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Field mapping - how to do good enough?

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My company supports about 500 Farmers in one small province in Isaac for organic certification.

For that we need maps of all fields, barns, houses. At the moment they are hand drawn and unreliable.

I would love to have exact locations with coordinates of all perimeters. We then would be able to integrate info into a database.

Needed would be GPS info with below 0.5m, ideally below 0,2m resolution and ideally matched to high resolution Arial photos which when bought are very expensive.

Budget for all the mapping is not more than 500k THB and we want to have a system we can extend with new farmers coming into the system.

Any ideas or do you know who could know helpful information? Thanks

Sent from my SM-N9005 using Thaivisa Connect Thailand mobile app

  • 2 weeks later...
Needed would be GPS info with below 0.5m, ideally below 0,2m resolution and ideally matched to high resolution Arial photos which when bought are very expensive.

(1) I don't think GPS per se can give you this kind of accuracy. (even without that level of accuracy I think it should still be better than "unreliable hand-drawn maps"?)

(2) I think you need to find a land-surveyor professional for an opinion on this. (or maybe there's some NGO out there that can help? )

Edited by build6

Contact Thai Drones through their Facebook page. They offer photo mapping services and I think can offer a resolution up to 5cm. Everything is geo tagged too.

Sent from my GT-S5300 using Tapatalk 2

  • Popular Post

Contact Thai Drones through their Facebook page. They offer photo mapping services and I think can offer a resolution up to 5cm. Everything is geo tagged too.

Sent from my GT-S5300 using Tapatalk 2

Resolution or precision? Any camera can get the resolution if they fly low enough. The fb page doesn't give much away.

To the o/p, if the hand drawn maps come from the local authorities, that's the best available! Some local authorities have more modern digital databases of farm properties. If not, and with a budget only 500K THB I'd get some digital globe images and have a GIS company ground rectify the images with GPS survey equipment.

  • 1 month later...
Needed would be GPS info with below 0.5m, ideally below 0,2m resolution and ideally matched to high resolution Arial photos which when bought are very expensive.

(1) I don't think GPS per se can give you this kind of accuracy. (even without that level of accuracy I think it should still be better than "unreliable hand-drawn maps"?)

(2) I think you need to find a land-surveyor professional for an opinion on this. (or maybe there's some NGO out there that can help? )

With the right equipment you can obtain sub-centimeter accuracy using D-GPS.Cost may be out of your budget however.

  • 2 months later...

1. A simple software called RouteConverter can be used to draw a line along a perimeter with GoogleEarth as backdrop.

2. The tools used to create OpenStreetMap can be used to create maps for private use.

or try app called "fields area" which plots points by GPS and then figures out area etc with google maps

If the fields are readily discernible on Google maps satellite view this tool may be accurate enough http://www.freemaptools.com/area-calculator.htm

Gets our 1.5 Rai to within 2m2 of the figure on the Chanote

Crossy, I would never have thought you could get that type of accuracy.

Quite amazing.

So do you enter in known lat/long coordinates or are you simply creating a waypoint with your curser over an identifiable position on the aerial imagery?

with the fields area map you walk the corners of the property and make a way point and it shows area and google map

my friend did it on his farm in Issan , thats how I knew about the App :)

always ask your smart friends what apps they have found as there are too many to find yourself !

If the fields are readily discernible on Google maps satellite view this tool may be accurate enough http://www.freemaptools.com/area-calculator.htm

Gets our 1.5 Rai to within 2m2 of the figure on the Chanote

Crossy, I would never have thought you could get that type of accuracy.

Quite amazing.

So do you enter in known lat/long coordinates or are you simply creating a waypoint with your curser over an identifiable position on the aerial imagery?

You have to place points on the Google map on that web page. At maximum zoom it's easy to discern the thickness of our boundary wall (yes it's burry of course). I have only one known piece of land to try it on but I did our parcel again just now and got within 10m2 of the chanote figure.

It all depends upon the accuracy you require and how big the area are (the bigger areas will yield smaller percentage inaccuracies), it's certainly good enough to tell if the land you're buying is 11 Rai or 10.5.

"I don't want to know why you can't. I want to know how you can!"

  • 2 months later...

I'm a hydrographic surveyor and would be able to survey it for you. Esiest way would be to establish a baseline from existing benchmark and survey it using a total station which which would typically be accurate to millimetres. If there is no benchmark you can set up aone using DGPS which if you log for a few hours will be accurate to 5 cm. You could also us RTK basestation and rover which you could hire and do yourself which is accurate to 2mm.

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