[vtkusers] volume rendering changes

Miguel Angel Martin Fernandez vtk at helios.tel.uva.es
Sun Sep 2 19:05:04 EDT 2001

Hi vtkusers!

I am quite interested in these changes in vtkVolumeRayCastMapper,and I
understood that they had already been released,  but
however haven't been able to find the "new" volume rendering

	In case they are already available, any tips on how to get to them
would be welcome, otherwise it would be very helpful for me to know when
these changes are expected to be made "public".

	Thank you!

On Mon, 20 Aug 2001, Lisa S. Avila wrote:

> Hello,
> I have just checked in some fairly significant changes to 
> vtkVolumeRayCastMapper. These changes are part of the "bigger picture" of 
> the rendering restructuring in VTK.
> Here are the highlights of the change:
>     * The vtkVolumeRayCastMapper now does its own ray casting (as opposed 
> to relying on the vtkRayCaster)
>     * The ray casting resolution is independent of the resolution at which 
> geometry is rendered - so when you drop to lower resolution ray casting for 
> interactivity the geometry does not become blocky
> Here are the API changes:
>     * All the methods in vtkRayCaster are obsolete. This includes:
>         * Methods to control the automatic image scale such as 
> AutomaticScaleAdjustmentOn, AutomaticScaleAdjustmentOff, 
> SetAutomaticScaleLowerLimit. Instead you should use these methods on the 
> vtkRayCastMapper: AutoAdjustSampleDistancesOn, 
> AutoAdjustSampleDistancesOff, SetImageSampleDistance, 
> SetMinimumImageSampleDistance, and SetMaximumImageSampleDistance
>         * The method to control the number of threads - this has moved from 
> vtkRayCaster to vtkVolumeRayCastMapper (SetNumberOfThreads)
>         * Methods to control nearest neighbor or bilinear zoom - in the new 
> vtkVolumeRayCastMapper only bilinear zoom is supported currently.
>     * Ray bounding for ray casting is no longer supported. Therefore the 
> SetRayBounder method is obsolete on the vtkVolumeRayCastMapper.
>     * A new variable IntermixIntersectingGeometry was introduced into the 
> vtkVolumeRayCastMapper. By default it is on. If you do not have 
> intersecting geometry (a bounding box around the volume is not 
> intersecting, a cursor drawn through the volume is) you may want to turn 
> this off to improve the performance and the low resolution image.
> Here is what's coming next:
>          Next Monday I will be checking in the next set of changes. This 
> will include removing two passes from the renderer (ray casting and render 
> into image). At this point I will remove the following obsolete classes:
> vtkRayCaster
> vtkViewRays
> vtkRayBounder
> vtkProjectedPolyDataRayBounder
> vtkOpenGLProjectedPolyDataRayBounder
> vtkMesaProjectedPolyDataRayBounder
> vtkRayCastStructures.h
> vtkVolumeRayCastStructures.h
> Let me know if you run into any problems or have any questions.
> Lisa

  _________(_                                                      _)_________
  \········(_   Miguel Ángel Martín Fernández                      _)········/
   \·······(_   ETSI Telecomunicación, Universidad de Valladolid   _)·······/
    \······(_   Campus Miguel Delibes, Camino del Cementerio, s/n  _)······/
     )·····(_   e-mail: miguel at atenea.tel.uva.es                   _)·····(
    /······(_   Tfno: +34-983-423000 Ext. 25548                    _)······\
  /__________)                                                 (_____________\

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