[vtkusers] stacking of 2d slices

[Mallya, Yogish (CORP, GEITC)]

hi folks,
          I am writing an application that has the following block structure

       	Image Stack-->| 2-D Processing |------>| 3-D Processing |-->output

             Here I want to  process the image stack sequentially  (i.e.
take single image from the image stack and process it)  and stack this
processed image so as to form a volume. Then pass this volume to 3-D
Processing.

         Currently I am using  vtkImageviewer for sequential processing of
image stack. The code somewhat look like this
		vtkImageViewer viewer
		viewer SetInput [TwoDProcess GetOutput]
		set x 0
		while { $x < 10 } {
			viewer SetZSlice $x
			viewer Render
		}
	
        I would like to know if there is
		1. Any class that has will replace the above code, since I
don't want  vtkImageViewer to perform sequential processing. 
		2. Any class to stack the output of 2D process . I used
vtkImageAppend for stacking, but when I tried to write the output of
vtkImageAppend to a file using the vtkImageWriter,  the writer seems to
re-execute the  2D pipeline by loading the whole image stack in to memory.
How can I avoid this execution ?     

 Thanks in advance,
Yogish