There are three option sliders in the Graphic settings, and four Visibility Range options to be used with it:
*Level of Detail
*Displayed Object Size
*Ground Detail Range
* Full Visibility Range
* Medium Visibility Range
* Short Visibility Range
* Ground Visibility Range
To me, of the three graphics settings, the DOS effects me in the most harsh manner, and then the GDR, and finally the LOD.
I've tested it out with the settings, and so far this is what I have come to believe:
LOD
Despite its name, the Level of Detail slider hardly effects performance at all.
What it does, is effect the level of detail in very minor areas. For one thing, if you increase the LOD it makes the trees look a little larger and more plentiful. It also increases the number of eye-candy background objects seen in the plane selection hangar.
DOS
Displayed Object Size effects the system in the heaviest manner. In a 3-dimenional game like this, portraying an object at long distances become a problem.
For example, there's a building at the horizon. How does the system depict it?
Does the system have to depict the building in full detail, chimneys and cornerstones and all, in a very small scale which the eye cannot perceive anyway?
Or does it use a simplified, modest, 'rounded-out' polygons at long distances, and then switch to more detailed polygons at closer range?
The former method is a system hog, the latter is more economical. When you increase the DOS you move towards the former, when you decrease it you move towards the latter.
GDR
According to visibility range settings the Ground Detail Range may or may not, become a heavy fps impact. I think everyone knows what the GDR does - it chooses the distance which ground object details including trees and stuff, is portrayed. Ground objects - including some field objects, trees, terrain eye-candy(like barns), GVs, bridges, roads... - outside the set GDR range is not portrayed.
Full Visibility Range(Shift+F1)
FVR portrays all objects in the manner set by the graphics settings upto all ranges.
Medium Visibility Range(Shift+F2)
MVR portrays all objects in the manner set by the graphics settings, only at lower altitudes.
Short Visibility Range(Shift+F3)
Ugh.. don't use this one.
Ground Visibility Range(Shift+F4)
GVR is a specialized setting for GVs, which greatly reduces the visibility range of the terrain at SVR levels, but increases GDR(Ground Detail Range) to 4 miles out.
.....
So, if you are using full visibility range with all sliders maxed out... imagine what happens when there's a CV task group attacking an airbase near the shore. This situation is the most appropriate to test out how your system is really dealing with AH2.
The system has to display all of the task group ships in full detail, as well as the town buildings and airfield buildings/objects, at all altitudes and distances(since you are using full visibility range).
The system has to deal with more luscious looking trees, and objects inside the main hangar, which is hardly even visible from the air.
At the same time it has to depict ack fire, flak fire, ground vehicles, smoke, explosion... and above all of that, calculate each of the planes moving.
So, if you set the settings to maintain a fps over 30 in the above situation, then basically it's good enough.
On a scale of 0% to 100%(0% being maximum performance, 100% being maximum detail..):
I set my system at:
* Medium Visibility Range
* LOD 50%
* DOS 0%
* GDR 70%
This gives out very natural results with high visual qualities that doesn't effect performance much. The only 'awkward' moments are when you change altitudes and the trees momentarily 'switch on and off'.