[OSM-ja] experience with Navitime.co.jp coordinate system?

[Tom Lee]

Thank you! I am embarrassed not to have been able to unravel this myself. I
appreciate the help.

On Tue, Feb 24, 2015 at 9:15 PM, 田渕直 <tabuchi_naoshi at trek.co.jp> wrote:

> Hi Tom,
>
> Some googling concluded that:
>   - The navitime's coords are ordinary lat/lng's, but
>   - they are represented in *milli-second angles.*
> (cf. http://ja.wikipedia.org/wiki/Wikipedia:%E5%9C%B0%E5%9B%B3%
> E3%82%B5%E3%82%A4%E3%83%88%E4%B8%80%E8%A6%A7#NAVITIME, etc.)
>
> So, dividing them by 3600*1000:
>         lat-or-lng / (3600*1000)
> gives you familiar values in degrees.
>
> For instance, the first line of your CVS:
>     511368020,156819220,079-1123
> transforms to:
>     142.0466722222222,43.56089444444444
> which points to a certain place in Hokkaido:
>     https://goo.gl/maps/6n9zO
> where, ignoring a slight gap bw. Tokyo Datum and WGS84, the postal code
> 079-1123 points:
>     https://goo.gl/maps/bnXhT
>
> hope it helps,
>
> Noashi Tabuchi (tabuchi_naoshi at trek.co.jp)
>
> On 2015/02/25 4:06, Tom Lee wrote:
>
>> I am still working to connect e-Stat data together into a shapefile of
>> postal boundaries in Japan. I have found myself encountering data from
>> services that use the navitime.co.jp <http://navitime.co.jp/> mapping
>> platform. These coordinates seem to employ an unusual datum. There are some
>> references on the web to it being the Tokyo Datum, and the constants
>> present in some of the navitime code <https://gist.github.com/
>> sbma44/49354581f45d3c7e10a9> indicate the Bessel Ellipsoid, which
>> supports this idea.
>>
>> However, there are some strange aspects to these coordinates, such as
>> multiplying them by constants like 1E3 * Math.PI / 648E3. I have been
>> unable to successfully transform them into a known coordinate system. Does
>> anyone have experience with the coordinate system used by the Navitime API?
>>
>> Here's a link to a CSV file of coordinates and post codes:
>>
>> http://cl.ly/1e413I1u1c12/navitime.csv
>>
>>
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>
>
>
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