Introducing CAVASS George Grevera a,b, Jayaram Udupa b, Dewey Odhner b, Ying Zhuge b, Andre Souza b, Tad Iwanaga b, and Shipra Mishra b a Department of Mathematics and Computer Science, Saint Joseph’s University, 5600 City Avenue, Philadelphia, PA b Medical Image Processing Group (MIPG), Department of Radiology, University of Pennsylvania, 423 Guardian Drive, 4th Floor Blockley Hall, Philadelphia, PA

What is CAVASS? ► A CAVA Software System ► What is CAVA?  Computer Assisted Visualization and Analysis ► So CAVASS is a Computer Assisted Visualization and Analysis Software System

3D CAVA Software Systems (MIPG) DISPLAYmini computer + frame buffer1980 DISPLAY82mini computer + frame buffer1982 3D83GE CT/T D98GE CT/T DPCPC-based1989 3DVIEWNIXUnix, X-Windows1993 CAVASSplatform independent, wxWidgets2007

What is CAVASS? ► Next generation of 3DVIEWNIX.  development started in 1987  released in 1993  development dates back to the ’70s  free  runs on Unix and subsequently Linux  60 person years of effort  distributed to 100s of sites  basis for over 15 specialized packages/apps Why CAVASS?

Significant, more recent developments 1. PC platform matures.  price spirals downward  performance increases dramatically  supplant Unix as the scientific workstation of choice 2. Network bandwidth greatly increases. 3. Useable parallel processing standards are defined and become freely available. 4. Toolkits such as VTK and ITK become freely available. 5. GUI concept matures and platform independent libraries are developed.

CAVASS features ► Image processing  for enhancing information about and defining an object system ► Visualization  for viewing and comprehending an object system ► Manipulation  for altering an object system (virtual surgery) ► Analysis  for quantifying information about an object system *Especially for large, multidimensional (at least 3D), possibly multimodality, data sets.

CAVA User Groups UG1 – CAVA basic researchers/technology developers UG2 – CAVA application developers UG3 – Users of CAVA methods in clinical research CAVASS is not aimed at: UG4 – Clinical end users in patient care

Key CAVASS features ► Built upon our experience with 3DVIEWNIX. ► Leverages the existing 3DVIEWNIX software base and user interface. ► Port to Windows and Mac OS with continued support for Unix and Linux. ► Implement parallel algorithms for time consuming operations. ► Support for stereo rendering. ► Interface to ITK.

Focus of the talk ► Overview of CAVASS software ► Other CAVASS related papers in Visualization Conference:  Image Processing Aspects  in Visualization Conference

CAVASS PortData Import DICOM EasyHeader VTK Matlab Export DICOM VTK STL PGM Matlab SaveScreen ToolsImageProcessingVisualizeManipulateAnalyze

An example of the CAVASS DICOM header explorer

DICOM Support ► Don’t reinvent the wheel for DICOM networking/image query and retrieve capability ► Integrate with commonly available DICOM networking software  SimpleDICOM receiver ► from the University of Pittsburg Department of Radiology ► Windows platform only  Conquest DICOM server ► Windows and Linux with source code  eFilm workstation package ► includes a DICOM server (version was the last free version)  DCMTK ► freely available for Linux, Unix, and Windows with source code

CAVASS PortDataTools Interface to ITK ScriptingShowScreen ImageProcessingVisualizeManipulateAnalyze

CAVASS PortDataToolsImageProcessing SceneOperations VOI Interpolate Filter Segment Classify Algebra Registration StructureOperations SurfaceNormals MergeStructures To Structure To Scene VisualizeManipulateAnalyze

Visualization and CAVASS ► All of the most popular modes of visualization are incorporated into CAVASS.  various 2D slice modes  reslicing  MIP  surface rendering  volume rendering  animation

CAVASS PortDataToolsImageProcessingVisualize Slice Montage Cycle Reslice Overlay Surface View Measure CreateMovie Volume View Measure CreateMovie ManipulateAnalyze

An example of overlaid slice display in CAVASS on the Windows operating system.

Another example of overlaid slice display in CAVASS.

3D rendering in CAVASS ► Surface rendering  utilizes digital shell and triangulated shell (t- shell) rendering algorithms  operates 6 to 30 times faster entirely in software than hardware-based rendering  implemented only in sequential and not parallel mode (because of their existing high speed)

3D rendering in CAVASS ► Volume rendering  based on shell rendering  implemented in parallel mode  compared to the implementation in VTK  CAVASS operates at least as fast as VTK and often achieves superior performance by a factor of 1.5 to 5

Examples of triangulated shell (t- shell) rendering in CAVASS on the Windows operating system.

Head mounted display employed by CAVASS for stereo viewing.

Portable graphics user interface ► Considered Qt, wxWidgets (formerly wxWindows), and FLTK.  Qt – proprietary, closed, fees  FLTK – free but doesn’t maintain native look- and-feel  wxWidgets ► one C++ API for all OS’s ► maintains native look-and-feel ► free, open source, multiplatform ► portable support for threads, copy-paste, drag-and- drop, print, etc.

CAVASS PortDataToolsImageProcessingVisualizeManipulate SelectSliceMeasureReflectCutMoveCreateMovie Analyze

CAVASS PortDataToolsImageProcessingVisualizeManipulateAnalyze Scene DensityProfile ROI Structure Kinematics

Experimental results

Description of datasets of varying sizes used in the comparisons.

Surface rendering timing comparison for CAVASS shell rendering (sequential implementation with and without antialiasing) and surface rendering as implemented in VTK.

Volume rendering timing comparison for sequential and parallel implementations of CAVASS volume rendering, VTK ray casting, and VTK 2D texture mapped volume rendering.

Time required for interpolation from anisotropic to isotropic data for various dataset sizes and CAVASS and ITK implementations. Multithreaded ITK employed a dual processor system and parallel CAVASS employed two single processor systems to afford a similar comparison.

Parallelism ► Considered:  MPI/OpenMPI ► Message Passing Interface  OpenMP ► Open specifications for Multi Processing

Parallelism ► MPI  free (for both Windows, Linux, and Unix)  part of base Linux install  COW (cluster of workstations model)  leverages existing hardware/computers  optional, inexpensive network upgrade  easily expandable ► OpenMP  requires purchase of specialized compilers  “multi-threaded, shared memory parallelism” model  requires purchase of expensive multiprocessor systems

Parallelism recommendation ► CAVASS uses MPI. YOU ALREADY

Thanks for your attention! ► Information about CAVASS is available from ► Release date: July/August ► The authors gratefully acknowledge NIH grant number R01-EB for support of this work.

Other CAVASS related presentations ► In Visualization Conference:  Image Processing Aspects  Visualization Aspects See