[GRASSLIST:5711] Re: v.proj problems - state plane to UTM

[Philipp Molzer]

Hi,
I'm about to apply your suggestions, but I just wanted to note how I 
obtained the projection info.  I got it from a meta-info file, excerpted 
below.  I can't recall all the info I had to provide to set up the 
location, but I believe I put feet for units because of the entry below 
called Planar_Distance_Units: Feet, which was the only reference to 
units I could find in the file.  I'll respond shortly with further results.
thanks,
Phil


Spatial_Reference_Information: 
    Horizontal_Coordinate_System_Definition: 
        Planar: 
            Grid_Coordinate_System: 
                Grid_Coordinate_System_Name:  State Plane Coordinate 
System 1983
                State_Plane_Coordinate_System: 
                    SPCS_Zone_Identifier:  2900
                    Transverse_Mercator: 
                        Scale_Factor_at_Central_Meridian:  0.999975
                        Longitude_of_Central_Meridian:  -74.3
                        Latitude_of_Projection_Origin:  38.5
                        False_Easting:  492125.98
                        False_Northing:  0
            Planar_Coordinate_Information: 
                Planar_Coordinate_Encoding_Method:  Coordinate Pair
                Coordinate_Representation: 
                    Abscissa_Resolution:  8.33
                    Ordinate_Resolution:  8.33
                Planar_Distance_Units:  Feet
        Geodetic_Model: 
            Horizontal_Datum_Name:  North American Datum of 1983
            Ellipsoid_Name:  Geodetic Reference System 80
            Semi-major_Axis:  6378137
            Denominator_of_Flattening_Ratio:  298.257

Eric G. Miller wrote:

>On Sun, Mar 02, 2003 at 12:13:23PM -0500, Philipp Molzer wrote:
>  
>
>>Hi,
>>I'm using grass5.0.0 on Linux RedHat8 (intel).
>>I have a DEM upon which I'd like to overlay some census data (vectors). 
>>The DEM is in UTM format while the vectors are in state plane format. 
>>Both locations are NAD83.  Both cover the area of Essex County, New 
>>Jersey, USA. When I use v.proj to bring the vectors from my state plane 
>>location to my UTM location, the resulting vector data has coordinates 
>>that seem to be incompatible with the DEM coordinates.  The east and 
>>west bounds of the imported vector layer appear to be way off.
>>    
>>
>
>  
>
>>Source of vectors
>>
>>Vectors were imported into a location with these specifications:
>>
>>   name:    State Plane
>>   datum:   nad83
>>   dx:      0.000000
>>   dy:      0.000000
>>   dz:      0.000000
>>   proj:    tmerc
>>   a:       0.63782064e+07
>>   es:      0.6768657997291094e-02
>>   x_0:     0.6096012192024384e+06
>>   y_0:     0
>>   k:       0.999975e+00
>>   lon_0:   74d40'w
>>   lat_0:   38d50'n
>>   -----------------------------------------------------------
>>   PROJ_UNITS file:
>>   unit:    foot
>>   units:   feet
>>   meters:  0.3048000000
>>    
>>
>
>I believe the above projection info is incorrect for New Jersey 
>State Plane of 1983 (it appears to be the spec for 1927, with the
>wrong datum name).  The biggest difference, will probably be that
>the 1983 coordinates are probably measured in meters.  I have the
>following projection spec., sans units (since states didn't necessarily
>follow the 1983->meters recommendation).
>
># 2900:State_Plane_1983_New_Jersey                                                   
>name: State_Plane_1983_New_Jersey                                                    
>datum: nad83                                                                         
>ellps: grs80                                                                         
>y_0: 0                                                                               
>es: 0.0066943800229                                                                  
>a: 6378137                                                                           
>dx: 0                                                                                
>dy: 0                                                                                
>dz: 0                                                                                
>lat_0: 38.8333333333333                                                              
>f: 298.257222101                                                                     
>proj: tmerc                                                                          
>lon_0: -74.5                                                                         
>k: 0.9999                                                                            
>x_0: 150000 
>
>Replace the mapset/PERMANENT/PROJ_INFO file with the above info, and
>replace the PROJ_UNITS file with:
>
>unit: meter
>units: meters
>meters: 1.0
>
>HTH,
>  
>