Finding centre point of a raster in ArcGIS?

Question

If I have, say, a rectangular and georeferenced raster file loaded in an ArcMap 10 document (.tiff w/ associated tfw), how do I easily find its centre point and store that point in a points vector layer?

Also, if I have multiple such rasters in my ArcMap document, how do I apply the process to all of them?

Unfortunately, I have zero Python experience. Therefore a programmatic solution is OK, but I will need specific instructions on how to load an existing script into ArcGIS 10, and run it on the rasters in questions. (BTW, the rasters are all in their separate layers).

Answer 1

Though the original question was for 10.0, I have updated the code below for 10.3.1.

Copy paste this into the python window in arcmap to create the RasterCenter function:

import arcpy, os
def RasterCenter(raster):
    #raster: string reference to raster
    raster = arcpy.Raster(raster)
    fcname = "{}_center".format(os.path.basename(str(raster)))
    x = raster.extent.XMin + (raster.extent.XMax - raster.extent.XMin)/2
    y = raster.extent.YMin + (raster.extent.YMax - raster.extent.YMin)/2
    featureclass = arcpy.CreateFeatureclass_management("in_memory", fcname, "POINT",spatial_reference = raster.spatialReference)
    with arcpy.da.InsertCursor(featureclass, ['SHAPE@XY']) as cursor:
        cursor.insertRow(((x, y),))
    mxd = arcpy.mapping.MapDocument("CURRENT")
    df = arcpy.mapping.ListDataFrames(mxd)[0]
    arcpy.MakeFeatureLayer_management(featureclass, fcname)
    layer = arcpy.mapping.Layer(fcname)
    arcpy.mapping.AddLayer(df, layer)

Then, you can use the python window to create your feature class by calling

RasterCenter("<reference to raster">)

So, for example, if you have a raster named DEM, you call RasterCenter("dem") in the python window, and it will add a layer named "dem_center" with a single point at the center of the raster. The layer is stored in memory, so if you want to keep it, export it.

To go one step farther, you can save the script to a .py file and place the .py file in the search path for python. e.g. save it as RasterCenter.py and place it in PYTHONPATH (normally the spot for this is C:\Python26\ArcGIS10.0\Lib)

Then you could do:

import RasterCenter
RasterCenter.RasterCenter("<reference to raster">)

Answer 2

Very easy, simple get the rasters properties and work out the centre point from min, max x and y

MinX = arcpy.GetRasterProperties_management("raster", "LEFT")
MinY = arcpy.GetRasterProperties_management("raster", "BOTTOM")
MaxX = arcpy.GetRasterProperties_management("raster", "RIGHT")
MaxY = arcpy.GetRasterProperties_management("raster", "TOP")

centreX = (MaxX + MinX) / 2
centreY = (MaxY + MinY) / 2

And the usual error checking etc....

Then add to your point table with an updateCursor