Using replaceDataSource to change geotiff file source?

Discussion created by slayback on Oct 12, 2010
Latest reply on Jul 15, 2015 by kekeje
I'm trying to take an existing mxd file and update it, automatically, with an updated raster layer. The rasters are geotiffs. However, I only get errors when I try to use replaceDataSource. Here is an example call, after I've setup "lyr" to point to the correct layer in the correct dataframe of the mxd:

>>> lyr.replaceDataSource("E:/Projects", "RASTER_WORKSPACE", "NewLayer_2010.tif")

Traceback (most recent call last):
  File "<pyshell#20>", line 1, in <module>
    floodlayer.replaceDataSource("E:/Projects", "RASTER_WORKSPACE", "NewLayer_2010.tif")
  File "C:\Program Files\ArcGIS\Desktop10.0\arcpy\arcpy\", line 179, in fn_
    return fn(*args, **kw)
  File "C:\Program Files\ArcGIS\Desktop10.0\arcpy\arcpy\", line 559, in replaceDataSource
    return convertArcObjectToPythonObject(self._arc_object.replaceDataSource(*gp_fixargs((workspace_path, workspace_type, dataset_name, validate), True)))
ValueError: Layer: Unexpected error

I have also tried using a Raster object, as returned by arcpy.Raster(filename), as the third parameter to this call, but also with no luck.

I am new to map automation in ArcGIS and arcpy - is what I'm trying to do simply not possible? Or is my syntax wrong, or I'm missing a critical step?

As an alternative, I also tried inserting (or adding) a new Layer (arcpy.mapping.AddLayer). This works, but requires a layer object to be added/inserted -- it wont work on a geotiff file. And I cant figure out how to make a geotiff file into a layer object automatically. I can do so interactively in the ArcMap session (Save As Layer File), but I need to automate this. Is there a way to do this automatically?

Or a better way all around to do what I'm trying to do? (Update one geotiff layer in mxd with a different one, where both have same size/extent/georeference etc just different values).

thanks for any tips or hints.