python定义影像投影

import os
import arcgisscripting
gp=arcgisscripting.create()
coordsys=r"C:\Winx86\ArcGIS\Coordinate Systems\Geographic Coordinate Systems\Asia\Xian 1980.prj"

root=r"c:\需要设置投影的目录"
for p,dirname,filename in os.walk(root):
    for name in filename:
	    ext=os.path.splitext(name)[1]
		if ext==".tif":
		    test=os.path.join(p,name)
			print test
			gp.defineprojection(test,coordsys)

print "DONE!"