[OSM-talk] [OSM-newbies] Tracing and offset error

[Michael S]

Since I am also interested in this discussion I'd like to crosspost my answer also to the talk mailing list:

Hello Gerhardus,

>In the absence of immediate local presence, is tracing acceptable and not wasted effort.

Personally I only do aerial image mapping to a limited extent because I fear that I will map wrong objects (e.g. nonexisting buildings, roads) because of outdated bing images. I feel much more comfortable to do bing mapping when I also do know the surrounding by own survey.
However, I would follow a pragmatic approach: E.g. If there is no railway at all in the map, and you think that it is likely that the railway is still there I would go for remote mapping.

Offset Problem:
Maybe you could compare objects already being mapped on a large scale ( larger towns ) and only do large scale mapping  like major roads, but no micro mapping like lake boundaries on a 50 m scale without having better offset information.

Michael


Am 01.12.2012 13:59, schrieb Gerhardus Geldenhuis:
> Hi
> I have mainly been doing tracing of Bing images in far flung corners of the world where I have been. However I have been reading about offset problems with Bing imagery and was wondering if this would all be wasted work? 
>
> I have mainly been doing work in Zimbabwe and South Africa with work being classified as:
>
>   * Tracing and classing buildings
>   * Making lake outlines more accurate. Lake Kariba as an example is a bit rough and ready. This is mainly prep work so I can add marinas and other amenities. 
>   * Tracing railway lines and roads in northern Zimbabwe.
>
>
> I might revisit a number of the places I have edited  and will then be able to get some GPS traces, building names etc that I could use to compare offset with. But in the meantime is there any other way to determine the offset of satellite imagery?
>
> So to summarize my questions:
>
>   * In the absence of immediate local presence, is tracing acceptable and not wasted effort.
>   * Is there a reliable way to determine offset in a specific location without GPS track data
>
> Regards
>
> -- 
> Gerhardus Geldenhuis
>
>
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