Correct Aircraft Size at Various Distances

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Correct Aircraft Size at Various Distances

Postby Six » Wed Feb 20, 2019 1:19 pm

Hello,

An F-15 Eagle is 63 ft. 9 in. long, and has a wingspan of 42 ft. 10 in. Is it possible to determine the length and wingspan of the F-15 when it is a half of a mile away? Is there a formula that can calculate the size of an object at various distances?

I would like to know because I would like to get aircraft and objects in flight sims to be the size they would be in real life.

Thanks for the help,

Six
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Re: Correct Aircraft Size at Various Distances

Postby B0ikat » Wed Feb 20, 2019 2:39 pm

The models are 1/1 scale. Dimension wise, the sim is modeling a full scale model.,

What you are asking about also would mainly depend on your "zoom" and monitor size. A "zoom" of around 50-55 is roughly equal to the natural "magnification" of the human eye. Other variables, like monitor size and distance between your eye and the monitor screen makes it extremely difficult to answer your question.
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Re: Correct Aircraft Size at Various Distances

Postby Six » Wed Feb 20, 2019 3:01 pm

If we knew, for example, at what distance the F-15 would fit inside of a dime, if we placed a dime on the computer screen and the sim F-15 fit into the dime and was at the same distance that it would fit into the dime in real life, then we would know that the sim aircraft is the correct size at that distance.
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Re: Correct Aircraft Size at Various Distances

Postby B0ikat » Wed Feb 20, 2019 7:40 pm

Again, you still have the variables of zoom factor, screen size and distance between your eyes and the screen.
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Re: Correct Aircraft Size at Various Distances

Postby Daube » Thu Feb 21, 2019 3:43 am

Boikat, I'm not sure a zoom value of 0.5 or 0.55 is equivalent to human vision at all. That value is still quite "de-zoomed" and as a consequence, objects and scenery (everything in the sim-world, in fact) look way smaller than they should.
I don't remember what is the "correct" zoom value, might be 1.0 but I'm not too sure anymore.

Now, the thing is, when playing on a monitor screen, players tend to prefer smaller zoom values, so that they can keep a good part of the virtual cockpit visible on the screen, when looking forward. This is the origin of the problem, probably something inherited from the previous century, back when people were using 2D panels instead of virtual cockpits. Back when I was still flying with a monitor, I switched to zoom values of 0.7x or 0.8x. I got used to moving the view up and down to look at my instruments or anything that was not visible in forward view. It was a little bit difficult at first, but it quickly became an habit. The effect it had on the rendering of the scenery was worth it. Finally, mountains started looking like mountains, not just small piles of dirt. It also became easier to estimate distances.

Finally, the only real way to get a constant 1:1 scale for world and objects is to use VR helmets. I'm using a Lenovo explorer since a few month, and I'm unable to go back to flying on a monitor. Seeing the world with correct scale and looking around your cockpit naturally is just priceless. Current VR helmets have quite a bad screen resolution though, excepted for the Pimax 5K+. But that helmet is quite expensive, and requires the most expensive/recent hardware.
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Re: Correct Aircraft Size at Various Distances

Postby B0ikat » Thu Feb 21, 2019 8:50 am

I think you're right about the "zoom". I was thinking along the lines of camera lens focal lengths and the image with regards to cameras. A normal field of view and magnification is linked to the focal length, and with a SLR, a 50 t0 55 mm lens gives about a 1/1 field of view.
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Re: Correct Aircraft Size at Various Distances

Postby Six » Thu Feb 21, 2019 5:28 pm

Let us put aside flight sims for a moment.

In real life, if we were watching an F-15 fly at close to sea level, when it was .5 of a mile away from us, it would appear to us a certain size. Its wingspan and length would appear a certain size to us. Is there any way to figure out what the aircraft's length and width would be?
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Re: Correct Aircraft Size at Various Distances

Postby B0ikat » Thu Feb 21, 2019 9:06 pm

(Deep breath because I sucked at math)

Googling I found the formula:

X=r x a x Pi/180

X = the length, width, or height of the object

r = the distance to one end of the object, like the left wing tip of an aircraft pointing at you nose first.

a = angle between left and right wingtip.

Pi/180 = 3.14159../180 = .01745...

Sooooo....

X=r x a x .01745

or

r x a x .01745 = X

Plug in your own values for "r" and "a".

Just a simple example, r = 1000 feet, a = 10 degrees, we get:

1000 x 10 x .01745 = 174.5 feet

How to do this based upon the image on a 2D screen, I have no idea. :shock:

But, like I said, I'm not an expert on math, and someone who is, may be laughing his butt off right now..... :whistle:
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Re: Correct Aircraft Size at Various Distances

Postby tjitah » Sun Feb 24, 2019 1:39 am

Not answering the question directly, but I think the earlier posts about monitor size, dimensions (and don't forget aspect ratio) are very relevant. I use an ultra-wide monitor with aspect ratio of 21:9 and resolution of 3440x1440. The best zoom for me is around 0.65 to 0.70. It still feels a bit too zoomed out and I think a value of 0.80 would probably be closer to real-life on my monitor, but I like the slightly zoomed out view as it gives me better peripheral vision on the wide-screen (despite a degree of distortion at the edges) and also keeps most of the instrument panel in view. I use TrackIR, so looking down/around is effortless.

You are going to drive yourself crazy trying to get the precise value to correspond to real-life and even if you succeed, it may: (a) not be pleasing to look at on a computer monitor, or (b) cut out essential parts of your vision, which in real life are filled in automatically by the fantastic field of view of the human eye. I suggest finding a zoom value which gives you a good compromise between what looks/feels good while still tricking the brain into believing that it is close to reality.
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