[Paraview] use the same scalar data to create contour and color the surface

[Cory Quammen]

Tom,

You can load your two images and, assuming they are the same size, use
the Append Attributes filter to combine them. However, chances are
good that the scalars in your image data will have the same name,
meaning that Append attributes will grab only the scalar values from
one of the images. To get around this limitation, you can "rename" the
scalar field in one image by using a Calculator filter on it and
setting the "Result Array Name" to something else. Your pipeline will
look like this *before* applying the Append Attributes filter:

Image1
---|
   Calculator1
Image2

To apply the Append Attributes filter, select the Calculator1 filter
and Image2. Use Ctrl-click on Windows to select more than one object
in the pipeline browser. Then select Append Attributes from the
Filters menu under the Alphabetical submenu.

Now you should have two scalar fields in an image data. You can use
one to do the contouring and the other to do the pseudo-coloring.

I've attached a state file with two Wavelet sources in place of image
inputs. It illustrates what I've described here.

Hope that helps,
Cory


On Sun, Apr 8, 2012 at 9:45 AM, Tom Schoenemann <toms at indiana.edu> wrote:
> OK, but is there some way to combine two image files, each with its own
> scalars, into one image?  What I'm thinking about is reading in 2 copies of
> the same image, and using the scalars from one to display the contour, and
> the scalars from the other to display the colors?  I tried doing this, but I
> can't get it to work. I loaded one as the contour, and colored it one color
> only (white).  I then added the copy, an tried to view it as a volume.  It
> let me change the color map parameters, but it seems to display the color
> UNDERNEATH the first one (that has the contour.  I'm sure there must be a
> way to do this, but how?
>
> Perhaps there is a way to add 2 scalar fields to one image? Maybe image
> calculator could do this??
>
> -Tom
>
> On Apr 8, 2012, at 8:30 AM, Cory Quammen wrote:
>
> Tom,
>
> An isosurface by definition has the same scalar value everywhere on
> the surface, so what you describe happening is exactly what should
> happen, unless I misunderstand. You could contour by one scalar field
> and color by another scalar field and expect to see different colors,
> but if you try to color by the same scalar, you should expect to see
> only one color on the surface.
>
> Cory
>
> On Sun, Apr 8, 2012 at 3:38 AM, Tom Schoenemann <toms at indiana.edu> wrote:
>
> I have a single volume dataset that has scalar values only on a surface, and
>
> zeros everywhere else.  The scalar values represent statistics we have
>
> calculated for each point on a surface.  I've been able using the contour
>
> filter to create an isosurface from this dataset, but I can't get the
>
> surface to display anything other than a single color.  I have tried setting
>
> "contour by" to "compute normals" and "compute scalars", and then going to
>
> "display" and choosing "color by" scalars.  However, only a single value is
>
> allowed.  I have tried unselecting "automatically rescale to fit data range"
>
> and then entering my own range, but only my minimum value is accepted (even
>
> if I enter a different value for the maximum).
>
>
> Perhaps I am using paraview the wrong way, but I have to say, it isn't
>
> intuitive.  Is there a way to use the same scalar data (same file) to both:
>
> 1) create a surface, and 2) color code the surface based on the same scalar
>
> values?
>
>
> Thanks for any hints or suggestions.
>
>
> -Tom
>
>
>
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> --
> Cory Quammen
> Research Associate
> Department of Computer Science
> The University of North Carolina at Chapel Hill
>
>
>



-- 
Cory Quammen
Research Associate
Department of Computer Science
The University of North Carolina at Chapel Hill
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