Creating a Surface Plot

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Wed, 07/20/2016 - 06:57 am

Hey there,

I'm new here, actually first time for me to join a forum, and I would need some help to solve it. :)

I have to make an analysis of some measurements, done by a Phd student. He measured the impedance and phase angle over a frequency band (of a piezo element). He did this in a pressured chamber from 0 to 60 bar (0,2,4,6 ...60bar). I created a surface plot from this data --> no problem
However he repeated this test with another piezo element and started again with 0,2,4,6 bar until 20 bar, than instead continuing with steps of 2 bar he took the decision to make steps of 5 bar (25,30,40,45 bar).
Now I got stuck because I need to make a surface plot from this inconsistent data but can't figure out how because of the change of pressure steps (0,2,4,6...20,25,30,40,45 bar pressure).
Usually I made a 2D matrix an changed the delta of the column to 2 (for the bar) and 1.5 for the rows (Hz for frequency), defined start for both, done. Easy as it gets! Now I can't do that for the pressure any more (first delta of 2 and than delta of 5).
I tried to create 2 2d matrices, one with 2 as delta (column) and one with 5 as delta (column). However, as soon as I combine those 2 it changes automatically to 2 for the combined matrix.
Somebody got an idea?

Greetings, Bernd

PS: enclosed there is one surface plot to get an idea
You can keep the two 2d matrices separate and plot them together in one surface plot. First create a surface plot with the first 2D wave, then in the Gizmo menu choose Append Surface... to add the second 2D wave that has different scaling. You'll need to define the appropriate start values for each matrix.

July 20, 2016 at 08:03 am - Permalink

It appears that you are asking how to display a surface from X-Y data that is not uniformly gridded. Here is one approach that comes to mind. In each regularly gridded subset, convert the data to an x, y, z triplet wave. Then concatenate the small triplet waves into a combined triplet wave. Use "1D X, Y, Z waves "Data->Packages->XYZ to Matrix" Voronoi method, or equivalently #include <XYZtoMatrix> in your procedure file. This adds three macros to interpolate separate X, Y, and Z waves or an XYZ triplet wave into a two-dimensional matrix of Z values. Then you can display the entire surface in Gizmo as a standard matrix wave.

July 20, 2016 at 08:05 am - Permalink

I recommend that you keep the data as XYZ triplets. You can combine the two sets into a larger XYZ triplet wave (e.g., using Concatenate). You can then use ImageInterpolate operation with the Voronoi keyword (that is what's called under the hood in XYZToMatrix).

Alternatively you can use the data that is sampled on a coarse scale and interpolate it down to the same scale as your fine scale data set and then combine the two sets with a single sampling.

A.G.
WaveMetrics, Inc.

July 20, 2016 at 01:00 pm - Permalink

Thank you so much for the support! :)
I managed it with the "Append Surface..." and it worked pretty straight forward. Actually I could have thought about that by myself *deeplyashamed*^^
I wish you all the best and greetings from Austria,

Bernd

July 20, 2016 at 10:45 pm - Permalink