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Douglas-Peucker updated

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Automatisierte Medienanalyse

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yeah everyone am I'm very happy to see you I was expecting a 5 friends and 5 most people solar system much more and they're going to talk about to do less a a Quaker and that is a very old system from the late seventies and I have some of the to share with you so the last biker West useful in reducing the number of points In a polyline so as when I talk about the polyline you image in line that seems to be of the line but in fact it's so small so signal of the light that thing by a point from which by used the name of points the that's when we it is easy to reduce the number of points you told 1 uh salt of through all 9 out of 10 and you have to uh this point but the shape of your uh line is distorted so you want to get there the thing to do you don't want to to changes the shape of the body so that the rest a worker I'm going says that you have to do all of base base line between the start and the end point and when you do you have done that and you say for the point that is at the that is the most distant from the baseline on on the on the borderline and you keep that point and then you break your body lying in the less part and what not and you do it again and again and again and again when you stop the the the when you stop when you have reached the maximum number of points that is 1 particular and the other quickly right to stop when you out there the end of that you have so that means the distance that you measure is if it is less than and the maximum amplitude want to pass so
this is an example of a polyline and I'm applying the do less political uh I'll do it and so on the red line is my baseline and I'm looking for at maximum the the fastest from the baseline there's a point there up so I keep that 1 and I do it again it was a green line as in the green baseline search for the biggest bigger distance and I keep that point and the same on the other and again and again and again the the so I just told you that you have to
uh to out when when you you stop the algorithm all you give a maximum number of point I want to uh have only thousand points then you have to dump on you just stop and the other is when the distance that you measure is uh is less about equal to the maximum allowed in each segment of course if you have your line and you have divided in in thousand pieces well you have to see that in each piece the today yeah it's a form of the last point the blast Boykin has 1 problem maybe more than 1 that this 1 is that the annoying 1 you have to apply the I would only when you know your last point so if you imagine that the loss of tracking with a GPS um your trip to sort of from you have to wait until you are in your destination point to start to reduce your the number of points the maybe you if you have a small devices maybe you have a already exceeded your maximum memory so it could be a public the results of the rest boycott are quite good and probably out of the the the community says that it is the the best and it is the best because the quality of the resulting line the the simplified borderline is something that is very nearly what people can do so we ask the people to do it by hand and I would not say that they have 2 in the same point but the borderline that they have when it is simplified if the is very comparable to do the rest would out with so why do why do I need to they do less work out with I can't 1 rate until the end point and the are the several a reason for that and 1 of the reason is that I can't store them all and this is the example going from here to start the France these small devices you probably will as not enough memory in a small device and maybe I cannot compute it fast enough when I arrive maybe I have a Roger devices are willing to suffer from and when I said to my litigation system shut down it has to start the computation but I turn the key of my car and the always is out and it's too late to compute and the reason there maybe I need to transmit the data but transmitting the data it's easier if you have any if you have uh we that is when you are on in your car transmitting after they go up every time that you have a point because on your ideas and bodies you have another uh in example of transmitting well there is always a cost and why should you to and with all your data to throw it away after so you better to have them addicted to bless pork and to try with on the go became a just go that about the and the date at the middle uh on that the mobile learning network going the cost is probably too high but I can wait a little bit so if I don't have the most recent data it's OK I can wait for a certain amount of time so the last part of the real the it's me the the I made a have to do well in times of of of points and the 1 why I want to keep give them the name of the essential point OK and all the other points are observation point an observation point can be promoted to be an essential for a and don't create new points I keep for the essential on and had to await the observation point um well that's the bad thing about the vision point there are doomed to be and and promoted of them that that slice or the point so when you stop there you very 1st point well it's like when you have a company if you add the first one you get promoted yeah when the 1st of the fission point is immediately promoted to essential and um for the rest of is look like the last point that means last week and I wait until I have to observation points OK but in the center what have to observation of and then I apply something that looks like uh the rest adult baseline between the last essential point was the very first one and the last observation point and then it's like I'm I'm looking from uh so imaging to reveal that such line I think there a position myself at the last observation point and I look to the last essential point and I look to a pipe so the form of the other is a straight pipe but the from of the pipe is completely up to you you can choose a square pipe overwhelmed by over 5 I don't care if you look in it and if all the observation points are into the pipe you have nothing to do then you take that before the next 1 and then the next 1 and you still did uh looking to the pipe and if you lose 1 of the of division by that point because it goes out of the 5 that 1 is promoted to the essential point bank it's like in
business if you are that good and you come out of the 5 you are promoted to listen to 1 so that the the form of the pipe is in effect you know a function um about the distance the so if you are talking in two-dimension it just a rectangle and if you go out of the rectangle you are promoted if you look In 3 dimension then you can have the pipe and the point that goes out of the pipe is promoted to the essential point all of the other observation point that are behind and over all of them the new promoter sorry the other it will never be promoted it is not necessary to keep them in memory so you can them but and you if you have to transmit the opposition you transmit the new promoted so essentially what it is but I don't have time Of course it could be that if you need to follow that say that's the trick you want to be updated at these every hour then even if the if the truck is on a straight line no point is being promoted but just keep the last 1 promoted it's just time it's back in business if everyone is retiring the guy will with stasis for more the new CEO the and this and you you you would do it again and again so you have your your last but essential point you have or you not have observation point you the standard you have a new 1 you just do the new R. with again you look in your pipe if there is 1 of his so that's nice them but if you have in a very very long straight well like the 1 between the Francisco and underneath that out of the gas and and being there but it seemed to be of very long straight line or if you are in uh train industry that there is something like 600 kilometres straight yeah you may be you need to have a maximum buffer size and it's just like the time interval if your better is nearly 4 promote the last 1 of them the others and the the point is just like me and you keep at but all right Irving what are the results of the the updated the last point well you have a little bit more points then into the blood sport and you have nearly the same quality which is not a surprise because the when you are doing that you don't know what was coming and if you wait you'll end point and OK it's easy to be better OK it's not but is not a big deal if you have to choose what you are going to do and if you are a little on on your memory in it's it's acceptable so you can just do the same with non-geographic data it's a little bit on the 2 will be surprised that I've done it weeks 0 temperature so if you keep the temperature at all sites for example well most of the time the temperature doesn't change so you don't need to the keep every the observation point and the temporal ways because this morning descendants shines than the temperate start to do then you would promote 1 of the for vision temperature to essential and the idea is just the same there are some problems in the a dated to do last spike you must take into account that you could have a straight lines that can be quite long you cannot use the criterium with a number of points because you don't know how long you will travel again after it so the only a container that you can a prime is the maximum penalty data so you you have to choose at you GPS is have been level M. if your GPS give you an uh horizontal dilution of 1 of position as is called an of 6 meters well you have it's this logic to have the maximum and from at least that value does make sense if you uh dominated doesn't give you but something better than 1 degree you cannot think of how that and then you you have a it 8 ships uh is only gives you an accuracy of 1 degree but you maximum element must be greater of the less you don't know what you are doing OK no it's a little bit hard to make that the demonstration of it but I have the track of over so this by blind node by line the the guidance that kind of of parachute and it now know that this is not better of as other people but that in system and they make some trips over the mountains and they have so it's the problem is suddenly three-dimensional 1 because sometimes they just keep turning around to get altitude and that is something that is so little bit where if you are using this time and the last point if you know maximum l is bigger then the circle it could be disappearing uh at a certain moment but that it looks like this and it's only a part of it
is to a real slide I have uh 399 from those who 99 observation point and that is mindful so you see that the circus field in there and also it's when he's trying to get some essential terms the chance of being have rendered the rest Boykov two-dimensional we set the maximum error of 10 meters and I have 3 of 47 points that you have promoted if I do it without looking what comes after my uh the point which I'm processing so the the the two-dimensional have 300 75 . if I do it on 3 health if you are the see that the difference tho so what when I said that the the quality of the updated you roast pork is nearly the same as a new class for the I'm not lying in you can see I will show you whether differences are the difference our can must be seen in a straight line the um so that is that the pork three-dimensional and this is the data from this is the point of changing there are some people is changing with the authority the shape of the poor line this is the same so to put all the results
uh on the line I had it on the mainland points with a maximal I should have taken 900 it's not for 1 . 0 just slide but I can apply and maximum and almost 10 meters and then you can see the differences so I have uh 8 % more points on the 2 dimensional and I have less than 1 % more points onto 3 uh dimensional so I think it's is a good idea to have earned the not to have to wait until the end point of the borderline before simplifying and I think it will be more and more you you will in a situation where you have to um we plot shows the position of the if you have a small uh devices to think about the watch all the GPS small of and a bicycle also that the smallest and lightest so I made that
is present to have a lot of time to answer your question it who is going to with the 1st question yes yeah the no it is said no it did not use in practice um I and of course of both GIS uh in 2002 they are the have you been um not far from here and when the path was explaining the rest for the it the problem is that you have the point and 2 is no way it is impossible to uh to do it in another way hello yeah impossible that a challenge so I don't know what what the set after that because I was thinking it must be possible and and I had the idea of the pipe and and the other was I put it on on the mind even being a good back to him as a type of I have something very interesting it I thing I have uh weasel that impossible problem he had a look instead of if you think that it's workable then you have to compare it to do less particle and you have to read all these and you make a lot of copies of of very interesting things that that to to read and I read them it took some time to understand what those people were there trying to explain and it was only but it's not too bad either at and don't want to diminish their life but it was a way of accelerating the computation of the young would but they didn't change anything on the algorithm itself so I start to wipe the something in a to show that the quality of the modified uh rest particle was nearly equal to the original 1 this idea that I going to be rich I'm going to work to get that of a patent on it in this the patents if you have 8 different points you you last well the use and your your your ID into something else that I have to change I have to go from here to the 2 to 3 dimensional that was a real book moments and have other things to do so I worked with the afterlife and then a set of we never be which not in that way I sold I'm going to ride in a very uh in some uh scientific go book or publication I go back to the provinces I'm on not I'm going to write them I mean maybe I will not be which but I will be saying what that the list of things that you have to do when n how then I decide to share it with you to the OK no questions so I hope to see you again next year again at 4 of them when I would like to talk about the same thing but above the temperatures and all of the things that are not as spatial are related and it will be already in the embedded there different OK about the units here if
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Titel Douglas-Peucker updated
Untertitel Or do you want to reduce your data
Alternativer Titel Geospatial - Douglas Peucker
Serientitel FOSDEM 2015
Autor Winnepenninckx, Stephane
Lizenz CC-Namensnennung 2.0 Belgien:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen.
DOI 10.5446/34386
Herausgeber FOSDEM VZW
Erscheinungsjahr 2016
Sprache Englisch
Produktionsjahr 2015

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