Detecting lines by intensity

This function generates a polyline by comparing intensity value of points along a direction, such as the intensity difference between marking lines and the asphalt. It generates a polyline with points at regular intervals specified in the parameters. The settings are the same as the edge detection, but also add the minimum intensity which is automatically set to the lowest intensity value between the two picked points.

The detection will create points along the bright line as long as the parameters are respected. This function needs a good density of points so that the lines are correctly detected. It needs two points on the line to start its detection. Below is a list of the parameters:

• Min. intensity: Minimum intensity value (in %) for a point to be part of the line. It is automatically set to the minimum of the two picked points. The check alongside allows to hide every point that has an intensity lower than the value.

• Max. segment length: Maximum distance between each point in the polyline.  

• Min. segment length: Minimum distance between each point in the polyline.  

• Tol. Elevation: Maximum difference of elevation from the last detected point and the next point to be considered.

• Tol. Distance: Buffer to find the next point.

• Tol. Deviation: Maximum deviation from the last detected point and the next point to be considered.

Once the parameters are setup, you will have to go to "Search by" and select between 2 options.

• Two points: You will pick the starting point of the detection and the 2nd point will indicate the direction to follow for the detection
• By Trajectory: Select an alignment or the camera path (For MMS) for automatic batch detection. You will have to select the offset left & right (search distance from the trajectory) and the start/end of the search by entering the index number for each or clicking on the point cloud directly ( you will need to click on "Start index" and "End index" respectively prior to click on the point cloud).

Once the mode selected, then click on "Start detection"

Once you are done with the detection, you will have the option to: 

• Save: Saves the selected polylines to a PLN format.
• Load: Loads a PLN file to the item list while clearing existing items.
• Append: Adds a PLN file to the item list. Does not clear existing items.
• Export: Exports selected polylines to .DXF, .MID or .SHP, GeoJSON or .KML format.
• Create chains: see "Picking points and lines".