[vtkusers] Requirements for multiple volumes in one render window

Wed Apr 20 09:04:32 EDT 2016

2016-03-04 12:00 GMT+01:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> 2016-03-02 21:16 GMT+01:00 Aashish Chaudhary <
> aashish.chaudhary at kitware.com>:
>
>> Elvis,
>>
>> thanks for the detailed information. I thought about a way of doing
>> this. Basically, I think the mapper has to take multiple inputs and if
>> multiple inputs are present, then we will construct a BBox around it
>> and used that for traversing. Now, internally, we would have to
>> transform the data position to each volume so that we can perform the
>> lookup and set some rules on how to perform compositing (replace,
>> modulate etc.). I will talk to the team here and will add in our todo
>> but we would have check on the priority of it.
>>
>
Any news on how you chose to prioritize this? Is it possible there will be
something in a 7.x point release, or is it further off?

Elvis


>
> Thanks a lot for looking into this and bringing it up with the team. It
> would be a very welcome addition for us, and surely to some others as well.
>
> The approach you outline seems sound to me, but I am a layman in
> visualization :)
>
>
>>
>> If you want to help us with this then I am more happy to guide you
>> with the process. It won't be very difficult but will require some
>> careful changes to the existing mapper.
>>
>
> I'm afraid we're in the middle of a product launch here at work, so I'm
> quite swamped. This is only a small part of the application I'm building.
> I'm also completely new to VTK and visualization in general, so I'm also
> afraid it would be more difficult and time consuming for me than you might
> think (as opposed to a seasoned VTK dev).
>
> I'm of course prepared to try out any changes you do on our data sets,
> should you decide to work on this.
>
> Thanks again,
> Elvis
>
>
>> Thanks,
>>
>>
>> On Mon, Feb 29, 2016 at 11:46 AM, Elvis Stansvik
>> <elvis.stansvik at orexplore.com> wrote:
>> > 2016-02-29 16:32 GMT+01:00 Aashish Chaudhary
>> > <aashish.chaudhary at kitware.com>:
>> >>
>> >> Hi Elvis,
>> >>
>> >> On Sat, Feb 27, 2016 at 12:06 PM, Elvis Stansvik
>> >> <elvis.stansvik at orexplore.com> wrote:
>> >> > 2016-02-25 17:10 GMT+01:00 Elvis Stansvik
>> >> > <elvis.stansvik at orexplore.com>:
>> >> >>
>> >> >> Hi,
>> >> >>
>> >> >> From searching around, I think I've gathered that to render multiple
>> >> >> volumes in a single window, each volume must have its own mapper and
>> >> >> volume
>> >> >> property. They can't share mapper or property.
>> >> >>
>> >> >> My question is whether I must use separate renderers for each
>> volume as
>> >> >> well, or if I can use the same renderer for them all?
>> >> >>
>> >> >> Also, I did read something in an old post about problems with
>> rendering
>> >> >> multiple volumes that intersect (share a voxel). Is this still a
>> >> >> problem?
>> >> >> I'm using VTK 6.2 and the vtkVolumeRayCastMapper.
>> >> >>
>> >> >> Thanks in advance!
>> >> >
>> >> >
>> >> > Including Donny's answer here, to keep the thread intact:
>> >> >
>> >> >> See this thread:
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> http://vtk.1045678.n5.nabble.com/Rendering-multiple-volumes-td5734685.html#a5734971
>> >> >
>> >> > Thanks, that clears some things up, and brings up some workarounds.
>> That
>> >> > thread was from oct/nov last year, so I guess it is still the case
>> that
>> >> > proper rendering of multiple volumes that share voxels in 3D space is
>> >> > not
>> >> > possible? (even with 7.0?).
>> >>
>> >> It depends what you define proper. If you have two volumes and they
>> >> share the exact same space, you can combine them into one volume. When
>> >> they share the same space but do not overlap that's when things get
>> >> tricky since then the outcome depends on how do you want to handle
>> >> this disparity. There could be some other ways such as you combine the
>> >> volume into one. At the rendering level it could get tricky.
>> >>
>> >> What exactly you are trying to do.
>> >
>> >
>> > I see, what I would expect I think is composite rendering of the voxels
>> > using some composite rendering function / blending mode (perhaps
>> > configurable?).
>> >
>> > Sorry if my use case wasn't clear, I'm attaching a rough sketch I did
>> just
>> > now which should explain it better.
>> >
>> > Each of our volumes is a piece of a drill core (see my photo previously
>> in
>> > this thread). The pieces were scanned stacked on top of each other in a
>> > plastic tube inside our machine. During scanning, they are not
>> necessarily
>> > aligned properly (as shown in the sketch, and also in the photo).
>> >
>> > We will do some algorithmic alignment of the volumes, but we must also
>> allow
>> > the user to override / supplement the automatic alignment when it fails.
>> > This means the user should be able to rotate and move (along Z axis) the
>> > pieces until they align. It's like a pussle with pieces of a drill core
>> :)
>> >
>> > While the user is doing this, the volumes may intersect (noone is
>> perfect on
>> > the first try). This is why I'm asking about rendering multiple volumes
>> that
>> > partially intersect in 3D space.
>> >
>> > It's very desirable that the user can see inside the volumes while doing
>> > this manual alignment, since the features (cracks, density variations,
>> ...)
>> > inside the rocks may be what guides the user in aligning the pieces
>> > properly. That's why I don't like the idea of letting the user work with
>> > extracted isosurfaces or similar instead.
>> >
>> > Hope this clears things up a little!
>> >
>> > Elvis
>> >
>> >>
>> >> - Aashish
>> >>
>> >> >
>> >> > Elvis
>> >> >
>> >> >>
>> >> >> Elvis
>> >> >
>> >> >
>> >> >
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>> >>
>> >>
>> >>
>> >> --
>> >> | Aashish Chaudhary
>> >> | Technical Leader
>> >> | Kitware Inc.
>> >> | http://www.kitware.com/company/team/chaudhary.html
>> >
>> >
>>
>>
>>
>> --
>> | Aashish Chaudhary
>> | Technical Leader
>> | Kitware Inc.
>> | http://www.kitware.com/company/team/chaudhary.html
>>
>
>
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