[OSM-talk] Unordered segments

Lester Caine lester at lsces.co.uk
Sun Apr 29 12:10:27 BST 2007


David Groom wrote:
> ----- Original Message ----- 
> From: "Lester Caine" <lester at lsces.co.uk>
> To: "Martijn van Oosterhout" <kleptog at gmail.com>; "OSM Talk" 
> <talk at openstreetmap.org>
> Sent: Sunday, April 29, 2007 9:13 AM
> Subject: Re: [OSM-talk] Unordered segments
> 
> 
> Martijn van Oosterhout wrote:
>> On 4/27/07, Dirk-Lüder Kreie <osm-list at deelkar.net> wrote:
>>> In my opinion it's not the incomplete flag, but that JOSM cannot somehow
>>> cope with ways that have been downloaded in several steps. Somehow it
>>> just patches the new stuff on, instead of rebuilding the way from the
>>> data now available.
>> The thing is, I've looked at the code and the problem that's occuring
>> simply Shouldn't Happen (tm). The problem is basically that somehow
>> multiple nodes with the same ID appear and some get attached to the
>> right object and some don't.
>>
>> I still don't understand the download merging process enough yet to
>> really look into it, but I'm thinking of piling in the debug info and
>> try to work out where it's going wrong...
> 
> I need to download a newer copy of JOSM and check the current version, but I
> have been seeing problems when tidying up legacy sections. Currently I have 
> a
> number of 'problem' ways in my area.
> http://www.informationfreeway.org/?lat=6806954.62272&lon=-208137.98291&zoom=14&layers=00B000
> 
> Some of the main routes already existed when I started adding tracks, but 
> some
> of the 'problem' ones have been constructed in stages with segments added to
> the existing base way, and the re-order option was always selected.
> 
> My problem now is tidying all this up, but since we are working in rural
> areas, then JOSM will not download a big enough area in one hit, so I have 
> to
> select a smaller area, then move over. At THAT point, I have previously been
> told I need to save - delete the data layer - and load clean, because if I 
> do
> not, then the new download does not have clean combined information. I 
> suspect
> that some of the current faults have been cause because of NOT doing that
> initially. Since the bulk of the newer data is clean.
> 
> I hope to get a few hours later today to download a new batch of tracks, and
> tidy some more bits, so any pointers to where I am going wrong ...
> 
> http://www.informationfreeway.org/?lat=6806925.95884&lon=-208196.505&zoom=17&layers=00B000
> This has roads with turning circles or turning bays at the end - how should
> they be drawn?
> And the element in the middle is a car park with a way round the edge - what
> is the correct way of putting that in. ( Two more car parks are not 
> appearing
> at all but once I get one right :) )

> Lester,
> 
> a lot of the ways in that area will reorder correctly however some wont:
> 
>  to be an ordered way, and to be able to be re-ordered into an ordered way, 
> a way must
> 
> a) be in a straight line, ie no forks or T junctions
'Split' roads need multiple ways, but we do need some means of grouping ways 
that make the one road? 'ref=' is OK for highways, but we don't want to add 
'name=' to all sections of the one unclassified road :(

> b) have all segments pointing in the same direction
I believe there is a method of correcting single segments in a way, I can 
remember doing it, but can't remember how :(
Perhaps something that re-order should correct? Flick problem ones to match 
the first segment. Once they are ALL the one way you can at least reverse the 
order if you need to.
( I make sure I'm right to start with, but some of the legacy ways seem to 
have alternate right and wrong )

> Bibsworth Avenue : effectively ahs two separate ways, the straight one 
> running east-west, and the right angular one which joins it
> Lifford Gardens: contains segments pointing in different directions, and 
> also splits into a "Y".
> Willow Close Mill Avenue, etc:  the turning circle you have created at the 
> end, with the way looping back on itself, means the way cant be ordered. 
> You will need to either:
> 
> a) accept this
> b) remove the turning circle completely
Possible solution, but not ideal

> c) make the turning circle one way, and the main part of the road a separate 
> way
Which comes back to the above. A road made up of multiple ways as is common on 
modern housing estates, and seems to be MY main problem. Loops and 'tree' 
structures for a single road.

-- 
Lester Caine - G8HFL
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