Terraservice data not aligning

[Gerry Creager N5JXS]

<Shameless Plug for the Great State of Texas>

For what it's worth, there's a good bit of very accurate data for the
State of Texas.  For those interested in Texas, please check out
http://www.tnris.state.tx.us and then go to the Digital Data tab.

The Texas Strategic Mapping Initiative has placed a *LOT* of data into
the public domain and we're trying to keep it updated.

</Shameless Plug for the Great State of Texas>

I recently went down map accuracy issues with Census and an interested
amateur cartographer.  Some of the errors are "interesting" and I'm a
little concerned that they claim to meet national map accuracy standards
with some of their data.  It appears to be more'n a little off...

Gerry

Stephen Woodbridge wrote:
> Camden,
>
> Tiger data is known to have varying accuracy from county to county.
> Sometimes the data is very closely aligned but in some areas it can be
> grossly off. The Census is spending $200 Million to improve the quality
> and accuracy of there data. See http://www.census.gov/geo/mod/maftiger.html
> The first changes from this project will be getting release in Q1'05 and
> will be getting rolled out twice a year over the next few years until
> the project is done.
>
> Until then we all have to live with it as it is or license commercial
> data which is typically very expensive.
>
> -Steve W.
>  http://imaptools.com/
>
> Camden Daily wrote:
>
>> Hello all.  I've got a layer in my map file that I'm grabbing from
>> terraservice, and it's mostly working great.  However, when I overlay
>> some Tiger/Line street data over the terraserver image, things aren't
>> quite lining up.  It's very, very close, but just slightly offset when
>> zoomed in (maybe by 20-50 feet).
>>
>> My map file, the terraservice layer, and the tiger/line data are all
>> projected as EPSG:4326, so I don't think it's a projection issue.  Has
>> anyone else experienced any issues mixing these two data sets?
>>
>> Is it possible to 'tweak' a layer so that it's offset by a short
>> distance?  I know about the 'offset' parameters for styles, but those
>> only take units of pixels (which will look good at some zoom levels,
>> but not others...)  I'd be grateful for any suggestions.
>>
>> -Camden Daily
>>
>> terraserver layer:
>>
>>   LAYER
>>     NAME "aerial"
>>     TYPE RASTER
>>     STATUS OFF
>>     MINSCALE 1000 # trying to grab too small a scale might result in
>> an error from terraservice
>>     CONNECTIONTYPE WMS
>>     CONNECTION
>> "http://terraservice.net/ogcmap.ashx?VERSION=1.1.1&SERVICE=wms&LAYERS=urbanarea&FORMAT=image/jpeg&STYLES="
>>
>>     METADATA
>>      "wms_srs" "EPSG:4326"
>>     END
>>     PROJECTION
>>       "init=epsg:4326"
>>     END
>>   END
>>
>> tiger/line layer:
>>
>>   LAYER
>>     NAME "aerial_road_small_near"
>>     TYPE LINE
>>     STATUS OFF
>>     DATA "tgr17031lkA"
>>     MAXSCALE 100000
>>     CLASSITEM "CFCC2"
>>     CLASS
>>       EXPRESSION /A4|A5|A6|A7/
>>       COLOR 150 150 150
>>     END
>>     PROJECTION
>>       "init=epsg:4326"
>>     END
>>   END
>>

--
Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
Page: 979.228.0173
Office: 903A Eller Bldg, TAMU, College Station, TX 77843