Hi list, By mistake I sent my remarks to Rafael directly.
Below you can see the what I wrote. Regards Arne > Anfang der weitergeleiteten Nachricht: > > > Hi Rafael, > > I have done a lot of manual river mapping in Somalia and Somaliland and here > are some remarks how I did it: > > - almost no river I mapped as perennial > - most of the rivers I mapped with intermittent=yes > > - the ditches or drains I mapped were ditches leading to farmland for > irrigation or leading to reservoirs (so called 'berkads'). > - all other waterways I mapped as stream or river, distinguishing both more > intuitively than by a fixed width. > - I don't remember having mapped a canal > - Riverbeds I mapped along some rivers where I thought it might improve the > understanding of the topography for the reader of the card > > - when flow direction was unclear if added a fixme > - for waterways ending somewhere in the desert or before reaching the sea > shore I tagged the ending point with waterway=stream_end. Josm validator > doesn’t know this tag and throws a warning that I ignore. > > - Crossing points of unclassified or higher class highways and rivers or > streams I mapped with ford=yes; for tracks and paths I didn’t do that > consequently. > - Highways crossing a broad riverbed: I tagged the part of the highways that > runs through it with ford=yes. I did this wether I mapped the riverbed or not. > - for highways inside a riverbed I did the same > > For the workflow you are defining, Rafael, my additional suggestions are: > > - describe how to handle stream_end > - describe how to handle the crossing between the imported rivers and the > very old and wrong highway-data in the area ( we were talking about it before) > - describe how to use ford=yes > - describe how to handle ditch or drain > - decribe fixme for unclear flow direction > > So far my 5 cents. > > Regards > > Arne > > > > > > >> Am 08.04.2020 um 12:42 schrieb Rafael Avila Coya <[email protected]>: >> >> Hi, Christoph: >> >> Thanks to your questions, I've consulted the info about the original tags, >> and I've found some info that can improve the data to submit for import to >> the users. >> >> ACC takes only 2 different values: "1" means accurate and "2" means >> approximate. But almost all of the 44,360 ways take the value "1", and only >> 45 take the value "2". So I guess we can safely ignore it. Not ignoring it >> would mean adding a fixme="please, check geometry accuracy" tag to those 45 >> ways. Easy to do, but I don't know if it is worth. I've checked all of them, >> by the way, and the majority will be simply ignored (deleted) during the >> import process. >> >> ACE_EVAL has the value 21 for all ways. It's meaning is "FZD: Evaluation >> deferred", so we ignore it. >> >> ALE_EVAL values don't give any info at all. Ignored. >> >> F_CODE and FCSubtype are equivalent. The values are: >> >> F_CODE;FCSubtype;Meaning;Number of ways >> BH020;0;Ditch;1 >> BH030;1;Canal;2,307 >> BH140;2;River;42,052 >> >> I've checked many objects with FCSubtype="1", and they appear to me to be >> more ditches than canals in the majority, so I would rather tag all "0" and >> "1" occurrences of FCSubtype with waterway=ditch, asking the users (as with >> all waterways) to decide if that tag is correct for each waterway in the >> workflow wiki. >> >> As for the rest of the ways (42,052), they will be tagged as river or stream >> by default according to the tag HYP as already told in the wiki, and with >> users deciding if changing its value or not during the import. >> >> FUN has only one way with value "Fully functional", so we ignore it. >> >> HYP has, as already said, 3 values: >> >> 1 = Perennial (267 ways) >> 2 = Intermittent (3,294 ways) >> 4 = Dry (40,799 ways) >> >> This will be difficult to translate to OSM tags. If any, I would put >> intermittent=no for the HYP="1" ways, and intermittent=yes for the rest. And >> then users deciding. Any thoughts on this? >> >> LOC has only one way with the value "44: On surface", so we ignore it. >> >> NVS has only one way with the value "0: Unknown", so we ignore it. >> >> SRC_NAME has 3 values: >> >> "0", meaning "Source is not known". 139 ways have this tag. >> "110", meaning "Very High Resolution Commercial Monoscopic Imagery". 9,321 >> ways with this tag. >> "112", meaning "High Resolution Commercial Monoscopic Imagery". 34,900 ways >> with this tag. >> >> I've checked the 139 ways. They are most of them very short segments, that >> don't present any problem, and can be checked against imagery. So I would >> rather ignore the SRC_NAME tag. >> >> UPD_NAME has 2 values: >> >> "0", meaning "Source is not known". 139 ways have this tag. >> "998", meaning "There is no possible value in the attriubte range that would >> be applicable. (May occur when the attribute is not applicable to the >> feature type (for example: the Airfield Type attribute of a Settlement >> feature type).)". All the rest of ways (44,221) have this tag. I would >> therefore ignore this tag. >> >> ZVAL_TYPE: All ways have 2 values: 139 ways have the value "0" = Unknown, >> and the rest (44,221) have the value "3" = Feature is 2D only. So it gives >> us no interesting information, and therefore we can safely ignore it. >> >> Cheers, and thank you very much again for your feedback, >> >> Rafael. >> >> O 07/04/20 ás 17:45, Christoph Hormann escribiu: >>> On Tuesday 07 April 2020, Rafael Avila Coya wrote: >>>> Hi, Christoph: >>>> >>>> What do you mean when you say that it lacks any information on the >>>> provenance and specifications of the source data? >>>> >>>> As explained in the wiki, I am saying that the data is coming from >>>> UNSOS, using SPOT imagery. You can download the data under data >>>> source site, in the Background subsection of the wiki. >>> I am sorry for being unclear - i was meaning: >>> >>> * what is the meaning of the various attributes in the source data? >>> Normally data sets like this come with a specification document that >>> tells you what for example an attribute like FCSubtype=* or HYP=1 is >>> meant to indicate. >>> * how has this data been created from the SPOT imagery mentioned? Was >>> it produced with some kind of AI algorithm? Was it traced by by >>> humans? If the latter was it done by people with local knowledge of >>> the area or by people from abroad? What was the original intended >>> purpose of generating the data? >>> >>> There are various peculiarities that can be observed looking at the data >>> but i am reluctant to draw any conclusions or make recommendations >>> based on these observations without knowing how the data was produced. >>> >> >> _______________________________________________ >> Imports mailing list >> [email protected] >> https://lists.openstreetmap.org/listinfo/imports > _______________________________________________ Imports mailing list [email protected] https://lists.openstreetmap.org/listinfo/imports
