Hi Severin and all others, Although I practically stopped working on OSM in CAR, I am still following the list and read your Wiki-page-style how-to with interest (reading it I realised I didnt make any of the errors you mentioned which is nice :) ). I hope to be able to contribute more in the coming months. Its nice to see so many people emergency-map for OSM (Yolanda etc), and I hope some will start to work on other areas as well which are hit badly by crises of a not-so-obvious nature.
Regards, Simeon Am 14.01.2014 19:24, schrieb Severin MENARD: > Hi Nick, > > Thank you for your email. My answers inline. > > > Date: Sun, 12 Jan 2014 13:48:00 +0000 > From: Nick Allen <nick.allen...@gmail.com > <mailto:nick.allen...@gmail.com>> > To: HOT@openstreetmap.org <mailto:HOT@openstreetmap.org> > Subject: [HOT] Validation queries > Message-ID: <52d29d10.6010...@gmail.com > <mailto:52d29d10.6010...@gmail.com>> > Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" > > Hi, > > Would you like me to join in with the validation process? I am > experienced in mapping OSM, but am fairly new to regularly mapping HOT > projects. > > Would be great! Thanks for the proposition! Indeed you have contributed a lot > in OSM. Mapping HOT > projects is not very complicated, as you saw with the Highway_Tag_Africa > <https://wiki.openstreetmap.org/wiki/Highway_Tag_Africa>, it is less detailed > then in developed > countries, at least regarding remote mapping. Maybe the difficulty is when > you do not know how > those contexts look like. A goo way to compensate this is to look for videos > posted on Youtube > (examples here <http://www.youtube.com/results?search_query=bangui&sm=3>), > especially the ones > taken along road or streets. This is how you figure out if properties > enclosures are walls, fences > or hedges, what is often a cultural feature. Ah, just saw you mapped some > wall enclosures (eg here > <http://www.openstreetmap.org/node/27564988#map=19/4.41952/18.51870>). They > actually are buildings > (houses) under construction. It is frequent in developing countries that such > works last a long > time or even be abandoned. > > > I'm responsible for some of the mapping in > http://tasks.hotosm.org/job/72, as well as trying to change some of the > more obvious 'highway=track to highway=residential or unclassified etc.. > or it may be easier to check what I've done using my OSM profile > > http://www.openstreetmap.org/user/Tallguy/history#map=13/4.4168/18.4936&layers=N > > How much validation is actually needed / done? Is it a proportion of the > whole task, or just until you are confident that, all things considered, > the task is fulfilled? You're never going to get 100% as some things > boil down to opinion about what the images actually are of, but the vast > proportion is pretty obvious. > > This is something that still needs to be settled and documented. I would say > a validation is about > both identifying mistakes/mapping lacks and standarzation/consolidation and > has 2 or three steps, > related to scale: > 1. At neighborhood scale, check notably if: > > * buildings are missing. Sometimes it happens and if actually it represents > a consequent number > of building over a TM task, it can be invalidated > * buildings are correctly traced. Hopefully it is not frequent, but > sometimes mappers made > really coarse outlines that do not respect either the buildings > proportions or angle. More > frequent are mappers that do not know how to square the buildings. In > this case, after having > checked what is their preferred editor, I generally send a message to > their OSM message box to > give them the tip to do it > * highway tags are correct. This is what you described. Some mappers put > tracks wherever it is > not a main road considering it is not paved, but this is not a meaningful > criteria in these > developing countries considering 99% of roads are unpaved. > * road geometry. Some mappers do not put enough details and other too much > (eg a node every 10 > or 20 m even if the road is straight). First case is quickly corrected > with the (magical) > Improve Way Accuracy mode in JOSM; second case requires deleting extra > nodes when they > actually make weave a straight road. > * start/end of roads. Some mappers are experts of giant snake roads or loop > roads, Requires to > pass the mouse over the streets to see their extent and cut them where it > makes sense. On the > contrary, some streets or roads are sawed without any reason (same tags > for all the sections) > * general issues of connections between objects. Some that should be > connected and those that > should not. Requires both Validator and also eye control > > 2. at the town or city scale, it is quite related to the road network and > its main highways. > Having a larger view to identify the highways that are not simple > residential roads. They are > often larger and frame a larger area or can be a parallel way to main roads. > It is also important > to check where they start and when they stop, what is often not possible to > do when you map with > the Tasking Manager. This is what I tried to do with Bouar > <http://www.openstreetmap.org/#map=14/5.9374/15.5879>; here are some examples > of issues for Bangui: > > * missing parts of highway > <http://www.openstreetmap.org/node/27564988#map=17/4.38964/18.54186>. > Looks weird on Mapnik and the check of the imagery confirms the two sides > of the road > separated by a drain are not finished > * road continuity > <http://www.openstreetmap.org/node/27564988#map=17/4.38686/18.50796>. The > situation here seems weird as well as we expect the 2 unclassified roads > to be connected and > not joined by a simple path. The imagery confirms that the southern > highway looks the same, > and should be tagged the same, whatever the tag. The example is actually > good as farther south > <http://www.openstreetmap.org/node/27564988#map=17/4.37643/18.50931>, it > changes for tertiary. > No reason for this, says the imagery. It should be cut when it becomes a > straight road, though > * isolated upper-level road sections > <http://www.openstreetmap.org/node/27564988#map=15/4.4070/18.5068>. > Drivable highways cannot > be isolated and connected to the drivable road network by paths, they > must be connected to it > * tagging coherence <http://www.openstreetmap.org/#map=15/4.4333/18.5314>. > in this example, the > primary and tertiary road are connected by a unclassified road. Same > thing between the two > tertiary roads. After having checked the imagery this road would deserve > to be tagged as > tertiary. This obvious example apart, this requires to check the streets > width to identify the > main ones that needs not to be tagged as residential but unclassified or > even tertiary. > > Hope this can help! I had in mind to give some tips and it became a start for > a future wikipage :) > Hope other people will read/discuss/complete this. > > Sincerely, > > > Severin > > Any constructive feedback from experienced HOT mappers is welcomed. > > > Regards > > Nick > > > > _______________________________________________ > HOT mailing list > HOT@openstreetmap.org > https://lists.openstreetmap.org/listinfo/hot
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