Aspect Ratio Management

General Information

The Aspect Ratio is the ratio of the pixel width of your display to the height of the display. Commonly you'll see it listed as a number (1.25 or 0.8) or as a ratio (5:4). Knowing your display's aspect ratio can help you optimize your visual display for a more balanced and less skewed graphical presentation.

OFP and ArmA are rather unique in that they have excellent support for arbitrary display resolutions and aspect ratios. Aspect ratios are defined specific to different application users, so it is possible to have multiple in-game profiles with different aspect ratios. Below is a listing of different aspect ratios available from different displays:

04:03   .75
05:04   .8
16:09   .5625
16:10   .625

x       y       scale   num
0640    0480    4:3     .75    
0800    0600    4:3     .75
0960    0600    16:10   .625
1024    0768    4:3     .75    (Common default CRT setting)
1088    0612    16:09   .5625
1152    0864    4:3     .75
1280    0720    16:09   .5625  (HDTV 720)
1280    0800    16:10   .625
1280    0960    4:3     .75
1280    1024    5:4     .8     (Common 17" and 19" LCD native resolution)
1600    0900    16:09   .5625  (Common mid-size laptop native LCD resolution)
1600    1200    4:3     .75    (Common upper limit of non-widescreen CRT's and LCD's)
1680    1050    16:10   .625
1920    1080    16:09   .5625  (HDTV 1080)
1920    1200    16:10   .625   (Various workstation-class laptops)
2560    1600    16:10   .625   (Apple/Dell 30")
3840    2400    16:10   .625   (IBM T220/1 and derivatives)

*0848    0480    .566037735
*1280    0768    .6
*1360    0768    .564705882
*1600    1024    .64

OFP / VBS1 specific information

The first generation of Bohemia Interactive products do not have an internal mechanism for adjusting the aspect ratio within the program, the values must be manually edited outside in the userinfo.cfg file. this can be found in the appropriate subfolder in the user profiles directory within the application installation location. Although it is possible to use the "-x=" and "-y=" startup parameters to dynamically set the display resolution, there is no other provision for display aspect ratio management. Restart is required to change the aspect ratio.

ArmA / VBS2 specific information

The second generation software has the ability to select from a hard-coded list of different aspect ratios from within the program. These values are then stored in the user editable username.Armaprofile or username.vbs2profile file located in the respective profile location in the My Documents system folder.

The default list includes 3:4, 4:5, 16:9, 16:10, and 12:3 for Matrox TripleHeadtoGo systems. There is no method for altering this list, aspect ratios not matching these values must be manually configured. Changing values within the internal selection list in the Video options dialog is effective immediately, unlisted values have be manually defined and require a program restart.

Aspect ratios and display resolutions are now handled exclusively within the respective .*profile and *.cfg files, the -x / -y startup parameters have been deprecated and have no effect.

Multi-display compatibility

Matrox markets two consumer-oriented products capable of combining two or three displays into a single virtual display. The : DualHead2Go combines two displays into a single channel, while the : TripleHead2Go combines three displays. Both generations of BI software automatically support these devices as they are capable of automatic display resolution and definable aspect ratios.

Logically these devices present to the computer a single virtual monitor with the dimensions of all connected devices combined. This allows DirectX applications limited by the Direct3D API to output a single rendered scene across multiple displays, up to the limit of the respective Direct3D API (DirectX 9 limits applications to a maximum of 4096x4096 pixels).

Nvidia has for many years provided a software option in their dual-port video cards as well that allows the two ports to be combined as a single virtual output as well. However, in their consumer-grade cards the secondary port's render channel is a dependent channel instead of a fully independent channel, which will result in noticeably reduced performance on the monitor attached to the secondary port. Most Quadro FX cards have fully independent channels and do not have this performance bottleneck.

ATI cards at the time of the publishing of the first generation software did not have support for combining dual outputs, it's unknown if this feature has been added in current generation models.

As listed above, ArmA and VBS2 include a single aspect ratio for TripleHead2Go usage. Other multi-display aspect ratios must be manually configured with the values listed below. Display resolutions available from the display aggregation provider will be automatically listed within the Video options.

x       y       scale   num    notes
2048    0768    8:3     0.375  Dual 1024x768
3072    0768    12:3    0.25   Triple 1024x768
2560    1024    8:4     0.5    Dual 1280x1024
3840    0960    12:3    0.25   Triple 1280x960
3840    1024    15:4    0.2666   Triple 1280x1024
4096    0768    16:3    0.1875 Double-Dual 1024x768

3840    1200    32:10   0.3125 Dual 1920x1200
3840    1080    32:9    0.28125 Dual 1920x1080
3360    1050    32:10   0.3125  Dual 1680x1050
3840    0800    48:10   0.2083  Triple 1280x800
3200    0900    32:9    0.28125 Dual 1600x900

While some DirectX 10 native cards may be capable of interfacing larger display resolutions with dimensions less than 4097 pixels, these require DirectX 10 native application on Windows Vista, and so are not applicable with current BI software.

The Double-dual configuration listed above requires a dual-channel Nvidia video card with both outputs merged into a single virtual output, with each physical port connected to a separate DualHead2Go.

Double-channel configurations are not compatible with SLI configurations, SLI systems must use an external aggregation device such as the Matrox products.

Further reading

It is possible to have very non-traditional display configurations eg 1200x3840 portrait orientation as opposed to 3840x1200 landscape orientation. Listing all possible options is beyond the scope of this page.

With multi-display configurations you may wish to reduce the aspect ratio to lower than the values specified to reduce extreme peripheral stretching. Zooming the FOV in with scripted cameras can also help alleviate that problem.

Net environment aspect ratios lower than approximately 3:1 (.333~) may be better displayed with multiple stations configured with scripted cameras offset to a designated source. Note that there is no provision for remote render synchronization or similar genlock capability support.

BI Forums post about setting the Aspect Ratio

Wikipedia : Display Resolution

Wikipedia : Aspect Ratio

See also Startup parameters for "-x=" and "-y=" parameter usage.