AZ-C SPCS definition

[Chad Streck]

Thanks Frank.  I used your values and changed units to ft and converted 
the x_0 to feet by multiplying 3.28084, and my points landed about 200 
miles east of where they should be.  So I figured it was a +/- issue, so 
I put a - in front of the x_0 and that shifted it about 500 miles west.  
So for giggles, I used you meters calculation and the points land where 
they are supposed to be, so I'm very confused at this time.

Here is what I have for the map file projection....

  projection
   "proj=tmerc"
   "ellps=GRS80"
   "units=ft"
   "lon_0=-111.916666667"
   "lat_0=31.000000000"
   #"x_0=699999.9999972"
   "x_0=213360.000"
   "y_0=0.000000"
   "k=0.999900"
   "no_defs"
  end                                                                   
       

... and for the layer that is in lat/long....

  layer
   classitem "status"
#    maxscale 1000000
#    minscale 0
   name "ace"
   data "procon/ace-cust"
   status default
   type point
   projection
     geographic
   end
   class
     color 0 64 128
     expression /A/
     name "Existing Customers"
     size 8
     symbol "hospital"
   end
   class
     color 128 64 0
     expression /B/
     name "New Prospects"
     size 8
     symbol "hospital"
   end
   class
     color 64 128 0
     expression /C/
     name "New Customers"
     size 8
     symbol "hospital"
   end
   queryitem "ddlong"
   tolerance 5
   query
     expression /./
     template ""
   end
  end                                                                   
       

I have some imagery that is in AZ-C NAD83 FT that I will now place on 
the vector data to see how far off I am.

Chad


Frank Warmerdam wrote:

> Chad Streck wrote:
> 
>> I'm working on a application that will display points on top of
>> imagery.  The imagery and the base data are in state plane AZ-C NAD83
>> FT, but the points I have are all lat long.  I defined the projection
>> for the point file as geographic, and I'm trying to define the AZ-C SPCS
>> for the main projection, but I don't seem to get the proper parameters.
>> I know that my low understanding of projections is probably at fault,
>> but could someone please help in defining the AZ-C projection, or point
>> me to a good reference or cheat-sheet on it?  I haven't been able to
>> find a good one so far.
>> 
>> I know I could just use ArcView to translate the point file to state
>> plane, but the future of the project will be using lat/long for the
>> points from an SQL database, so I need to get this projection working
>> sometime, and now would be a good time.
> 
> 
> Chad, 
> 
> I have this definition for Arizona Central, NAD83:
> 
> +proj=tmerc +lat_0=31.000000000 +lon_0=-111.916666667 +k=0.999900 +x_0=213360.000 +y_0=0.000 +ellps=GRS80 +units=m  no_defs
> 
> Since you are using feet, you will need to translate the x_0 value to feet
> and change +units=m to +units=ft.
> 
> Let me know if this works.
> 
> Good luck,
> 
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for Rent
> 
>