Discussion Forum

Hi,

There are two options that are useful for "Cut Point 3D" data sets:

To display the value of a property at a point, add a Point Evaluation node under Results>Derived Values. Then select the "Cut Point 3D" data set that you want to use from the "Data set" list and choose an expression to evaluate. The value(s) of that expression appears in a Table window.

To plot the value of a property at a point, add a 1D Plot Group node under Results; then right-click that 1D Plot Group node and add a Point Graph node. Then select the "Cut Point 3D" data set that you want to use from the "Data set" list in the 1D Plot Group and choose an expression to plot in the Point Graph. The plot is probably most useful to plot values in a point over time or for a parametric sweep. For a single stationary solution the plot shows a single "dot" for the value of the expression in that cut point.

You can plot the values at several cut points in the same graph by adding additional Point Graph nodes under the same 1D Plot Group and select a different "Cut Point 3D" data set in each Point Graph node (instead of the default setting to use the data set "From parent").

Best regards,
Magnus Ringh, COMSOL

Hi Magnus,

thanks for the advice. However, I still have questions. The "Point Graph" node only gives me a function graph. What I'd like to have, is rainbow colored points that are displayed within the 3D geometry of a 3D plot.. The same way as a "Line" node is displayed as rainbow colored line within the 3D geometry of a 3D plot.

Is that somehow possible?

Greetings,
Joerg

Hi,

Thanks for this input!

One way of getting something like what you want to plot is to use a Scatter Volume plot (which you add from the More Plots submenu). In the Expression section then use the spatial coordinates (x, y, z), and in the Evaluation Points section you enter (manually; no connection to the Cut Point data sets) the coordinates of the points (change the "Entry method" to Coordinates). In the Color section you select the expression used to color the points. You may also need to tweak the settings under Radius to plot points (spheres) of a suitable size.

Best regards,
Magnus Ringh, COMSOL

Hi Magnus,

thanks für that answer. In the Scatter Volume Plot one can only enter a regular grid, right?
Let's say I only want to plot the values in the two points (1,2,3) and (6,7,8), I would enter in the coordinate fields of the "Evaluation Points" section the following:

x grid points: 1, 6
y grid points: 2, 7
z grid points: 3, 8

However, this doesn't plot two points, but eight points (taking the cartesian product of the coordinates). Is there a way to enter a user-defined list of points? Ultimately, I am looking for a plot that behaves like MATLAB's "scatter3"-function.

Greetings,
Joerg

Hi,

This is how the Scatter Volume plot works, and it is therefore not ideal for what you want to do. What you enter are really not two distinct evaluation points; instead, they are points on axes that define a grid. In general, for Scatter and Arrow plots, it is more useful to evaluate on a grid than to evaluate in a set of points.

Best regards,
Magnus Ringh, COMSOL

Hi,

thanks for the answer. I think some users might benefit from an additional scatter plot that behaves like MATLAB's scatter3 function in order to visualize arbitrary measurement points who have been imported from some other simulation software. So maybe that could be added to the feature request list for one of the next releases? I certainly would appreciate this feature.

Thank you once again, Magnus, for all the valuable explanations you've given me here.

Greetings,
Joerg