# Thread: What sort of scale works?

1. ## What sort of scale works?

ok I have a gorgeous seamless skybox and turned my attention towards terrain.

I drew a simple grid but my height relative to it doesn't look right. I wanted 1 unit to be equal to 1 foot but if I translate myself 6 units away from a 1 unit square it's smaller than expected. I experimented by putting a 1 ft square piece of paper on the ground and looking down at it for comparison.

2. ## Re: What sort of scale works?

It is more a matter of ratio. If your near clipping plane is at z = 5.0 (-5.0??), and you draw a square in the x-y plane, then if you draw the same size square at z=10.0 (-10.0??) It should look about half the size. So, you will probably want to use squares parallel to the display screen plane and figure out the size that looks like it would = a foot, then use that value as = foot. You cannot just assume that 1 unit = 1 foot or 1 unit = 1 mile.

Hope that helps

3. ## Re: What sort of scale works?

I wanted 1 unit to be equal to 1 foot but if I translate myself 6 units away from a 1 unit square it's smaller than expected. I experimented by putting a 1 ft square piece of paper on the ground and looking down at it for comparison.
If you want to make such a comparison, you must make sure the field of view of your projection matrix matches the field of view formed by the window on your screen. For example, if you have a full screen window (say 30 cm high, also note that I'm talking about real world length here), and you're sitting, say, 50 cm away from your screen, the horizontal field of view you pass to gluPerspective should be 2*arctan(30/(2*50)) = 33 degrees (in this example). Anything other than this value will not represent what it looks like in the real world. Larger fov will result in smaller objects.

[This message has been edited by Bob (edited 02-06-2003).]

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