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I am making an object and i need to figure out a way to trick the brain in a VR game i am making but i cant figure out this simple problem.

Standing on a ship 18km in length the characters avatar will be 20 m tall since i cannot change the actual dimensions of the character or the room i need to scale everything to make it look to the character that he is 20 m tall. How would i find out the scaling i am going to need for the 18km surface?

more information* edit

A person lets just say is 6 feet is not tall enough for what i need him to be. I need him to be 20 m tall and picture it being a humanoid so he would see from the high of the 20 m or 19.5 m. Because the real person is 6 feet i would need to scale the ship as if the person was 20 m tall.

What is the length of the ship if the avatar was 20 m tall. when the avatar starts at 6 feet tall.

i have no idea how to do this.

Ian W
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  • You need to post some more details to get a good answer. In your game what does it mean to be 20m (other than it's about $1/1000$ than the length of the ship)? Are there other objects with heights on the order of 20m? What viewpoint will one view the avatar? From high above? from approximately 20m high? from 1cm high? From 1cm high the surface will look infinitely long and the avatar will be very tall. At 1 end of 18km surface from 20m high avatar will look same height as viewer and other end of the surface would be similar to a 6ft man looking at end of 1 mile surface (1:1000 ratio) – Χpẘ May 08 '17 at 17:47
  • How about now is this enough information? – Ian W May 08 '17 at 18:00
  • I still don't understand. You already said ship was 18km, but your edit asks how long ship is. Do you want to know that given an avatar of 6ft and a ship that is 18km, how to scale the ship if you scale the avatar to 20m? If so then it would be $18km * 20m/6ft$ – Χpẘ May 08 '17 at 18:13

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Your lengths should simply be scaled reciprocally. That is: If your Avatar is ten times as tall as normal, scale everything else down by a factor of $\frac1{10}$.

There are some caveats, though: Be sure to adjust the physics accordingly. If a 2m person drops a ball from the height of his head, the ball will hit the ground after 0.45 seconds, but if a 20m person does the same it takes $\sqrt{10}$ times as long (1.4 seconds), just as if the gravitational acceleration was 0.98 m/s² instead of 9.8 m/s².

Hagen von Eitzen
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