Derivative Filter (Horizon)
The Derivative Filter operation removes points from a horizon with a strong change in the gradient.
Use the derivative filter to identify and remove low quality picks, especially in areas where automatic propagation may have tracked a different event (e.g. in areas with faulting and other geophysical anomalies).
- Where is the derivative filter operation?
- Configuring the derivative filter
- Completing the operation
Note: The Filter button is disabled if the horizon is waiting for another operation (such as propagation). Insight notifies you to complete the previous operation before continuing.
Derivative filter is found in the Map View, under the Operations tab (along with other horizon operations).
- Open the Map View.
- Expand the left panel and open the Operations tab.
- At Operation, select Derivative Filter.
Tip: Click the Help icon to read more information about this operation.
- In the navigation bar, select the horizon for the filter.
- At Max gradient (ms/m), enter the maximum gradient to allow. Points on the horizon that exceed this value will be removed.
At Minimum size, enter the minimum number of connected points to remove.
- A minimum size of 1 removes single points anywhere on the horizon.
- A minimum size of 5 only removes patches of five or more points.
- At Area, select a polygon/probe to constrain the operation
- Click Filter.
After running the operation:
- Click Discard to cancel this calculation and delete the results.
- Click Replace this horizon to save this horizon containing the extracted values and replace the previous one.
- Click Save as New Horizon to create a new horizon.
The following are examples of a horizon in the Map View before and after derivative filtering:
Note: By default, the new horizon will be named: "horizon_name (filter gradient value)". For example, the operation above will yield a new horizon called "Sample (filter >1 ms/m)". To rename the horizon, see Horizon Details and Configuration.