A second-order theory of texture for depth from focus

2026-08-10

AI Summary

This study addresses the failure of conventional passive depth estimation methods on textureless surfaces, which lack sufficient intensity variations for reliable matching. By formulating a second-order texture theory grounded in wave optics for rough surfaces, this work reinterprets subjective speckle patterns as valid texture signals—thereby transcending traditional definitions of texture. The authors propose enhancing speckle contrast through narrowband spectral filtering and integrate this approach with depth-from-focus algorithms to achieve high-precision passive depth reconstruction. Comprehensive validation via theoretical analysis, simulations, and real-world experiments demonstrates that the method substantially improves depth estimation quality in scenes conventionally regarded as textureless.

Abstract

We present a theory of textured appearance of optically rough surfaces based on wave optics, emphasizing the role of texture for passive depth from focus. Our theory shows that even surfaces that traditional computer vision would consider textureless can produce textured appearance, due to subjective speckle from surface microgeometry. We analyze the properties of this second-order texture, and show that we can enhance its contrast under natural ambient lighting by simply using a narrowband spectral filter. Doing so results in dramatic improvements in passive depth reconstruction of seemingly textureless scenes, as we demonstrate through extensive theory, simulations, and real-world experiments.

Problem

• depth from focus
• textureless surfaces
• passive depth estimation
• speckle texture
• optical roughness

Innovation

• second-order texture
• depth from focus
• subjective speckle
• wave optics
• narrowband spectral filtering