should be correctly oriented should be geo-referenced but maybe you deal with point cloud and you do not have access to original data you do not have the ability to work on the structure from motion software or you are not acquiring data on the field and processing them in in software so you just get the data and sometimes if data are like that you have the ability to correct the orientation in this way level tool is really a simple tool but it's quite efficient in order to allows you to have a better experience inside the software working on the point cloud feel free to feel the comments below if you'd like to share this video I really appreciate otherwise you can contact me www metrical talks comm thank you thank you for watching gonna see you in the next video ciao

Channel: Metrical Talks

Views: 1,459

Keywords: cloud compare, level tool, point cloud, 3d, software, metrical talks, open source, open source software, tool, tutorial, how to

Id: FylRG1gZ1Js

Length: 12min 56sec (776 seconds)

Published: Tue Apr 21 2020