[vtkusers] Overlaying a slice on top of a vtk volume

[Anja Ende]

Got it! many thanks for this!

Anja

On 8 February 2010 22:45, David Gobbi <david.gobbi at gmail.com> wrote:
> Hi Anja,
>
> Yes, you can rescale your MR slice to [0,255] and then you will not
> have to use vtkImageMapToColors.  However, you will still need to
> convert your slice to "unsigned char" with vtkImageCast or
> (equivalently) rescale and cast it in one step using
> vtkImageShiftScale.
>
> By default the image will appear inside the volume.  That is why I
> suggested that you should add a clipping plane to your
> vtkVolumeMapper, so that you can clip away the part of the volume.
>
> If you really want the image to appear in front of the volume (though
> I think that clipping the volume is a better way of doing things),
> then you can move it by using vtkImageActor::SetPosition().
>
>   David
>
>
>
> On Mon, Feb 8, 2010 at 3:33 PM, Anja Ende <anja.ende at googlemail.com> wrote:
>> Hi David,
>>
>> Thanks for the quick reply!
>>
>> So with this I can just create a vtkImageActor, set my volume as an
>> input and then use the SetDisplayExtent to show the relevant slice.
>> This actor, I guess just gets added to the renderer. Thanks for the
>> top on adding the vtkPlane to the volume mapper. Just a couple of
>> questions:
>>
>> - Is there something that I will have to to ensure that the volume is
>> behind the image actor?
>> - Also, I am not very experienced with using the vtkImageMapToColors.
>> So, I have a grayscale MR slice and I would like to display it the way
>> it is. I guess just scaling the values to [0, 255] would do the
>> trick... Could you give me some further pointer on how I can go about
>> doing this?
>>
>> Thanks again for your help.
>>
>> Anja
>>
>>
>> On 8 February 2010 22:20, David Gobbi <david.gobbi at gmail.com> wrote:
>>> As long as an orthogonal slice is okay (i.e. along the x, y, or z
>>> direction), just use vtkImageActor and use the SetDisplayExtent method
>>> of the image actor to set the slice that you want to display.
>>> ImageActor expects RGB (or RGBA) data, so you will have to pass the
>>> image through vtkImageMapToColors (with an appropriate vtkLookupTable)
>>> before putting it into the image actor.
>>>
>>> You will probably also have to add a vtkPlane to the VolumeMapper as a
>>> clipping plane, so that you can clip away the part of the volume that
>>> would otherwise be in front of the image.  The clipping plane must be
>>> set to coincide with the image slice shown on the image actor.
>>>
>>>  David
>>>
>>>
>>> On Mon, Feb 8, 2010 at 2:56 PM, Anja Ende <anja.ende at googlemail.com> wrote:
>>>> Hello everyone,
>>>>
>>>> I am going a simple volume rendering with vtkVolume and it seems to
>>>> all work ok. One thing I want to do is overlay a slice on top of this
>>>> rendered volume. For doing the volume rendering, I used David Gobbi's
>>>> Medical4.cxx example and it works quite well.
>>>>
>>>> So, I want to create a small animation where I render the volume and
>>>> render some particular slice (vtkImageData) on top of it. What would
>>>> be the best way to go about doing this?
>>>>
>>>> Cheers,
>>>>
>>>> Anja
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>>>
>>
>>
>>
>> --
>> Cheers,
>>
>> Anja
>>
>



-- 
Cheers,

Anja