projectAs help

[JamesCrandall]

I'm attempting to implement some of the functionality found here:

http://support.esri.com/en/knowledgebase/techarticles/detail/40730

I need to acquire the x/y values where mouse click occurs, convert the values into Latitude/Longitude and then report these values.

The plan is to require a layer to be loaded in the map TOC, so there will be a defined spatial reference to go from.  No problem getting these projected x/y values so far but I am not able to project these to WGS1984.  Is this even possible?  Or will I have to use in_memory in some capacity here?

      def onMouseDownMap(self, x, y, button, shift):         print "x: " + str(x) + " y: " + str(y) ## this reports as expected!                          ## get a layer loaded in the TOC to determine the spatial reference                 mxd = arcpy.mapping.MapDocument("CURRENT")         df = arcpy.mapping.ListDataFrames(mxd)[0]         testCount = len(arcpy.mapping.ListLayers(mxd, "", df))         if testCount==0:             msg = "There are no features selected to report"             pythonaddins.MessageBox(msg, 'Report Latitude/Longitude Values', 0)         else:               for lyr in arcpy.mapping.ListLayers(mxd):             dsc = arcpy.Describe(lyr)             spref = dsc.spatialReference              lpoint = arcpy.Point()             lpoint.X = x             lpoint.Y = y             ptGeometry = arcpy.PointGeometry(lpoint)             #ptGeom = arcpy.PointGeometery(arcpy.point(x,y),spref, False, False)              to_sr = arcpy.SpatialReference('WGS 1984')                                  projectedPoint = ptGeometry.projectAs(to_sr, r'NAD_1983_HARN_To_WGS_1984')             prjX = projectedPoint.X             prjY = projectedPoint.Y             print "X:" + str(prjX) + " Y:" + str(prjY) 

The code above fails on the line:

[INDENT]projectedPoint = ptGeometry.projectAs(to_sr, r'NAD_1983_HARN_To_WGS_1984')[/INDENT]



Error msg:
"projectedPoint = ptGeometry.projectAs(to_sr, r'NAD_1983_HARN_To_WGS_1984')
  File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\arcobjects\arcobjects.py", line 761, in projectAs
    return convertArcObjectToPythonObject(self._arc_object.ProjectAs(*gp_fixargs((spatial_reference, transformation_name))))
ValueError: NAD_1983_HARN_To_WGS_1984"

[TimDine]

Check that you're using a valid transformation for the projections you're using by feeding the shapefile to the project tool in a model and exporting it.  I tried two variations of a script with different options for the transformation parameter.  The transformation you're using blew up with the same error you're getting, and a transformation that I used from the exported script worked perfectly.  I got the error you're using when I had a typo in my transformation string as well.


This code blows up with your error

import arcpy
theFC = r"c:\temp\myFeatureclass.shp"
g = arcpy.Geometry()
to_sr = arcpy.SpatialReference('WGS 1984')
geometryList = arcpy.CopyFeatures_management(theFC, g)
for geometry in geometryList:
 projectedGeometry = geometry.projectAs(to_sr,r'NAD_1983_HARN_To_WGS_1984')
 print projectedGeometry.centroid.X, projectedGeometry.centroid.Y

This code works great

import arcpy
theFC = r"c:\temp\myFeatureclass.shp"
g = arcpy.Geometry()
to_sr = arcpy.SpatialReference('WGS 1984')
geometryList = arcpy.CopyFeatures_management(theFC, g)
for geometry in geometryList:
 projectedGeometry = geometry.projectAs(to_sr,'NAD_1983_To_NAD_1983_CSRS_4 + NAD_1983_CSRS_To_WGS_1984_2')
 print projectedGeometry.centroid.X, projectedGeometry.centroid.Y

[JamesCrandall]

Thanks, tim.  However you are still requiring an input shapefile, but I will go back and see if I can rework things prior to my new approach. 

I was hoping to avoid this and simply convert the geometry to a different spatial reference (WGS1984).  Doesn't look like this is possible, so I came up with an "in_memory" implementation that seems to do what I need.  The first click event takes about 3 seconds to build the in_memory FeatureClass but subsequent clicks the Lat/Lon values are reported immediately.

Solution:

    def onMouseDownMap(self, x, y, button, shift):
        print "x: " + str(x) + " y: " + str(y)
        
        ## get a layer loaded in the TOC to determine the spatial reference        
        mxd = arcpy.mapping.MapDocument("CURRENT")
        df = arcpy.mapping.ListDataFrames(mxd)[0]
        testCount = len(arcpy.mapping.ListLayers(mxd, "", df))
        if testCount==0:
            msg = "There are no features selected to report"
            pythonaddins.MessageBox(msg, 'Report Latitude/Longitude Values', 0)
        else:    
          for lyr in arcpy.mapping.ListLayers(mxd):
            dsc = arcpy.Describe(lyr)
            spref = dsc.spatialReference
            
            lpoint = arcpy.Point()
            lpoint.X = x
            lpoint.Y = y
            ptGeometry = arcpy.PointGeometry(lpoint, spref)

            ptFC = "in_memory\lpoint"
            if arcpy.Exists(ptFC):
                arcpy.Delete_management(ptFC)
                
            arcpy.CreateFeatureclass_management("in_memory", "lpoint", "POINT", '', "DISABLED", "DISABLED",  spref, '')
            
            cursor = arcpy.da.InsertCursor(ptFC, "SHAPE@XY")
            cursor.insertRow((lpoint,))
            del cursor
            
            to_sr = r'GEOGCS["GCS_WGS_1984",' + \
                     'DATUM["D_WGS_1984",' + \
                     'SPHEROID["WGS_1984",6378137,298.257223563]],' + \
                     'PRIMEM["Greenwich",0],' + \
                     'UNIT["Degree",0.017453292519943295]]'
           
            flds = ["SHAPE@X", "SHAPE@Y"]
            scursor = arcpy.da.SearchCursor(ptFC, flds, '', to_sr)
            prjx = 0.00
            prjy = 0.00
            for row in scursor:
                #print "X: " + str(row[0]) + " Y: " + str(row[1])
                prjx = row[0]
                prjy = row[1]

            del scursor

            
            msg = "Latitude: " + str(prjx) + "\n" + "Longitude: " + str(prjy)
            pythonaddins.MessageBox(msg, 'Report Latitude/Longitude Values', 0)

this appears to be a good solution, but if anyone can spot any issue with the above, I'd appreciate it.

[TimDine]

The fact an input shapefile is being used shouldn't be relevant.  As long as you get a pointgeometry object somehow with a defined spatial reference the projectAs should work fine. 

Your first solution shouldn't have any issue other than something being wrong with your transformation parameter (r'NAD_1983_HARN_To_WGS_1984').  I get your same error if I use the shapefile and your transformation.  The samples I provided were simplified to use shapefiles to eleminate the rest of the code as being an issue.

[JamesCrandall]

The fact an input shapefile is being used shouldn't be relevant.  As long as you get a pointgeometry object somehow with a defined spatial reference the projectAs should work fine. 

Your first solution shouldn't have any issue other than something being wrong with your transformation parameter (r'NAD_1983_HARN_To_WGS_1984').  I get your same error if I use the shapefile and your transformation.  The samples I provided were simplified to use shapefiles to eleminate the rest of the code as being an issue.

Understood -- I will re-work the original attempt. 

Thanks again,
j

[ChrisSnyder]

It makes the code a bit harder to comprehend, but how about using the WKID (well known id) for your projections and transformation definitions? I have notices some "discrepencies" in the naming conventions, and well, computers like numbers, right? I just pull the codes from these documents:

C:\Program Files (x86)\ArcGIS\Desktop10.1\Documentation\geographic_transformations.pdf
C:\Program Files (x86)\ArcGIS\Desktop10.1\Documentation\geographic_coordinate_systems.pdf
C:\Program Files (x86)\ArcGIS\Desktop10.1\Documentation\projected_coordinate_systems.pdf

[JamesCrandall]

The fact an input shapefile is being used shouldn't be relevant.  As long as you get a pointgeometry object somehow with a defined spatial reference the projectAs should work fine. 

Your first solution shouldn't have any issue other than something being wrong with your transformation parameter (r'NAD_1983_HARN_To_WGS_1984').  I get your same error if I use the shapefile and your transformation.  The samples I provided were simplified to use shapefiles to eleminate the rest of the code as being an issue.

Tim -- I tried the code below but getting the same error for the transformation:

line 217, in onMouseDownMap
    projectedPoint = ptGeometry.projectAs(to_sr, 'NAD_1983_To_NAD_1983_CSRS_4 + NAD_1983_CSRS_To_WGS_1984_2')
  File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\arcobjects\arcobjects.py", line 761, in projectAs
    return convertArcObjectToPythonObject(self._arc_object.ProjectAs(*gp_fixargs((spatial_reference, transformation_name))))
ValueError: NAD_1983_To_NAD_1983_CSRS_4 + NAD_1983_CSRS_To_WGS_1984_2

Code:

   lyr = arcpy.mapping.ListLayers(mxd)[0]
   dsc = arcpy.Describe(lyr)
   spref = dsc.spatialReference
            
   lpoint = arcpy.Point()
   lpoint.X = x
   lpoint.Y = y
   ptGeometry = arcpy.PointGeometry(lpoint, spref)
   to_sr = arcpy.SpatialReference('WGS 1984')
     
   ## fails on this line               
   projectedPoint = ptGeometry.projectAs(to_sr, 'NAD_1983_To_NAD_1983_CSRS_4 + NAD_1983_CSRS_To_WGS_1984_2')
   
   prjX = projectedPoint.X
   prjY = projectedPoint.Y
   print "X:" + str(prjX) + " Y:" + str(prjY)

[JamesCrandall]

It makes the code a bit harder to comprehend, but how about using the WKID (well known id) for your projections and transformation definitions? I have notices some "discrepencies" in the naming conventions, and well, computers like numbers, right? I just pull the codes from these documents:

C:\Program Files (x86)\ArcGIS\Desktop10.1\Documentation\geographic_transformations.pdf
C:\Program Files (x86)\ArcGIS\Desktop10.1\Documentation\geographic_coordinate_systems.pdf
C:\Program Files (x86)\ArcGIS\Desktop10.1\Documentation\projected_coordinate_systems.pdf

Thanks for your input!

I attempted to set a WKID value but end up with the same error:

    projectedPoint = ptGeometry.projectAs(to_sr, r'1900')
  File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\arcobjects\arcobjects.py", line 761, in projectAs
    return convertArcObjectToPythonObject(self._arc_object.ProjectAs(*gp_fixargs((spatial_reference, transformation_name))))
ValueError: 1900

            lyr = arcpy.mapping.ListLayers(mxd)[0]
            dsc = arcpy.Describe(lyr)
            spref = dsc.spatialReference
            
            lpoint = arcpy.Point()
            lpoint.X = x
            lpoint.Y = y
            ptGeometry = arcpy.PointGeometry(lpoint, spref)
            to_sr = arcpy.SpatialReference('WGS 1984')
                    
            projectedPoint = ptGeometry.projectAs(to_sr, 1900) #<--attempted with both integer value and r'1900'
            prjX = projectedPoint.X
            prjY = projectedPoint.Y
            print "X:" + str(prjX) + " Y:" + str(prjY)

The from system is NAD83 HARN Florida East FIPS 901 Feet, so perhaps my ignorance on the details for these coordinate conversions is just completely the cause here.

[ChrisSnyder]

Just use the integer (don't format as string):

projectedPoint = ptGeometry.projectAs(12345, 54321)

[JamesCrandall]

Just use the integer (don't format as string):

projectedPoint = ptGeometry.projectAs(12345, 54321)

Thanks again...

From the geographic_coordinate_systems.pdf (pg 35) the WKID for "WGS_1984" = 7030
From the geographic_transformations.pdf (pg 66) the WKID for "NAD_1983_HARN_To_WGS_1984_2" = 1900

Here's the updated code only using the WKID's:

            lyr = arcpy.mapping.ListLayers(mxd)[0]
            dsc = arcpy.Describe(lyr)
            spref = dsc.spatialReference
            
            lpoint = arcpy.Point()
            lpoint.X = x
            lpoint.Y = y
            ptGeometry = arcpy.PointGeometry(lpoint, spref)
                   
            projectedPoint = ptGeometry.projectAs(7030, 1900)
            prjX = projectedPoint.X
            prjY = projectedPoint.Y
            print "X:" + str(prjX) + " Y:" + str(prjY)

Here's the output error:

    projectedPoint = ptGeometry.projectAs(7030, 1900)
  File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\arcobjects\arcobjects.py", line 761, in projectAs
    return convertArcObjectToPythonObject(self._arc_object.ProjectAs(*gp_fixargs((spatial_reference, transformation_name))))
RuntimeError: Object: CreateObject error creating spatial reference