Spectral domain grid filters tool (GridFFT) (T40)

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This chapter refers to the current Spectral Domain Grid Filters tool (GridFFT).

You can use the INTREPID GridFFT to enhance a grid dataset by:

• Enhancing features so that you can analyse them to better effect,
• Correcting the measured position of features,
• Removing irrelevant features, patterns or 'noise' in the grid.
• Transform the signal using the principles of physics.

The INTREPID GridFFT process has three basic steps:

1. Prepare and transform your grid dataset from the spatial domain to the spectral domain, using a Fast Fourier Transform (FFT).
2. Apply a range of geophysical, directional, noise removal and wavenumber dependent filters. It can apply filters singly or combine as many as you wish.
3. Transform your grid dataset back to the spatial domain, using a Reverse Fast Fourier Transform (ReverseFFT).

In this chapter:

• How to use this chapter
• Using the GridFFT tool (interactive only)
• The GridFFT window
• Specifying Input and Output (Filtered) Datasets
• Frequency, wavelength and distance unit multiples
• Fundamental and Nyquist Frequencies of the Input Grid
• Pre FFT Grid Conditioning
• Post-filter transformation options
• GridFFT filters overview
• Combinable filters
• Compound derivative filters
• Apply the filters (interactive only)
• Exit from GridFFT (interactive only)
• Help (interactive only)
• Task specification (job) files in GridFFT