Cross-correlation is a statistical measure of similarity between two inputs as a function of time shifts.
This process computes the cross-correlation between a volume and another volume, trace, or wavelet. Use this process to determine time shifts, repeating signals (multiple) or to quantify phase and time differences between input traces.
Note: Shifts are applicable to the primary input volume. The shift value is the amount applied to the primary input trace to achieve the correlation result.
Create a Cross Correlation process
- In the Control Panel, open the Process tab.
- At the tab header, click the Add icon and select New Process.
- Scroll down and double-click on Cross Correlation.
- Type a name for the process and click OK.
Configure the Cross Correlation process
- In the Details Panel, select the input Volume.
- Headers: Output the trace shift that would result in the best correlation (in ms, metres, or feet) and/or the best correlation value (0-1000) in selected headers. The input sample data is left unmodified.
Correlogram: Output a correlogram of cross-correlations, each sample corresponding to a particular shift.
- Normalise: When selected, normalises the correlogram.
- Matching trace for each input trace: Cross-correlate each trace in the primary volume with a corresponding trace from the reference volume.
- Single gather: Cross-correlate each trace in the primary volume with a corresponding trace from the reference gather. The reference volume must contain a single gather or record.
- Single trace per gather: Cross-correlate each gather in the primary volume with a corresponding trace from the reference volume. The reference volume must contain a single trace per gather location.
- Single trace: Cross-correlate each trace in the primary volume with the trace in the reference volume.
- Wavelet: Cross-correlate each trace in the primary volume with the specified wavelet.
Select the Reference Volume/Wavelet.
- Wavelets must be a single wavelet and not a multi-wavelet field.
# of lags (half window): The number of relative shifts to cross-correlate.
- If producing a correlogram, the correlogram will be 2N + 1 samples long, where N is # of lags. I.e. N negative shifts, the zero shift, and N positive shifts. The zero shift is at time=0. Negative shifts are output at negative times and positive shifts are output at positive times.
- input volume: Apply a window to the input volume before correlating.
- reference volume: Apply a window to the reference volume or wavelet before correlating.
- For Windowed trace window:
- Start of window: The start time/distance (or horizon) of the window.
- Length of window: The length of the input volume window.
Example configuration for Cross Correlation
Good cross correlation between input gather volume and trace mix volume showing strong zero phase event at 0 ms and non-coherent event below.