[Talk-us] Big Island, Maui, Lanai, and Molokai (was Re: Characterizing Systematic Errors in Hawaii and US Pacific Island Data)

[Scott Atwood]

Big Island (Hawai'i Island):
I spot checked the road network here.  With the exception of portions of the
Kailua-Kona area, the roads everywhere I checked hadn't been edited since
the 2007 TIGER import.  And all data (even most of the Kailua-Kona data that
had been manually edited) suffered from the same NNW offset as the rest of
Hawai'i.

Big Island should probably have its road network wiped out and reimported as
well.  It doesn't seem that there has been very much manual work at all.

-Scott

On Mon, Oct 5, 2009 at 1:05 AM, Scott Atwood <scott.roy.atwood at gmail.com>wrote:

> Lanaʻi:
> This is a small island with a relatively limited road network, concentrated
> mostly in a single small, central town.  It looks like there has been
> extensive manual editing of the road network, and it seems to correspond
> fairly well to the satellite photos.
>
> Molokaʻi:
>
> The coastline data seems to be fairly accurate.  The road network on this
> island seems to have had little or no manual editing since it was imported
> from TIGER in 2007.  The roads appear to be displaced approximately 300m to
> the west and 400m to the north, based on on the satellite photos.
>
> Maui:
>
> The coastline data seems to be fairly accurate.  I spot checked a number of
> locations in the road network, including Lahaina, Kahului, Wailuku,
> Haleakala Highway, and Hana Highway.  Every placed I checked had not been
> manually edited since it was imported from TIGER in 2007, and seems to have
> the same NNW displacement as seen on Molokaʻi.
>
>
> Next steps for Lanaʻi, Molokaʻi, and Maui:
>
> I think Lanaʻi can be left as is.  Given that there has been little or no
> substantial manual editing of the road networks of Molokaʻi and Maui, and
> these islands both suffer from a substatial offset (presumably due to an
> incorrect datum in the initial import), I suggest that we remove all
> roadways from the previous TIGER import, and re-import from the latest TIGER
> data, ensuring that it uses the correct datum.
>
> I don't have the necessary expertise to do the removal and re-import.  Is
> there anyone on the list who can take on this task?
>
> -Sctt
>
>
>
> On Fri, Oct 2, 2009 at 12:39 PM, Scott Atwood <scott.roy.atwood at gmail.com>wrote:
>
>> Lehua:
>> This is a tiny, uninhabited islet off the coast of Niʻihau.  The shoreline
>> data could use some cleanup, but it is roughly correct.  The boundary data
>> seems to come from the same low resolution source, but the 1km east
>> displacement error seems to have been manually corrected.
>>
>> Molokini:
>>
>> This is a tiny uninhabited islet between Maui and Kohoʻolawe.  The
>> shoreline data is roughly correct, but could use some cleanup.  There
>> doesnʻt appear to be any boundary data.  I suspect that this is an
>> accidental oversight, since this island is officially a part of Maui County.
>>
>> Niʻihau:
>>
>> This is smallest of the inhabited Hawaiian islands.  The shoreline data
>> appears to be roughly correct. The boundary data is low resolution, and
>> appears to have been manually shifted to correct the 1km eastward
>> displacement.
>>
>>
>> Next steps for Lehua, Molokini and Niʻihau:
>>
>> Once again, if the political boundaries are supposed to correspond exactly
>> to the shoreline data, the whatever is done for Kohoʻolawe and Lanaʻi should
>> also be done for these three islands to correct the political boundaries.
>>  The rest of the data can be easily cleaned up manually.
>>
>> -Scott
>>
>> --
>> Scott Atwood
>>
>> Cycle tracks will abound in Utopia.  ~H.G. Wells
>>
>>
>>
>
>
> --
> Scott Atwood
>
> Cycle tracks will abound in Utopia.  ~H.G. Wells
>
>
>


-- 
Scott Atwood

Cycle tracks will abound in Utopia.  ~H.G. Wells
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-us/attachments/20091005/592e1e11/attachment.html>