Menu | Tools > Surfaces > Interpolate > By Range |
Tool |
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Menu | Tools > Surfaces > Interpolate > By Range |
Tool |
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Interpolation fills empty nodes in a grid using values from surrounding populated nodes.
The Interpolate by Range command allows you to manually interpolate specific areas of a surface by drawing a bounding box around an area containing holes. All holes within the area will be filled iteratively using the values of the surrounding nodes, according to user-specified criteria. Holes must be completely within the bounding box in order for them to be filled.
When a hole is selected for interpolation using this command, the process begins by classifying all nodes in the surface as data, holes, or no-data (areas beyond the surface data but within the extents of the surface). The classification information is saved to a temporary Holidays layer. This is done entirely in the background and will not be visible in the application.
The classifications for the nodes in the selected area are then used to interpolate the holes based on the user-specified criteria. The process runs iteratively until the selected holes are completely filled. If a hole cannot be completely filled, any changes that may have been applied to that hole will be reverted and a message will be displayed in the Output window.
This interpolation method implements changes on the selected source surface. These changes cannot be reverted using the Undo command; it is recommended that you back up your data prior to running the interpolation.
Related commands:
• Interpolate Surface By Pointing
Interface
The Interpolate by Range command uses the following dialog box.
Option | Description |
Matrix size | The number of nodes surrounding a hole that will be analyzed for populated values. The options are 3x3 or 5x5, meaning the application will analyze a square area around each pixel of the hole that is either 3 pixels high and 3 pixels wide, or 5 pixels high and 5 pixels wide. |
Neighbours | The number of pixels within the matrix area that must contain data in order for the hole to be interpolated. For example, if you select the 3x3 matrix size option and enter a neighbours value of 6, that area must have at least 6 populated data nodes in order for a pixel in the hole to be interpolated. If there are not enough populated nodes present in the matrix area, it is possible that only some pixels in the hole will be interpolated or the hole will be skipped entirely by the process. |
In the image below, the blue square represents a 3x3 matrix area. Each dot within the square is a node. Of those nodes, only the 6 shaded nodes contain data.
If the Neighbours field is defined as 6 or less, this would be sufficient to interpolate the pixel at the centre of the square. If the square were shifted to centre on each pixel in the hole, you can see the entire hole could be interpolated using the specified criteria.
Procedure
1. Select the root layer of the surface containing the holes to be interpolated.
2. Select the Interpolate By Range command.
A dialog box is displayed to define the interpolation settings and the cursor changes to indicate the interpolation method.
3. Select a Matrix size option.
4. Type a value in the Neighbours field.
The values entered for Matrix size and Neighbours will be remembered the next time the command is run. |
5. Click and drag to draw a bounding box around the holes you want to fill.
6. Release the mouse button when the desired area is encompassed.
The process performs as many iterations as needed to fill the selected hole(s) and flags those nodes as interpolated. A Depth Interpolated layer is added to the surface. This layer can be used to identify the interpolated data.
This command will remain selected and active until:
• the command is manually toggled off,
• another command is selected, or
• another layer is selected.
7. [Optional] Draw additional bounding boxes to interpolate any remaining holes in the surface.
If further interpolation is performed on the surface, the existing Interpolation layer will be updated rather than creating another layer.
8. Turn off the Interpolation command.
