Mobile devices with passive depth sensing capabilities are ubiquitous, and recently active depth sensors have become available on some tablets and AR/VR devices. Although real-time depth data is accessible, its rich value to mainstream AR applications has been sorely under-explored. Adoption of depth-based UX has been impeded by the complexity of performing even simple operations with raw depth data, such as detecting intersections or constructing meshes. In this paper, we introduce DepthLab, a software library that encapsulates a variety of depth-based UI/UX paradigms, including geometry-aware rendering (occlusion, shadows), surface interaction behaviors (physics-based collisions, avatar path planning), and visual effects (relighting, 3D-anchored focus and aperture effects). We break down the usage of depth into localized depth, surface depth, and dense depth, and describe our real-time algorithms for interaction and rendering tasks. We present the design process, system, and components of DepthLab to streamline and centralize the development of interactive depth features. We have open-sourced our software at https://github.com/googlesamples/arcore-depth-lab to external developers, conducted performance evaluation, and discussed how DepthLab can accelerate the workflow of mobile AR designers and developers. With DepthLab we aim to help mobile developers to effortlessly integrate depth into their AR experiences and amplify the expression of their creative vision.

Peer-to-peer overlays envision a single overlay substrate that can be used (possibly simultaneously) by many applications, but current overlays either target fast, few-hop lookups for contacting directly the responsible nodes, or slower multi-hop lookups that can be used by applications that exploit the overlay topology (like multicast or anycast). In this paper we present Pastel, an extension to Pastry that bridges the gap between the two types of overlays. Pastel maintains both Pastry routing tables and a full information table, and we show how we can exploit synergies between the maintenance of the two. We also propose a novel API that is richer than the one offered by existing overlays, to give applications control over the type of lookups (structured, multi-hop routing, or attempt direct contact). We implemented Pastel in a discrete-event packet level simulator and our results show that Pastel has lookups that are usually more efficient than Pastry's. Furthermore, the bandwidth required by Pastel is modest, even for a system with thousands of nodes.