Visualisation tips

We record here some useful tips for visualising simulations.

Viewing the mesh

To insert a mesh into an elevated plot insert a standard pseudocolour plot and then select Operator->Geometry->Edge. Important: If you then add another pseudocolour plot to fill the mesh the edge plot should be raised slightly (e.g. plot chi+0.05 in the edge plot instead of just chi). Otherwise there are points where the mesh disappears behind the other pseudocolour plot and the mesh looks broken as a result.

Making movies

For high quality films output a series of png images via Output->movie and then convert to a film with ffmpeg:

ffmpeg -framerate 2 -i chi_png0%03d.png -c:v libx264 -pix_fmt yuv420p out.mp4

ffmpeg might complain that the size is not divisible by two or so in which case one has to crop a pixel off by invoking:

for f in *.png; do convert $f -resize "XPIXELS"x"YPIXELS" $f; done

To add a wav file for audio use:

ffmpeg -i video.mp4 -i audio.wav -c:v copy -c:a aac -strict experimental output.mp4

Formating

• Insert a time slider via Controls->Annotation->Objects. This can be made to look much nicer with all sorts of options e.g. colour etc.

• Get rid of the title of the variable and the weird "Pseudocolor" text by selecting

    Controls->Annotations->Objects->Legend 
  

  and then untick "Draw title". Then insert custom title (or indeed any text) with

    Controls->Annotation->Objects->Text.
  

• If the plot is dark and the text and triad are above the plot change the foreground colour to white via Controls->Annotation->Colors Foreground Color.

• By default VisIt prints a ridiculous number of decimal places but this can always be changed by looking for the "number format" option in the appropriate section of Controls->Annotation.