Hi, SteveC wrote: > Has there been any discussion on what people here feel 'substantial' > means in the context of the definitions of the ODbL? I've banged > around the wiki looking but might might have missed it.
It hasn't been discussed a lot. I guess you have read the often-referred-to pp28-32 of http://edina.ac.uk/projects/grade/gradeDigitalRightsIssues.pdf which of course are not specific to OSM. RichardF once summarised; > Dr Waelde also notes that under EU database right it's not just a > matter of percentage, but also of a "qualitative analysis". To me it > appears clear that a single street name isn't substantial, the whole > of Cambridge is. We could spend hours discussing this but I suspect it > comes down to "don't take the piss". I could think of a number of ways of defining substantialness. Any workable definition must 1. be compatible with the EU database directive 2. be absolute (no "more than 0.01% of data means substantial") 3. be practical For the sake of 2. and 3., I would define something like this: "A substantial extract is an extract that covers more than one square kilometre *and* more than 25 features, where a "feature" is either a way with all its nodes and tags, or a single tagged node." This would mean that an area of 1000 x 1000 metres could always be fully extracted as insubstantial and used for any purpose. That's roughly the size of Green Park in London. It is not something of a huge value; it is something that can be mapped in an hour, or make it half a day if you want all house numbers and pubs in a densely populated area. For a densely populated area, the 25-feature constraint will always be met within a square kilometre and thus ineffective. For a sparsely populated area, it might be possible to fully extract a larger area as long as it contains less than 25 features. The 25-feature constraint becomes interesting when someone does queries; one could extract the 25 highest mountains or the 25 largest buildings or 25 catholic churches that are within 100 metres of a pub. Because whole ways are allowed, the 25-feature constraint might even allow the extraction of the whole motorway network of a small country. When you think about what you can do with 25 features, always bear in mind that you must not combine multiple insubstantial extracts - if you manage to extract the motorway network of a small country in 25 features then you cannot also get the coastline or the primary roads, even if someone else extracts them for you or if you do it another time. Of course the numbers can be changed but I think that a definition like this is easy to understand and apply. There is some potential for abuse because someone could quickly connect all things of interest to him into one large way and then extract that but I think such behaviour could be ruled out by proper wording. Our goal in defining "substantial" must not be to allow as little as possible. The database directive allows free use of insubstantial extracts, and says the database owner must not disallow such use. If we try to circumvent the rule by issuing a definition of "substantial" that basically makes everything that is useful also substantial then we are in breach of the database directive. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09" E008°23'33" _______________________________________________ legal-talk mailing list legal-talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/legal-talk
