As promised last time, this post talks about contouring of zone quantities such as stress and strain. As you probably know, some data is associated with gridpoints (e.g. displacements and velocities) and some data is associated with zones (e.g. stresses and strains). Methods for contouring data at discrete points are well known; therefore the contouring of gridpoint data is included in 3DEC. These contours can be accessed through Blocks – Contours in the plot item list.
Contouring zone data is not so easy. To do the contouring, we need data at discrete points, but how do we do this? Use the centroid of the zones? Use gridpoints and take the average value of all connecting zones? There is clearly some sort of interpretation required. At Itasca we have always been careful not to impose interpretations on the model data. This is why contours for zone data are not included in 3DEC. Instead you can plot each zone as a solid color through Blocks – Color Scale.
However, after many user requests we have decided to include zone contouring in future versions, and allow the user to choose the method of smoothing. Since the new version of 3DEC won’t be out for a while, I have included here a FISH function to plot stresses as contours by putting zone stress data in the vertex extra variables. This function finds all zones connected to each gridpoint and calculates the average stress weighted by zone volume. The vertex extra variables can then be plotted as contours. An example plot is shown below. You can use this function to plot any zone data as contours – just replace the stresses with whatever it is you wish to plot. Enjoy!