[talk-ph] Be careful in tracing from Bing Maps

Rally de Leon ralleon at gmail.com
Thu Jan 6 04:04:51 GMT 2011

the one i'm using on windows: JOSM (version 3767)

While Bing Imagery & GPS traces are shown on the JOSM's background:
click on menu: Imagery --> New offset

then a new window will pop-up "Adjust imagery offset" (with Easting /
Northing correction & Bookmark name)
while this pop-up is showing,
-use mouse "left-button" to drag, align/correct offset of Bing Imagery
-use mouse "right-button" to pan & drag the entire workspace,
to check & verify if your "offset correction" is the best-fit for the
particular area.
re-adjust (using left-button) as necessary. once you are happy with the offset,
you may want to bookmark that particular offset settings for that
particular place
on JOSM by saving it under a "bookmark name" --

To access the particular bookmarked "offset/correction", click
Imagery->New offset

to delete/manage Offset bookmarks: press F12 ---> WMS/TMS button -->
Offset bookmarks (tab)

On Thu, Jan 6, 2011 at 2:33 AM, Eugene Alvin Villar <seav80 at gmail.com> wrote:
> Here's an example of aligning Bing Maps imagery.
> This first image shows the default view of Bing Maps in Potlatch 2 and
> with GPS traces loaded (the yellow arrows show the offset needed to
> align the imagery):
> http://wiki.openstreetmap.org/wiki/File:Bing_not_yet_aligned_in_GMA,_Cavite.jpg
> This next image shows the Bing Maps layer moved to provide a best fit
> alignment with the GPS traces:
> http://wiki.openstreetmap.org/wiki/File:Bing_now_aligned_in_GMA,_Cavite.jpg
> This last image shows streets traced from Bing Maps now that it is aligned:
> http://wiki.openstreetmap.org/wiki/File:Bing_now_aligned_and_traced_in_GMA,_Cavite.jpg
> Tips: When trying to align the image, look over a larger area where
> GPS traces are available and do a best fit over that area. In
> addition, the best spots to inspect for alignments are intersections
> and curves in the roads.
> On Thu, Jan 6, 2011 at 2:03 AM, Eugene Alvin Villar <seav80 at gmail.com> wrote:
>> Hi guys,
>> Please be careful in tracing from Bing Maps aerial imagery. It is
>> known that some of the imagery is not aligned to the correct position.
>> To show an example, please see this Bing maps screenshot: [1]. The
>> image shows the boundary between two satellite imagery. The imagery on
>> the top covers Metro Manila is is for the most part correctly
>> positioned. The imagery at the bottom covers parts of Cavite, Laguna,
>> Batangas, and Rizal[3] and is *not* positioned correctly. Notice that
>> the residential streets do not line up.
>> In order to avoid the misaligned imagery problem that has been
>> plaguing contributors in Google Map Maker, please try to align the
>> imagery to GPS tracks or known good data before tracing.
>> In Potlatch 2 and Merkaartor 0.17, the imagery can be moved by
>> pressing down the spacebar then dragging. I don't know how to do this
>> in JOSM but it also has a way to move the background image.
>> [1] http://wiki.openstreetmap.org/wiki/File:Bing_misalignment_in_Daang_Hari_-_Bacoor.jpg
>> [2] http://www.openstreetmap.org/?way=28738861
>> [3] http://www.openstreetmap.org/?way=87284547
> --
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