Table of Contents
atCalc_FFTPlugin information
Using atCalc_FFTApplying the forward transformTo calculate the fast Fourier transform (FFT) of the heightfield, select the 'Extensions→atCalc_FFT→Calculate FFT of heightfield' menu option. The output will be two maps called “HF_FFT_Amplitude” and “HF_FFT_Phase”, which will be added to your project. For a typical noisy heightfield, these maps will look like:
Note that both maps are normal floatingpoint maps. The phase map appears in colour because the default palette for the phase map is “rainbow”, which maps the PI→PI value range into a blue→red colour range. Applying the inverse transformTo calculate the inverse transform, select the 'Extensions→atCalc_FFT→Calculate heightfield from inverse FFT' menu option. This will overwrite the heightfield by inversetransforming the “HF_FFT_Amplitude” and “HF_FFT_Phase” maps created by the previous use of the 'Calculate FFT of heightfield' menu option (see above). The output of the inverse transform of the amplitude/phase images is a hightfield such as this:
Notes
The atCalc_FFT plugin will only work on square heightfields that are a power of two. This is a requirement of the FFT algorithm. If you want to transform heightfields of different sizes, you should look into implementing the general (and really slow) Fourier transform algorithm.
Changes2009/03/26
2008/07/1
2007/05/14
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