Hi Eric,
Because now of course our scalar image data needs to be associated with cells,
not to points. But vtkImageData in many cases only deals with the scalar data
attached to the PointData.
Could you use the concept of a dual grid? In other words make your vis
grid node centered with the nodes located on the cell centers of your
computational grid? Your arrays end up in PointData that way with no
interpolations required.
Burlen
Eric Nodwell wrote:
Francois,
Thank you for the reply.
Using 2x2x2 points for one voxel is fine in principle. The difficulty is, you
can't really conveniently (as far as I can tell) use a vtkImageData object for
this purpose. Because now of course our scalar image data needs to be
associated with cells, not to points. But vtkImageData in many cases only
deals with the scalar data attached to the PointData. For example, this is
from vtkImageData.cxx :
//----------------------------------------------------------------------------
// This method returns a pointer to the origin of the vtkImageData.
void *vtkImageData::GetScalarPointer()
{
if (this->PointData->GetScalars() == NULL)
{
vtkDebugMacro("Allocating scalars in ImageData");
this->AllocateScalars();
}
return this->PointData->GetScalars()->GetVoidPointer(0);
}
Notice that is method just grabs the Scalars from PointData, and other methods
of vtkImageData are similar, so if you want to store the scalars in CellData,
which is necessary represent voxels, it is quite difficult.
Eric
Date: Tue, 1 Jun 2010 13:26:15 -0400
From: Francois Bertel <[email protected]>
Subject: Re: [Paraview] Finite-size voxels and Point vs. Cell Centered
Image Data
To: [email protected]
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
Hello,
in vtkImageData, "Dimension" is the number of points along each axis,
not the number of cells along each axis. If you want one voxel, then
you need 2x2x2 points.
Note that using GetDimension() is OK but SetDimension() is only here
for backward compatibility, use SetExtent() instead:
image->SetExtent(0,1,0,1,0,1);
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