How well do reflectorless total stations perform when shooting dirt?
We have a 14’ to 20’ deep excavation, which is 100’ by 75’ wide, that we need to determine quantities on, and it is not accessible to go into the pit.
Will a reflectorless TS provide fairly good results shooting the dirt against an excavation wall or pit floor?
Thinking about renting one for this project…
My Nikon NPL-350 seems to shoot dirt just fine, though probably only to about 200' max (depending on the color of the dirt). I have shot up many an as-built Underground Storage Tank excavation with it and the narrow beam seems to eliminate any confusion to what you are shooting.
Should be no problems...
Tell the instrument company that you are thinking of purchasing so could you have a trial run on that job. That way you will be blown away and want to buy one!
RADU
I know our Leica robot will do it. There is even a program in it for it to automatically turn at a specified interval and area and take/record shot.
Since we do scanning also now, we would just do that though.
We use reflectorless for inaccessible faces in gravel pits and quarries regularly. The data collector can be set to put the instrument in reflectorless tracking mode, and to record points every few seconds. Look through the eyepiece, turn on the recording and start dialing across the face of the slope as fast as you think appropriate for the required level of detail, working back and forth until you've covered the area.
I like this method better than just shooting a grid because you can pick your spots and adjust as you go. If you see something of interest then you can spray in more shots for that area then carry on from there.
I have one of the earliest reflectorless TS's, Leica TCR 305.
Within it's very limited range (about 100') is shoots dirt just fine.
One observation that I have regarding measuring directly to the ground surface is that the limiting factor is typically that as the angle of incidence of the edm beam to the surface become more and more oblique with increasing distance from the instrument, the accuracy of the shots tails off.
In this case where you are looking down into the pit, the depth should work in your favor, plus part of what you are measuring to will be the vertical wall of the excavation. The darker the object the shorter range to which most reflectorless instruments will successfully measure. You may be able to extend the range a bit by picking our lighter surfaces such as light colored gravel for instance.
But with the dimensions of the pit you describe, the range should not be an issue at all.
If you have trouble shooting the dirt that is dark, and you can't have someone paint some stuff white for you, bring along some small white landscape stone, or stop at the concrete plant and grab a bucket of agg. Toss it over the area and shoot the rocks.
A few days ago I got a trimble S6 demo, it shot a black power line at 454 feet. I bet it would shoot the heck out of your little hole in the ground.
Not bad. I have the Topcon GTP 3005LW. The Reflectorless is amazing. I've located power poles out to 3000', running traverse, changing the prism constant to the center of the pole +/-, checking pole locations from the forward trav pt to just a few hundreds. I've done the same with roadway shooting the cl reflectors. 6,000' of roadway from 1 setup. That's the big reason I keep this gun. Oh! I go back to a correct prism constant. It'll do BIG HOLES!
Bring along a paintball gun with white paint balls
I have a Topcon GPT3005LW which should have no problem doing what you want. Just stand there and fire away. It's manual (no motors). It's mostly collecting dust, unfortunately.
I'm pretty much the only person who touches that instrument, though.
You could go over to CSDS and see if they will rent you an S6 with a DC. The S6 will take a grid of reflectorless shots as specified by you. Just start it running and take a nap or whatever.