[Proj] Need help converting Goode to latlon
mkennedy2 at earthlink.net
Thu Jul 23 15:23:07 EST 2009
>Date: Wed, 22 Jul 2009 22:14:46 -0700
>From: David Turover <dturover at student.santarosa.edu>
>Subject: Re: [Proj] Need help converting Goode to latlon
>To: proj at lists.maptools.org
>Message-ID: <20090723051446.GA26464 at busstudent.santarosa.edu>
>Content-Type: text/plain; charset=us-ascii
>On Wed, Jul 22, 2009 at 10:04:18AM -0400, Gerald I. Evenden wrote:
>> On Wednesday 22 July 2009 2:39:52 am David Turover wrote:
>> > Example: http://segfault.cs.sonoma.edu/~dturover/gisbug/projectionError.jpg
>> The projection in the above jpeg looks like Near-sided perspective. At any
>> rate, it certainly is not Goode's pseudocylindrical Homolosine.
>The jpeg is the result of attempting to reproject from Goode to geographic
>coordinates. I have confirmed with an ESRI tool that the original shape is
>in Goode, so the problem is in my use of proj.
>+proj=sinu produces similar results except that the tip of South America
>is pulled further west. Since sinu is the middle half of goode and the
>polar regions use a different algorithm, this should be expected.
>However, it may be worth mentioning that I can't get sinu to match the
>country shapes to their borders either.
>Most tweaks that I attempted to make to the proj arguments resulted in
>no change in the output, including turning off +no_defs and giving both
>the input and output projections the same datum "+datum=WGS84".
>I had the output projection as a null string to default to geographical
>coordinates. "+proj=latlon +units=degrees" gives the same result.
>Overstating +a (the earth's radius?) will pull shapes to the east as
>they are stretched, including things at the equator that were well
>"+lon_0=-90" drew the South America shapes in the middle of the Pacific
>Ocean. This makes sense since the original projection is based on the
>Greenwich meridian, so this just moved everything west.
>I turned on the PROJ_DEBUG environment variable but the only notice it
>gave was that proj_def.dat could not be opened. I fixed this by exporting
>PROJ_LIB so it searched in the right place. This did not affect the
>The ESRI projection definition includes an option named "Option" that
>is set to 1. This does not sound very important, but might it have an
> - David T.
The 'option' parameter is used to determine whether to use the 'land' or
'ocean' version. That is, if '1', the interruptions will occur in the oceans.
If '2', the interruptions will occur on land. The standard Goode's (land) prj
file is using WGS84, so the radius is 6378137.0.
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