View Full Version : Probably OT: Tree Finder

06-11-2012, 08:15 PM
There may be some maching content in here somewhere.

My house has a view of distant mountains. In between is the enemy of views -- trees. After many years, a few of them are now on my kill list.

The problem is how to find them They are 400 to 600 yards from the house, on rough ground, and probably 80 to 100 feet tall. They are way too big to shake, and there's no hope of finding them by walking a compass bearing.

The only solution I can think of (short of artillery) is to wait for twilight, paint them with a powerful light located on a tripod at the house, then stumble around in the woods after dark, find the illuminated tree, and mark it for attention later.

One of the many "million candlepower" spotlights would probably put out enough light to do the job, but none of them have focusable beams, so they would probably be useless for identifying a single (though large) tree at that range.

Anyone know how to build a simple collimator for such a spotlight?

Anyone have a better idea of how to ID those trees?

Thx, J

06-11-2012, 08:26 PM
Laser pointer and scope?

06-11-2012, 08:44 PM

Don't think I could see a laser pointer from the ground. Remember, the illuminated part of the tree will be 80 to 100 feet off the ground. I'll be on the ground looking up, trying to see the light beam through the foliage from as much as a couple hundred feet away.

06-11-2012, 08:45 PM
Another approach (borrowed from Special Forces) would be to have one or more "operatives" stationed in the woods somewhat closer to the target area, in radio communication with the fire-control base (your house, with you stationed at the viewing location) and have them "designate" various nearby trees one at a time, either by means of a handheld spotlight or perhaps a green astronomical laser pointer, such that presumably if you can tell an operative "yes, that's one of them" by coded radio transmission, then they will be in a good position to either more permanently mark the tree(s) in question, or else gather GPS coordinates and close-up reconnaissance photos to help the tree extraction team do its thing later on.

06-11-2012, 09:23 PM
While fairly simple, this idea would take a bit of time. Long ago I made up a round frame with a lip around it, and stretched some space blanket over it. Glued all around the edges to make it airtight. Then through a suitably placed tube I could create some suction behind it. That pulled the space blanket into a pretty good concave. If you mounted three arms on that, coming to a point, then mounted a single halogen bulb at that point, you could focus it by varying the suction. It won't be optically perfect, but you'll get a not too shabby beam out of it. The longer the arms, the shallower the concave would have to be, and the better the performance. Definitely need a tripod or some adjustable mounting method so you can point it properly.

Another idea- put a diode in series with the ac supply to the bulb. That will drop the output, but it will also make the bulb output a stronger 60 hz signal. Once it's pointed at the tree, you can use a listening device to detect the reflected 60 hz signal. For a listening device, a solar cell can be the pickup. You may or may not need an amplifier between the cell and the headphones, but it's possible that sensitive headphones would be able to pick up the reflected light from the tree.

06-11-2012, 09:33 PM
Hmm ... this is making me think. How about a car headlight powered by a battery charger, collimated (sort of) with a fresnel lens. Problem is, I don't know diddly about optics & wouldn't know what lens specs to look for.

06-11-2012, 09:41 PM
Have your "Scout" with radio bring alone a helium filled baloon with a string attached on a calm day. You see the balloon in front of a tree you want gone tell him to "X" it with spraypaint. Just a thought.

Errol Groff
06-11-2012, 09:47 PM
Clear cut them all?

06-11-2012, 10:04 PM

Now that's a bright idea! Only problem is getting the balloon down again once it's up -- we're talking about deep, dark, thick, Walt Disney spooky forest. But balloons are cheap. I could use a half dozen and just let them go if I can't get them down. And it would work in daylight -- big advantage.

06-11-2012, 10:20 PM
Well, you can buy a fresnel lens that's 8-1/2 x 11 in a dollar store. It's usually called a magnifying sheet. You could stretch it across a frame to keep it flat. Or you could check thrift stores to find a magnifying screen designed to sit in front of small tvs. You'll have a lot better luck with that than the magnifying sheet. In any event, the best results will be obtained by using something close to a point source of light, hence my suggestion to use a halogen bulb. A car headlight bulb will work fine- the bulb itself that is. The best result you'll get is a nicely focused image of the filament itself on the 'target'.

It might be a stretch to say you can plant a circle of light on a tree 600 yds away though. You might find that even with the best focusing, your spot would still be quite broad. You might have to make good use of twilight or darkness.

06-11-2012, 10:37 PM
WTFPIC* Use an industrial laser. Just burn the tree off at the height you wish! :D

*With Tongue Firmly Planted In Cheek

06-11-2012, 11:16 PM
If the trees were closer, the top could easily be shot off with a high power rifle.

That has been done here with very large branches that were overhanging dangerously.

BUT,, this wasn;t done at 600 yards.:eek:

06-12-2012, 12:00 AM

No one's going to shoot the top off these suckers with anything short of artillery.

So far, the spotter, balloon & chainsaw method is in the lead. :-)

06-12-2012, 12:07 AM
If you are in the West, you could simply wait for beetles, or a forest fire to destroy all the trees. We're going to start missing them around here!

06-12-2012, 12:19 AM
I can think of a few things, including;

Take that million power light to the tree, and illuminate it from below. On a dark night the tree will light up well. The spotter with a cell phone can then direct you left , right, etc.

An interesting spot beam can be made with a 3 watt minimag light and an older C or D cell maglight. Take the head off both of them. Insert the minimag into the head of the D cell light. move in/out till it's focused.

Here's one I made with a delrin adapter.


Twenty feet down the hall;

and a tree 300 feet from my house, first in ambient light and then with the turbo minimag



06-12-2012, 12:36 AM
I asked the question when I was out tonite. The best response was the helium balloon trick. Tie some ribbon to the balloon so it shows up better in the light. 2-way radio, have a helper, etc. If you don't have a helper, you let the balloon up the side of a likely tree and tie it there. Then go back and see if you can spot the balloon from the house. Go back and move it, hopefully to the right tree. PIA, but it will eventually get you there.

06-12-2012, 12:52 AM
+1 on the balloon. We use this trick to determine azimuth for microwave antennas when the tower at the other end of the link hadn't been built yet.

06-12-2012, 01:05 AM
RC helicopter w a camera?

Mike Amick
06-12-2012, 01:44 AM
Just use a GREEN laser .. there pretty cheap and accessible now. In the dark
you can actually see the beam. It would like a bright green string all the way
to the tree.

Just don't point it up .. pilots will report you and ... like the point of this
post .. its easy to find the source. (believe me)

06-12-2012, 03:07 AM
+1 for mikeamick's suggestion. Do it just after dawn on a slightly foggy day to avoid having to walk around the woods in the dark.

If you have a two GPS units, you can establish a bearing line from your house to the tree with one. Do it again from another vantage point with the other, and go find the point on the ground where the bearing lines cross. I've seen that method used to find downed model planes when you had two observers on the field who noted where they were standing and where they last saw the plane.

06-12-2012, 03:12 AM

OK, I'm from the tiny UK, where every detail of the land has been mapped in great detail and where every bit of land is owned by someone or some organisation. More importantly it is actively watched by the owners or the nosey Joe public.

I have to ask whether, in the US, you can just go onto adjacent land and cut a tree or trees down because they are, in your opinion, spoiling your view? Not a criticism, but I would be interested to know.


06-12-2012, 03:36 AM
I have to ask whether, in the US, you can just go onto adjacent land and cut a tree or trees down because they are, in your opinion, spoiling your view?

If the land is yours, you can (with some exceptions).

06-12-2012, 02:11 PM
Your original spotlight idea may work. I have a small spotlight as used for stage lighting. I don't have a bulb for it so I can't test it, but it does seem to have decent adjustment range. I think it's a parabolic reflector and about 5" diameter glass lenses. If you go to a place that rents studio equipment and tell them your intent, he can tell you if it would focus down enough for you. I think it will. About 500 watts at dusk should light up a tree top. Might be worth a try rather than buying lenses etc. Mine is about 8" diameter and less than 2 feet long. It's balanced on a U shaped bracket which can be bolted to any suitable stand.

Edit to add that it also has an iris diaphragm so the beam can be narrowd down to a smaller spot just like you see on stage when the light follows the performer.

Jaakko Fagerlund
06-12-2012, 03:40 PM
Eyeball the distance and direction, adjust elevation, load 120 mm mortar and pull the cord :D Repeat until satisfactory.

If I would be doing that alone, I would take the green laser route for its easiness of testing. If with a friend, I would have him under the trees with a powerful LED flashlight pointing up at trees and phoning him to move as needed and then marking the tree with paint or just dynamiting it on the spot.

06-12-2012, 03:51 PM
Green laser is the best bet. They are very bright even in the low power types. You can't tightly collimate a white light with a lens since every wavelength has a different path through a refractive medium. A mirror will work as Darryl suggested. That can be done using a small reflecting telescope.

You could also have a look using Google Earth. Unlike Google Maps Google Earth shows the elevations and is in 3D. Depending on the time of day the images were taken it may also be possible to estimate the tree height if it has cast a decent shadow on the ground instead of surrounding vegetation.

If it will be of any use to you I can make you a custom contour map of the area of interest. All you need to do is to PM me your latitude and longitude and indicate what distance and direction you want included.

This is my area with 5 metre contours. The contour interval is adjustable down to 1 metre. It only takes a few minutes to make with Google Earth and Trimble Sketchup. Trimble owns Sketchup now and this is why. They are the biggest name in mapping and GPS systems. You don't need Google Earth to do this. It's built in to Sketchup.


Incidentally, I just became a mapping expert now that Trimble has bought Sketchup. I just might look for a job with the people planning the new mine out west. :D

06-12-2012, 08:58 PM
If you cut the trees down,you will be able to see the mountains. You won't be able to see the trees.If the mountains are so small that a few trees hide it,then they are hills,not mountains.
having a little fun,mike

Paul Alciatore
06-12-2012, 09:05 PM
I have to say that this thread triggers some concerns on my part. Are these trees on your own property? If not, are you serious about a "kill list"? I would hope not as there could be criminal penalties.

If all is legal here, then I would suggest using the contour lines to plot a vertical sketch of the azimuth to the tree. I have used Excel to do similar plots to show where trees would interfere with a microwave path. You tabulate the ground level data and then add the tree levels to that in a second column. Then generate a graph that shows both values. It will clearly show the high points to whatever level of accuracy that you selected for the X axis of the data and plot. As tree tops in the wild are generally at a very similar level, the offending trees are most likely on the high points of the terrain.

If you are old fashioned, the same thing can be done with pencil and paper. Or pen and paper if you are cocky.

06-12-2012, 09:42 PM
How about a posting a picture showing the mountains and the offending trees? I'd like to see what the problem is.

06-12-2012, 09:54 PM
Green lazer works great. I use it to mark trees. Sure helps when one guy wants you to cut them down - I point the lazer and say - "that one?". removes ambiguity, which can be expensive...:(

I also have a transit. Easy to get the bearing(s) and mark it on a map. With accurate distance, you can also figure the height - important if you fell from the gound and don't want it to exceed distance to a structure.

06-12-2012, 09:55 PM
Two people and two walkies talkies. One at home and one out in the woods . Maybe a looking glass for the person at home.

06-12-2012, 09:59 PM
If you cut the trees down,you will be able to see the mountains. You won't be able to see the trees.If the mountains are so small that a few trees hide it,then they are hills,not mountains.
having a little fun,mike

LOL.... I have 10000 foot mountains 10 miles behind 175 foot trees... Can see anything unless on the highway.

06-13-2012, 09:05 AM
The bumper sticker on my truck:


Clear cutting does the same:rolleyes:

06-13-2012, 09:27 AM
I have to ask whether, in the US, you can just go onto adjacent land and cut a tree or trees down because they are, in your opinion, spoiling your view? Not a criticism, but I would be interested to know.


A question unanswered....are the trees on your property or public lands?

06-13-2012, 09:59 AM
Re: Roscos post are the trees on your'e land?

Now,, THAT would have been a GOOD point to establish here first!!