Polar densityplot

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Dear All,

I would like to plot a 3D polar plot or density polar plot I don't know how to call it (see attachement). I have a matrix (2500, 360) of point corresponding to Z intensity, each column corresponds to one degree and the row number to the radius (the number of row is the same for each columns). How can I do an image with? Should I change to cylindrical coordinate triplets or can I manage directly with this matrix?

Thanks for your help
Matias
You'll need to convert the data to rectangular format. Given that you have a very large number of points, the following method is recommended over ImageInterpolate.
Function fDemo()

    Make/O/N=(2500, 360) polarMatrix
    SetScale x, 0, 1, "radius", polarMatrix
    SetScale/P y, 0, 1, "degrees", polarMatrix
   
    polarMatrix= p*q
   
    Make/O/N=(2500,2500) matrix
    Variable radiusMax= DimOffset(polarMatrix,0)+DimDelta(polarMatrix,0)*(DimSize(polarMatrix,0)-1)
    SetScale/I x, -radiusMax, radiusMax, "", matrix
    SetScale/I y, -radiusMax, radiusMax, "", matrix
    MultiThread matrix= FindZInPolarMatrix(polarMatrix,x,y)
End

ThreadSafe Function FindZInPolarMatrix(polarMatrix,x,y)
    Wave polarMatrix
    Variable x,y
   
    Variable/C rTheta= r2polar(cmplx(x,y))  // cmplx(radius,angleinRadians)
   
    Variable radius= real(rTheta)
    Variable degrees= imag(rTheta)*180/pi
    if( degrees < 0 )
        degrees += 360  // assuming all angles in polarMatrix are >=0
    endif
    if( degrees > 359 )
        degrees= 359    // assuming all angles in polarMatrix are <=359
    endif
   
    Variable radiusMax= DimOffset(polarMatrix,0)+DimDelta(polarMatrix,0)*(DimSize(polarMatrix,0)-1)
    Variable radiusMin= DimOffset(polarMatrix,0)
    Variable zVal= NaN
    if( (radius >= radiusMin) && (radius <= radiusMax) )
        zVal = polarMatrix(radius)(degrees)
    endif
    return zVal
End


See the attached graphic for the before and after with my demonstration data.

--Jim Prouty
Software Engineer, WaveMetrics, Inc.
polarMatrix.png (31.09 KB)

June 1, 2011 at 03:35 pm - Permalink