Hi. Currently, I am doing my thesis in civil engineering, I wanna know how to measure the angles between the two walls by using point cloud. It is like checking whether the two walls are 90 degrees or not(i.e. when u look in your room u may see the corners of the walls are 90 degrees). I am going to use a 3D laser scanner and using Matlab for programming.
you can see the following links:
1. https://arxiv.org/pdf/2108.03378.pdf
2. Article A study on measurement of building wall thickness from 3D object model
Three points define a plane. Pick three widely spaced points on a wall A, B, and C. For more precision, make the points by calculating the geometric mean of a small region of points on a wall. Subtracting one point‘s coordinates from another defines a vector between two points. The normal to the wall can be calculated as the cross product of two vectors lying in the plane of the wall. So the normal is
N = (B - A) X (C - A)
which one is first determines whether the vector points into or out of the wall. This normal has arbitrary length. Make it a unit vector by dividing by its length
n = N / sqrt( N dot N )
if you do this for two walls, then the angle between the two normals can be found from the dot product
angle = arccos( n1 dot n2 )
As Mike Albert already suggested. To improve the calculation and to get an accurate estimation of the statistical uncertainty, you can try to fit a plane function to the respective parts of your data set and calculate the normals from that.
Regards,
Michael
Thank you, everyone, for ur kind answers.
Saad Zahraw Sekhi Mike Albert Michael Rüsing
- Badges
- Science topic
- Similar topics
- Instrumentation Engineering
- Instruments