Osmose is showing that in my mapping there are a lot of River Deviation issues of variable length. Any idea what that is and how I can fix that or if it is something even to fix?

Example: https://www.openstreetmap.org/way/80989910#map=12/-0.2400/28.1875 Osmose says "river deviation of 39m".

As far I remember, I improved the river accuracy.

Thanks in advance.

asked 10 Jun, 15:17

mmahmud's gravatar image

mmahmud
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accept rate: 4%

edited 10 Jun, 16:45

Can you provide a link that shows the problem?

(10 Jun, 16:33) SomeoneElse ♦

@SomeoneElse : I updated the question with example. Kindly check.

(10 Jun, 16:47) mmahmud

It (obviously) doesn't give an osmose warning at https://www.openstreetmap.org/way/80989910#map=12/-0.2324/28.1562 and I don't see any reference to one at http://osmose.openstreetmap.fr/en/map/#zoom=13&lat=-0.2272&lon=28.194&item=xxxx&level=1&tags=&fixable= (which is the same area). Can you provide a link that shows the problem?

(10 Jun, 16:59) SomeoneElse ♦

Thanks - but I'm not sure what that actually is telling us. Maybe someone who's more familiar with Osmose can help?

(10 Jun, 22:16) SomeoneElse ♦

@SomeoneElse: Yeah. I feel like it might have been me fixing the accuracy. The previous drawing was crude, very crude. Since river is a major feature, the changes I made and the previous crude version differs a lot. Maybe Osmose is just trying to understand why this deviation of the two version, but this is just my guess. Thanks for looking into it.

(11 Jun, 06:27) mmahmud
showing 5 of 6 show 1 more comments

I contacted Osmose directly because I was not getting a solution. Following is the direct reply that I got:

"The deviation is caused by sharp angle on nodes. By refining the way it should deseaper automatically on next refresh."

So that is the thing. So when there is a sharp angle on a river path, Osmose detect it as an issue. The path has to be smooth as river paths are suppose to be smooth.

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answered 18 Jun, 15:33

mmahmud's gravatar image

mmahmud
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accept rate: 4%

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@mmahmud I've marked this as the accepted answer (since you won't be able to do it yourself) - hope this is OK!

(18 Jun, 15:37) SomeoneElse ♦
1

@SomeoneElse : Thanks. Appreciate it. I also figured out why it was showing me an error in spite of making the rivers accurate. This is written on Osmose page: "This page shows issues on elements that were last modified by 'mmahmud'. This doesn't means that this user is responsible for all these issues." Meaning, if I work on even one node of the river and the rest of the river has sharp angles, it will show up in my statistics.

(18 Jun, 15:44) mmahmud

Rivers change course a bit, they erode the outside of bends and deposit on the inside. Flood seasons often result in bigger changes. We would need very recent satellite images to check it's present position. Is this the problem or have i missed something?

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answered 10 Jun, 21:42

andy%20mackey's gravatar image

andy mackey
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accept rate: 4%

@[andy mackey] : I am not sure that is the issue. Osmose has no way of knowing the river's current position unless someone draws it and the most recent version drawn are by me. I fixed the accuracy from previous version which was very rough and therefore a deviation occurred. I think maybe that is what Osmose is detecting.

(11 Jun, 06:30) mmahmud

Thank you mmahmud for message that says Osmose detect sharp turns as fault in river mapping, I suppose sharp turns are unusual but could occur when rivers meet rock. I had thought that maybe their system could compare the latest images with what was mapped, or a local had added a map note.

(21 Jun, 07:50) andy mackey

Just relax and ignore the worming from Osmose. The new/your riverline is much more precise and detailed compared to the former/older riverline. It also well coincides with the corresponding river in the satellite image maps. Whatever interpretation of "deviation" Osmose uses (standard, max...) it just indicates that the two lines are not the same but this measure and indication is in this case useless.

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answered 12 Jun, 15:14

sanser's gravatar image

sanser
665333453
accept rate: 5%

@sanser: Thanks for the assurance. I was thinking the same. Now there is a marking option Osmose provides. 1. False Positive. 2. Issue Fixed. Since there is nothing to fix, should I mark it as False Positive? Thanks

(12 Jun, 15:18) mmahmud
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question asked: 10 Jun, 15:17

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