Does anyone know of a site or formula to calculate acreage in boundry of land? I have the lontitude and latitude for the corners.
Acres = length in feet x width in feet
43,560
Ron, I know that part of it. I don't know how lontitude and latitude convert to feet.
If you look on a USGS map of the area there will be a scale....it changes as you move north or south , though
I don't know much about a GPS but could a person enter the corners as waypoints and let it tell you how far from one to the other?
If you have a fancy GPS it might do that. There are programs that interpret GPS data on your computer and most of the Windows based ones seem to have that function. Not my Mac one , though :(
I got one, now to figure how to use the DanG thing, bout all I ever got out of it mph when on a boat. Reckon them things is like computers, get a 13 year old to show ya how they work?
Lots of ways to do it. Convert from lat and long to state plane or UTM coordinates. State plane is usually in feet, X/Y coordinates. UTM is in meters. Corvallis Micro Technology (CMT) has a free program on thier website called Cogo CAD. Convert to state plane or UTM set up the program correctly and get acreages or whatever you need. It takes a bit of patience to learn how to use it but its real handy.
There are websites where you can put in your lat and long and convert to UTM. Or just plug them in the GPS as waypoints and change the coordinates to UTM on the setup screen. You may need to know what UTM zone you are in, fortunately there are websites that have that info as well.
Thanks everyone, I will look and see what I can come up with on the web.
Go here and download the Army Corps of Engineers Corpscon program. Corpscon will convert your geographic coords to a usable numbered coordinate system.
http://crunch.tec.army.mil/software/corpscon/corpscon.html
What type of data you have and what accuracy you want to achieve go hand in hand. Be careful and be aware of the validity of your data. ie. if you mapped the corners with a handheld GPS your error can be rather large and your area estimate can have a plus or minus of 1-2 acres.
BB
> a GPS but could a person enter the corners as waypoints and let it tell
> you how far from one to the other
Yes, my Garmin did that. You could map out a whole lot that way.
Plus, you could set one way point and have it tell you when you traveled XXX number of feet to set the other and it would count down how many feet you were away from it while walking.
Some GPS units will get very accurate if you leave them turned on and sitting in place with out moving them for a while.
> Does anyone know of a site or formula to calculate acreage in
> boundry of land?
Been a few years since I used it to blueprint a factory building, but, I think (now) Microsoft Visio will do that if you feed in actually dimensions. It will not do it from raw coor. data.
Go to Yahoo and use these search words ( calculate acres gps software ) to pull up these, amoung others:
http://www.palmgear.com/index.cfm?fuseaction=software.showsoftware&prodID=38923
http://www.eurocool.com/author/?author=18893
This should give you everything you need :-)
Street Atlas will do it. Send them to me and I will give it a shot.
Sprucebunny got me to thinking, boy what a headache. Using the scale on the USGS topo maps I took a dial indicator and broke scale down to thousandths of an inch, figured how many ft per, measured the lines on the piece of property and did the math.
I checked this against the surveyed deed on the farm I live on and came very close, less than 5%.
This is close enough for what I want as I bought the property by the boundry, only reason for wanting to know is to try to get rough projections, which is a guess at best, of possible yeild on down the road.
I would not suggest this method if you need exact measure though I am sure it would work a lot better on land that had straight property lines.
Thanks everyone for your input,
Bill
Another way may be to use graph paper and UTM or NAD 83 coordinates (m/feet). As long as you use a liner scale you can measure the distance between corners at the scale of your drawing to figure lengths. If its irregular, layout the plot into triangular segments and calculate each triangle. (1/2 x base x height). You can place a line segment or side of a triangle to compensate for that portion inside the triangle vs that outside. (cross hatch is outside bounds)
There is freeware GIS mapping software available at www.globalmapper.com
Go to their download and purchase link and download the trial version. You will need to find topo maps in a format which this program can use. They are readily available but may be a little more difficult to find for free. In Massachusetts they are availble for downloac from the state GIS web site. They are also available at www.geocomm.com along with many,many other types of maps. Again, finding the ones you want will be the most difficult part.
Once you get the topo map loaded into the program it's pretty easy to draw the property in question and it calculates acreage right at the bottom of the screen. Larger acreages will be easier to do that smaller ones. The Lat/Lon information is displayed at the bottom of the screen and changes as you move the cursor. Just move it to where you want your corner and click. Once the property is enclosed on all sides the acreage will display.
I am no 13 year old computer whiz but with some figuring have gotten the basics of the GIS mapping stuff figured out.
If you don't want to spend the time trying to figure out how all this works, read your GPS manual. Then navigate from point to point on your boundary. This will give you a bearing and a distance for each leg. Draw this out to scale on graph paper using a protractor and ruler then figure out the enclosed area as described in the other post above.
The attached image is a screen capture from Street Atlas . On it you will see the boundary's in light green with letters at the corners. I walked the line and did a capture with my GPS at every pin. At home I cabled up to my computer and uploaded the coordinates, then used the draw tool to connect all the points. If you right click on the line and show properties it gives you the acreage and perimeter of a closed drawing. 166.52 acres 16446.8 feet
The survey showed it to be just over 166 acers.
Will post the image when Jeff gets the gallery working
(https://forestryforum.com/gallery/albums/userpics/10066/johnjbc-map.jpg)
Good job Jeff
Below are the plots for the boundary shown on the map
39.882967, -78.156117, Gate
39.883017, -78.156117, A
39.881083, -78.156717, B
39.880233, -78.155250, C
39.879050, -78.156617, D
39.877367, -78.155283, E
39.877450, -78.153667, F
39.890433, -78.157150, T
39.878500, -78.152750, H
39.878433, -78.151733, I
39.878650, -78.151250, J
39.878700, -78.150050, K
39.879783, -78.147433, M
39.879000, -78.146233, N
39.879000, -78.145417, O
39.880183, -78.146450, P
39.880300, -78.146333, Q
39.884617, -78.163783, Power Line
39.888400, -78.152167, W
39.878067, -78.152933, Gt
39.879650, -78.149700, Lt
39.884983, -78.157583, Turn Off
39.884350, -78.152617, Stage Area
39.881700, -78.147400, Buck Rub 1
39.883133, -78.150867, Buck Rub 2
39.886900, -78.150767, Dead End
39.880698, -78.153895, STAND
39.884984, -78.157586, TURN-Off
39.892141, -78.154421, S
39.888386, -78.151921, NARROW
39.889560, -78.154072, U
These are the same Way-Points loaded into DeLorme 3D TopoQuads
(https://forestryforum.com/gallery/albums/userpics/10066/johnjbc_topo_map.jpg)
cool topic, computers, you can hate them, but, you have to love them too :)
Looks like you might have a few select intersections on that there map that would be ideal for a deer stand ;D
Yes, they look to be well placed in those gullies, according to the contour map. ;D
Yes the Deer hunting is good. Its located in the center of a tract about 12 miles around with farms on all sides. When hunting pressure starts the deer come visit me. :D :D
This is my favorite Deer Stand. Its 100 feet from the trailer and will be my front porch when the cabin built
(https://forestryforum.com/gallery/albums/userpics/10066/johnjbc_deer_stand.jpg)
View from the stand
(https://forestryforum.com/gallery/albums/userpics/10066/Johnjbc_View_from_deer_stand.jpg)
View without the snow. Notice how open it is. The hurricane flooded the entire valley and washed all of the under brush away.
(https://forestryforum.com/gallery/albums/userpics/10066/Johnjbc_View%20from_deer_stand1.jpg)
My deer. Shot from the Blue Barrel.
(https://forestryforum.com/gallery/albums/userpics/10066/johnjbc_Deer.JPG)
Larry's deer He got 2 with his 41 magnum pistol this year.
(https://forestryforum.com/gallery/albums/userpics/10066/Johnjbc_Larrys_deer.jpg)
Quote from: SwampDonkey on February 06, 2005, 01:43:40 PM
Another way may be to use graph paper and UTM or NAD 83 coordinates (m/feet). As long as you use a liner scale you can measure the distance between corners at the scale of your drawing to figure lengths. If its irregular, layout the plot into triangular segments and calculate each triangle. (1/2 x base x height). You can place a line segment or side of a triangle to compensate for that portion inside the triangle vs that outside. (cross hatch is outside bounds)
A little fixer upper to this post.
If your triangles are not right angled, then what?
You have to do the calculation for area in two steps.
First find the coefficient of the triangle, we'll call it S.
S= 1/2 (a + b +c)
Then find the area A
A= Square root {S x (S-a) x (S-b) x (S-c)}
You could set this up in a spread sheet to do the area of a property with straight sides, with length of each side known.
Example: I have a triangle with sides measuring 5, 8, and 12
S = 1/2 (5 + 8 + 12) = 12.5
A = Square root {12.5 x (12.5-5) x (12.5-8) x 12.5-12)}
A = Square root {12.5 x 7.5 x 4.5 x 0.5}
A = Square root {210.9375}
A = 14.5237
or it's 1/2 the two known sides times the sine of the interior angle of the two known sides.
to find the length of an unknown side "a", two sides known and their interior angle (alpha) is known it's:
a = square root{ b
2 + c
2 - 2bc x cosine (αlpha)}
Spreadsheet attached.
If you downloaded the spreadsheet 5 minutes ago I had to upload it again with a correction. Excel only does trig on radians, so I had to convert to degrees π/180 for the unknown side calculation.
If you can find the property on Google Maps, then the Planimeter works pretty well: http://www.acme.com/planimeter/ . Just put way points wherever the property line changes directions. View as a satellite, topo, or usgs doq image.
I'm lacking a little in the math department, so I got a Garmin Etrex GPS. It has an area calculator built in. Just set it to area calc. and walk around the area in question. It's pretty accurate and is right with the State Forestry's $4000.00 GPS.
It dosen't work as well on cloudy / rainy day's.
Andy
According to my 'learnin' 60 seconds to a minute, 60 minutes to a degree and one degree = one nautical mile, this is true for N-S lines(lattitude), E-W (Longitued) degress will equal 1 degree per nautical mile along the equator, but he further North or South you go from there, the closer the degree marks get, for obvious reasons. 1 Nautical mile equals 1.15 miles or about 6,072 feet. so if you divide according to the avobe information, one minute = about 101.2 feet, one second will = about 1.6 feet.
To figure acres within a polygon, you would have to know the 3-D lay of the ground, I am not a Surveyor, but have done lots of work following Survey parties around in Alaska, as a member of their helicopter support crew, and from what I have been able to glean, survey only concerns itself with the 2-D area of any given Polygon, i.e. if you have a square mile (640 acres), you follow a line 1 mi. on all 4 sides, and if you were to divide that area into say 2 acre parcels, you could come up with 15 to 20% more acres on the small survey than on the large one, just because you are not walking every contour of the land in between the mile long sides, so you always come up with some "bonus" acres whenever you take a large parcel and cut it down to small bits- at least that is the way I have found to visualize it.. wokrs for me, I hope its a bit clearer than mud:-)
Go metric.
Use grid ref (10m points) instead of lat/long - you can probably use an on line converter as each point is unique. Another way could be to convert minutes/seconds of angle to metres and do it that way.
Then calculate hectares 100mx100m, then convert that to acres, again using an on line converter.
I know we invented the imperial system, but it's easier to count in 10s!.
Madmurdock,
All legal land surveys are in 2D, even those for 2 acre parcels. While there may be a "bonus" in surface area when there is topographic relief, there is no "bonus" in acreage.
Quote from: BaldBob on May 14, 2009, 03:08:33 PM
Madmurdock,
All legal land surveys are in 2D, even those for 2 acre parcels. While there may be a "bonus" in surface area when there is topographic relief, there is no "bonus" in acreage.
Ditto, to Bob's post. Surveying is on horizontal distance, not slope distance and thus not surface area of the landform. And as far as bonus, there is no extra trees on a plot with a big dip than there is with a plot that is flat. Trees grow toward the sun, not perpendicular to the land surface. Otherwise the woods would look like a pin cushion. When you GPS a plot you can get 3D relief because z-valued are collected, but the area and perimeter are 2D (perimeter is also computed for slope distance).
(https://forestryforum.com/gallery/albums/userpics/11009/SD_GPS_Plot.jpg)
Circled in yellow.
I am no surveyor, as I stated. I have been puzzled though, that whenever we apply herbicides on commercial forest land here in the west, (ORE, WASH, IDAHO, N. CALIF), almost without exception, when the customer supplies their .shp file (polygon), for us to use in the helicopter, and we fly the area, the acreages do not match exactly, almost every time the area sprayed differs form sometimes up to 5-7 percent from the area that the customer supplies drawn from their GIS dept, or walked on the ground with a plugger. The ground we cover is very vertical, usually greater than 20% slopes. Thoughts??
A lot of agencies are using consumer grade GPS with a lot of multipath that they are not base correcting. All my GPS traverses have to be corrected from my GEOXM in order to be accepted by the NB forestry companies. But, a GPS with capability to average positions at each vertex will have almost no need for corrections. This is possible with my GEOXM and ArcPad from ESRI. To do base corrections I need GPS Correct from Trimble for the TSIP protocol (Arcpad extension) and an internet connection to a base correction site, in my case I use Acadia Timber in Edmundston, NB. I could also use a base at Caribou, Maine but it is an unreliable site. Also, the capability to filter out non 3D positions, high PDOP and minimum elevation above the horizon for useful satellites (usually set to 15°) will help accuracy. I have distortion free aerials and all my traverses line up, whizz bang, with any roads and cut boundaries I see on the corresponding aerial. 3-5% discrepancy is acceptable, an 8% difference or more is subject to scrutiny, but that only pertains to my situation as the local standards may vary by region.
If the so called survey ends up with more acreage by adding up smaller parcels inside the limits then they did not do slope correction or the surveys have gross errors. Tree thinners think they should be paid on surface area, the standard established a long time ago is slope corrected distances. That argument comes up every season. For the slopes and areas we are working on it wouldn't add up to anything significant. I had a guy last summer question it and he took out his string box to prove himself wrong. I been around long enough to know when a guy is working and when he's pull'n a fast one. ;D
Horizontal = COS (θ) x Slope Distance
θ = ArcTAN (Slope %) using a % SUUNTO clinometer
100
mad murdock,
How are you determining the acreage sprayed? You may be determining the slope surface area, which, as swamp donkey pointed out, is of no meaning in determining the acreage to be sprayed area since plants grow vertically - not perpendicular to the land. This is quite likely what is occurring, since spray choppers tend to fly at a fixed height above the land the land rather than at a fixed altitude.
Swamp Donkey,
I can see a case for paying more for thinning on steep ground - not paying for more acres (surface vs. slope corrected), but paying more per acre simply because of the greater difficulty in getting around.
Yes in that case, you are correct. The rates are based on density and difficulty. If you want to eliminate all the head ache just pay a good rate and take the good ground with the bad. ;) We don't work on over 35 % slope, 99 % of work areas are less than 20 % slope. I like some slope, trees tip real good and come to the ground with no effort. ;D We start a block tomorrow at 6:00 am, can't wait to start mow'n them down and listen to all the blat'n. ;) :D
I have used Deed Plotter and Topofusion, both are some of the best in acre calculations based upon known bearing and distances for use in Deed Plotter, and one can get estimated bearing/distances by using Topofusion; which will also give you Lat/Long as well. These are the 2 best programs that I have used in the land management work that have have done.
Pap
I've used Deed Plotter as well for string box and compass traverse. Very easy to use and you can also export DXF to bring into a GIS program. I never went that way however because you needed a starting lat/long position or your map was at 0,0 on the globe. Our traverses never started at a known position such as a corner, they were out in the middle of a woodlot, even though most hit the marked property boundary. Best you could do was guess from photos and orthophoto maps. Many times the contractor never even knew where he was. A certain timber company got some free thinning. ::) By the time we had GIS we also had Trimble GEO3 GPS's within a couple years.
That's why you could use Topofusion and get within 3 feet of any lat/long for a start and do your traverse on Topo. It would also give you acerage, but the PI's used on the Deed Plotter would be more acurate. Neat thing about Topofusion, in combo with Faststone software, is you can save it in a Word document as a picture and then describe the enclosure. With Topofusion you can use it with aerials, USGS, and 3-d topos. Great stuff.
Attached is a spreadsheet with illustrations. I calculated in meters and hectares. You can change the area column to get acres by substituting "10000" (m2) with 43560 ft2 to get acres. A meter is 3.281 feet. You can see my results and compare with the bottom illustration showing the area calculated on a GIS program.
I might as well toss this in here. It was a thinning block, outlined in yellow, that I created a 3D topo map out of. It's actually exaggerated 3-times it's actual relief. You can see a hardwood ridge to the north with a road corridor, it looks sharper in this map than it actually is because of the exaggeration used. You can see contour lines in orange every 20 meters in elevation. This was done using Landsat and creating a TIN file. Then I draped the aerial photo over it. I then compared surface area with map area and the difference was only 0.03 ha on a 45 ha block. I could get a lot more accuracy if I took a GPS point at all slope changes in the perimeter and strip lines. The satellite only took points every 200 meters as I understand it, much courser resolution.
(https://forestryforum.com/gallery/albums/userpics/11009/SD_BT4090864_3D.jpg)