[talk-ph] Be careful with unaligned Bing imagery!

tutubi tutubi at backpackingphilippines.com
Thu Feb 9 01:21:43 GMT 2012

my traces for ilocos sur, particularly along the coast of the towns of
santa, sta maria, narvacan et al are generally aligned on most parts, my
traces were generally at fault in some segments due to the straight lines
(that time i was still using ordinary trace, not the diagnostic logging of
my nuvi) but the main highways are generally aligned, just need to smoothen
some segments

i was looking for the trunk road from ilocos sur to abra, not yet on OSM,
but that area is not included in the new imagery :(

On Thu, Feb 9, 2012 at 6:46 AM, maning sambale
<emmanuel.sambale at gmail.com>wrote:

> Agreed. Also consider reading this page:
> http://wiki.openstreetmap.org/wiki/Armchair_mapping
> On the other hand, I know many of us travel a lot around the country  so I
> assume we know the basic highway class to trace. If in doubt, use the
> highway=road tag.
>  On Feb 8, 2012 11:44 PM, "Eugene Alvin Villar" <seav80 at gmail.com> wrote:
>> Hi guys,
>> With all of the new Bing imagery that's available, I'd like to remind
>> everyone to be careful with unaligned Bing imagery.
>> Here's an example showing how two different satellite images are not
>> aligned with each other (look at the LBC roof sign):
>> http://mvexel.dev.openstreetmap.org/bingimageanalyzer/?lat=14.517377504551362&lon=121.00218251959474&zoom=18
>> Obviously, one (and likely both) of the images is not positioned
>> correctly. This shows that Bing's imagery (and even Google's) is not
>> always aligned or positioned very accurately. There may be an offset
>> of up to 10 meters.
>> If there are multiple GPS traces in the area, you should use them to
>> align the satellite imagery first before tracing buildings, roads, and
>> other features. You can average multiple GPS traces to get a good
>> enough positional accuracy and Potlatch, Merkaartor, and JOSM all
>> support manually moving the background imagery to the correct
>> position.
>> If there are no available GPS traces, then it's acceptable to trace
>> the Bing imagery directly. Someone can realign the map later on when
>> GPS traces would become available.
>> For more information, please check out this e-mail that I sent last year:
>> http://www.mail-archive.com/talk-ph@openstreetmap.org/msg02829.html
>> Happy tracing!!! :)
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I explore, therefore I blog.


"I don't need a map! I have the GPS. Never need a map again, thank you"
                              - Car lost on Route 66, Radiator Springs
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