VTK/Geovis vision toolkit

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Requirements

There are two parts to the project:

  • Video / related meta data rendering and interactions.
  • Displaying video / meta data in geospatial context.

As per our discussion we have gathered following requirements for the project.

  • Easy to put together.
  • Provides 2D and 3D mode where in 2D it will allow quick validation, manipulation abilities.
  • Provides the ability to visualize, video, track, and associated ranking.
  • Ability to provide input as sequence of images or a video file.
  • Provides the ability to manipulate track data. User should be able to insert a new one, modify the existing one.
  • Provides the ability to select a region with pixel level accuracy and draw a track on top of it.
  • Provides the ability to play many video files (small or large video) files.
  • Provides a layout for the videos in space so that each can be seen clearly for a view point.
  • Allows the videos to play individually or globally.1
  • Provides the ability to toggle different layers of information.
  • Provides geo spatial context.

Design

This is a graph with borders and nodes. Maybe there is an Imagemap used so the nodes may be linking to some Pages.

  • vtkVideoElementRepresentation would contain all the information layers and make sure that they are in sink.

Also this is the representation thats responsible for consuming the data for each video.

  • vtkVisStrategyRepresentation
// Interface for this class is not as clear as it should be. Basically it transforms all layers
// associated with any given vtkVideoElementRepresentation and represents this transformation via 
// some geometry. 
class vtkVisStrategyRepresentation : public vtkRenderedRepresentation
{
public:  

  // Return transformation matrix that can be used to offset any other representation. 
  vtkMatrix4x4 GetMatrix(); 

  virtual void PrepareForRendering(vtkRenderView* view); 
};


class vtkVideoElementRepresentation : public vtkRenderedRepresentation
{ 
public:
  void AddTrackRepresentation(vtkTrackRepresentation* tr); 
  void AddVideoRepresentation(vtkVideoRepresentation* vr); 
  void SetVisStrategyRepresentation(vtkVisStrategyRepresentation* vsr);

  // Update all the layers and call \c PrepareForRendering(....) on each. 
  virtual void PrepareForRendering(vtkRenderView* view);

private: 

Internal* Implementation; 
};


class vtkTrackRepresentation : public vtkRenderedRepresentation
{
public: 

  virtual void PrepareForRendering(vtkRenderView* view);
}


class vtkVideoRepresentation : public vtkRenderedRepresentation
{
public: 
  void SetScalarProperty(double value, double range[2]);

  // Can have 0 or many scalar representations. 
  void AddScalarRepresentation(ScalarRepMode);

  virtual void PrepareForRendering(vtkRenderView* view);
}


Geovis

  • Dealing with precision issues

When dealing with large numbers (earth radius is 6357000) in rendering causes issues of Jitter. This is a known problem as the GPU uses single precision floats as the data type. There could be couple of ways this issue can be dealt with.