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Author	Thread: Merge Tracks
Bill Homan Posts: 3	Merge Tracks Posted: 18 Feb 10 3:38 AM I need some help merging tracks. I uploaded 3 tracks. Then I merged 2 together with no problem. Now I am trying to merge the last 2. The tracks merge in the map editor but when I go to save the map I keep getting an error "Save Failed" "Server Error". I have tried different times of the day and different browsers (Firefox 3.5.7 / Google Chrome 4v / IE8 ). If I can not merge them I would like to at least change the order of the tracks. Right now the last track is on the top of the list. Is there a way to change the order? I am using XP Pro SP3 Here is my trip - http://www.trimbleoutdoors.com/ViewTrip/618716 Any help would be appreciated. [Reply][Quote]
Bob Wold Posts: 890	Re: Merge Tracks Posted: 18 Feb 10 4:03 PM Bill, We'll look into this today. I just tried it on a few test trips and it worked for me, but we should be able to look into this and see what is causing your issue. Thanks for letting us know about your issue. -Bob [Reply][Quote]
kevin77 Posts: 1237	Re: Merge Tracks Posted: 18 Feb 10 7:08 PM Wow, Bill, what an awesome trip. Good job on putting it together. Unfortunately, the problem you ran into was simply due to the fact that your tracks had 78,561 points in it. The most I've seen on our site since was just over 40,000. Where did the track data come from? If you zoom in all the way, the track is pretty "noisy". It has a bunch of small "saw teeth" in it. (Also, I'm curious, what web browser were you using to do the editing? And how fast of a computer do you have?) Well, to help you out, I've taken your trip, made a copy of it, then applied the Douglas-Peucker point reduction algorithm to your tracks, and re-saved your trip. You will notice that there is a small decrease in the total distance, but like I said, the track was very noisy. You should not notice any visual difference between the reduced track and original track. The pages should load a lot faster for you now. So I'll leave it up to you if you still want to combine your two tracks (I did fix the order of them as well). I think having the second track representing the start of the second day looks good. (Oh, feel free to delete the copy of your trip that I made.) Again, great job on the trip. Thanks for sharing. Thanks for the interest and feedback. Let us know if there is anything else we can help you with. [Reply][Quote]
Bill Homan Posts: 3	Re: Merge Tracks Posted: 19 Feb 10 2:47 AM Thanks for all the help. The map works great. The new map after you used the reduction algorithm loaded in a few seconds. The copy loaded in 45 seconds the same as before. I used Google Chrome 4v with an Intel single core P4 running at 3.19, 1 gig ram. The original map was edited with Firefox 3.4v. I got the trip data from an Amod AGL3080 GPS Data Logger that a friend has. Thanks for all the help, You guys are great. Bill [Reply][Quote]
Bob Wold Posts: 890	Re: Merge Tracks Posted: 19 Feb 10 8:45 PM Bill: If we had an option to run the same point reduction algorithm when you import the data, and it was defaulted to On, would you appreciate the feature, or would you think it was too intrusive? [Reply][Quote]
Bill Homan Posts: 3	Re: Merge Tracks Posted: 20 Feb 10 2:37 AM I would appreciate it. For those of us that may not know all the in's and out's of this track log stuff an option like this would be great. Also I do not feel it is intrusive because the track did not look any different. The algorithm did not change where I walked it just made the track worked better. Thanks again for all the help. I can't wait to post a few more hikes this summer. [Reply][Quote]
grcom Posts: 3	Re: Merge Tracks Posted: 01 Mar 10 6:06 PM So long as the feature is obvious and can be disabled prior to upload I wouldn't care if it was selected On default. However, personally, I think it would be intrusive if point reduction was done by default. I edit my tracks to limit the points and wouldn't want them modified further when I upload. Sometimes the track points are clustered closely for a reason and I don't want any removed. Dave [Reply][Quote]
Bob Wold Posts: 890	Re: Merge Tracks Posted: 01 Mar 10 6:13 PM Dave, Thanks for the opposing point of view on this one. I'd like have someone on our team make copies of a few of your trips and run them through our point reduction algorithm to see what you think. Would you mind if we put a few reduced versions of trips into your account so you can review them and see what you think? The thought is that we want to improve your trips in a way that a human really can't do was well as a computer, and hopefully the only difference you would notice would be that they load faster :-) Would you like to help us run this test? Thanks! Bob [Reply][Quote]
grcom Posts: 3	Re: Merge Tracks Posted: 02 Mar 10 7:57 AM Bob, I have used track reduction. Track reduction using the Douglas-Peucker algorithm assumes that all you care about is getting from point A to point B. If I record tracking based on time I can tell where my slow areas are and where my fast areas are for a particular route/trip. For example, if I am mtn biking down a difficult but otherwise long and 'straight' trail I will end up with many closely spaced track points. I can use this clustering of points to document the length of the slow/difficult sections of the trip. (e.g., .5 mi rocky downhill, be careful). For the same reasons, I wouldn't think that AllSport tracks would be reduced -- it would affect the results. I'd expect that the vast majority of the trips posted are point A to point B type of trips and reduction wouldn't matter since the user will still know how long the entire trip took. Dave p.s. Your web team is very responsive and really seems to care about putting out a good product for the users! [Reply][Quote]
Bob Wold Posts: 890	Re: Merge Tracks Posted: 02 Mar 10 6:41 PM Thanks Dave, I'm glad you think so! That is pretty impressive that you have run into the DP Algorithm in the past, and you are 100% right in the flaw of using it when you care about more than just lat/lon. But in practice we have found that you usually don't cover too much distance without the DP deciding to include one of your points depending on the threshold that you use in your point reduction. Another alternative is to add more than just the 2D lat/lon to the calculation. If you consider elevation and speed as additional dimensions you can also significant points for those also. Right now we don't do that though, we just use he basic D.P. so I think you are right about ensuring that it is configurable. Also: I would still like to have someone run a few copies of your trips through the reduction if you don't mind taking a few minutes to look at them. I think you might be impressed with how well the basic lat/lon DP works on your data. Thanks! Bob [Reply][Quote]
grcom Posts: 3	Re: Merge Tracks Posted: 04 Mar 10 7:37 AM I have a test trip in my account. Go for it. I tried a 3D DP algorithm which brought the trip from 102 points to 43 (vs the standard DP which went from 102 to 10). The one section where I want the track points is between the two waypoints. Dave [Reply][Quote]
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