How to set transparency of object in Paraview

I am using paraview 3.6.2, and sometimes, it is useful to display the object and make it transparent. In this way, I can see the data and the boundary of the objects as well. To do this, load your object data, and go to tab “Display” in the “Object Inspector” window. From there, look for the section “Style”. After “Point Size” and “Line Width”, you wills see “Opacity”. Change the level opacity to make the object transparent.

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Using Paraview to plot selection over time

Paraview is a nice visualization software and it is equiped with a lot of tools to analyze the data. In my current project I have a time sequence data which is stored in different VTK legacy files. The files are stored in this convention Etot.00010.vtk, Etot.00020.vtk, where the numbers are the time steps. To load the data do the following:

  1. Open paraview.
  2. Click “File->Open”
  3. Go the folder where the data files are located, you will see Etot…vtk, with a plus sign on the left. If you click the plus sign you will be able to select a particular time step data. But since we want to load all, click the upper most line, i.e. Etot…vtk.
  4. Click “Apply”.
  5. To view¬† cut plane, click the icon “Slice”, and click Apply.

Now, for example we are interested to plot the data over time from a particular point. To do this:

  1. Click the button “Select points on”, i.e. button with triangle and three red dots.
  2. And then choose menu “Filter->Data Analysis->Plot selection over time”. This will take some time depending on how many time steps you have. Once done. You will see another 2D plot view open up.

Fixing icons and menu in OpenOffice 3.2 Kubuntu Hardy

I am not sure what happened, but when I open Impress, and my mouse is over the icons or menus, they are gone. When the mouse is over a selected icon, that particular icon appear the rest on its sides are not displayed.

Somehow, I managed to find the solution that works from this page: this page. What I did was to:

export SAL_GTK_USE_PIXMAPPAINT=1

to my ~/.kde/env/gtk-qt-engine.rc.sh file.

and then restart the OS

Problem saving image in paraview 3.6.2 “Error: GLXBadContext 154”

I installed the binary paraview 3.6.2 in Kubuntu Hardy, but whenever I wanted to save image or animation, I got this error “Error: GLXBadContext 154”, this is the screenshot of the error message and the result of the saved image:

To resolve this problem:

  1. Go to “Edit” -> “Settings”
  2. click tab “Render View”-> “General”
  3. Uncheck the option “use offscreen rendering for screenshots”.
  4. Click OK.

After I did this, I can save the image savely. This is the example of the correct image:

Saving scalar finite element data from Matlab to VTK

I found this link to save scalar and vector data from Matlab to unstructured grid in VTK legacy format:
http://people.sc.fsu.edu/~burkardt/m_src/twod_to_vtk/twod_to_vtk.html

However, I need only the scalar part, so I modified accordingly. You can download my code here:
Download

Plotting irregular finite element data in matlab/octave

I am solving a 2D finite element problem and I got x,y,z vectors. The length of these vectors are the number of nodes in my problem. To use the function “mesh”, we need to have x and y coming from “meshgrid”. To plot these data, use the following:

[xi,yi]=meshgrid(x,y);
zi=griddata(x,y,z,xi,yi);
mesh(xi,yi,zi);

Note that xi,yi, and zi are now a matrix.

The difference between Science and Engineering

I found the following article interesting, on how it describes briefly how science and engineering are different:

The Antiparallel Structures of Science and Engineering