Polar Keystone

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Calibration/Polar Keystone

Performs keystone and blobbing processes for a single or multiple devices using polar coordinates. ​


The Polar Keystone box blends the coordinates from multiple devices using the polar coordinates to generate blobs. The parameters use the metric system, like most of the laser device. The outputted data is in Normalized Screen Coordinates.

General Use Case: The box is useful to process data from laser detection devices like the Hokuyo and Sick Laser. Usually multiple laser inputs are used for a better accuracy. As Lasers detect points on multiple angles, the detected positions need to be unified into one blob.

Additional actions may be done in the preview window when the box is selected.
- Resize detection zone.
- Ctrl+I: Reinitialize the detection zone.
- 1-9: Focus on given devices.
- A: Focus on all devices.
- M: Move Device mode.
- T: Turn Device mode (rotate)
- Mouse Wheel: Zoom view
- Ctrl+Mouse Wheel: precise Zoom
- F1: Quick Help


Device-[N] Float2 Vector Receives the data generated by the laser input.
Limits Float2 Received the laser limits.


Blobs-[N] 2D Points Outputs the coordinates of the Device-[N].
Data View 2D Texture Outputs the preview texture.
Merged Blobs 2D Points Outputs the points of the merged blobs.



Device Count Int Sets the number of devices and enables the corresponding input and output pins.
Enable Output Pin: Data View Toggle Enables the Output Pin: Data View and output the preview texture in a pin.


Noise Removal

Filter Mode String Sets the Noise Removal filter preset.
Averaging Sample Count Int Sets the maximal number of points used to determine a merged blob.
Input Confirmation Sample Count Int Sets the minimal number of points in a blob to be valid.
Discard Weak Signal Samples Toggle Enables the distinction of the radial distance in the blob validation process.
Weak Samples Flicker Tolerance Float Sets the minimal radial distance between two points to be considered in different blobs.


Across Devices
Device Merge Distance Float Distance within which overlapping blobs are merged across different devices.
Within Device
Proximity Merging Toggle Enables the merging of blobs based on their proximity.
Merge Distance Float Sets the maximal distance between blobs to merge.

Device 1


Scale Float Scale of the device distance data.
Center Float2 Sets the center of the device in meters. Devices can also be moved in the preview window using the shortcut "M" when the Polar Keystone box is selected.
Rotation Float Sets the rotation, in degree, of the device. Devices can also be rotated in the preview window using the shortcut "R" when the Polar Keystone box is selected.

Axis Flip

Mirror X Toggle Inverts the device on the X axis.
Mirror Y Toggle Inverts the device on the Y axis.
Swap Axis Toggle Swaps the X axis with the Y axis.


Top Margin Float Sets the top margin from where inputs are ignored.
Bottom Margin Float Sets the bottom margin from where inputs are ignored.
Left Margin Float Sets the left margin from where inputs are ignored.
Right Margin Float Sets the right margin from where inputs are ignored.
Use Texture Mask Toggle Enables the use of an arbitrary shaped detection mask.
Mask Filename Uri Indicates the path of the image file to use as a mask. Black pixels allow detection while white pixels block the detection of blobs,
Mask Color Float4 Sets the color representing the blocked pixels in the Data View texture.

See Also

Boxes related

Blob Detection, Blob Tracking, SICK, Pointer Device, Point Mapping, Point Simulator, ​​

Version Information

Current documentation version: 2.1.2. ​ ​