Allow user customization of terrain masking influence in inverse location
Inverse location currently ignores terrain masking effect. When the user
a ground location that in fact would be being some other ground feature as seen from the
spacecraft (and therefore should not be visible in direct location), the computation is
done ignoring this effect. This implies that two different ground points could theoretically
be mapped to the exact same sensor pixel in inverse location, whereas this pixel location would
be mapped to only one of these ground points in direct location.
The current process is perfectly sound in some image processing chains
when the masking effects
are considered later on in the processing. However, in some cases it would be interesting for user
to be able to select a different behavior and be warned that the specified ground point cannot be
seen during this spacecraft pass over the area. There are two possibilities for this: either an exception
should be thrown or simply a null result could be returned. The second possibility (null return) seems
more logical for this case, as it is simply equivalent to a "No DATA" information, its not a logical
error as would be implied by an exception.
(from redmine: issue id 186, created on 2015-01-13)