[vtkusers] Announcement: New image rendering classes for VTK

[Aaron Boxer]

Awesome!!! Nice work; can't wait to use these classes.

Aaron

On Sun, Jun 26, 2011 at 6:15 PM, David Gobbi <david.gobbi at gmail.com> wrote:
> I'm pleased to announce that I have finally completed my work on several new
> image rendering classes for VTK.  They are in the VTK git development tree,
> and a few of you have already tried them out (if you are one of those
> people, note that several feature and performance enhancements were added
> last week).  More info can be found at the following wiki page:
>
> http://www.vtk.org/Wiki/VTK/Image_Rendering_Classes
>
> In brief, these classes replace vtkImageActor and provide a much higher
> level of functionality.  They are new VTK actor and mapper classes
> specifically meant for image viewing.  What they are not: they are not
> widgets or viewers, although they provide machinery that can be used to
> write widget and viewer classes.  In other words, they are meant for people
> who like to roll their own image viewers.
>
> The three new classes that I recommend for people to use are the following:
> vtkImageSlice - the new actor class for images
> vtkImageResliceMapper - mapper for drawing images for MPR viewers
> vtkImageProperty - for controlling lookup tables, window/level, opacity, etc
>
> Typical use cases:
>
> 1) For an MPR viewer, use vtkInteractorStyleImage and set it to your desired
> view orientation. Then set the following properties in
> vtkImageResliceMapper:
> mapper->SliceFacesCameraOn()
> mapper->SliceAtFocalPointOn()
> The interactor will then allow you to pan, zoom, window/level, and (in 3D
> mode) rotate and slice.  See
> VTK/Examples/ImageProcessing/ImageInteractorReslice.py for an example.
>
> 2) For a 3D ortho object, use multiple vtkImageResliceMapper objects, and
> for each one make a vtkPlane that describes the normal and position of the
> slice to extract. Then call these methods:
> mapper->SetSlicePlane(plane)
> mapper->ResampleToScreenPixelsOff()
> Turning the "ResampleToScreenPixels" option Off makes rotation faster, so it
> is recommended when rotations are going to be common operations.  Example:
> VTK/Rendering/Testing/Cxx/TestImageResliceMapperOffAxis.cxx
>
> Features:
> 1) oblique views (obviously!)
> 2) nearest-neighbor, linear, and cubic interpolation
> 3) modify image orientation with respect to world coords by setting
> vtkImageSlice's UserMatrix
> 4) fully multi-threaded reslicing and color mapping operations
> 5) streaming, i.e. only pulls the data needed for rendering
> 6) works well with very large images (as long as they fit in memory)
> 7) LOD-style interaction (switches to faster rendering for interaction)
> 8) blend images by adding multiple vtkImageSlice objects to a vtkImageStack
> 9) checkerboard images by setting "CheckerboardOn" in the vtkImageProperty
> 10) thick-slab views (see vtkImageResliceMapper for details)
> 11) works with vtkCellPicker for picking image voxels as points or cells
>
> For large image viewing, on a 4GB computer (64-bit OS X) I've displayed
> images up to 3GB in size with full interactivity, but YMMV.  As long as the
> mapper's ResampleToScreenPixels option is On, the mapper will never try to
> load the full image onto the GPU (which is what causes the vtkImageActor to
> be slow for large images).  The size of the images that you can display is
> limited only by main memory, I have displayed stacks of RGB images that are
> 10000x10000 pixels in size.
>
> I do not plan to push these into the VTK 5.8 release (even if Kitware were
> to give me the go-ahead), because the VTK development tree has diverged too
> far from the VTK 5.8 release tree.  These new image classes are only
> possible due to recent improvements that I've made to the picker, lookup
> table, and image reslice classes and they probably depend on a handful of
> recent changes made by other people, as well.
>
>  - David
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