We propose a depth scaling method that enables visualization of arbitrary-shaped 3D scenes on 3D displays. Most current 3D displays have a depth limitation, while the scene to be displayed has not. The trivial solutions as clipping or linear scaling of the scene's 3D bounding box suffer from nonoptimal utilization of the display's capabilities. Our approach uses spatially adaptive depth scaling that maximizes the perceptual 3D effect. From the original scene geometry, the topology and local depth ordering among objects are preserved, while depth linearity is disregarded. The scaling method applies to nearly all 3D displays, such as glasses-based, head-tracked, multiview, holographic and volumetric 3D displays. Subjective tests with the dynamic dimension display system show that our method significantly increases the perceptual 3D effect.