FSX/P3D: Horizon Alignment

[devsim]

Hi all,

On a default FSX or Prepar3d setup, the horizon line goes right through the center of the screen vertical edges. My phsyical eye point is fixed and based on the underlying cockpit setup and the projected screen position and size is fixed as well, I'd like to move the horizon towards the lower edge of the projected area.

I tried pitching the camera via Cameras.CFG as well as using Ctrl-Shift-Q and Ctrl-Q for paning the camera. Both methods have the same effect: The horizon is lowered but all vertical elements such as buildings, the tower etc is tilted too. Most importantly, it doesn't work well when more than one screen is in play as the alignment goes of at the edges between two projected areas.

Any ideas?

Regards,
DevSim

[Peter Dowson]

On a default FSX or Prepar3d setup, the horizon line goes right through the center of the screen vertical edges. My phsyical eye point is fixed and based on the underlying cockpit setup and the projected screen position and size is fixed as well, I'd like to move the horizon towards the lower edge of the projected area.

Yes, and it is quite annoying. I had exactly the same problem. I know exactly where my horizon should be in relation to the edges of the front windows of my 737NG cockpit. I can't tilt the cockpit up or down and FSX has no means of shifting the view up or down other than raising the eyepoint itself (which is no good because to get the horizon looking right that way you have to be so high you look down on everything which should be on your level, etc etc), or by tilting the camera view.

The horizon is lowered but all vertical elements such as buildings, the tower etc is tilted too.

With a 10 foot wide projection only 6 feet in front of my window that was my problem. it still is a bit, but i used the projector facilities, there to counter distortion from titlting, to actually distort the screen shape to be narrower at top than at bottom. So I have some blank sceen at top left and right and some lost image off the edges bottom left and right. I settled for a slight distortion of verticals at the edges, but this is only really noticeable when up fairly close to a building edge or post.

It's a compromise, but the only one I could come up with which sort-of works.

Most importantly, it doesn't work well when more than one screen is in play as the alignment goes of at the edges between two projected areas.

Ah, yes. I don't have that problem -- not enough side space for side views I'm afraid. "Luckily" I have RP giving me severe tunnel vision, so provided I keep eyes front i don't notice the lack of a peripheral view (it's the only advantage of this sight defect though).

I'm afraid I've no idea how you'd get over that problem -- except maybe physically tilting the screens themselves to compensate? Might help. or not? I'm trying to work it out in my head ...

Regards
Pete

[wledzian]

No amount of camera tilting or eyepoint shifting will produce a correct result. As you have already figured out, what you need is an offset frustum. I don't think FSX can do this, unless you can specify a window that is taller than the display height. I can test this when I get home tonight, but if you want to beat me to it, you can try altering the fourth term of the ScreenUniCoords parameter in your .flt file window definitions (vertical height component) to a value larger than 6144. For example, if it works, a value of 8192 should put the horizon about 1/3 up from the bottom. Of course, this will mean that FSX is wasting effort drawing off-screen pixels.

Prepar3d does have facilities to specify frustum geometry, but I haven't had a chance to try it out yet, and am therefore unfamiliar with the details.