Volume Tracking

Feature tracking can be used to correlate extracted objects from one data set to the next.


Feature Tracking on Unstructured Datasets

FVis5D - Vis5D Enahanced with Feature Tracking


 

The evolutionary events can be characterized as follows:

Continuation
An object continues in consecutive time steps (with rotation or translation), as it increase (decreases) in volume or magnitude.
Creation
A new object appears.
Dissipation
An object disappears.
Bifurcation
An object separates into two or more substructures.
Amalmagation
Two or more objects merge.

 


 

Assumption

Time between successive data sets is small.

Heuristic

Corresponding objects in succesive data sets overlap in space.

Methods

  • Correlation of objects is performed based on minimum difference.
  • An octree spatial data structure is used to implement the algorithm.

 


 

Examples of 3D Volume Tracking

 

Pseudospectral simulation of coherent turbulent vortex structures with a 128^3 resolution (100 time steps). Variable being visualized is vorticity magnitude (thresholded isosurfaces at 48% of maximum).
Simulations by Dr. V. Fernandez


In this video, no feature tracking was performed. It is hard to visually follow regions and measure their energy change. Feature tracking helps understand the energy transfer mechanisms in these vortex interaction (energy cascade). It is also helpful for data reduction, data base management, and model building.

Click here to view the VIDEO.

 


In this animation, feature are extracted using segmentation based upon thresholding, and they are followed over their lifetime. Objects are colored based on the tracking result. The color of an object is inherit from its parent (with the larger volume in the case of amalgamation).

Click here to view the VIDEO.

 


In the first animation, one object is isolated and the rest are colored in grey. In the second animation, one object is isolated and the rest are removed. The change in mass and volume are shown below.
 

 

 


In this animation, objects are rendered with the volume rendering technique to reveal the inner detail. The rainbow colormap indicates the variation of the scalar value inside each object. 

Click here to view the VIDEO.


 

Statistics

Once objects have been tracked, we can also track properties of the objects, such as mass, volume, moments, etc.

 


 

Image Gallery

                                            

                                            

                                            

 


 

Applications

Geophysics
Inlet Design
NCAR Weather Simulation 
IBM Weather Forecast 
EPA Weather Simulation 
Plume 
Isotropic Turbulent Decay Simulation
Oceanography
The Shock-Elliptical Interaction - It has been adapted to 2D dataset!


Acknowledgment

The work is supported by DARPA HPCD (DABT-63-93-C-0064), DOE (DE-FG02-93ER25179.A000), NASA (NAG 2-829), and the CAIP Center.

Xin Wang's Thesis: XinWangPhd.pdf


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