[Proj] question about rotation

Roman Kazmin kata at rambler.ru
Wed Feb 9 08:19:09 EST 2005


Hi Gerald and anybody.
I apologize for my persistence, but I wanted again to ask the same 
question. I have not understood as to use your advice. If it is not 
difficult, you could not explain in more detail.
Now I try do two calls of pj_inv with:
"+proj=stere +ellps=WGS84 +lat_0=%.9f +lon_0=%.9f +units=m". I 
received Lat/Lon
and then for these Lat/Lon:
"+proj=ob_tran +o_proj=eqc  + ....."
but it does not help me. May for second call I use not correct 
parameters.

> I sensed that was your quest.  You simply call the inverse function 
> (pj_inv) with the
> easting/northing (x,y) input.
> 
> On Feb 8, 2005, at 5:34 AM, Roman Kazmin wrote:

> Thank's Gerald for your answer. But while it is not help me. I 'd like 
> to correct my question. I have Polar Stereographic Projection Grid and 
> I want to receive lat/lon from this.
>
>
>> For Oblique Stereographic are do you want a projection that uses an 
>> intermediate
>> Gaussian sphere?  If so, then use "+proj=strerea".  Sterea projection 
>> is more commonly
>> used outside of the US.
>> Cartesian output/input of the projection library is easting and 
>> northing synonymous with
>> x and y axis.  Sorry, no other option.
>> Full specification of Oblique Stereographic projection would be:
>> +proj=sterea  (optionally stere)
>> +lat_0=, +lon_0=  latitude, longitude of center of projection
>> k_0=  scale factor at origin
>> x_0=, y_0=  false easting, northing
>> +ellps=GRS80
>> On Feb 7, 2005, at 12:47 PM, Roman Kazmin wrote:
>> Hi anybody.
>> I'm beginner in LibProjj4. I have coordinate system and the following 
>> parameters:
>> sprintf(strProj, "+proj=stere +ellps=WGS84 +lat_0=%.9f +lon_0=%.9f 
>> +units=m", lat1, lon1)
>> FalseEasting   = 0;
>> FalseNorthing = 0;
>> Besides there is one parameter with which I do not know what to do. 
>> It is orientation. As I know it decsribes the orientation of the grid 
>> i.e., the east longitude value of the meridian which is parallel to 
>> the y-axis (or columns of the grid) along which latitude increases as 
>> the y-coordinate increases.
>> I want to receive transformation of coordinates from given to 
>> latitude and a longitude.
>> Thanks all.
>>
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>>
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