Polar Intensity Plot ... similar to Ultrasound

[abhi_vt]

Hello,

I am looking for a VI, or an algorithm, to display the intensities in polar format. I acquire data in LabVIEW by rotating the probe radially to scan the sample. The data will naturally be saved as an array, which I can then reshape. The reshaping will give me a 2-D matrix. Let's say that if the columns represent Theta (instantaneous angle of probe) and rows represent Radius (Depth information of the sample), how do I actually present these intensity data points in polar format so that they look like an Ultrasound scan except that the plot will cover all 360 degrees.

I did check out this link (http://forums.ni.com/t5/LabVIEW/polar-plot-of-a-data-matrix-help-is-needed/td-p/736567) but have not succeeded in getting the intensity plots to displayed in polar format.

Thanks

[Elizabeth_K.]

There is no polar intensity plot available in LabVIEW.  The way to do it would be to convert it to x/y coordinates using x=r*cosine(theta) and  y=r*sine(theta) and then use an intensity graph.  The graph will still be circular.

A good example program can be found in the forums here: Multiple polar plots into a 3d plot.

Regards,

Elizabeth K. 

National Instruments | Applications Engineer | www.ni.com/support 

[InspectorUT]

I have tried to do this in an intensity plot and it will not work. I won't work because the intensity plot does not allow you to specify x and y, you can only specify a two-dimensional array of z values. I have tried taking the "radius" and "theta" values, converting them into "x" and "y" values, and then using them as indices for placing the "z" values into the two-dimensional array that is input into the polar plot,x but this does not work. The number of r,theta combinations that are required to fill every x,y index in the two-dimensional array is too high; you will have memory full errors. If too few points are used, then the array is not completely filled, resulting in empty cells in the two-dimensional array.

[Austin_S]

I don't know of an easy way to do this in Labview.  Your link above was broken, so I'm not sure if this is the same thread or not, but I found this forum thread from another user trying to also create a polar intensity plot. 

http://forums.ni.com/t5/LabVIEW/Polar-Intensity-Plot-new-idea/td-p/779128

Does this help for what you're trying to do?

[abhi_vt]

Helllo,

Attached is the LabVIEW code for polar intensity plot that I wrote and have been using. This program will generate a matrix of certain # of rows and columns and intensity plot by default, presents it in a cartesian format. 

The program determines the size of the matrix. The number of rows of will represent the number of radii and the number of columns will be the number of angles. It assumes that the data was acquired over 360 degrees. The heart of the program is the 2D interpolation of the input matrix intensity values over another matrix created by "cartesian to polar" subVI.

Please let me know if you have any questions or there are any errors in the logic.

Thanks