Detecting lines by intensity
- Jonathan Duguay (Unlicensed)
Menu: Survey / Line 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. Parameters are like the ones of the edge detection, but 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 asked parameters are met. 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. Here is a list of the parameters:
Min. intensity: Minimum intensity value (in %) for a point to be part of the line. It's automatically setted to the minimum of the two picked points. The check beside allow to hide every points that has an intensity lower then the value
Direction tolerance: Maximum deviation of the polyline from one segment to the next.
Min. segment length: Distance between each point in the polyline.
Elevation tolerance: Maximum difference of elevation from the line for points to be considered.
Distance tolerance: Buffer to find the next point.
Starting point: To specify the starting point, first select the “Pick 2 Points” button and pick the point where the line must begin and another point on the line for global starting direction. Both coordinates will be entered.
Once parameters are set, the “Start” button will launch the detection. If the detection does not show any results, the parameters may be too restrictive. If the line detected diverges from the marking line, closing the “Pick point” window without saving points and putting an higher intensity should generate better results. Note that this tool can also be used for electrical wires and cables.
There is also the possibility to use it with a corridor instead of two points to detect lines. Using "By corridor" will generate all lines possible to find with the set parameters inside the specified corridor.
