OpendTect User Documentation version 4.2
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4.4. Random line

If you right click on the Random line option in the tree, two options will be available: New... and Load.

Load...: Load pre-existing random line geometries. Moreover, an existing line can be edited at a later time.

New: Create new random lines. The following options are available:

Empty: Right click on Random line and select 'Empty'. The new random line will be added as a sub-element of the random line. By default, this is the centre inline of the cube. To create the new arbitrary direction of random line, the user can modify nodes by editing or inserting nodes. With multiple nodes, the random line can also consist of multiple flat sections. The sections of one single random line may intersect one another. In interact mode, the little plane of a node can be used to drag the node laterally, and the vertical tube can be used to shift the edge of the random line vertically. Nodes can be added from the pop menu by right clicking on the random line in the Interact mode.

From Existing: Generate random line(s)from existing random line(s). There is an option available to generate random line at some distance away from existing random geometry and store it in new random line geometry.

Along Contours: Create random lines between specified contour ranges. Note that a interpreted horizon grid will be required to provide the contours.

From Polygon: Create random line from saved polygon.

Create From Wells: Connect several wells by a random line. The line follows the deviated well paths (optional). By right clicking on the random line tree, and selecting Create from wells, a dialogue box appears with a list of wells that can be selected in order to set up the random line path. Tip: use in SSIS (Sequence Stratigraphy Interpretation System) when creating a 2D line-section that follows the well paths.

From Table: Create random line from table. The input will be X/Y coordinates, Inline/Crossline and Z ranges

Interactive: Create random line from interactive mode. A horizon or Z slice must be loaded in the scene first, where after a random line can be created by picking nodes.
Once a Random line is created, right clicking on it in the tree gives the following options in a pop-up menu:

Add attribute: When selected, choose to display data from stored cubes, an attribute from the current attribute set or an output node of the current neural network. To display an attribute or neural network, select or create an attribute set or neural network first.
Add Volume processing attribute: Display volume created from the volume builder
Add HorizonCube display: Display generated HorizonCube
Add System tracts display: Add system tracts
Show histogram: Display a histogram of the selected random line.
Duplicate: Duplicate the line as an empty element in the tree. Display different attribute on the duplicated line whilst keeping the original data.
Reset Manipulation: Reset any change in the position of the random line (or its nodes) you have applied and set line to original position. This option is only available if changes have been made to the position of the element.
Properties: The Properties option refers to display parameters such as Ambient reflectivity, Diffuse reflectivity, Transparency.
Resolution: Choose between standard/higher/highest resolution
Correlate wells: Start the WCP (Well Correlation Pannel) module
Edit Nodes: Edit or add ateral coordinates of nodes. Right click on the inline/crossline or X/Y position of a node to insert/remove nodes from the table.
Insert node: Insert a new node before the selected node.
Create from wells...: Generate a new random line between the wells.
Save: The Random line node positions and Z range can be saved at any time during the building process.
Save as 2D: Create a 2D line from a Random line. Right click on Random line in the tree and select Save As 2D. A window will pop up, as shown below. Select the input cube, the output line and the line name. The first trace nr number of line is also necessary.

Note:

survey type

Create 2D Grid: The random lines (with two nodes only) can be used to create a 2D grid with a fixed grid spacing. When selected, the Create 2D Grid window is launched (see below). Here, specify the input 3D seismic volume and the ouput lineset name. The output grid is generated according to the dip (perpendicular) and strike (parallel) direction of the selected random line. The prefix labels are used as prefixes to the output line names, stored to the specified new lineset name. The grid spacing is the constant spacing between the two line. At the bottom, the total number of parallel and perpendicular lines will be updated according to the grid spacing. By pressing Proceed button, a batch process will start to generate the 2D grid. When the batch program is finished, the data can be displayed in the scene (see 2D Seismic section for details).

Lock: Locks the selected object. Prevents accidental removing, moving or displaying data on the object. After clicking lock again, all editing is again enabled.

Remove: Remove the random line from tree and from graphic area.

Export to Google KML: Export selected random line to a Google KML file. Specify the KML file parameters in the pop-up dialog. Note: annotate the start and end of the random line with a user-defined line annotation in the output file settings.

4.4.1. Manual Mode (Empty)

Manual Mode. In manual mode, the random line will first be displayed in the 3D scene. Nodes may be added and their position changed interactively, in a second step. This starting random line will have two nodes, one at each end of the central inline. More nodes can also be inserted in the right click menu of the random line in the tree (see figure below). Please note that the same menu is available with the right-click on the random line in the scene.

Adding/inserting new nodes between the existing nodes.

The node on the left-hand side of the newly created random line is designated node 0, and the one in the right hand side node 1. It is possible to insert a node before node 0, before node 1, and after node 1. The node will be created half-way between the two surrounding nodes. In order to move a node to a desired position, click on the random line to make the nodes visible/editable. In the interact mode, click at the node plane (horizontal/vertical) to move the node location. A purple surface appears around the node and the node can be moved in any direction inside the survey area.

The node can be moved in two directions (horizontal and vertical). The node's orientation can be changed by placing the mouse pointer over the node and pressing the Ctrl key.

Editing or modifying the position of the nodes is also possible through clicking the option Edit nodes.... The following windows will pop-up and the nodes are editable. Modifying or inserting new nodes is also enabled. In this table, each node is defined by its inline/cross-line or X/Y position. The nodes can also be removed by right clicking over the desired cell and selecting the 'remove node' option. Similarly, for the pop-up menu, more nodes can be inserted before/after the selected cell (node).

4.4.2. Create from existing

This option allows the user to generate random line offset from an existing random line. There is an option available to generate a random line at some distance away from existing random geometry and store it in new random line geometry.

Create Random line from existing line geometry in left/right or both directions. The direction is defined by the path described by the nodes, in the order seen in the table.

The first generation parameter is the input random line, which has to be chosen between the already existing random lines. Then, define the distance from input in meters and the direction in which the node will be added. There are three directions: left, right, and both. The final step is to name the output random line.

Click on the Display Random line on creation box to immediately visualize the random line.

4.4.3. Create along contour

Random lines can be create along the contour geometry. For this, an interpreted horizon grid will be required. The horizon grid is use to generate the random lines at a selected index contours range. All contour values that are present within the given Z-range, are used to construct the random lines. When the process is completed, you can edit the random lines also. This functionality is important to see the seismic section along the contours (e.g. AVO responses, DHIs or hydrocarbon contacts).

First, specify the input horizon, and optionally select if it is within a polygon. Then define the contour Z range and the step. Then the Random line Z range, there is an option to chose whether the random line Z range will be made relative to the horizon or not. Last step is to give a name to the newly created Random line set. If you want to display the random line on creation, check the box Display Random Line on creation.

The option Display Random Line on creation can be selected and the new random line will be displayed after clicking OK.

The following picture shows an example of result for a random line created along contour, it is composed of a set of random lines that satisfy the contour z range and therefore is composed of more than one element.

An example random line generated along a fixed contour line.

4.4.4. Create from polygons

This option allows the user to create random line definition from already created polygon. In the parameters, select the existing polygon and sub-select the Z-range for the random line, which will be generated. Write an output name for this random line and optionally, set check to display random line on creation so that after creation it will be displayed in the scene/tree. Press OK to proceed.

An example random-line generated along the white colored polygon. The polygon approximates the closure of a gas anomaly.

4.4.5. Create from wells

A random line can be created in such a way that it follows wells path. By right-clicking on Random line in the tree, and selecting Generate > From Wells ..., a dialog box appears with a list of wells that can be selected in order to set up the random line path.

Use the arrows to add and/or remove wells. Use the second set of arrows to setup a well sequence. Specify whether you want to use only the well top position or not. When you use all well points, you can specify the order by clicking the "Change Order" arrows.
The Extend outward allows the extension of the random lines in both sides away from wells

Press the preview button to see a top view of the random line that will be created. If the preview does not show exactly the desired random line, then change the parameters (the wells involved or the order in which they are listed). You can save the newly created random line by specifying the name in Output Random line(s) field. If you want to display the random line on creation, check the box "Display Random Line on creation".

The following picture is an example of random line created from wells.

In this picture, a random line goes through four wells following a random path between these wells (which are used as constraints).

4.4.6. Create from table

This is launched from: Random line > right click > New > From Table

This allows the user to create a random line from table. The input here is whether X/Y coordinates or Inline/Crossline and Z ranges

The random line resulting from this table is shown below

4.4.7. Interactive mode

This option is launched via Random line > Rightclick > New > Interactive...

This allows the user to create random line from interactive mode. A horizon or Z slice is first loaded in the scene, then a random line can be created by picking nodes.

A window pops up asking the user to create a randomline from Polyline.
The user can now pick nodes on Z -slices or Horizons like it is shown below.

After clicking OK, a random line is created.

An attribute can then be displayed

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