On 1/16/2016 5:37 AM, Kenneth wrote:
> I took a look at that web page, and it *is* difficult to figure out how the
> color blending (for depth cues) should be done.
>
> But here's a 'thought experiment':
>
> Let's say that on a clear day (in the real world), the distant horizon is twenty
> miles away (just a guess.) Between 19 1/2 and 20 miles out, there is almost *no*
> 3D effect that we can discern; whereas, from your eyes to 1/2 mile out, there
> is much more of a 3D effect. (In fact, the '3D appearance' of objects in a scene
> becomes much more pronounced, the closer those objects are to our eyes.)
>
> Translating that into color blending (using two random colors): If pure GREEN is
> located at your eye position, and pure BLUE is 20 miles out, it would seem that
> the 'middle blend' of the two colors should *not* be at the 10-mile mark, but
> should be much closer to your eye position-- maybe at the 3-mile mark(?)  So, it
> seems that the color blend should not be linear, but exponential in some way.
>
>
>
>


In section 3.4.2.1.3 Angles of the docs it gives the following formula:

direction_length = 0.5 * right_length / tan(angle / 2)

Maybe distance is related to the perceived change in foreshortening in 
the same way, based on tan(angle)?

Mike

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