To throw another spanner in the works, I have just run some tests on changing the hemisphere only (not the date). This is a necessary first step for those of us who are in the (ahem) better southern hemisphere before even setting the date. I have found that the change does not seem to have any effect.
1. Create a new route and session
2. In a route layer add seasonal scenery. Note that their appearance matches the current date and NORTHERN hemisphere
3. Save both route and session. Exit Surveyor
4. Load both route and session into Surveyor, scenery still appears correct as per date and NORTHERN hemisphere
5. Open Edit Environment. Set hemisphere to SOUTHERN. After a short delay (a few seconds) the scenery changes to match the season for the SOUTHERN hemisphere. DO NOT CHANGE ANYTHING ELSE. Save as a new route (different name) and session. Exit Surveyor.
6. Load route only saved in step 5 above into Surveyor (note that the thumbnail is NOT a guide to the actual season). Scenery appears correct as per date and NORTHERN hemisphere, not SOUTHERN. Open Edit Environment and check, do not change, that the hemisphere is unchanged as SOUTHERN. Exit without saving.
7. Load route and session saved in step 5 above. Scenery appears correct as per date and NORTHERN hemisphere. Open Edit Environment and check, do not change, that the hemisphere is unchanged as SOUTHERN.
8. Select the route layer and move a scenery item. Open Save command. Note that the options presented are
Overwrite existing route and
Create new session confirming that no change has been made to the session. Change selection to
Overwrite existing route and
Do not save session. Save and exit.
9. Load route only saved in step 8 above. Scenery still appears correct as per date and NORTHERN hemisphere.
EDIT: More testing reveals that a change to the hemisphere will only save if a change is also made to the date.
EDIT 2: As a result of further testing I am now able to answer my original questions.
if you load a Session into Driver, which has its date set to summer, and its parent Route (also loaded, obviously) has its date set to winter, will the end result be summer as per the Session?
The date set in a Session overrides the date set in a Route to become the visible season.
if you load a Session into Driver and the Session has not been saved with a set date, and using the same Route as above then will the end result be winter as per the Route?
The date set in the Route then becomes the visible season.
if no date has been set for the Session and the Route, then will the end result in Driver be the season according to today's calendar date and the latitude?
This
seems to be correct although I would have to wait until the actual change of season according to the calendar to confirm this.