Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices Matthias Trapp, Lars Schneider, Norman Holz, Jürgen DöllnerHasso-Plattner-Institute, University of Potsdam, Germany


motivation :3D virtual environments (3DVE) goes mobile: Nurminen did that before (2006) but: new advances in mobile graphics hardware hardware accelerated 3D rendering is available experiments with high-order visualization determine current device limitations ! 3D visualization of points-of-interests (POIs): facilitate navigation & exploration in 3DVE involves per-frame geometry management and rendering applications: augmented reality, pedestrian navigation ? motivation 2 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


result preview ::: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: 3 result preview 3D halo projection 3D halo circle


agenda :challenges & problem statement 3D visualization of point-of-interests 3D halo projection & 3D circle approach occlusion management implementation overview discussion & conclusions & future work agenda 4 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


challenges & problems :adaptation of 2D halo approach [Baudisch 2003]: direction ? distance ? 3D virtual environments exhibit: varying perspectives object occlusion amount of geometry and texture (more) complex interaction scene management on mobile devices: real-time rendering constraints limited device capabilities (e.g. memory, screen size, …) challenges & problems 5 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


points-of-interest & 3D visualization :point-of-interest (POI) / waypoint: useful or interesting point location usually specified in 2D coordinates objects-of-interest: 3D shape that represents important building can have multiple POIs (entrances, offices…) can be (partially) outside/inside view frustum main problem: POI visualization depend on user perspective (virtual camera) 3D geometry of objects and scene points-of-interest & 3D visualization 6 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


points-of-interest & 3D visualization :A: high perspective + vertical extend of building B: low perspective + vertical extend of building C: low perspective + horizontal extend of building points-of-interest & 3D visualization 7 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


appropriate representation point (ARP) :δ: compute cloud-of-interest (COIObject) for an object (set of suitable POI for visualization) σ: select ARP that represents a POI according to… object‘s shape current setting of the virtual camera use selected ARP for visualization/rendering appropriate representation point (ARP) 8 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


3D visualization of off-screen point-of-interests :2D approaches to estimate direction & distance: halos, scaled arrows, stretched arrows experiments with four 3D approaches: 3D halo spheres (worldspace) 3D halo billboards (worldspace) 3D halo projection (screenspace) 3D halo circles (worldspace) :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: 9 3D visualization of off-screen point-of-interests


3D halo projection :: conceptual overview ::: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: 10 3D halo projection :: conceptual overview


3D halo projection - results ::: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: 11 3D halo projection - results


halo projection - results :halo projection - results 12 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


3D halo circle :: conceptual overview ::: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: 13 3D halo circle :: conceptual overview


3D halo circle :: results :3D halo circle :: results 14 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


3D halo circle :: results ::: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: 15 3D halo circle :: results


occlusion management for points-of-interests :prevent points-of-interest (targets) from being occluded by unimportant scene objects (distractors) occlusion management for points-of-interests 16 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: [Elmqvist 2008]


occlusion management for points-of-interests :primary purpose: object discovery single view paradigm object-space solution environment properties: high object density, but low object complexity proximity object interaction:  we choose virtual X-ray pattern :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: 17 occlusion management for points-of-interests [Elmqvist 2008]


visual representation of distractor buildings :omit rendering visual representation of distractor buildings wire-frame style no management 18 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: problem: no α-channel  no alpha blending


results :: occlusion management + POI visualization :results :: occlusion management + POI visualization 19 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


implementation :: overview :target platform for proof-of-concept implementation: iPhone 3D & iPod Touch (not limited to) dedicated GPU (PowerVR MBX Lite 3D) 128 MB RAM ( ~ 11 MB video RAM) APIs: Apple iPhone SDK developed a custom light-weight scene graph API based on OpenGL ES 1.1 (now 2.0 available) per-object view-frustum culling implementation :: overview 20 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


implementation :: rendering at a glance :implementation :: rendering at a glance 21 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


implementation :: performance evaluation :two test data sets (medium/large) 41,032 / 56,654 vertices 624 / 5924 objects ~4/8 MB texture data performance results: implementation :: performance evaluation 22 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


discussion :both approaches: enable distance & direction estimation exhibit visual cluttering for multiple POI but require user evaluation 3D halo projection approach: problem: POIs behind the virtual camera 3D halo circle approach : estimation becomes harder for POIs farther away open issues for occlusion management: landmark-landmark occlusion :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp :: 23 discussion


conclusions & future work :wrap-up: approaches for 3D POI visualization rendering of simple 3D GeoVE on mobile devices limited device capabilities (memory, cpu, gpu, battery) future work: reduction of visual cluttering semi-transparent occlusion style discuss possible advantages of a POI service conclusions & future work 24 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::


thank you for your attention… questions ? :thank you for your attention… questions ? Contact: Matthias Trapp matthias.trapp@hpi.uni-potsdam.de Lars Schneider lars.schneider@students.hpi.uni-potsdam.de Norman Holz norman.holz@students.hpi.uni-potsdam.de Jürgen Döllner juergen.doellner@hpi.uni-potsdam.de Computer Graphics System Group www.hpi.uni-potsdam.de/3d Researchgroup 3D-Geoinformation www.3dgi.de 25 :: LBS 2009 :: Strategies for Visualizing Points-of-Interest of 3D Virtual Environments on Mobile Devices :: Matthias Trapp ::