To drone, RTK, both, or break out the paper and pencil?

We are under contract for a recently clear cut 40 acre plot of land (stumps in place) and I wanted to get more accurate contours from the property so I can start planning out our future homestead.

I already looked at the USGS contours, the national DEM files which I created contours from, the local DEM files which I created 10ft contours from, etc ... I don't feel any will help me too much as those were taken with the trees in place ... even the latest lidar scan clearly shows features on the land which were not there in person when I walked it since the scan was taken before the clear cutting. (I work with maps for a living so I am pretty familiar with the software used)

My thoughts are to try to map it with a drone using orthography and RTK correction to get 1cm accuracy, smooth that out, and create an action plan from there forward then follow up with several rescans (for just orthography) in the future to track progress / regression etc. I am curious if anyone has done this and what "stack" (to pull a word from the programming world) you use.

I have previously accurately mapped a 1 acre lot using a rotary laser, compass (in this case a suunto tandem), ruler, measuring wheel, and a gridded out printout of the property taken from satellite ... it wasn't too hard but took a while ... it seems like that would take forever on 40 acres lol

Thoughts?

Sounds like a cool project. I contemplated doing this myself and soon realized that it was way more complicated than I needed to make it. Is there a particular reason you want to get to this level of detail? When starting to plan out our place I ended up with just a paper and pencil and hand drawn contours. I have not yet gotten to the serious layout of our future home, so I may circle back to high detail survey on parts of the land in the next couple years.


One thing I am doing and do recommend when feasible is to do an as-built survey on anything that goes underground when it's installed.

I used the 14 day trial of DroneDeploy to map some fields with a drone. It can make a nice topo or 3D map. Also 3 zone maps based on the total colors on the map. The price is $100 a month, which is more than I have use for. With most drone software there is free software that can do the same thing without the user friendliness, expects you to have programming skills.

To me it is about trading time for money. That is if I go with the drone setup and RTK I save a lot of time on generating contour maps, orthogonal maps, etc. I can then use these to plan out the homestead digitally to account for things like shadows for example on a computer.

While I could also do it all by hand and throw the contours on my hand drawn map into the computer the time required to do it seems significant less there is another better way of doing this I am not seeing. The level of detail is a bonus and with a drone we will better be able to track seasonal changes on the property before we start establishing access / water / structures etc.

It is "complicated" for sure but I feel like we get several useful tools out of the project. The drone, which can be used for various purposes including our social media presence, and if we go with the RTK we gain a surveying tool which would save time when installing things like roads, foundations, footprints, etc. Hell you could even "install" a tree and "mark" it with the RTK go back to your computer and plot it on your property in your computer ...

It just seems like the "right" way to do it to me since I work with maps for a living lol

Grady Houger wrote:I used the 14 day trial of DroneDeploy to map some fields with a drone. It can make a nice topo or 3D map.

I recall it being limited to just orthographs? I know the business plan for DD allows for LAS and point clouds.

Just regenerated "2ft contours" using the DEM from my site provided by the state ... compared it to the lidar (which is also wrong) and there are a some distortion anomalies in the resulting contours and nothing really captures the flat sections where water sits properly :/

The ladar shown here looks detailed till you zoom in to find artifacts as well from when it was scanned because of the tree cover. But at least the lidar shows the marshy wet lands correctly in upper right.

LIDAR does pretty good with nature-made stuff, but gets kind of confused on man-made stuff like swales, rock walls, and that sort of thing. I would not think you would have a whole lot of the latter in the North Country though.

Travis Johnson wrote:LIDAR does pretty good with nature-made stuff, but gets kind of confused on man-made stuff like swales, rock walls, and that sort of thing. I would not think you would have a whole lot of the latter in the North Country though.

It is funny to see how LiDAR interprets buildings for sure ... With trees it all depends if it can penetrate them or not. I have seen rock walls show up pretty well (if you mean stacked walls used as boundaries and not something like a gabion) ...

Don't suspect we will need swales up here with 81" of snow and more precip than I can shake a stick out ... might end up with a couple to redirect water though or get drier ground to plant in as required.

Looking at software packages out there now ... man they can be pricey >__< ... also trying to hunt down anything that is open source if I can.

Burton Rosenberger wrote:

Travis Johnson wrote:LIDAR does pretty good with nature-made stuff, but gets kind of confused on man-made stuff like swales, rock walls, and that sort of thing. I would not think you would have a whole lot of the latter in the North Country though.

It is funny to see how LiDAR interprets buildings for sure ... With trees it all depends if it can penetrate them or not. I have seen rock walls show up pretty well (if you mean stacked walls used as boundaries and not something like a gabion) ...

Don't suspect we will need swales up here with 81" of snow and more precip than I can shake a stick out ... might end up with a couple to redirect water though or get drier ground to plant in as required.

Looking at software packages out there now ... man they can be pricey >__< ... also trying to hunt down anything that is open source if I can.

Yeah, LIDAR works great for finding old rock walls. I am on the hunt for geology, so I will use the rock walls to determine what is in the ground, and approximately where, but I suspect where you are, rock walls might be a little rare.

We have land in the Lisbon and Landaff areas, and both places have SOME rock walls, but not like we do here in Maine. Still a nice location though. Very interesting geology though. :-)

Most of the rock walls I have seen here are loose stacked and often no higher than 3' ... we also have a lot of stone foundations.
All of the straight rough lines in the attached image of land near a place we were looking at in sugar hill nh are rock walls.

You can find them all over north country if you know what they look like :D

Burton Rosenberger wrote:Most of the rock walls I have seen here are loose stacked and often no higher than 3' ... we also have a lot of stone foundations.
All of the straight rough lines in the attached image of land near a place we were looking at in sugar hill nh are rock walls.

You can find them all over north country if you know what they look like :D

We got 30 acres in Landaff just over the mountain from Sugar Hill if you go the backway from that Pancake Parlour. There are some old farms there for sure. They do not radiate off from the roads much it seems, but that area is not my stomping grounds per se, so what do I know. I am from Maine, and my wife is from that area, so that is why we got the land and houses there. It is a nice area for sure.

There is some nice geology there too though. I have not heard if Sugar Hill has any gold, but there is plenty in Landaff, Lisbon, Benton and Bath of course. I would imagine it would be on that side of the mountain as well. But rock walls were the reason the old Prospectors found the gold in that region. They were walking along a rock wall and spotted it glistening in the quartz on the rock wall they were traversing.

It is a nice area, super high property taxes, but also has some nice jobs...

Yeah, it looks like Drone Deploy only lets Business and Enterprise subscriptions access the serious file formats.

https://support.dronedeploy.com/docs/data-export-formats

I wouldn't mind paying if it was $100 a year, or even $100 per field, if anyone finds surveying software that isn't for full time professionals.

Grady Houger wrote:Yeah, it looks like Drone Deploy only lets Business and Enterprise subscriptions access the serious file formats.

https://support.dronedeploy.com/docs/data-export-formats

I wouldn't mind paying if it was $100 a year, or even $100 per field, if anyone finds surveying software that isn't for full time professionals.

I have some land on a few different properties and after going down a lot of wasted rabbit paths regarding mapping, I found just asking the local USDA-NRCS office for a LIDAR and 2 Foot Contour maps is just the easiest thing to do. They are good at what they do, and it is a free service. I have them send me both a digital copy, and a printed copy.

The state geological survey websites have a lot of maps as well. I use bedrock maps, and surficial maps to tell what is underneath the soil for bedrock, and then figuring out what is for soil, and where it originally came from. That has really helped me make some sound farm decisions. Like this spring I was asked by a gravel contractor about selling some of my gravel. Well a look at the Surficial map showed that while I do have 8 acres of deep gravel, it is also all I have. To me, it just makes more sense to keep it for my own use, rather than sell it. A surficial map from the Geological Survey was instrumental in that decision.

Incidentally, a local copy center can print off maps up to 42 inches wide, any length for a mere $2 a square foot. Photo quality printing is $5 a square foot. To me that is very affordable.

For added information, a person can download and print off the USDA Web Soil Survey report for the area and there would be a nice file started right there to get started with.

Like Burton suggests, at least here in New England, anything over 40 acres will make planning very difficult because a person will be most likely traversing lots of different soil types and terrain. How do you plan for that? Even on my Forestry Plan that takes in the totality of the entire farm in all areas, and both states, it is broken down into individual stands of timber. Some are an acre in size, and some are thirty acres. It is by adding these individual stands together that I generate an idea of what I have for forest resources as a whole.

But maps are limited...they only tell a person where things are. In the example of selling my gravel, a look at the map showed it did not extend beyond the 8 acres where I knew gravel existed. That is all the information I needed; 8 acres of gravel, 32 feet deep is only 400,000 cubic yards of gravel. From that a farm decision can be made.

For my farm, what is as important, is what is inventoried for a given area.

To do that I have taken the information my forester has ascertained, and then put it on a Excel Spreadsheet. In this way, as I log, and remove the forest resources, I can deduct what is in that stand. This gives me up to the minute information on what my forest has for timber and its value! I can do that because I calculate in growth, as well as wind-throw, disease and rot; and that sort of data. It is all very easy. Using percentages, growth rates, harvest rates, etc, my Excel program automatically calculates what that stand is doing in real time. In totality it tells me what my whole farm is doing in real time. To me that is as important as knowing where the trees are because maps do not tell me value; data does. For instance, seeing 10 acres of trees means little, but knowing that 20% of those trees in that area are Yellow Birch; now from that I can start making some decisions.

I have only done this for forest resources, but I am working on doing this for mineral resources as well,  so I can ascertain what I have in the soil and in the bedrock.

So what I am saying is, maps are important to show a landowner where, but it really needs to be integrated into spreadsheet form so calculations on the what is can also me decided upon.

Travis many of those resources you mention local EDU's here provide for free online ;) https://granitview.unh.edu/html5viewer/index.html?viewer=granit_view

I use this and my shadow / aspect / telcom layers I generate to make decisions as well.

The lidar for my property was done prior to all the trees being cleared so there are canopy artifacts ... which is ironic given there is ML which can use said artifacts to ID species of trees lol

While we have high property taxes here that is pretty much our only tax. We moved up from VA and our property tax there was 3500+ a year ... here it is about 3k but we don't pay sales tax anymore or income tax to the state. :D

Update:
I found the raw data source for the lidar used to create the hillshade maps I previously hand georeferenced (many like will be like what did he just say? lol) ... The grey images above are from laser derived elevation maps taken from an aircraft.

Anyway I used that to project out some contour lines with some other data layers and my own annotations for the property. I think this will work for now but I am still aiming to get a PTK / drone in the near future so i can walk the property with the PTK and add a georeferenced point + notes which should auto popup on my maps going forward. :D

Basic contours and some extra info:
https://drive.google.com/open?id=1PVREqDAcFSbd3HmPADwxXDs-S_NAa2ec

Same + soils:
https://drive.google.com/open?id=1g3kWucg1SKfj193HoLIriHCZRD_30xOD

Same + the hill shade laid under the information:
https://drive.google.com/open?id=1adU70NvrkUERxeaVx7Ne-STDZ9wQERk6

Side note ... these were created from "Bare earth" DEM (digital elevation model) files which were projected from the raw lidar data ... they are suppose to have 2.5ft linear and 9cm horizontal accuracy which is good enough for now till i can get on site to see what changed.

Updates:
I have since flown 4 drone missions using my phantom 4 pro v2.0 at 150-160ft elevation from the takeoff point with a 70% overlapping pattern on several different occasions while at the property. This effectively provided for a 63% overlap in images with about a .5in/pixel resolution before the photos are processed. I have been using pix4dcapture on a samsung s4 tablet for the missions and given the size of the property I had to split the property in half to ensure the battery didn't run out. These images are then post processed using open drone map (ODM) where they are stitched together into one large image where each pixel is equal to 1 inch. This is then imported into my QGIS project for the property to view it as opening it with an image viewer would either crash the viewer or refuse to open because of size constraints.

The above missions were done without ground control points (GCPs) as I did not have the means to do them accurately enough where they would make a difference. This means the images are all "off" from one another and from reality but they are "close enough" to use for planning purposes.

Since these missions however I have acquired a set of Emlid M2's with LORA antennas and have started to use it with my planning process as the accuracy it provides between the base unit and the rover is 1mm over a km, and the base unit is accurate within a 3 cm square on my property in coordinate space. This is really a different topic as to how I did this but simply put I can now create GCPs and this means I can re-run the previous imagery using the new GCPs which would make them all line up with each other ... this assuming I use visible features (like rocks or stumps)

So this is where I am at right now ... I have not created any DEM models from the drone footage as they would all be "off" from reality and I was waiting to get some GCPs in place before taking the effort to convert the LAZ output from the ODM into something I could then generate a contour / hydrology / slope map from. If all goes well I plan on capturing GCPs this weekend and running another drone mission to capture changes since the last time I flew one about 3 weeks ago.

I have included four areas of interest showing the changes over time from the previous missions.

Burton Rosenberger wrote:Updates:
...
Since these missions however I have acquired a set of Emlid M2's with LORA antennas and have started to use it with my planning process as the accuracy it provides between the base unit and the rover is 1mm over a km, and the base unit is accurate within a 3 cm square on my property in coordinate space. This is really a different topic as to how I did this but simply put I can now create GCPs and this means I can re-run the previous imagery using the new GCPs which would make them all line up with each other ... this assuming I use visible features (like rocks or stumps)

Burton, I'm interested in how those Emlid M2's have worked out. Have you been able to use RTK correction from them via wifi in a cell phone, or do you use one Emlid M2 as rover and one as base?


Brian
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Brian Cady wrote:
Burton, I'm interested in how those Emlid M2's have worked out. Have you been able to use RTK correction from them via wifi in a cell phone, or do you use one Emlid M2 as rover and one as base?
Brian
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If by cell phone wifi you mean NTRIP corrections I have not. My phone, and my wifes phone, cannot act as a hot spot but I am not sure it would work as well as the method I am using now where I use one as a base and one as a rover. The two of them plus the LORA radios combined was still less than the cost of a complete RS2 unit and it is pretty easy to make an enclosure for the M2's using PVC.

To establish my own "known point" on the property I found a spot which was visible to most of the property and setup the base station letting it run for a good 8 hours. I then collected this data and downloaded the local CORS ( https://geodesy.noaa.gov/CORS/data.shtml ) station data for the same time frame 17 miles away. Using RTKCONV I processed the Base station data then used RTKPOST with the CORS  station set as the Base and the "Base station" set as the Rover.

This produced several charts and graphs which told me my location for the "known point" within 3 cm square (about 1 inch). I copied the location provided and now when I "setup" over the "known point" I manually enter this as the location of the base station. So long as I have line of site to the base station from the rover I always have a "fixed" solution. If I don't then sometimes I have to wait a minute or two to get my location.

Just for fun I did try to upload my data to OPUS ( https://geodesy.noaa.gov/OPUS/ ) , the new method using the gravity based geoid, to compare but it was rejected every time. OPUS only accepts L1/L2 right now ... which is kind of odd given the accuracy of those are subpar compared to L3-L5 satellites. I think the accuracy I get with the Emlid M2's was worth the cost for sure.

GENERAL UPDATE:
My mapping rig for ODM (open drone map) somehow developed an unknown issue where it would no longer process a full set of data ... even previous dataset would fail at a specific point in the process. I have been trying to reconstruct it and document it this time so I can get processing again as I have a dataset from two weeks ago ready to go and it is over 1500 pictures :D

If there is interest I can post my whole process here.

Edited:
added links to some odd acronyms used above.

Burton Rosenberger wrote:

Brian Cady wrote:
Burton, I'm interested in how those Emlid M2's have worked out. Have you been able to use RTK correction from them via wifi in a cell phone, or do you use one Emlid M2 as rover and one as base?
Brian
-

If by cell phone wifi you mean NTRIP corrections I have not. My phone, and my wifes phone, cannot act as a hot spot but I am not sure it would work as well as the method I am using now where I use one as a base and one as a rover. The two of them combined was still less than the cost of a complete R2 unit and it is pretty easy to make an enclosure for the M2's using PVC.

Wow, so you spent about $1-1.5K dollars ? I misread 'M2' as 'R2'

Burton Rosenberger wrote:
To establish my own "known point" on the property I found a spot which was visible to most of the property and setup the base station letting it run for a good 8 hours. I then collected this data and downloaded the local CORS station data for the same time frame 17 miles away. Using RTKCONV I processed the Base station data then used RTKPOST with the CORS station set as the Base and the "Bast station" set as the Rover.

What's 'CORS' mean? And OPUS? I'm confused by "Bast station".

Burton Rosenberger wrote:
This produced several charts and graphs which told me my location for the "known point" within 3 cm square (about 1 inch). I copied the location provided and now when I "setup" over the "known point" I manually enter this as the location of the base station. So long as I have line of site to the base station from the rover I always have a "fixed" solution. If I don't then sometimes I have to wait a minute or two to get my location.

Just for fun I did try to upload my data to OPUS, the new method using the gravity based geoid, to compare but it was rejected every time. OPUS only accepts L1/L2 right now ... which is kind of odd given the accuracy of those are subpar compared to L3-L5 satellites. I think the accuracy I get with the Emlid M2's was worth the cost for sure.

GENERAL UPDATE:
My mapping rig for ODM somehow developed an unknown issue where it would no longer process a full set of data ... even previous dataset would fail at a specific point in the process. I have been trying to reconstruct it and document it this time so I can get processing again as I have a dataset from two weeks ago ready to go and it is over 1500 pictures :D

If there is interest I can post my whole process here.

I envision a set up with an Emlid M2 as a base station, connected, instead of to a LoRa radio, to a Wifi tranceiver. I can use my Samsung Note 3 cell phone as a hotspot, so transceive with the base station wifi, to get NTRIP corrections to my cell phone in real time.  Can you critique that vision? And what' s ODM?

Looks like the Emlid M+ and M2 both tranceive Wifi signals already:
https://store.emlid.com/product/reachm-plus/
Maybe with just one M+ in a known position, I can get GPS position, make the correction factor, and send the correction factor to cell phone via NTRIP protocol, to get an inch-level-accurate cell phone position.

Brian Cady wrote:Looks like the Emlid M+ and M2 both tranceive Wifi signals already:
https://store.emlid.com/product/reachm-plus/
Maybe with just one M+ in a known position, I can get GPS position, make the correction factor, and send the correction factor to cell phone via NTRIP protocol, to get an inch-level-accurate cell phone position.

Not via NTRIP: "NTRIP does not support point-to-point communication e.g. you can not use it to transfer corrections from one Reach to another directly. In NTRIP terminology there are servers, clients and caster. Server sends correction to a caster and clients can receive them by connecting to that caster." webpage

Brian I went back and edited my post a little to add links and fix the spelling mistake you found ;)

The M+ and RS+ are both single band devices and cannot talk with the M2 / RS2 devices which are multi-band if I recall correctly (you might be able to disable the multi-band of the M2/RS2 to only use GPS but it would defeat the point of having it).

NTRIP is used with a single device to get your known point using local CORS station data but has a max range of 30km for the M+/RS+ and 100km for the M2/RS2 ... the further you are away the longer it might be to get a "fixed" solution ... and if in the woods it could be harder ... both will give you cm accuracy (max 7mm for the M2 / RS2 series ... NTRIP might not be free though.

I think my setup cost ~$1430 ... (1190 for both M2's with antenna's, ~240 for the LORA modules to match).

Emlid M2 as base + NTRIP over cellular hot spot will give you the location of the M2 in real time with ~7mm accuracy.

Burton Rosenberger wrote:...Emlid M2 as base + NTRIP over cellular hot spot will give you the location of the M2 in real time with ~7mm accuracy.

So Emlid M+ = server, Hotspot = caster, cellphone = rover, all connected by Wifi, using NTRIP.
Or could correction data transfer via TCP using Wifi from Emlid M+ to cellphone.
I'd be satisfied with remaining within wifi range of base while I survey with cell phone, I think.

Brian Cady wrote:
So Emlid M+ = server, Hotspot = caster, cellphone = rover, all connected by Wifi, using NTRIP.

M+ is the rover, it is connected to your phones hot spot, the M+ is also configured to get NTRIP connections. The NTRIP sends corrections from CORS stations which act as the Base in this case.

You walk around with a survey pole with your M+ attached. When you get to a point you want to capture you stop, get the survey pole level, then collect the data point with the Emlid app.