VTK/Geovis vision toolkit: Difference between revisions

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<source lang="cpp">
<source lang="cpp">
// 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
class vtkVisStrategyRepresentation : public vtkRenderedRepresentation
{
{
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   void AddTrackRepresentation(vtkTrackRepresentation* tr);  
   void AddTrackRepresentation(vtkTrackRepresentation* tr);  
   void AddVideoRepresentation(vtkVideoRepresentation* vr);  
   void AddVideoRepresentation(vtkVideoRepresentation* vr);  
   void AddTrackRepresentation(vtkScalarRepresentation* sr);  
   void SetVisStrategyRepresentation(vtkVisStrategyRepresentation* vsr);
 
 
   // Update all the layers and call \c PrepareForRendering(....) on each.  
   // Update all the layers and call \c PrepareForRendering(....) on each.  
   virtual void PrepareForRendering(vtkRenderView* view);
   virtual void PrepareForRendering(vtkRenderView* view);
  void SetUseWorldMatrix(vtkMatrix4x4 mat);


private:  
private:  
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{
{
public:  
public:  
  template<t>
 
  void SetScalarProperty(T value);
  // Can have 0 or many scalar representations.
  void AddScalarRepresentation(ScalarRepMode);
   virtual void PrepareForRendering(vtkRenderView* view);
   virtual void PrepareForRendering(vtkRenderView* view);
}
}
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{
{
public:  
public:  
  void SetScalarProperty(double value, double range[2]);
  // Can have 0 or many scalar representations.
  void AddScalarRepresentation(ScalarRepMode);
   virtual void PrepareForRendering(vtkRenderView* view);
   virtual void PrepareForRendering(vtkRenderView* view);
}
}


</source>
</source>
== 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.
** On the fly change of origin
** Piecewise change of origin
** Using FO (floating  approach as described in this paper link??. http://www.floatingorigin.com/pubs/thorneC-FloatingOrigin.pdf
** Use lat / lon in radians and height in Km instead of meter.
** RTC / RTE approaches as suggested here: http://blogs.agi.com/insight3d/index.php/2008/09/03/precisions-precisions/#more-80
** Use double precision all and cast it to float. (It does help a bit but the problem exists).

Latest revision as of 23:39, 5 February 2010

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

<source lang="cpp">

// 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);

}

</source>


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.