Software Defined Visualization (SDVis): Get the Most Out of ParaView* with OSPRay
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This document summarizes a presentation about software-defined visualization using ParaView with OSPRay. The presentation covers: - An overview of rasterization and ray tracing for visualization rendering. - Available software-defined visualization libraries including OpenSWR, OSPRay, ParaView, GLuRay, and GraviT. - A demonstration of ParaView with OSPRay, showing its capabilities for volume rendering, soft shadows, ambient occlusion, and more realistic lighting compared to traditional OpenGL. - Hands-on tutorials using ParaView with OSPRay to visualize wavelet data, isosurfaces, and volumetric data with shadows. The benefits and limitations of OSPRay integration in Para
Software Defined Visualization (SDVis): Get the Most Out of ParaView* with OSPRay
- 2. Software-Defined Visualization: Getting the most out of ParaView w/ OSPRay ▶ Intel HPC Developer Conference November, 2016 Paul A. Navrátil, Ph.D. TACC David E DeMarle Kitware
- 3. Software-Defined Visualization Performant Visualization across Hardware Platforms 3
- 4. Agenda ▶ Part I-A: Visualization Rendering – A Brief Overview ▶ Hardware configurations and considerations ▶ Rasterization summary ▶ Ray tracing summary ▶ Part I-B: Obtaining SDVis Components (sdvis.org) ▶ OpenSWR – openswr.org ▶ OSPRay – ospray.github.io ▶ ParaView– tacc.github.io/pvOSPRay ▶ Part II: Demonstrations – ParaView + OSPRay ▶ Wavelet data source ▶ Meningioma ▶ FIU ground core sample ▶ Remote Visualization to TACC 4
- 5. Part II : Hands On 5 ❏ What you need ❏ SSIS Intel_Connect pwd “saltlake16” paraview (download 5.2 RC4) data: www.paraview.org/Wiki/ Intel_HPC_Dev_Con_ParaView_and_OSPRay_Tutorial USB’s (please return them) local SMB fileshare: “afp://172.17.4.105” or “smb://172.17.4.105”.
- 6. Workflow Overview – HPC vs. Vis 6
- 7. Typical HPC Workflow Initial Conditions 01001101011001 11001010010101 00101010100110 11101101011011 00110010111010 α β γ Parameters Simulation Timestep 1 01001101011001 11001010010101 00101010100110 11101101011011 00110010111010 Timestep n 01001101011001 11001010010101 00101010100110 11101101011011 00110010111010 Results 7
- 8. Typical Visualization Workflow Timestep 1 01001101011001 11001010010101 00101010100110 11101101011011 00110010111010 Timestep n 01001101011001 11001010010101 00101010100110 11101101011011 00110010111010 Visualization Algorithms Geometry Rendering Images Display Iterate! 8
- 9. Original Community Solution: Move All Interaction to Client for Vis File Size 100 Gbps 10 Gbps 1 Gbps 300 Mbps 54 Mbps 1 GB < 1 sec 1 sec 10 sec 35 sec 2.5 min 1 TB ~100 sec ~17 min ~3 hours ~10 hours ~43 hours 1 PB ~1 day ~12 days ~121 days >1 year ~5 years Files too large to move out of data center where they were generated 9
- 11. Vis Algorithm Renderer Scientific Visualization Process ▶ the primary goal of visualization is insight ▶ a picture really is worth 1,000 words or (potentially) tera-/peta-/exa-bytes of data ▶ as dataset sizes increase so does the need for scientific visualization 01001101011001 11001010010101 00101010100110 11101101011011 00110010111010 Raw Data Geometry Pixels 11
- 12. Rasterization and Ray-Tracing ▶ Rasterization – project 3D data onto 2D image plane, step across image plane to determine color ▶ Often accelerated by purpose-built hardware ▶ Performance complexity a function of total geometry ▶ Shading typically not physically-based ▶ Ray Tracing – sample 3D data through 2D image plane, simulating light ray travel ▶ Efficient with modern many core, wide vector CPUs ▶ Performance complexity a function of visible data (acceleration structure build a function of total data) ▶ Physically-based shading “easy” (performance varies) 12
- 13. Rasterization Pipeline Modeling Transformatio ns Rasterization Display Trivial Rejection Illumination Viewing Transformatio ns Clipping Projection Starts with data or models that are described in (x,y,z) coordinates. The data usually defines solids or boundaries in terms of their skins. Transform from data coordinates to something called world space. Object Space World Space (tessellated) 13
- 14. Rasterization Pipeline Modeling Transformatio ns Rasterization Display Trivial Rejection Illumination Viewing Transformatio ns Clipping Projection Attempt to eliminate any objects that can not possibly be seen. Check endpoints of a triangle, line segment or point and store a flag for inside or outside. Perform a logical and of the endpoints to determine whether the entity is wholly in or out of the view. 14
- 15. Rasterization Pipeline Modeling Transformatio ns Rasterization Display Trivial Rejection Illumination Viewing Transformatio ns Clipping Projection Compute normals at the endpoints for lighting calculation: Ambient Diffuse Specula r 15
- 16. Rasterization Pipeline Modeling Transformatio ns Rasterization Display Trivial Rejection Illumination Viewing Transformatio ns Clipping Projection Change coordinate systems such that the eye sits at the origin and the viewing plane is defined. This is called eye space. -X Y Z Right Handed Viewing System 16
- 17. Rasterization Pipeline Modeling Transformatio ns Rasterization Display Trivial Rejection Illumination Viewing Transformatio ns Clipping Projection Eliminate any triangles or points that are not within the view frustum (outside the scene) so that we don’t have to draw them. -X Y Right Handed Viewing System Z 17
- 18. Rasterization Pipeline Modeling Transformatio ns Rasterization Display Trivial Rejection Illumination Viewing Transformatio ns Clipping Projection Project 3D objects to 2D Viewing plane. This is a projection from eye space to screen space. -X Y Z Right Handed Viewing System 18
- 19. Rasterization Pipeline Modeling Transformatio ns Rasterization Display Trivial Rejection Illumination Viewing Transformatio ns Clipping Projection Convert the object into pixels using some sort of interpolation (usually linear). 19
- 20. Rasterization Pipeline Modeling Transformatio ns Rasterization Display Trivial Rejection Illumination Viewing Transformatio ns Clipping Projection Starts with data or models that are described in (x,y,z) coordinates. The data usually defines solids or boundaries in terms of their skins. Transform from data coordinates to something called world space 20
- 21. OpenGL Pipeline Vertex operations such as lighting, clipping, projection and viewport mapping Series of framebuffer addresses and values. Series of conditional tests such and modifications such as blending and z-buffering 21
- 22. Recursive Ray Tracing Example A C B D A CB D ray tree E E … 22
- 23. Recursive Ray Tracing Example A C B D A B C D ray tree primary ray secondary rays 23
- 24. Acceleration Structures ▶ First ray tracers tested every object for intersection Created acceleration structures to reduce object tests ▶ Focus object tests on those that are likely to be hit ▶ Bound a complex object with a simpler one if simple test fails, no need for complex test ▶ Partition space to group objects, only test objects when a ray enters their partition ▶ Acceleration structure creates groups of scene data ▶ These groups determine which data are accessed together ▶ Nearby objects accessed together only if they occupy the same part of the acceleration structure 24
- 25. Bounding Volume Hierarchy A C E B D A B C D E • Subdivides object space • Bounded regions can overlap • Must test all regions per level to find nearest intersectionboxes for B and C overlap C and E are nearby in the scene but occupy different parts of acceleration structure 25
- 26. K-D Tree ▶ Subdivides scene space ▶ Objects may be duplicated or split to fit ▶ Structure can be unbalanced and deep A C E B D A C ED B, C C overlaps C duplicated in tree 26
- 27. Why Ray Tracing? Jeffrey Howard, Intel Corporation • Images compare “easy” rasterization with “easy” ray tracing • Advanced rasterization can simulate some ray tracing effects, but ray tracing produces higher quality and is generally easier to implement intereflection caustic soft shadows anti-aliasing 27
- 28. Realistic Optic Effects Motion Blur Depth of Field R. Cook, T. Porter, L. Carpenter T. Kim 28
- 29. Accurate Simulation of Light Travel Copyright Audi AG 29
- 30. Better Lighting for Visualization C. Gribble and S. Parker local shading ambient occlusion shadows diffuse interreflections 30
- 31. Better Lighting for Visualization C. Gribble and S. Parker 31
- 32. Richtmyer-Meshkov Instability Carson Brownlee, Aaron Knoll, Paul Navrátil, TACC Ingo Wald, Carsten Benthin, Sven Woop, Intel OpenGL version – flat lighting, constant shadows, limited depth perception 32
- 33. Richtmyer-Meshkov Instability Carson Brownlee, Aaron Knoll, Paul Navrátil, TACC Ingo Wald, Carsten Benthin, Sven Woop, Intel Embree RT version – rich lighting, ambient occlusion, improved depth perception 33
- 34. Richtmyer-Meshkov Instability Carson Brownlee, Aaron Knoll, Paul Navrátil, TACC Ingo Wald, Carsten Benthin, Sven Woop, Intel Embree RT version with ‘glass’ planes – integrated, realistic material behavior 34
- 35. South Florida Ground Core Sample Sade Garcia, Michael Sukop (Florida International University), Kevin Cunningham (US Geological Survey), Carson Brownlee, Aaron Knoll (TACC) OpenGL version – flat lighting, constant shadows, limited depth perception 35
- 36. South Florida Ground Core Sample Sade Garcia, Michael Sukop (Florida International University), Kevin Cunningham (US Geological Survey), Carson Brownlee, Aaron Knoll (TACC) Embree RT version – rich lighting, ambient occlusion, improved depth perception 36
- 37. South Florida Ground Core Sample Sade Garcia, Michael Sukop (Florida International University), Kevin Cunningham (US Geological Survey), Carson Brownlee, Aaron Knoll (TACC) Embree RT version – rich lighting, ambient occlusion, improved depth perception 37
- 38. Implicit Surface Intersection ▶ Ray tracing can intersect surfaces directly without explicit tessellation ▶ Example: molecular data from materials simulations ▶ “ball and stick” surfaces + potential field volumes 20× – 100× memory savings and faster image generation! 38 A. KnollA. Knoll
- 39. Simulation of N-Acetyl-L-tryptophanamide through a Cellular Membrane Alfredo Cardenas, Ron Elber (ICES UT Austin) Aaron Knoll, Anne Bowen (TACC), Ingo Wald (Intel) 39
- 40. tryptophan locations clearly expressed Simulation of N-Acetyl-L-tryptophanamide through a Cellular Membrane Alfredo Cardenas, Ron Elber (ICES UT Austin) Aaron Knoll, Anne Bowen (TACC), Ingo Wald (Intel) 40
- 42. SDVis Rasterization ▶ Mesa 3D Graphics Library – mesa3d.org ▶ Open-source general OpenGL implementation ▶ Often included in Linux distros ▶ Convenient, if not always performant, default for CPU ▶ OpenSWR – openswr.org ▶ Open-source OpenGL implementation tuned for Intel CPUs ▶ Performant rendering using wide-vector instructions ▶ OpenGL coverage for visualization and more (integrated into Mesa3D 12.0) 42
- 43. SDVis Ray Tracing ▶ GLuRay – tacc.github.io/GLuRay/ ▶ Provides basic ray tracing via OpenGL intercept ▶ Fallback to rasterized OpenGL (OpenSWR, Mesa, HW) ▶ Supported in part by NSF award ACI-1339863 ▶ GraviT – tacc.github.io/GraviT/ ▶ Provides efficient memory management and work scheduling for distributed-memory ray tracing ▶ Uses GLuRay for basic interface, advanced interface for improved performance and feature support ▶ Designed to generalize for use in simulation codes ▶ Supported in part by NSF award ACI-1339863 43
- 44. SDVis Ray Tracing ▶ Manta – mantawiki.sci.utah.edu ▶ Open-source, generally performant ray tracer ▶ ParaView plug-in available ▶ OSPRay – ospray.github.io ▶ Open-source ray tracer tuned for Intel hardware ▶ ParaView plug-in available (tacc.github.io/pvOSPRay/) ▶ OptiX – developer.nvidia.com/optix ▶ Closed-source ray tracer tuned for NVIDIA hardware ▶ Supports CPU execution (though less performant) ▶ IndeX – nvidia-arc.com/products/index.html ▶ Closed-source DVR tuned for NVIDIA hardware ▶ Requires license to operate 44
- 45. Part II : Hands On 45 ❏ What you need paraview (download 5.2 RC4) data: www.paraview.org/Wiki/ Intel_HPC_Dev_Con_ParaView_and_OSPRay_Tutorial USB’s (please return them) local SMB fileshare: “afp://172.17.4.105” or “smb://172.17.4.105”.
- 46. Part II : Hands On 46 ▶ What is ParaView? An application and architecture for display and analysis of massive* scientific datasets. Client/Server architecture lets it runs on variety of platforms from netbooks to the largest machines in the world Open Source, commercially friendly BSD license Large user/developer base Commercial support available through Kitware ▶ http://www.paraview.org/download/ ▶ http://www.paraview.org/Wiki/The_ParaView_Tutorial Presented Monday @ SC 1.1 Trillion Cells on 1/19’th of DOE Trinity & OpenSWR
- 47. ParaView History Started in 2000 as collaborative effort between Los Alamos National Laboratories and Kitware Inc. (lead by James Ahrens). ParaView 0.6 released October 2002. September 2005: collaborative effort between Sandia National Laboratories, Kitware Inc. and CSimSoft to rewrite user interface to be more user friendly and develop quantitative analysis framework. 3.0 May 2007, Qt, Python, 2d Plots 5.0 October 2015 - SWR, TACC pvOSPRay plugin 5.1 May 2016 - integrated OSPRay for surfaces 5.2 November 2016 - add OSPRay volumes 47 ▶ Based on VTK Visualization Pipeline OSPRay integrated into VTK, so any VTK app can use https://blog.kitware.com/ray-traced-rendering-revisited/
- 48. 48 User Interface Menu Bar Toolbars and Shortcuts Pipeline Browser Properties Panel Apply Button Search Field Show Advanced 48 ▶ http://www.paraview.org/Wiki/The_ParaView_Tutorial Presented Monday @ SC
- 49. File->Open “disk_out_ref.ex2” Filters->Contour Click on disk_out_ref.ex2 to make it active again Filters->Extract Surface Filters->Clip SHOW HIDE
- 50. OSPRay Rendering Wavelet : procedurally generated volumetric data Sources->Wavelet Outline, Surface, Solid Color -> “RTData”, Volume View Section at bottom of Properties -> Enable OSPRay Volume->Wireframe, zoom in compare 50 Not colormapped? Too thin? Thick? OSPRay OpenGL
- 51. Part II : Hands On 51 Filters->Contour isosurfaces Turn on Shadows Notes: * scene and self shadowing * speckle shadow bug with line/cylinders and point/spheres * “LightKit” 6 lights in scene, mostly above and from camera better controls soon
- 52. Part II : Hands On 52 Volumes Cast Shadows w/ OSPRay
- 53. Level Of Detail - not at all helpful 53 Unlike rasterization framerate doesn’t really depend on how many primitives in scene. Also switching back and forth is slower than with GL. Glyph Mode : Uniform Spatial -> All Points Glyph Type : 2D Vertex -> Sphere Disable ParaView’s LOD Edit->Settings (OSX: ParaView->Preferences) -> Render View -> LOD Threshold to max
- 54. Implicit Spheres and Cylinders 54 Filters->Glyph Traditional: Glyph Type = Sphere Ray traced implicit : 2D Glyph, Vertex
- 55. Part II : Hands On 55 ▶ Scaled Implicits, finer control than “Point Size” Filters-> Python Calculator : expression = RTData/max(RTData) uncheck “Interpolate Scalars before mapping” check “OSPRay Use Scale Array on” change from “OSPRay Scale Array = RTData” to “= result” Hit “OSPRay Scale, Edit” to change value->Radius transfer function “
- 56. Part II : Hands On Real Data: Meningioma longitudinal study Load MRBrainTumor1,2 isocontour slice extract VOI, volume render 56
- 57. Part II : Hands On Real Data: FIU 57
- 58. Part II : Hands On ▶ Demonstration : remote visualization ▶ https://portal.tacc.utexas.edu/user-guides/maverick#visa pps-paraview ▶ possibly File->Connect (internal) or TACC startup with desktop forwarding ▶ Run parallel job ▶ Explain secondary rays problem, GraviT, Intel’s MPI DMP volumes 58
- 59. TACC Remote Visualization 59 Why Visualize Remotely? - Avoid moving data (especially TB or PB!) - Access many nodes for enhanced analysis power Hundreds to thousands of compute nodes available - Visualize together with simulation computation - in situ / co-processing - computational steering
- 60. TACC Remote Visualization 60 Two Connection Models: - TACC Visualization Portal https://vis.tacc.utexas.edu/ - SLURM Job on Login Node ssh stampede.tacc.utexas.edu OR ssh login-knl1.stampede.tacc.utexas.edu sbatch -A <acct> /share/doc/slurm/job.vnc <opts> - Both use VNC remote desktop
- 61. TACC Visualization Portal 61 - Which machine - Project to be billed - Session Type - VNC - Rstudio - iPython / Jupyter Notebook - VNC desktop resolution - Number of compute nodes - Number of processes per node - Click < Start Job > - Before first run, must set VNC Password (different from login, 6-8 char) Need TACC or XSEDE login credentials
- 62. 62
- 64. TACC Visualization Portal 64 - VNC job blocks on this xterm (black background) Close it to end job - Closing the web browser DOES NOT end the VNC job - Allows you to reconnect without losing work - If not expressly ended, job will run until time limit reached
- 65. 65 Select Jobs tab for running jobs Click Terminate Session to end job
- 66. VNC SLURM Job 66 After connecting to login node: vncpasswd # only needed before first execution touch vncserver.out # only needed if file does not exist sbatch -A <acct> /share/doc/slurm/job.vnc <opts> for example: sbatch -A A-ccvis /share/doc/slurm/job.vnc -geometry 19020x1080 monitor job status by following output file: tail -f vncserver.out
- 67. VNC SLURM Job 67 When job runs, displays VNC port connection info: Created reverse ports on Stampede KNL logins Your VNC server is now running! To connect via VNC client: SSH tunnel port 36602 to login-knl1.stampede.tacc.utexas.edu:36602 Then connect to localhost::36602 To tunnel port from localhost (for secure connection): ssh -f -N -L 36602:login-knl1.stampede.tacc.utexas.edu:36602 login-knl1.stampede.tacc.utexas.edu Then connect VNC viewer to localhost:<VNC port> vncviewer localhost:36602
- 68. FIU Dataset Demo 68 Groundwater flow through karst limestone core sample data courtesy of Florida International University and U.S. Geological Survey Data available at /work/00401/pnav/data/fiu_nhdr We will visualize: the karst substrate (rho, ~0.9 GB) the fluid flow (u, ~1.4 GB)
- 71. 71 Enable ambient occlusion (AO)
- 74. 74 ▶ What’s next? ▶ In-situ optimizations ▶ Progressive Refinement, Path Tracer, Lights, Materials ▶ Secondary Rays in DMP ▶ Want to know more? ▶ The ParaView Tutorial, Monday at SC16 ▶ Come see us at the TACC, Kitware and Intel booths ▶ Sunday talk by Paul ▶ Sunday talk by Dave Thank you!