How would I figure out (besides trial and error) how large a reflector I need to take a measurement with an EDM. I want to put reflective tape on the side of a building but I want it to be as small as possible for aesthetic reasons. Obviously the target size is dependent upon the distance between the EDM and the target. Does anyone how to obtain this information?
For two different reflector areas each at the max reliable distance, ignoring atmospheric attenuation (significant for prism range but not reflectorless range)
D2/D1 = sqrt(sqrt(A2/A1))
A2/A1 = (D2/D1)^4
will get you in the ballpark.
For Red Laser Reflectorless; I cut the reflective tape into 1/2" squares and it works fine with my Leica equipment. Be aware that reflective tape comes in several different reflective qualities with the SOLAS brand having the highest reflective properties. Reflective tape also comes in different colors... so if you put red reflective tape on a red brick building, it'll be pretty hard to see unless you know where to look.
I think that the instrument that you are using will have a lot to do with the answer to you question. If you are using a top grade instrument, with long range targeting capabilities, you will be able to use a smaller target. Most modern instruments, with reflectorless capabilities, have a narrow beam and would allow for a very small target. What instrument are you using?
I was told size doesn't matter...
Just make sure you have a clean lens.
> size doesn't matter...
> Just make sure you have a clean lens.
That's what she said:-D
Why can't I use the flash button anymore?
LOL:-D
I'm not using reflectorless. I'm using a Topcon GTS-700 series gun.
Bill,
I'm sorry, I don't understand the equations you gave me. Why in the equations do you have two distance and two area factors?
What he is trying to say is: The angle of the dangle is directly proportional to the heat of the meat.
What is the diffusivity factor per 100 feet or some such distance for your machine?
In that case your best option is mini prisms. You probably need to be inconspicuous with your target placement, but for the sake of accuracy, you need the best possible setup. Without reflectorless capability you won't be able to take full advantage of a stick-on target. It's not really that hard to mount small prisms to a surface but the cost is slightly more.
What you should do is tell us more of the specifics of the project and we could give you more help. Is is a tunneling project and you have to monitor the surrounding structures....
The more information you give the more help you'll get. 🙂
Radar...
> Why can't I use the flash button anymore?
I don't know.
If I click the "Embed" button under the YouTube video, I get this:
If I click the flash button here on Beer Leg and paste the above string into the resulting "Code" field, it doesn’t work.
However, if I right-click on the YouTube video itself and select "Copy embed html" from the resultant drop-down menu, I get this:
If I click the flash button here on Beer Leg and paste that string into the resulting "Code" field:
[flash width=640 height=390] http://www.youtube.com/v/Ccdu8yZIanM?version=3 [/flash]
Voila!
I was thinking reflectorless as well although you never said that. You had wondering me why you need a target in reflectorless mode. My bad.
I/we had shot all kinds of stuff, water included, in reflortless mode and it always came out just fine. I was sent out solo once on a topo to locate everything I could find including the paint stripes on a very busy 4-lane plus center turn lane in reflectorless mode. Some of it was uphill but most was downlhill and a couple hundred yards away. I worried about it but couldn't check it since I didn't have F2F setup. I was amazed how well the drawing came out.
(sorry to get off somewhat topic....)
> I'm not using reflectorless. I'm using a Topcon GTS-700 series gun.
Might be time to upgrade! Although mini prisms would work reflectorless would be a much better option.
reflectorless is great for busy roadways. We had one where we shot the reflectors in the roadway to get the lane stripes.
reflectorless is so useful for things you never think of until you have it.
Good luck with the reflective tape... I'd probably use a peanut prism too if I didn't have a total station with reflectorless.
The prism ideally needs to be about one-half the size of the opening of the total station's objective lens. However this is ideal, and assumes a perfect prism and no diffraction. So in reality, you probably want a slightly larger prism than one-half the objective lens size for long distances, so add ~25% to the size you calculate.
If you go with a prism smaller than this, the returned signal will not fill your whole lens. If you go larger, much of the signal will diverge in a pattern larger than your lens and miss the total station lens and sensors. This is also why long distance triple prisms are 3 smaller prisms rather than one giant prism.
The actual range you get depends on the instrument and the reflective material, and probably requires a measurement to find the max range of some particular size target.
The equations let you use that measurement to predict range performance of other size targets over moderate distances. An important observation is that the size needed grows pretty fast.
An additional assumption is that the beam from the instrument spreads out to cover the whole target. So the equations don't work if you are very far away. For a good reflector, the max range will probably be large enough that the beam dispersion does cover the target. However if you try to extend too far with a huge sheet of reflector, the whole sheet won't fall within the beam and only a better reflecting surface will help.
Radar...
Sweet, I was wondering about this as well. Thanks!
It will also work if you check the box "Use old imbed code". Time to start posting music!
It might be time. I'm in my 6th year of reflectorless. My current setup gives me great accuracy reflectorless out to 3,000 feet to power poles. I have a power prism setting in reflectorless that puts me in and close to the center of power poles. I've traversed out to and over 3,000 feet shooting power poles, and checked locations backward to the power pole to within hundreds of a foot. My rodman loves me! LOL!
I used 3 of these babies on a monitoring job a while back. Drilled a 7/16 hole in mortar between bricks, some silicon in the hole, black tape on the back of the prism to reduce signal loss through the prism, pushed them into the holes & let them set up.
Had 3 points on a sidewalk that we occupied weekly and shot the prisms and other points. After 4 months it was determined that 2 out of 3 pieces of sidewalk were moving merrily downhill at a rate of 0.13/month. Used a small screwdriver to remove the prisms then patched the mortar. Can't tell anything was there now.
I've had great luck doing the same. Being able to shoot lane reflectors 3,000 feet each way gives enough geometry on Interstates to recreate row's, and find row markers. I love shooting power line conductors to get elevations for road crossings. I've got to where I don't measure houses anymore. Locating fences and gate, mail boxes, water meters, just any thing is easy as the rodman walks to the next station.