[Proj] Oblique Cyl Eq Area

Gerald I. Evenden gerald.evenden at verizon.net
Thu Jul 7 13:31:21 EDT 2005

First. "trillion" seems to have a ambiguous definition in Kdict so I am
not sure about
your what you mean here.  Is it greater or lesser than a gazillion?  :-)
sorry about my humor.

Secondly, I am not sure I am aware of the +ellps=sphere option.  When I
try it on lproj
I get a segmentation fault which I am looking into at this moment.  Note
any undefined
ellipsoid name creates the same error.

One thing I will note is that I am more familiar with specifying the two
points in an west
to east orientation so that point  1 would be 22.5,90 and point 2
-45,180 so that I am
not sure that reversing the order will not generate unexpected results.

There is definitely one bug item here and you will hear more from me in
the near

On Thu, 2005-07-07 at 10:14 -0500, William K wrote:

> Sorry to repeat, but I need to know if anyone has any ideas on this:
> I want to set up a map with the Oblique Cylindrical Equal Area  
> projection (ocea).  I couldn't find much info on parameters needed  
> and the effects of them.  From what I found in the USGS projections  
> book I need two points for the oblique line (lat_1, _2, lon_1, _2).   
> Simple enough.  Yet I get projected coordinates in the trillions!   
> It's not an easting/northing problem - I get +/- trillions around the  
> center of the projection.
> this is what I used (Australia/SE Asia region):
> proj +proj=ocea +ellps=sphere +lat_1=-45 +lat_2=22.5 +lon_1=180  
> +lon_2=90
> (I tried ellps=WGS84 also)
> Changing the distance between the oblique points seems to affect the  
> projection a bit - instead of at the limits of the area of interest,  
> if I make them say 1/10 of that apart, the coordinates go down by up  
> to a trillion.
> Anyone have any definite info on setting up this projection?  If it's  
> normal, what do those large numbers really mean (if not meters)?  Did  
> I miss a parameter?
> -----
> William Kyngesburye <kyngchaos at kyngchaos.com>
> http://www.kyngchaos.com/
> "History is an illusion caused by the passage of time, and time is an  
> illusion caused by the passage of history."
> - Hitchhiker's Guide to the Galaxy
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really free is the amount of security enjoyed by minorities"
---Lord Acton, 1907 
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