Re: Address -> coords

Hi G,

Lookit that, so they should, at least for North America. I did some
searching around, and found other sources that said much the same
thing. That said, the data that we were discussing earlier should match
up pretty well. I have seen the VMAP data I used match up with other
data sources pretty well, so I'd speculate that there may be something
that needs to be adjusted with the TIGER data. Of course, it would be
helpful to compare the TIGER data against some finer-grained VMAP level
1 data to see if it's an accuracy problem (the VMAP level 0 data is
made from 1:1M data), but I don't have any that matches my TIGER data.

- Don

On Friday, October 12, 2001, at 01:13 PM, Guillermo Payet wrote:

>
> Hi Don,
>
> mmmm... A few references I've found agree with this:
>
>> The ideal solution to all of the above problems would be a spheroidal
>> model that has both the correct equatorial and polar radii, and is then
>> centered on the actual center of the Earth. One would then have a
>> spheroid, that when used as a datum, would accurately map the entire
>> Earth. All lat/longs on all maps would agree. That spheroid, derived
>> from satellite measurements of the Earth, is GRS80, and the datums that
>> match it are NAD83 and WGS84.
>
> Wouldn't this mean that NAD83 and WGS84 should match?
>
> --G
>
>
>
>
> On Fri, Oct 12, 2001 at 11:24:13AM -0400, Donald Dietrick wrote:
>> I checked out some my my esri street data (I think that was TIGER data)
>> versus VMAP level 0 data, and found that they are off, too. I went to
>> the US Census TIGER site, and they do say that TIGER data is in the
>> NAD83 datum, as opposed to the WGS84 datum of OpenMap projections and
>> of
>> the other data sources used. That explains the offset - it's the TIGER
>> data.
>>
>> So, to get the maps to match, something needs to go through coordinate
>> translation.
>>
>> - Don
>>
>> On Thursday, October 11, 2001, at 02:16 AM, Guillermo Payet wrote:
>>
>>>
>>> Hi Don,
>>>
>>> This is what I mean:
>>>
>>> http://dev.wifinder.com/search.jsp?map=map&scale=0.9012346&lat=37.74302&
>>> lon=
>>> -122.34541&loc=&add=&x=131&y=81
>>>
>>> The streets come from TIGER data, and the land forms come from the
>>> NationalAtlas site.
>>>
>>> --G
>>>
>>>
>>> On Wed, Oct 10, 2001 at 03:30:32PM -0400, Donald Dietrick wrote:
>>>> Hi G,
>>>>
>>>> On Monday, October 8, 2001, at 02:56 PM, Guillermo Payet wrote:
>>>>
>>>>>
>>>>> Hi Don,
>>>>>
>>>>> We're looking at the service from www.geocode.com for this. If
>>>>> their
>>>>> price is right, then we'll use them. Otherwise I'll be writing the
>>>>> software.
>>>>>
>>>>> Also: I'm noticing that the state boundary shapefile data from
>>>>> nationalatlas.gov and the street data from the census bureau
>>>>> (shapefile
>>>>> conversions downloaded from ESRI) don't match. That is...
>>>>> coastlines
>>>>> and streets are offset by quite a bit, and a lot of streets show in
>>>>> the middle of the ocean. Strange.. What's the deal? Which one is
>>>>> wrong?
>>>>
>>>> It's probably not that one of them is wrong, just that they don't
>>>> match
>>>> each other. I bet they have different datums if the error is
>>>> constant
>>>> with respect to direction. If the differences are more random, than
>>>> it
>>>> could be that you've exceeded the accuracy of the state boundary maps
>>>> (that depends on what the source for them is).
>>>>
>>>> - Don
>>>>
>>>>>
>>>>> --G
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Mon, Oct 08, 2001 at 10:23:46AM -0400, Donald Dietrick wrote:
>>>>>> Hi G,
>>>>>>
>>>>>> Several people have asked about it recently, but nothing has been
>>>>>> submitted to BBN. This would definitely be something that we would
>>>>>> love
>>>>>> as a contribution, and would include it in the package if
>>>>>> submitted.
>>>>>>
>>>>>> - Don
>>>>>>
>>>>>
>>>>> --
>>>>> [To unsubscribe to this list send an email to "majdart@bbn.com"
>>>>> with the following text in the BODY of the message "unsubscribe
>>>>> openmap-users"]
>>>>>
>>>>>
>>>
>>>
>>>
>>> --
>>> Guillermo Payet
>>> O C E A N G R O U P
>>> President/Chief Technology Officer
>>> email: gpayet@oceangroup.com
>>> web: http://www.oceangroup.com
>>> public key: http://www.technosterone.com/crypto
>>> U s e d a t a E N C R Y P T I O N ! ! ! !
>>>
>>>
>
>
>
> --
> Guillermo Payet
> O C E A N G R O U P
> President/Chief Technology Officer
> email: gpayet@oceangroup.com
> web: http://www.oceangroup.com
> public key: http://www.technosterone.com/crypto
> U s e d a t a E N C R Y P T I O N ! ! ! !
>
>

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