| OpendTect Workflows Documentation version 4.2 |
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Purpose: Sharpen ridges in a Similarity Cube.
Theory: The filter compares in the time-slice domain three neighboring similarity values in six different directions and outputs the largest ridge value. The ridge in each direction is the: sum (values on either side) / 2 - center value. In most evaluation points there are no ridges and the values thus tend to be small but when you cross a fault there will be a large ridge perpendicular to the fault direction. The filter outputs the largest value i.e. the ridge corresponding to the perpendicular direction.
Software: OpendTect + Dip-Steering
Workflow:
- Open the attribute set window and open the default set called: Ridge enhancement filter. Select seismic and steering cube.
- Apply the Ridge enhancement filter to the seismic data in batch: Processing - Create seismic output, or on-the-fly: right-click on the element in the tree (e.g. part of a time-slice).
Tips:
- In the default attribute set you calculate 9 similarity values at each output point. The process can be speeded up (almost 9 times) by calculating a Similarity Cube first and to extract the similarity values from this pre-calculated cube. You must change the attribute set. Use the "Reference Shift" Attribute instead of Similarity.
- Ridge-enhancement can be used to enhance any type of ridge cube. Note that ridges are either positive or negative and that you need to modify the ridge enhancement attribute (Mathematics max or min) accordingly.
- In the default attribute set Dip-steering is used to create better (dip-steered) similarity. This is not a pre-requisite for ridge-enhancement filtering.