GPS acreage determination.

[+Team MGGPS]

I'm trying to determine some acreage based on GPS coordinates.

I have coordinates for each corner. I know it won't be survey accurate

I just need a good approximation.

How do I do this?

[+Timpat]

I'm trying to determine some acreage based on GPS coordinates.

I have coordinates for each corner. I know it won't be survey accurate

I just need a good approximation.

How do I do this?

The simplest way (if you're using Garmin and MapSource. You didn't specify.) would be to use the Tools/Track Draw/ tool by traversing around the perimeter using your points. When you Right click on this new track, under Track Properties, you will see Points, Length, and Area.

[+Team MGGPS]

I'm using Magellan and Mapsend Topo.

[+embra]

If you have a Magellan Explorist, you can use menu/advanced features/area calculation. Since you specified MapSend Topo, I suspect you have a SporTrack or Meridian. I don't know of a way to get area using what you have, nor do I know of any freeware that will calculate the area for you (someone might). DeLorme TopoUSA v6 would do it, but that cost $.

[+Jamie Z]

You could also find the distance between all the points (What's the shape of the area?) and figure it out geometrically.

 

Presumably, a double integral will do this too, if you know the functions which represent the shape of the area.

 

Jamie

[dave and jaime]

I'm trying to determine some acreage based on GPS coordinates.

I have coordinates for each corner. I know it won't be survey accurate

I just need a good approximation.

How do I do this?

 

since you list cad as an occupation the easiest way is to use grid coordinates(utm, mtm etc) from the gps to create a pline in autocad and then select the properties and area bounded by the line is listed.

[Suscrofa]

I'm trying to determine some acreage based on GPS coordinates.

I have coordinates for each corner. I know it won't be survey accurate

I just need a good approximation.

How do I do this?

 

since you list cad as an occupation the easiest way is to use grid coordinates(utm, mtm etc) from the gps to create a pline in autocad and then select the properties and area bounded by the line is listed.

 

True, just switch to metric, using UTM, you get it very easily, one are is a square 10m by 10m (100m^2), an hectare is 100 (hecta prefix) ares and 100ha is 1 square km (one square on UTM 1km grid) !

Any 10 years old kid can do it (I was that age when I learned how to !)

 

Who still use acre anyway ? One acre is the area that can be plowed by a horse in one day, I guess

 

But if you desperatly needs it, then convert hectare to acre. Easier than to try to ge a horse and plow the area no ?

Edited October 10, 2006 by Suscrofa

[+Team MGGPS]

Great idea D and J. I converted my Lat and Longs to UTM and drew it out on AutoCad.

I ran an area routine on the pline object and it returned with a square meters value which

I converted to acreage.

Suscrofa,

The person I was doing this for required acres. If I had done it in hectares they would have been

lost. I remember learning that when I was 10 also. Didn't they tell us that everything would

be metric by the year 2000?

Thanks to all,

MGGPS

[+apersson850]

I've always heard that the entire US is indeed going metric. Inch by inch...

 

However, if you have coordinates, that are in UTM, or any other system, based on squares, you can compute the area rather easily. Had I been able to use subscripts and such, this would have been easier, but I'll try anyway:

 

Assume you have n points, called (xk, yk). Since I can't use subscripts, I'll use computer language-like notation, i.e. x(k) and y(k). I can't write the greek Sigma character either, so I'll instead write like this:

A = 1/2 * sum(k=1, n-1, x(k) * y(k+1) - x(k+1) * y(k))

 

I don't know, but I assume this is the formula they use in the GPS receivers. My thought is supported by that this formula will also give you a zero area for the figure 8, if both loops are of equal size.

[peter]

I've used the formula given by apersson in Excel to determine areas based on tracklogs. It's easily derived and works fine as long as the area is small enough that earth curvature issues can be ignored.

 

A freeware program that'll calculate acres of an enclosed area is USAPhotoMaps (http://jdmcox.com). Just enter the perimeter points as a closed 'route' and it'll display the number of acres.

[d.higgins]

I'm trying to determine some acreage based on GPS coordinates.

I have coordinates for each corner. I know it won't be survey accurate

I just need a good approximation.

How do I do this?

You can also take your UTM's from a track file, import to Excel (or any text editor), get rid of everything but the UTM's.

And use the Utm's in a script file (.scr). Or use GPS trackmaker to do the same thing.

Then run the script in AutoCad.

Doug

Edited October 11, 2006 by d.higgins

[+Airmapper]

I gotta learn this stuff. I'm a Drafting student and use AutoCAD. I knew it could be done, but so far haven't learned how to plot location info in AutoCAD.

[+EraSeek]

I've always heard that the entire US is indeed going metric. Inch by inch...

 

 

Yeah! We are a buncha numskulls that can't seem to do anything sensible or in a timely manner anymore. We should have gone metric long ago. Its not even talked about anymore.

[d.higgins]

I gotta learn this stuff. I'm a Drafting student and use AutoCAD. I knew it could be done, but so far haven't learned how to plot location info in AutoCAD.

 

Try this, Open Notepad and enter the following:

 

pline

2,2

2,4

4,4

4,2

end

close

 

Name and save, find the file and rename .txt to .scr, go to AutoCad/Tools/RunScript...

find your .scr file double click.

If you substitute 2,2 etc. to your Lat/Lon you just plotted your location.

Doug

[Suscrofa]

I've always heard that the entire US is indeed going metric. Inch by inch...

 

 

Yeah! We are a buncha numskulls that can't seem to do anything sensible or in a timely manner anymore. We should have gone metric long ago. Its not even talked about anymore.

 

Scientific work, most of engineering is done in metric. Even drug dealers use metric

 

Companies no able to work in metric are and will be hurt more and more as it will be harder for them to sell outside of the US.

 

Anyway, from the very basic questions found on this forum related to distances measurment, area, etc..., you can see everyone would benefit from talking metric as very few seems to master the arcane of the UK/US "system" of units.

Edited October 11, 2006 by Suscrofa

[+GClouse]

Scientific work, most of engineering is done in metric. Even drug dealers use metric

 

Companies no able to work in metric are and will be hurt more and more as it will be harder for them to sell outside of the US.

 

Anyway, from the very basic questions found on this forum related to distances measurment, area, etc..., you can see everyone would benefit from talking metric as very few seems to master the arcane of the UK/US "system" of units.

 

Yes we WERE supposed to go metric in 2000, but since that numbskull publisher in Nashville had everyone here scared of the "Y2K" bug, all of the conversion work was shelved and forgotten about.

[ossumguywill]

Scientific work, most of engineering is done in metric. Even drug dealers use metric

 

Companies no able to work in metric are and will be hurt more and more as it will be harder for them to sell outside of the US.

 

Anyway, from the very basic questions found on this forum related to distances measurment, area, etc..., you can see everyone would benefit from talking metric as very few seems to master the arcane of the UK/US "system" of units.

 

Yes we WERE supposed to go metric in 2000, but since that numbskull publisher in Nashville had everyone here scared of the "Y2K" bug, all of the conversion work was shelved and forgotten about.

that publisher is a !@#$%^& *&^%$#@! . Life is so hard with the US system. How are we supposed to remeber that there are 12''>foot, 3'>meter, 5280'>mile. AARRGGGHHH!!!

[malcolmspeak]

If you have a pda, there's are 2 good products - Gengiscad (free but you have to find the Spanish/English traslation on their home page) and GPSMETER. There's an early version floating around on the internet that doesn't need registering. Otherwise, the Garmin function has never failed me yet!

 

peace

 

Malcolm