[Proj] request help with Lambert Conic Conformal (2SP) SOLVED

Thu Aug 16 16:54:04 EST 2012

Mikael and Carl,

From the correct shape file, the point touching the bounding box on the Eastern side is 2345137.5423228294, 1430204.1095800549.  Comparing these with numbers from proj with the lat/long inputs, the easting is within 0.1%, and the northing is within 1%, which I believe is close enough (for points picked from on line maps).

Mikael wrote:

> you could try this Proj.4 definition: +init=epsg:2992

The following two return the exactly same numbers when I input -116.463726 45.614818:

proj +proj=lcc +lon_0=-120.5 +lat_0=41.75 +lat_1=43.0 +lat_2=45.5 +x_0=400000 +y_0=0.0 +units=ft

proj +init=epsg:2992

Now I have to figure out how to merge the change file coordinates into the original file!

Thanks for solving the problem!

Rick

________________________________
 From: Mikael Rittri <Mikael.Rittri at carmenta.com>
To: Rick Graves <gravesricharde at yahoo.com>; PROJ.4 and generalProjections Discussions <proj at lists.maptools.org> 
Sent: Thursday, August 16, 2012 9:52 PM
Subject: Re: [Proj] request help with Lambert Conic Conformal (2SP)

Rick,
I don't know about the shapefiles, but you could try this Proj.4 definition

  +init=epsg:2992

which I think will be equivalent to Carl's definition. 

(I'm not sure how you can verify that it works, but maybe you
can compare the Oregon data location with other data sources.)

Mikael Rittri
Carmenta
Sweden
http://www.carmenta.com

16 aug 2012 kl. 14:44 skrev "Rick Graves" <gravesricharde at yahoo.com>:

Mikael and Carl,
>
>
>Maybe there is a problem with the Oregon shape files, or maybe I made an incorrect assumption about the contents.
>
>
>The Oregon redistricting web site is down for me at the moment:
>
>
>www.leg.state.or.us/redistricting/
>
>
>But the Oregon shape files are available here:
>
>
>http://www.srrproject.org/resources/redistricting-shapefiles/
>
>
>
>(Click on Oregon to get the link.  If you do not instantly know which one is Oregon, you can hover the mouse and a tip will display telling which state is under the pointer.  Oregon is on the West coast just North of California.)
>
>
>The zip for Oregon includes two sets of files, Congressional_Districts.* and Congressional_Area_Changes.*. 
>
>
>I assumed that I should go with the latter file.
>
>
>I ran diff against the two .prj files, and there is no difference.
>
>
>However, I just now discovered that the contents of the shapefiles are radically different.  Here are the bounding boxes:
>
>
>Congressional_Districts
>
>(183987.16863517463, 88653.9580052495, 2345137.542322829, 1677526.0958005222)
>
>
>
>Congressional_Area_Changes
>
>(427663.998031497, 172986.72867454588, 1005007.5570866163, 1488902.549212602)
>
>
>
>Sorry for being a beginner, but is there something I should know to do with these two files?  Or should I be asking Oregon what is the deal?
>
>
>Thanks,
>
>
>Rick
>
>
>
>
>
>________________________________
> From: Mikael Rittri <Mikael.Rittri at carmenta.com>
>To: PROJ.4 and general Projections Discussions <proj at lists.maptools.org> 
>Sent: Thursday, August 16, 2012 6:42 PM
>Subject: Re: [Proj] request help with Lambert Conic Conformal (2SP)
> 
>
>Carl,
>In fact, I don't think you are missing anything. 
>
>
>I made a quick back-of-an-envelope calculation - not using
>proj, just a plain calculator - starting with the projection
>origin, assuming 111120 meters per degree of latitude,
>and 111120 * cos(lat) meters per degree of longitude.  
>
>
>For the test point, I got 
>
>
>Easting = 1408985 ft
>Northing = 2341613 ft. 
>
>
>That's close enough to your (Carl's) result, with my simple method. 
>
>
>I may have made a mistake, but Rick: could you double-check your expected coordinates - I am pretty sure they are wrong. 
>
>
>Regards,
>
>
>Mikael Rittri
>Carmenta
>Sweden
>http://www.carmenta.com
>
>16 aug 2012 kl. 05:30 skrev "Carl Godkin" <cgodkin at gmail.com>:
>
>
>
>>
>>
>>On Wed, Aug 15, 2012 at 8:00 PM, Rick Graves <gravesricharde at yahoo.com> wrote:
>>
>>Hey,
>>>
>>>
>>>The good news is that Oregon is the last one I need to get working.  The bad news is I do not have it working yet.
>>>
>>>
>>>Here is the metadata from the .prj that I got from the state:
>>>
>>>
>>>PROJCS["NAD_1983_Oregon_Statewide_Lambert_Feet_Intl",
>>>GEOGCS["GCS_North_American_1983",
>>>DATUM["D_North_American_1983",
>>>SPHEROID["GRS_1980",6378137.0,298.257222101]],
>>>PRIMEM["Greenwich",0.0],
>>>UNIT["Degree",0.0174532925199433]],
>>>PROJECTION["Lambert_Conformal_Conic"],
>>>PARAMETER["False_Easting",1312335.958005249],
>>>PARAMETER["False_Northing",0.0],
>>>PARAMETER["Central_Meridian",-120.5],
>>>PARAMETER["Standard_Parallel_1",43.0],
>>>PARAMETER["Standard_Parallel_2",45.5],
>>>PARAMETER["Latitude_Of_Origin",41.75],
>>>UNIT["Foot",0.3048]],
>>>VERTCS["NAD_1983",
>>>DATUM["D_North_American_1983",
>>>SPHEROID["GRS_1980",6378137.0,298.257222101]],
>>>PARAMETER["Vertical_Shift",0.0],
>>>PARAMETER["Direction",1.0],
>>>
>>>
>>>I initialized proj as follows:
>>>
>>>
>>>proj +proj=lcc +lon_0=-120.5 +lat_0=41.75 +lat_1=43.0 +lat_2=45.5 +x_0=1312335.958005249 +y_0=0.0 +units=ft
>>>
>>>
>>>I assume something is not right.
>>>
>>>
>>>
>>>
>>
>>
>>I think there are two things wrong:  
>>1. Your false easting is here given in feet while I believe proj always wants meters.  The number is about 400000m.  (See http://trac.osgeo.org/proj/wiki/GenParms).
>>2. You didn't include an ellipsoid or datum so I'm surprised that proj worked at all since I get an error without +datum=NAD83 or +ellps=GRS80.
>>
>>
>>However, correcting both of those, I get  X=2344859.57 ft, Y=1434192.31 ft, which isn't what you want either.  
>>
>>
>>Now I want to know what I am missing!  Let's hope someone cleverer than me answers.
>>
>>
>>carl
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