how to get the remote-sensing image coordinate system and geo information

leadstool  15  how to get the remote-sensing image  coordinate system and geo information in visual c++?

 

If you're referring to the GeoTIFF file format, you can obtain Geo Keys information using:
LFile::SetGeoKey
LFile::GetGeoKey
LFile::WriteGeoKey
LFile::ReadGeoKey
LFile::EnumGeoKeys
LFile::EnumGeoKeysCallBack

oh,thanks

if the file is ecw format, what can i do?

L_VOID GetGeokeyExample(LFile& file)
{
   L_UINT16 L_FAR*pData = NULL;
   L_UINT uCount;
   L_UINT uType;
   L_INT nSize;

   nSize = file.GetGeoKey(1024, &uType, &uCount, NULL);
   if(nSize <= 0)
      MessageBox(NULL, TEXT("The GeoKey was not set, or an error occurred!"), TEXT("FAILURE"), MB_OK);
   else
   {
      // allocate an array large enough to store the GeoKey data
      pData = (L_UINT16 L_FAR*)malloc(nSize);
      if(pData != NULL)
      {
         nSize = file.GetGeoKey(1024, &uType, &uCount, pData);
         if(nSize <= 0)
            MessageBox(NULL, TEXT("Error getting the GeoKey!"), TEXT("FAILURE"), MB_OK);
         else
         {
             // do whatever you want with the GeoKey data
            MessageBox(NULL, TEXT("works Fine!"), TEXT("SUCCESS"), MB_OK);
         }
         free(pData); //// free the pData buffer
      }
   }
}

 

i use this code to get the info.

but  using 1024-3071 ,i only get the message that is  "The GeoKey was not set, or an error occurred"; and my file has the geo info.

why?

I'm afraid we don't have function to retrieve such data from ECW files.

you said the tiff is ok

it's the result that tiff file  is tested

 

Hello,

Could you explain in greater detail what you mean by "it's the result that tiff file is tested"? The noted methods work specifically with reading GeoKeys in GeoTIFF files. The method does not support reading metadata from ECW files.

If you're trying to extract GeoKeys from a TIFF file, could you provide a sample file so that we can test out this issue here as well?

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the  file i used to  testing is earth-4km.tif

 i want to get the geoInfo ,such as the coordinate system, LTx,LTy,RBx,RBy coordiate , the projection system,etc.

and  can you get the information of  the file which was the ecw format ,

 

the example files.

 

 

the ecw file

the ecw file

The proper method for getting the specified GeoKey data from a TIFF file is the LFile::ReadGeoKey
function. You can also use the LFile::EnumGeoKeys which will enumerates all the GeoKeys in a GeoTIFF file.

For more information about GeoKeys, please refer to the help topic "Implementing GeoKeys (GeoTIFF tags)".

As I said, this will not work with the ECW file and we do not have functions to read such keys from ECW.