Diorama Forced Perspective Calculator

Scale is expressed as 1:X, so a larger X means a smaller model — a 1:87 figure is smaller than a 1:35 figure of the same real subject. Using a larger scale denominator for background elements makes them shrink relative to the foreground, which is exactly the visual cue that tricks the eye into reading them as farther away, reinforcing the diorama's actual physical depth with an exaggerated apparent depth.

It's a flat rule-of-thumb percentage of your total diorama depth built into the calculator, not a formula based on your viewing angle, focal length, or the specific scales you chose. It's a reasonable starting point for most builds, but you should mock up the transition and shift it forward or back by eye depending on how sharply your particular foreground and background scales differ.

It's simply your background scale denominator divided by your foreground scale denominator (e.g., 87/35 ≈ 2.49x), representing how much smaller background-scale objects are relative to foreground-scale objects. A higher ratio means a more dramatic size drop-off between the two zones, which generally reads as a stronger depth illusion but also makes the transition point harder to disguise.

Apparent Depth multiplies your entered physical depth by the Perspective Ratio, estimating how much deeper the scene will read to a viewer than its real footprint because the shrinking background scale compresses more implied distance into the same physical space. It's a planning number for judging whether your scale choices are creating a worthwhile illusion, not a measurement you can verify with a tape measure.