[GRASSLIST:4679] Re: robinson projection

[Ian MacMillan]

I noticed that I had the same problem if I used a Winkel Triple 
projection instead of a Robinson projection.  It seems like a function 
that might be used a lot is one that lays down a latlong grid in any 
projection, but maybe that is just me.  In any case, as a workaround, I 
made a grid in 5.3 with v.mkgrid (unfortunately not available in 5.7) 
in my latlong location, projected it into the robinson location with 
v.proj, and converted it to a 5.7 vector with v.convert.  Worked like a 
charm.

-Ian


On Oct 28, 2004, at 6:12 PM, Ian MacMillan wrote:

> Hi all again, I have a weird problem.  I am trying to make a world map 
> using the robinson projection.  I have projected in a raster map of 
> the world into this location, and instead of obtaining the nice 
> oval-ish shape we are used to, the new raster is a rectangle with 
> areas at the edges duplicated.  The edges are distorted as they should 
> be, but there is no way to determine where the edges of the original 
> map lay.  I figured this is ok if I could project in a vector box of 
> the world (from a latlong location), and just use that as a mask.  
> Trouble is that when I project in a vector area with bounding 
> coordinates of n=72 s=-72 e=180 w=-180 in latlong space, it comes into 
> the Robinson location as a box, not an oval-ish shape.  This doesn't 
> make any sense to me.  Is this a problem with proj.4?  Or is it 
> impossible to delineate lines of longitude in the Robinson projection 
> (measurement units are meters)?
>
> Thanks for any input y'all might have,
> Ian
>