MEAD: Volume VisualizationDavid Porter, U. Minnesota/LCSE

•Data Pipeline

•A3D

•HVR

•Tiled Commas Output

•Windows & Unix

•Formats & Frameworks linking to MEAD

Data PipelineHydro-code:WRF/COMMAS

ROMSRaw Fields (U,V,W,…)Formats: (HDF5, WRF, cdump)

Data Post-Processing:A3D

Block-Tree HierarchiesDerived Fields (Humidity, Vorticity)

Volume Visualization:HVR

Raster Data: (Images, Movies)

A3D: More Than Just Compression, Conversion, Scaling

•Reads in raw 3D fields onto a stackTiled cdump, BoF, HDF4, HDF5, netCDF?

•Performs calculations on this stack fields+-*/, d/dx, spatial filters, map from sigma-coords. (mm5)

•Produces statistical reductionspower spectra, structure functions,histograms, radial & vertical profilesBoF, BoB, SoF, SoB files cross-correlations

as well as Block Tree hierarchies for visualization.

Energy Spectra(k) MLT coefficients(Z) MM5 simulation

Block Tree Hierarchy: Basic Idea

Illustration: A 2 level hierarchy in 2D

• 16x16 array is split into 4 tiles•Each tile is sampled at a stride of 2x2•8x8 array of info in each node of tree

3D Block-Tree •A 3D mipmap

•Browse even the largest data sets at interactive speeds.

•Full size of data only limited by disk.

•Trees can be both logically and spatially irregular.

•Highest resolution need not span entire domain.

•Block size tuned to both hardware and application. = 128x128x64

256

32

4

1

HVR•Organize voxel data into a Block-Tree hierarchy

Stage large volumes of data on diskData compression: 1 byte per voxel & Tree PruningControl rendering quality vs. speed via tree traversalDCOM rendering server: HVR-SERVER

•Use key framing to specify complex path in space and timeInteractive GUI driven: HVR-GUI

•Tree hierarchy + key framing facilitate remote renderingRoot of Block-Tree hierarchy ideal for local key framing needsKey framing software delineates division of labor between

Local and remote resources & work.Optimized use of network bandwidth

Rendering Tolerances

Tolerances based onAngle subtended by voxelColor map index errorAbsolute resolution

(For speed only)

2D illustrationQuad-tree hierarchyEach tile might be 256x256

Tolerance: Based on Angle Subtended

Viewpoint

If a voxel at a given resolution subtends to great an angle, then scan down to finer resolution.

Tolerance: Based on Max. Error in Value

•Nodes have bound on error

•Const color no error

•Stop at nodes w/ no error

Remote Rendering: Routines

Local

•HVR-GUI•HVR-SERVER•MOVIE PLAYER

Remote

•HVR-SERVER

Remote Rendering: Data

Local

•Finder Bricks•Key Frame Parameters•Color & Alpha LUT•Low-Mid Sized Movies

Remote

•Block-Tree Hierarchy•Key Frame Parameters•Color & Alpha LUT•Low-Mid Sized Movies •Power Wall Movies

Tiny KB-Small MBMedium GBLarge TB+

Example: Tiled COMMAS•PC-cluster simulation produces “tiled output”

Titan clusterLogistics: 103 files randomly distributed across ~102 nodes

•Tiles are collected to post-processing hostsSCP to LCSE PC-rendering clusterLogistics: cdump files redistributed across 10-100 nodes

•A3D reads tiled cdumps and produces derived scalar volume data in block tree format.

Fields: W, vorticity, cloud water (*.hv files)Logistics: hv files redistributed to rendering cluster

•HVR produces images & movies

Logistics: Need data a base: MySQL

COMMAS: 96x96x36 (4x4 tiles)

COMMAS: 250x250x72 (5x5 tiles)

Porting to Unix

Windows Unix

OpenGL OpenGLWGL GLUTDCOM CORBA? Condor?

GUI: MFC FLTK? XML? Command line?Subroutine? Your framework?

Data Formats

I’m looking for a few good data sets.•WRF•ROMS

In a few relevant formats•netCDF•HDF5

Data Sets Please …

Frameworks

I’m looking for a few good frameworks

Connecting a few relevant centers

APIs Please …

Web Link

http://www.lcse.umn.edu

•Downloads of volume rendering apps for your PC

•Downloads of software under GNU GPL

•Many volume rendered movies

•User Guide to the Graphical user interface: hvr_gui

•Description of the Hierarchical Volume Rendering server hvr_server

•Software for producing volume data in Block Tree format

LCSE MEAD Milestones

(Q1) Simplified code (COMMAS) running w/ SHMODHVR Vol Vis of WRF datasets via data postproc w/ a3d

(Q2) Simplified code with dynamic load balancingHVR vis of ROMS data.

(Q3) Simplified code running in fault tolerant mode

(Q4) Simplified code running on TeraGridHVR vis of data on TeraGrid.