On 3 September 2012 06:51, Russell Edwards <[email protected]> wrote:
> On Sun, Sep 2, 2012 at 1:17 PM, 4x4falcon <[email protected]> wrote: >> Actually I have to ask also why are you tracing from bing imagery when you >> have gps traces and should be adding them as source=survey > Is that not the done thing? > GPS traces are usually 5-15 m in error in a random direction. Bing's pixels > are about 20 cm wide. So I assumed Bing would be a much better option as > long as it is aligned properly? Firstly, You have surveyed the area and gathered traces. You have checked the imagery alignment. You have access to both aligned imagery, and your traces as you map. You've introduced yourself to the community, and checked what you are doing. That's a fantastic start. All the due diligence is done! The question is what source to put on the object. That is an object that you have surveyed, gathered traces, and then finally decided to align to the imagery as it is better than the trace? Some OSMers may regard data that has resulted from a survey as superior to what has resulted from tracing imagery. Imagery can be outdated, etc. Survey confirms what is on the ground. As such, they may like to see roads that have been confirmed by survey marked as source:survey - even if there is some alignment to imagery where the traces can be shown to diverge. To a certain extent I think this is a bit historical, as areas were initially traced from poor quality imagery, then updated with a survey and the source correspondingly changed. However, in my opinion I don't think there is any common practice in this regard. Areas that have been surveyed are commonly marked as source=bing when the roads are aligned to the imagery. Personally, when I'm deriving the location from bing (even if confirmed with a GPS trace) I generally use source:location=bing. However, I certainly don't think it would be wrong to use source=survey if the location was confirmed by survey. Ian. _______________________________________________ Talk-au mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-au
