ExportToTif width / height calculation

Discussion created by josepharmbruster0lat on Oct 3, 2013
I am using arcpy to export of a dataframe to geotiff. The dataframe contains all of the feature / raster data for a JOG sheet. The code looks like this:

dpi = 300
output_tif = #... path to the output geotiff
path_to_mxd = # ... contains the path to the mxd of interest

mxd = arcpy.mapping.MapDocument(path_to_mxd)

# we assume basemap exists...
target_data_frame = arcpy.mapping.ListDataFrames(mxd, 'BaseMap')[0]

mxd.activeView = target_data_frame

map_document = mxd,
out_tif = output_tif,
data_frame = target_data_frame,
resolution = dpi,
world_file = True,
color_mode = '24-BIT_TRUE_COLOR',
tiff_compression = 'NONE',

After exporting, I end up with a 640x480 image. For the content of a JOG map sheet, this is obviously not what I want. There are two additional parameters I can provide to this function; df_export_width and df_export_height but I am not certain how they should be calculated using only the meta-data that is available via the arcpy interfaces (mapdocument, pagesize, elementsizes / etc...). I would like to reproduce the exact-width and height values for a given DPI, the same way the "Export Map" dialog calculates it within arcmap. The detail here is that I am using a dataframe, not a layout view. For layout view, the formula is trivial:
- df_export_width = mxd.pageSize.width * conversion_factor * dpi
- df_export_height = mxd.pageSize.height * conversion_factor * dpi

In my case, the page units are centimters, so the conversion factor is 0.393701. Obviously, this logic does-not make sense when using a dataframe...

So what is the formula for width and height when using a data frame?

Thank You in advance.