3D laser scanning can work, but it extremely expensive. Further, it creates "literal" 2d images in three-D that, once rotated, show exactly the images from only the original scanned direction. The final software - after MANY multiple images from the entire plant scanned area are "joined together with each other to a common reference point and axis" - need to be "sewn together" into a single very large file of approximate outside dimensions. And those dimensions are "outside of pipe" = NO centerlines nor work points nor distances. Only the outside of the flashing and insulation approximations.
So, what I do is complex, but works to 1/8 inch or so when you are on the floor, and the pipes are 45 to 90 feet up.
First, KNOE EXACTLY how accurate you need your numbers to be. Don't fool yourself, but don't pretend you can get 0.016 inch accuracy on a pipe location. Then again, when you cut a pipe, +/- 1/8 to +/- 1/4 inch is "less than the width of a welding rod" ...
And you can use this method for less than $200.00. Anywhere.
1. Go to your local Home Depot or Lowes. Get a TALL right-angle gage (I use a 4 ft gage used for marking 4x8 plywoods and a three-way level gage used for fence posts. Mount the 3-way level gage to the right angle gage so you can actually tell "what way is "up"" when you use the laser distance detector.
See, the biggest problem with those is that you CANNOT "look up at the pipe" while reading the laser while aligning the laser to a specific point while KNOWING absolutely that you are really are measuring some vertical point high overhead while telling when you are perpendicular to the floor/slab/gravel. While trying to hold the laser distance finder some exact distance from the floor/slab/gravel.
So you get very, very sloppy readings. Unless you are laying on the gravel trying to simultaneously click the laser distance while aiming the laser from the gravel at the bottom of the pipe!
In the photo's below, I'm simulating measuring the width, centerline, and heights-above-floor for a fan blade in the living room.
- Mount the 3-way level gage at a convenient height above the floor - I use 36 inches, since I can hold the square perpendicular in x while looking up at the pipe while holding it near-vertical in y. (A true 3-way level square on a tripod a fixed distance above the floor would be ideal, but then you are assuming your floor/slab is dead-level.)
- Set the laser range finder to "measure from the back of the range finder".
- Hold the laser range finder at the square on the 3-way level gage, then move the level gage and laser so you are aiming at the center of the pipe overhead. The square will keep you accurate to the floor, and you need to keep moving the assembly until the 3-way level gage is "near-zero" deviation and the laser pointer is where you want to measure overhead.
- Press the "measure button" when your laser is at the right point overhead.
-Have your helper (or yourself) mark the position on the floor where you measured! Use a marks-a-lot or crayon or Sharpie. DO NOT SKIP THIS STEP. After a few minutes, I will guarantee you will not be able to re-create the geometry.
- For pipes, look for the lowest point on the insulation, for a bare pipe at the low point, or for the "center" between two tangent points. The pipes will vary slowly with the cosine near the centerline, so you won't be too far off if you miss by a few millimeters or 1/86 inches left or right of CL.
- Near the same point where you took an elevation, take two tangent point measurements. Mark them on the floor or plywood panel you are using.
- Your CL elevation will be 1/2 (tangent distance) + bottom elevation above floor. Then try to figure out how high your floor is.
