[Proj] request help with Lambert Conic Conformal (2SP)
gravesricharde at yahoo.com
Thu Aug 16 21:40:11 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).
> 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
Now I have to figure out how to merge the change file coordinates into the original file!
Thanks for solving the Lambert Conic Conformal (2SP) problem!
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)
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.
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:
>>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:
>>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.
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