Changeset: 55787946
Updated numerous sidewalks throughout the neighborhood.
Closed by FightinGobbler
Tags
changesets_count | 22 |
---|---|
created_by | iD 2.6.0 |
host | https://www.openstreetmap.org/edit |
ideditor:walkthrough_completed | yes |
ideditor:walkthrough_progress | welcome;navigation;point;area;line;building;startEditing |
ideditor:walkthrough_started | yes |
imagery_used | Bing aerial imagery |
locale | en-US |
Discussion
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Comment from freebeer
Hi,
I saw that your updates to sidewalks included shifting the position of several in https://overpass-api.de/achavi/?changeset=55787946 .
That is often the case of poorly-aligned background imagery. So I thought I would take a look, as I know the available aerial imageries in the US have gotten much worse.
This is what I saw, as you used the newer poorer Bing imagery to shift, most strikingly, the small circular path west of Crowley Parkway, but not the wavy path directly east of same, which should align to older aerial imagery.
This is in fact what I see; Bing and other imagery providers match well your changes, but not the original data.
This imagery is known to be often poorly adjusted with perhaps several metres offset.
For aligning things, if a sharper imagery is not available, I like to use the USGS Large Scale imagery, and indeed, here it matches well with the wavy line, but north of where you shifted part of it, and probably those ways you have not shifted.
It is a pity there is not better imagery in your area, and that you spent your time moving things from a more correct position to one that is less accurate, rather than repositioning the background instead.
If you align the imagery to the original wavy path, you will then see that the roads line up much better.
I hope you understand what I am trying to say.
Unfortunately I cannot tell you exactly how to compare and shift the background imageries in your particular editor, but maybe someone else can be a better help with this.
Sorry for all your extra work! -
Comment from FightinGobbler
Thanks for that detailed response. I totally get what you’re saying. Is there a way to just throw out all the sidewalk edits?
My original intent was to simply complete the neighborhood by extending all the sidewalks to connect with each other, and I got sidetracked updating all of the alignment to the background picture.
Again, thanks so much for your detailed response. It will really help me moving forward.
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Comment from freebeer
Howdy, PugnaciousPoultry...
I have again taken a much closer look at the achavi URL, and I *believe* this particular changeset is almost nothing more than shifting the geometry.
That is, my cast-off LED flatscreen doesn't clearly distinguish green from yellow, but I don't think I see any newly-added sidewalks.
The red->green is where you moved things; a green-only without your name on the data seems to mean it was connected to something you changed, but is not new.
.
That is, I believe it is easiest to revert every change made in this changeset to restore how things used to be, and start anew.
(There are probably sidewalk-mapping tips you should be getting as well, but I'm not looking closely at that yet.)
Then you can spend some time to familiarise yourself with the different (lousy) aerial imageries available in your area. And if you want to get really depressed, visit other areas with sharp and detailed ESRI Community World Imagery, such as the entire state of Connecticut, select parts of California, Florida, Basel (Switzerland), and the zoomlevel 20 Bing imagery showing its age around major USian metro regions.
If I do see anything go missing completely from a revert, I might be able to restore it. But if you've added buildings, they were not done here and will not be touched.
I think that would be easier than moving things back (assuming you agree about the positioning) with as much work you put into being sidetracked earlier.
.
That is, I think this is good news. The Bad News is that like you, I'm still a beginner and have not carried out a full changeset revert, preferring to keep my hands clean, so someone will have to volunteer to help you with that.
I'm glad my first reply did not quite trigger a tl;dr reaction, but I'm sure everything I write can be given that treatment by someone better skilled with fewer words. -
Comment from FightinGobbler
I’m totally fine with a full revert of this changeset . It was only around 30-45 minutes and not a big deal at all if something else gets removed. Unfortunately, I have no idea how to initiate that. I’ll check out the help forums and see what I can find.
Thanks again! -
Comment from freebeer
Hi, sorry for not replying sooner...
The easiest way to have a revert happen will probably be if someone takes pity and offers to do it Just This Once...
.
Before you do any more mapping, and while awaiting a revert, can I ask you to become familiar with the different background imagery -- including that which was used for the original tracing?
If I understand, there should be either the command `b' in editor iD or an icon like layered papers referring to Background imagery layers.
The default is Bing; others to note are ESRI, two DigitalGlobe offerings, Mapbox, and USGS Large Scale imagery to cover the US.
Don't actually move any sidewalks as that could make a revert difficult -- look, don't touch; play, don't save.
.
But, I'll point you to this forum discussion:
https://forum.openstreetmap.org/viewtopic.php?id=60988
In it is a URL that you can use as a learning tool, which gives you access to the old imagery (ESRI Clarity) that is clearer, even if well older, than anything for your area.
I've added it to my Potlatch editor to verify it brings up what I expect.
And it does! Yay!Don't use it for tracing until the legal permission is clarified; but then, almost everything near you was already traced from it.
Note how it perfectly matches those sidewalks you have not yet moved. I think I measured over 3 metres offset between this and the default imagery.
Also, get a feel for how bad each of the other imageries are compared to this, even if they are newer.
.
And if you can discover how you can adjust the background images in your editor to line up, such as on the dual-Y diamond shape on the wavy walk, that would be great -- for me with Potlatch, it is holding down the Space bar and clicking and dragging the background in the editor, but I'm sure it's not that for anything else.
Notice how perfectly the waterbody outlines match this background too.
I'll try to explain details about each imagery and zoomlevel for your area, if it's not too much writing and you want to learn ;-)
However, I think now lack of sleep is taking its toll, as I was unable to carry out a conversation a short while ago, despite thinking I was awake, so I'll try to use this kezboard as a pillow for some time.
More later... (words of impending DOOM) -
Comment from freebeer
This changeset has been reverted fully or in part by changeset 55820191 where the changeset comment is: user requested revert of aligning ways to poor Bing aerials, rather than aligning background image to ways
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