LISP/Visual Basic - Point Cloud tracing - averaging points to produce lines

Zleceniodawca

Thomas Putko

Opis

Problem:

We process here laser scans. The result is a point cloud, which we are slicing at certain levels (100mm below the ceiling and 200mm above the slab). We end up with dotted line which represents the line of i.e. column or core wall.

Right now we are tracing average centre line by eye, the same as my other colleagues in the scanning business. The only program so far which allows for averaging is PointSense.

Below the link to demonstrate how this PointSense program for CAD is working. Good idea which in case of this program does not work very well – command on exe is freezing CAD for good minute before it takes off and I am not running it on sack of potatoes – it is Dell Precision with 32GB of RAM.

https://youtu.be/iYMWbAF_buY?t=47

Solution:

Write a code in LISP or Visual Basic for CAD which will trace average line using selected points. I believe development could be staged into few advancing steps:

1. Producing a straight line from selected points by determining first and last point of the line and area on both sides which marks the points. With the option to determine the distance on both side of the lines which is going to be demarcation line. (in this case it was 8mm on both sides. The Z value for the purpose of producing the line can be ignored.

2. Producing a curved line.

3. Simplifying the process of producing the lines by marking the whole column instead choosing manually line by line.

This automation of the process would save 40% of processing time.

Here are the links to information which might be relevant:

List of CAD libraries which contains LISP and VB programs

http://www.cadtutor.net/forum/showthread.php?40733-Lisp-library-very-handy

App already written which somehow covers the subject. Date-bombed though.

https://apps.autodesk.com/ACD/en/Detail/HelpDoc?appId=6199983470941523733&appLang=en&os=Win32_64

I’m sure you are familiar with the maths of the solution but here it is nevertheless

https://en.wikipedia.org/wiki/Total_least_squares

https://en.wikipedia.org/wiki/Deming_regression

https://en.wikipedia.org/wiki/Polynomial_least_squares