Comment 2 for bug 1384674

The environment variable `TMPDIR' controls the placement of temporary files
as documented in section "Tuning Memory Usage" of the Enblend and Enfuse
manuals.

The actual, assigned directory for the ImageCache can easily be inquired by
calling Enblend or Enfuse with the option pair `--verbose --version' or shorter
`-Vv', and the relevant part of answer looks like this:
    Extra feature: image cache: yes
      - environment variable TMPDIR not set, cache file in default directory "/tmp"
or
    Extra feature: image cache: yes
      - environment variable TMPDIR set, cache file located in "/work"
if
    TMPDIR=/work

Both options, `--verbose' and `--version' are documented, too.

The user is responsible for setting up TMPDIR (if required at all) as well as
for feeding properly overlapping images with suitable alpha channel into
Enblend or Enfuse.