[gdal-dev] Re: [gdal-java-1.8.0]TransformPoint() - different values for same inputs, why?

[Jean-Claude Repetto]

On 07/06/11 22:54, mett wrote:
>
> Jean-Claude Repetto wrote:
>>
>> Probably because your projection is not cylindrical. What projection are
>> you using ?
>>
>> The projection is
>> `PROJCS["User-Defined WGS84/Lambert Conformal Conic (IS.)",GEOGCS["WGS
>> 84",DATUM["WGS_1984",SPHEROID["WGS
>> 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433],AUTHORITY["EPSG","4326"]],PROJECTION["Lambert_Conformal_Conic_2SP"],PARAMETER["standard_parallel_1",64.25],PARAMETER["standard_parallel_2",65.75],PARAMETER["latitude_of_origin",65],PARAMETER["central_meridian",-19],PARAMETER["false_easting",500000],PARAMETER["false_northing",500000],UNIT["metre",1,AUTHORITY["EPSG","9001"]]]'
>>
>> I did the follow step:
>> - Got the Upper Left corner of the image with
>> GetGeoTransform(adfGeoTransform)
>> - Found out the others corners in this way:
>> double miny = adfGeoTransform[3] + width*adfGeoTransform[4] +
>> height*adfGeoTransform[5];
>> double maxx = adfGeoTransform[0] + width*adfGeoTransform[1] +
>> height*adfGeoTransform[2];
>> - Convert all these 4 points related to the corners with TransformPoint();
>>
>> So, what should I do to have correct values from the conversion? I cannot
>> find a good solution.
>>

I think your results are correct, because PROJ.4 gives exactly the same 
ones :

proj -I -f "%.12f" +proj=lcc +lat_1=64.25 +lat_2=65.75 +lat_0=65 
+lon_0=-19 +x_0=500000 +y_0=500000 +datum=WGS84 +units=m +no_defs
258321.25943477 655225.28062628
-24.391630217716	66.299640570965
258321.25943477 574605.28062628
-24.242820669640	65.579229590843

Jean-Claude