Fwd: [vtkusers] orthogonal slices through a volume (and now non-orthogonal too).

[Mark Gooding]

sorry meant to reply on list.

---------- Forwarded message ----------
From: Mark Gooding <mark.gooding at gmail.com>
Date: Aug 23, 2006 2:17 PM
Subject: Re: [vtkusers] orthogonal slices through a volume (and now
non-orthogonal too).
To: David Gobbi <dgobbi at atamai.com>


On 8/23/06, David Gobbi <dgobbi at atamai.com> wrote:

> > ERROR: In \vtk\source\Filtering\vtkStreamingDemandDrivenPipeline.cxx,
> > line 628
> > vtkStreamingDemandDrivenPipeline (026B50E8): The update extent
> > specified in the information for output port 0 on algorithm
> > vtkImageReslice(026B4028) is 182 182 0 359 0 177, which is outside the
> > whole extent 0 363 0 359 0 0.
>
> This is an issue with vtkImageActor.  The first time it runs, it sets
> its DisplayExtent from the WholeExtent of its input.  If the WholeExtent
> of the image ever changes afterwards, then it gives out the error that
> you reported above.

Whoops!!! I had a imageActor->SetDisplayExtent() left over from my
display of othogonal planes. That was causing the error.

> The trick is to reset the image actor DisplayExtent by setting it to
> (-1, 0, 0, 0, 0, 0), which will force the image actor to recompute its
> extent and position from the new WholeExtent instead of using old,
> invalid values.  The idea here is that vtkImageReslice is giving you
> exactly the slice that you want, so vtkImageActor should not be doing
> any extent or slice selection.

Ok, so changing my faulty code, either by
SetDisplayExtent(-1,0,0,0,0,0) or removing the line altogether,
results in the imageActor being displayed. But the plane is only the
middle z-plane now, regardless of the AxesDirection specified in
vtkImageReslice. (and the image displayed is correct for that
location)

Really puzzled now! Surely the imageActor can't change where
vtkImageReslice is slicing?!?

I also tried setting the display extent to the full image area, but
that caused a terminating crash!

Mark