Filter Surface Points By Normals
Description
This Step is used to exclude unwanted surface points based on their normals so that a better surface can be obtained.
Workflow
The process of configuring this Step is shown below.
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Configure the input. Connect the ports manually or select the input(s) under Input in the parameter configuration panel.
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Determine whether to use feature region. For more information, please refer to Use Feature Region.
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Set the angle parameters.
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Set other parameters.
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Select the output item Depth Map (selected by default).
Parameter Description
- Use Feature Region
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Feature region defines the area to be filtered. When this option is selected, this Step will only process data within or outside the feature region.
Default setting: Unselected
Instruction: Please set the parameter according to the actual requirement.
- Feature Region Mode
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Once Use Feature Region is selected, this parameter is used to set the mode of the feature region, that is, to select whether to filter the surface data within the feature region or the data outside the feature region.
Options: Include data in Region, Exclude data in Region
Default setting: Include data in Region
Instruction: To filter surface data within the feature region, select Include data in Region; otherwise, select Exclude data in Region.
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For more information on how to set the feature region, please refer to Set the Feature Region. |
- Angle-Based Filtering
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The relevant parameters are explained as follows:
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Min Polar Angle: The minimum acceptable angle of the normals with respect to the Z-axis.
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Max Polar Angle: The maximum acceptable angle of the normals with respect to the Z-axis.
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Min Z Angle: The minimum acceptable angle of the XOY projection of normals clockwise around the Z-axis and relative to the positive X direction.
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Max Z Angle: The maximum acceptable angle of the XOY projection of normals clockwise around the Z-axis and relative to the positive X direction.
As shown in the figure above, OA is the normal, OB is the XOY projection of normal, ∠a is the polar angle of normal, and ∠b is the Z angle of normal.
The parameters Min / Max Z Angle and Min / Max Polar Angle specify the angle filtering range for normals. Data points with normal’s polar angle or Z angle outside the range will be excluded.
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- Remove Noise
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This parameter eliminates noise that can be introduced by normal calculation. Please select the level according to the tolerance to noise.
Options: None, Small, Medium, Large
Default setting: None
- Smooth Size
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The size of the filter window.
Apply a mean filter to the surface data before calculating the normals to avoid abrupt normal changes due to noise. The default value is 1.
Normal Vector Calculation
- Normal Search Radius
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For surface processing, points within a circle with a set radius are used to calculate normals. The unit is millimeters (mm).
Default setting: 1.000 mm
- Half Kernel Size
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For depth map processing, points within a square with a side length of twice the set value will be used to calculate the normals. The unit is pixels.
Default setting: 1 pixel
Output Description
The output of this Step is a processed depth map that can be used as input to other Steps.
Troubleshooting
Invalid Parameter
| No. | Error | Possible Causes | Solution |
|---|---|---|---|
1 |
Inappropriate smooth size |
The set smooth size is less than 1. |
Reset Smooth Size and ensure that the value exceeds 1. |
2 |
Inappropriate polar angle |
The set polar angle is not within the range of 0–90°. |
Reset Min / Max Polar Angle to ensure that the polar angle is within the range of 0–90°. |
3 |
Inappropriate Z angle |
The set Z angle is not within the range of 0–360°. |
Reset Min / Max Z Angle to ensure that the Z angle is within the range of 0–360°. |
4 |
Inappropriate normal search radius |
The set normal search radius is not greater than 0. |
Reset Normal Search Radius and ensure that the value exceeds 0. |
5 |
Inappropriate half kernel size |
The set half kernel size is not greater than 0. |
Reset Half Kernel Size and ensure that the value exceeds 0. |