[vtkusers] On-demand loading of volume data

[Aashish Chaudhary]

Hi Elvis,

On Wed, Feb 3, 2016 at 4:27 AM, Elvis Stansvik <elvis.stansvik at orexplore.com
> wrote:

> Hi all,
>
> I'm working on tool for visualizing and working with tomography and
> spectrometry data coming from the analysis of drill cores.
>
> One of the views in the program is supposed to be a vertical view of the
> entire bore hole, with a scale showing the depth down the hole, with some
> charts showing analysis results (mostly element concentrations) along the
> the hole.
>
> Now to my VTK-related question: At low zoom levels, the view should just
> show a schematic view of the drill core (essentially just a rectangle), but
> at higher zoom levels, where less than ~3 meters of core is in view, slices
> through the volumes obtained from our tomography should be used to
> visualize the core. The attached rough UI sketch explains the setup much
> better than I can with just words.
>
> The idea is to use VTK for the visualization of the core at higher zoom
> levels. Since the volumetric data for the entire (~1000 m) core is huge, it
> obviously can't be loaded into a VTK pipeline all at once. Some kind of on
> demand loading is required. So my questions are:
>
> 1) What (if any) mechanisms does VTK provide for loading volume data on
> demand, based on what region of space is currently shown in the view
> presented to the user?
>

Let me try to answer this question but someone who has looked into the
pipeline more recently can provide a better answer. You can look into the
vtk pipeline mechanism in detail specifically streaming demand drive
pipeline (
http://www.vtk.org/doc/nightly/html/classvtkStreamingDemandDrivenPipeline.html#details).
You can write new filters that will fetch only the relevant dataset using
this pipeline. Also, it sounds to me that you may need to write you
application in two threads.

>
> 2) How would you go about tackling this visualization problem using VTK?
> Any pointers and advise is highly welcome, as I'm completely new to VTK.
>

Are you asking about What mappers to use?

>
> An overall requirement is that the UI should be reasonably responsive
> while scrolling the view at high zoom levels. Obviously there will be some
> time required for VTK to render the new volume data when the scrolling
> stops, but the scrolling itself should not be jerky. The program is to be
> run on a reasonably fast laptop.
>
>
Thanks,



> Best regards,
> Elvis
>
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-- 



*| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
*| http://www.kitware.com/company/team/chaudhary.html
<http://www.kitware.com/company/team/chaudhary.html>*
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