[Liblas-devel] Re: GetProj4() string and NAD83

[Adam Stylinski]

On Wed, Jan 11, 2012 at 3:38 PM, Adam Stylinski <stylinae at mail.uc.edu>wrote:

> On Wed, Jan 11, 2012 at 3:03 PM, Frank Warmerdam <warmerdam at pobox.com>wrote:
>
>> On Wed, Jan 11, 2012 at 11:44 AM, Adam Stylinski <stylinae at mail.uc.edu>
>> wrote:
>> > Like I mentioned in previous posts, other NAD83 geotagged las files
>> produce
>> > similar issues (for example fayetteville).
>>
>> Adam,
>>
>> Where are these coming from?  What are they generated with?
>>
>> You referred to "most of the data on the internet".  What sort of
>> sampling have you done?
>>
>> If the problem is very limited then I think it is better to fix
>> the producer or work around the issue.  If it is truely widespread
>> then we might as well buckle under and make our consumer
>> more robust.
>>
>> Best regards,
>> --
>>
>> ---------------------------------------+--------------------------------------
>> I set the clouds in motion - turn up   | Frank Warmerdam,
>> warmerdam at pobox.com
>> light and sound - activate the windows | http://pobox.com/~warmerdam
>> and watch the world go round - Rush    | Geospatial Software Developer
>>
>> Here is the one I was referring to:
>
> http://data.capcog.org/Information_Clearinghouse/data/LiDAR/Sample_LiDAR_LAS_File.zip
> Many of the listed examples from lastool's compilation of ladar examples
> that use NAD83 have a different issue (not particular this one).  This is
> all I can find that is freely available, anyway.  The proprietary data that
> we have and I'm currently working with uses WGS84, so I cannot speak for
> other sources of data other than that which is available freely on the
> internet.
>
> Here is what getProj4() and getWKT() return for these datasets:
>
> GetProj4() = +proj=lcc +lat_1=28.38333333333333 +lat_2=30.28333333333334
> +lat
> 27.83333333333333 +lon_0=-99 +x_0=1968500 +y_0=13123333.33333333
> +datum=NAD83
> nits=us-ft +no_defs
> GetWKT() = COMPD_CS["unknown",
>     PROJCS["unnamed",
>         GEOGCS["NAD83",
>             DATUM["North_American_Datum_1983",
>                 SPHEROID["GRS 1980",6378137,298.2572221010002,
>                     AUTHORITY["EPSG","7019"]],
>                 AUTHORITY["EPSG","6269"]],
>             PRIMEM["Greenwich",0],
>             UNIT["degree",0.0174532925199433],
>             AUTHORITY["EPSG","4269"]],
>         PROJECTION["Lambert_Conformal_Conic_2SP"],
>         PARAMETER["standard_parallel_1",28.38333333333333],
>         PARAMETER["standard_parallel_2",30.28333333333334],
>         PARAMETER["latitude_of_origin",27.83333333333333],
>         PARAMETER["central_meridian",-99],
>         PARAMETER["false_easting",6458320.416666665],
>         PARAMETER["false_northing",43055469.44444443],
>         UNIT["US survey foot",0.3048006096012192,
>             AUTHORITY["EPSG","9003"]],
>         AUTHORITY["EPSG","32140"]],
>     VERT_CS["NAVD88 - Geoid03 (Feet)",
>         VERT_DATUM["unknown",2005],
>         UNIT[,1,
>             AUTHORITY["EPSG","9003"]],
>         AXIS["Up",UP]]]
>
> When I try to perform these projections with proj4, it gives me
> coordinates somewhere in the middle of the pacific.  So no, the default
> parameters are not zero, but something is making the proj.4 library behave
> incorrectly.  I apologize for assuming it was the same issue just because
> it was the same coordinate system.  Still, there is a problem, and your
> help on why this is happening would be appreciated.
>

And that does say +units=us-ft, that was just a copy&paste error.
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