OpenStreetMap

OSM becoming a patchwork of different referencing systems

Posted by jidanni on 24 February 2020 in English (English)

Each imagery offset is different, and over time a patchwork of different referencing systems emerges… one big disaster, worse than “GCJ-02” (which is at least “smooth and not noticeable”.) Happens even with just one person editing. You’ll notice it when you finally join village A to village B. Editors of village A have been pulling the imagery downwards to match what they have already mapped. And editors of village B have been pulling the imagery upwards…

I hope one day, after offsets are finally no longer present in imagery, Artificial Intelligence (?) will somehow fix the mess.

Location: Wuyaokeng, Qingfu Village, Dongshi District, Taichung, 42351, Taiwan

Comment from kucai on 2 March 2020 at 07:17

Each imagery has different “zoom and skew” even if all the imageries are aligned to a surveyed point. In my experience for my country, Bing has the clearest/cleanest image, then Esri then Maxar. But Maxar Premium has the newest.

In this case, I align Bing to a ref point, then go to my area of interest. I find an obvious building to trace the outline, then I’ll align Maxar to this building. Trace what needs to be traced from Maxar and then return to Bing again.

Unless all imagery companies agreed to a single source provider, or agrees on a set of ground control points (GCP), there’ll always be discrepancies.

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