[GDAlgorithms-List] RE:

[Steve W. <Ste...@im...>]

> From: Kirk Hammond <kha...@to...>
> Date: Fri, 14 Jul 2000 16:27:23 -0400
> 
> This has been something I have mulled for some time.  What _really_
> denotes scale in a 3D engine?  I currently run a ROAM based terrain
> engine with units like tanks, planes, yada yada.  Obviously 
> the scale of
> objects moving by the viewer affects the perception of speed 
> and size of
> a world unit.
> 
> So, this would lead one to believe that as long as you are consistent
> with your units (as I am), then everything would be fine.  And indeed,
> if I put a 2000 m cruiser in space and fly in a ship at 200 
> m/s it takes
> 10 sec to fly by the ship.  Fine and dandy.
> 
> But... something about this just doesn't seem correct.  I saw 
> a previous
> thread on this but I still think I need someone to shed some light on
> this for me...
> 
> (e.g. if you have in the same 3D engine the view from an ant on the
> ground and a view from a human walking above...  aren't there viewport
> changes from the two vantages beyond moving the camera around and the
> fact that the camera is higher above the ground on the human?  I mean,
> if the human stuck his eye on the ground level with the ant's 
> viewpoint,
> doesn't the human still see more of the terrain than does the ant?)
> 
> -kirk
> 

Kirk,

Other than determining what texture size is large enough so that up close it
won't get too grainy and small enough so it won't slow the engine down, I
think this is something that we all "play" with until it "looks" right.
Thankfully we only have to find a familiar perpective and the geometry
pipline will make the world at that scale.

Personally, I used a grid pattern of 1 unit squares for a floor, then placed
a 8 cubit unit square box (2 units per side) on it and placed a optimal 256k
bitmap on each side that included text (Front, Back, Left, Right, Top,
bottom), then using cameraview stepped back from it, up to it, around it,
and looked over it until I decided what that size means to me...if I didn't
like it then I tweaked my pipeline with a different viewport and/or changed
the speed at which I can move the cameraview around until it felt real and
the box looked real.

Hmm, now that you mention it the size WOULD be relative. To me one unit in
my engine represents roughly 5' cause I'm 6' tall and my eyes line up with
the text on the box which is located .2 units above the centerline.
However, if someone about 4' tall (about 20% of target audience) was playing
the game then they would think it's smaller...say 1 unit = 3.3'. If an ant
was playing the game (I think anyone can get a credit card these days) then
it would think it was like .1". There isn't that much of a difference
between 4' and 6' until you get up close, and you mind will probably make up
the difference far away.

R&R