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With the UAV Workflow you plan, acquire and process your drone magnetics data and perform all the key steps to prepare your data for targeting and modelling.

The webinar will focus on the major benefits of using the UAV Workflow in Oasis montaj and what concepts to consider before you start.

Join Seequent’s Joanne Demmer (Project Geophysicist) and Mark Lowe (Senior Project Geophysicist) who will discuss:

  • An overview of the UAV Workflow in Oasis montaj and examples of using drone magnetics.
  • Survey Planning – how to design a UAV survey allowing for VLOS, no-fly zones and survey drape.
  • Visualising and sharing survey results.



Joanne Demmer
Project Geophysicist – Seequent

Mark Lowe
Senior Project Geophysicist – Seequent


35 min

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Video Transcript

<v Joanne>Hello everyone</v>

and welcome to this months Technical Tuesday.

I’m just going to wait for one minute before starting

just to give everyone a chance to get connected

and to join the session.

Thank you all for joining this months

Technical Tuesday session,

which is on How To Plan A Drone Magnetic Survey

Using The UAV Extension In Oasis Montaj.

I’m Joanne Demmer, a project geophysicist

at Seequent Australia.

In this session,

we’ll cover why collect magnetic data with a drone?

We’ll go through some case study examples.

I’ll give you some tips and tricks on survey planning.

We’ll go through a quick outline of the processing workflow.

And finally, tips on how to visualize

and share your results.

So what is a UAV?

UAV is short for unmanned aerial vehicle

and they’re commonly referred to as drones.

In the last decade, they’ve been many advances

in the commercialization of UAV systems

and developments in sensor technology,

which is changing how we investigate the surface

and the subsurface of the earth.

Drones provide a means to acquire high resolution

magnetic data at a fast pace.

They are lightweight, powerful

and improvements in battery technology

have increased flight times, payloads and ranges.

Drones can easily and cheaply go where humans can’t

and they don’t put people at risk.

So when would you consider doing a drone magnetic survey?

UAV surveys are not displacing the conventional ground

or airborne surveys,

rather filling the gap between them.

Consider doing a drone survey if you have, for example,

an area of steep terrain

that is too rugged for a helicopter to draw it adequately.

An area too dangerous to access by foot.

Perhaps you’ve got marshlands, tailings

or danger zones that contain unexploded ordinance.

Or a densely populated area or farmland.

Drones are quiet so reduce disturbance

to residents and livestock.

So what types of problems

can a drone magnetic survey resolve?

They can be used to locate near surface buried objects

or infrastructure with a magnetic signature.

For example, archeological discoveries

or detecting buried cables or unexploded ordinance.

This first example shows the results from a Mag Arrow survey

that was conducted to detect and delineate

buried oil and gas pipelines.

The pipes can be identified from the TMI grid on the left,

which shows high anomalies that have a linear trend.

Drone magnetic surveys can also detect hazards

such as sink holes or mine shafts.

This example, also a Mag Arrow survey,

was conducted to identify abandoned oil and gas wells,

and the results were compared with legacy data.

The TMI highs on the grids on the left

highlight well locations.

These have been plotted in blue

on the Mag heat map on the right

and compared with the legacy locations

that have been plotted in black.

As you can see, the old information was not very accurate.

Drone magnetic surveys can also map

environmental contamination.

The results from this Mag Arrow survey

were used to characterize a landfill site

and it was used to identify areas with buried steel

and isolate areas with buried organic waste

to try and assess the volume

of potential methane gas emissions.

The data from the three examples I’ve shown

were provided by Ron Bell of Geometrics,

and they’ve been presented at past sequence Lyceum events.

Our fourth and final example demonstrates

how and why drone magnetics is being used

in mineral exploration.

A senior project geophysicist, Mark Lowe,

talked to Adam Kroll,

the principle geophysicist at AirGEOX

about their recent Near Mine Project.

<v ->Hi, my name is Adam Kroll.</v>

I’m the principle geophysicist of AirGEOX

a drone magnetometer acquisition company.

These are my details down here in the bottom left

in case you want to contact me after this presentation,

and thanks Mark for inviting me.

So these are a couple of the drones that we use.

We’ve got to Gasser Heli at the top

and a Gasser Electric Hybrid Multirotor

down the bottom there.

That’s the one we’ve developed ourselves

and flies for about an hour and a half up to two hours.

This is magnetometer that we’ve developed ourselves.

We use a magnetometer that has a sensitivity

of one picoTesla per square root Hertz.

So about the same as a gem or Cintrix magnetometer.

In the nose here, we also have our

GPS IMU laser altimeter,

data acquisition system,

all that good stuff and a battery

that gives it two hours flight time,

and the best thing, 500 grams weight

so great for endurance of a drone.

Essentially all of the,

everything we’ve done to design this bird has been to

develop the highest sensitivity,

most accurate magnetometer data possible.

So the magnetometers in the tail,

whereas all the electronics are in the nose.

We also towed the magnetometer bird down here,

20 meters under the multirotor by a rope.

And that removes it from any of the electromagnetic noise

generated from the multirotor.

Now this survey that I’m going to talk about

is a near mine site exploration for gold

hosted in ironstone sediments.

So obviously being iron, it’s magnetic,

the best technique is using a magnetometer.

The problem that the client has is that

they’ve flown the area with a plane

and they’ve covered a lot of the ground

with this ground magnetics.

Problem with the ground magnetics is that

they hadn’t had a makeymite there

and the makeymite produces a lot of really high frequency,

high intensity results that obscure the deposits

that they’re looking for.

And what we found is that that 15 meters altitude

were effectively filtering out that makeymite noise,

but we’re seeing deposits

sort of 15 meters diameter and larger.

I’ll you a little video of how assist flies.

(drone engine revving)

And is the drone up here and the bird down the bottom.

(drone engine revving)

And as you can see, 15 meters is a really low altitude.

It’s not that high above the car.

And that’s all good and well when you’ve got flat ground

like this with low level traps.

But what happens when the client says,

can you fly over our pit, our open pit, and our dump.

Flying it that at 15 meters is a little bit hairy,

but we said, oh, we’ll give it a go.

So what we did was

(clearing throat)

sorry, and here’s a just at the bottom here is a

it shows that we’re sort of at 330 meters altitude there,

it drops by 45 meters into the pit, comes out and then the

dump is 15 meters high.

So we flew along and as we descended it was going okay.

And then it went across the pit floor,

but the trouble started when we started climbing.

So the drone stopped its horizontal movement

and then started climbing vertically.

But the momentum of the bird kept it moving forward.

And essentially the bird just smashed into the pit wall

and it dragged off the hole out of the pit wall,

which really wasn’t nice to see.

And yeah, pretty much storied out bird.

So we went to the client and we said,

you know, we can’t do this.

We can’t descend into the pit.

What we’ll do is we’ll just descend say 15 meters

and then fly level through the pit.

And so to do that, I generated a DEN

where if you see here we’ve got the DEN,

but then it flat lines

after we’ve descended 15 meters into the pit.

So that’s what we did.

So we flew to that flight profile and here,

you know, Y system shows our GPS altitude, the DEN,

the drawing essentially flies along, drops at 15 meters,

flat lines over the pit, climbs again.

And it does a pretty good job of climbing the dump.

So everything went well after that little test.

So let’s have a look now at

whether we achieved what the client wanted to achieve.

So this is the plain magnetic data that they had previously

and this is at a high resolution drone magnetic data.

So from the outset, all of the features is the same.

One thing to note is that over the mine site,

there was no adverse effects from flying

over the pit or over the dump.

We can see here, there’s really not much going on there.

There is some ironstone here off to the side of the pit,

which is a depth.

And there’s probably some

small amount of dumped ironstone there,

but generally everything went well over there.

But can we detect the small ironstone deposits

that they’ve paid us to detect?

If we scroll over here a little bit,

we can see there’s a large ironstone deposit

and here’s a little anomaly off to the side.

So if we zoom into that and we measure it up,

we can say that that’s about a 25 meter wide anomaly

in both directions.

And if we look at the ground,

we can sort of see tracks coming off here,

perhaps drilling was done over here but

for this spot doesn’t look like any drilling

has been done there in the past.

And so that’s exactly what the client wanted to see.

High frequency, normally anomalies is like that.

And as we can see, the data’s really smooth.

Really nice.

We don’t see makeymite

so these ironstone deposits stand out.

So it’s a good result for the client.

We’ve flown now thousands of line kilometers

for them over this area and that relationship continues

because essentially they’re happy that the drone data

is providing them with something that they can’t get

from ground mag and they can’t get it

from traditional airborne mag methods.

Thank you for your time.

<v Joanne>Tips and tricks on how to plan</v>

a dry and magnetic survey.

So I’ve created a new project in Oasis Montaj,

and I’ve loaded the UAV extension.

The first option is survey planning.

So it’s really easy to plan a UAV survey

and to create a flight line plan.

All you need is a DTM grid

and an area of interest polygon file.

If you don’t have a DTM or it’s not an adequate resolution,

you can use the public tab to download free SRTM data.

You can define an area of interest

using CAD tools in Oasis Montaj.

This area can be inclusive or exclusive

if you need to navigate over or around cultural obstacles,

such as pylons or property.

The area bound by the yellow box

is an inclusive area of interest.

And I’m going to modify this

to incorporate an exclusion zone.

To do that, I go to map tools, CAD tools,

and I’m going to create a polygon PLY file.

My area is going to be exclusive,

and I’m going to append this to the current

AOI polygon file.

I’m going to draw this interactively on the map.

So there is a property here which

we’re not allowed to fly over.

So I’m going to

create an exclusion zone over that,

and redraw my polygon file.

So I’ve now added the exclusion zone to my area.

So once I’ve defined my area of interest,

I can go back into the UAV extension and plan a UAV survey.

The data that I’m using for this example

was a Mike Arrows survey

on data was supplied by Ron Bell from Geometrics.

So I’m going to give it a survey name.

I’m going to define the area of interest polygon file

that I’ve just made.

It’s automatically detected the coordinate system

based on this polygon.

So I’m going to plan my UAV survey to a DEM grid

and specify the DEM grid here.

You can also plan to a constant elevation.

A terrain clearance flight line and flight line spacing

should all be decided based on your target of interest

and the depth of the target and its orientation.

Drones can fly really close to the ground

so this improves signal strength.

I’m going to put a terrain clearance of 35 meters

in this example.

And my flight lines are going to be east-west.

So 90 degrees.

And the flight line spacing, I’m going to put 50 meters.

You can choose to add tie lines,

it’ll automatically calculate the flight line spacing

at 10 times the flight line spacing.

I would recommend adding the tie lines in a separate

flight plan and merge them in later on,

this will improve your leveling.

You can also display the results in 2D and or 3D.

Under the more options,

you have further options to

change the sample spacing.

You can change the line extension

beyond the area of interest.

I’m going to put 10 meters.

This is advisable to accommodate four terms and also

push end of line processing artifacts

outside of the chargeable kilometers boundary.

You can also change the numbering and the number increment.

If there is a particular area of interest

that you want to force your flight plan over,

you can include weigh points

and you can locate these interactively on the map.

If I want to force my flight plan over this point,

I can.

So under drape options,

you can calculate a drape survey altitude for the drone.

So drones can

cope with severe changes in elevation really well

and they can stick to tightly draped flight plans.

So there’s no need to smooth the drape

and the climate descent angles can be near vertical.

I’m going to put 90 degrees.

So the ability to collect data

at a consistent height above the ground

significantly improves data quality

and interpretation later on.

So once you’re happy with your settings,

you can hit okay.

This step produces a survey report,

which gives you the line kilometers

for each plan survey line,

along with the total line kilometers for all of the lines.

It gives you the kilometers

for all of the area and just the area inside

the area of interest.

It also produces a flight plan database.

All of the flight planned lines are shown.

Note how it split the line around the exclusion zone

by appending a version one.

Each line is defined X, Y, latitude, longitude,

DEM and drape value.

You can view the flight plan in 3D,

or in 2D.

And note how it’s split the lines

around the exclusion zone there.

You can also export the flight plan as a K and Z

and view it in Google Earth.

So how do you take into account

short fluctuations of drones?

So you can generate sorties within the survey area

based on the drone’s flight range.

And you can do this back in the UAV extension

in survey planning to find sortie sub areas.

So this allows you to take the master flight plan

that we’ve just made and split it up into sub areas.

The sortie in length is in meters,

and this is calculated from the maximum flight time

of the drone in seconds.

Each sortie sub area polygon

is calculated to cover 90 percent of this value.

10 percent is reserved to allow for distance

traveled to and from the takeoff location.

You can include sub area overlap,

and this is recommended to improve leveling.

And then reduce this to 20 meters

and the lateral sub area overlapped to 10 meters.

And then I’m going to hit, okay.

This has created eight sub areas,

and it’s added a takeoff location within each sortie,

just shown by the white dots.

And these are automatically set

to the highest elevation point within the sub area.

If you want to modify the sortie sub areas,

you can.

You can add areas, delete them,

or interactively edit the sub area.

And you can also move takeoff locations.

To help you adjust the takeoff locations,

you can add Azure Map imagery to include roads,

and this will help you identify site access areas.

So the Azure Roadmap has been loaded.

I’m just going to untick my DT, so I can see it,

or you can make it transparent.

And I’m going to move the takeoff location

for sub area 1-1 and position it on this road.

So to do that,

I go back to my survey planning tools in UAV,

and I want to move takeoff location.

You can select the sub-area that you want to work in

and the map that you want to work on.

You can include access point files

if you’ve got positions saved in a CSV,

otherwise you can interactively locate the new position.

Once you happy with your sortie sub areas,

your takeoff locations and access points,

we need to define the sortie paths.

So we go back to the survey planning options

to find sortie paths

and this calculate separate flight paths

for each individual sortie sub area.

You can do this for all of the sub areas or individually.

I’m just going to select 1-1.

I’m going to extend the flight plan lines

10 meters beyond the sub areas polygon file.

And this again is to accommodate for

the drone turning and

to remove any edge effects that might creep in

around the survey boundary.

You can load each sortie

flight plan into individual databases,

and you can display the results on individual maps.

The survey report is appended with the line

title line kilometers for the sub area.

So stats like these are really useful

to estimate how much time is required to conduct the survey,

and also helpful to calculate how much it will cost

and how much you can charge the client.

You can use it as well to prepare project proposals.

This step also produces a CSV file,

which contains all of your takeoff locations in X,Y,Z.

So this is useful to put into a GPS and take with you.

It also produces a flight plan map of the sub-area

along with a flight plan database of the sub area.

For regions where regulations require the UAV

to be visible to the controller at all times during flight,

we can test the VLOS the visible line of sight

from the takeoff location.

We can do this in the survey planning menu,

the UAV extension test line of sight.

So we are working in a sub-area 1-1.

And the map we are working from was the

flight plan map for area 1-1.

We don’t have an access points file,

but if you had access point locations save to a CSV,

you can load that here.

To demonstrate what happens when you lose line of sight,

I’m going to put the terrain clearance

and the takeoff height to one meter.

The terrain clearance should be the

terrain clearance that you used in your flight plan.

And I’m going to display on map.

So a notification pops up

telling me that 89.5 percent of the points

on the full survey path are visible.

If I click okay,

and move this box out the way,

it’s displayed the area that is not visible

from the takeoff location on the map.

And you can display, you can see from the color bar,

the depth below the line of sight that those points are at.

So I can include up to four extra observers

and add them to points on the map

and see if that improves the visible line of sight.

So I can activate an observer

and I can locate their position interactively on the map.

And I’m going to place that observer on this road.

Put an observer height again of one meter

and display map.

And this time the notification is telling me

that a hundred percent of the points

on the full survey path are visible.

So I now know before heading out into the field

to conduct my drone magnetic survey

that all the rules and regulations have been adhere to,

and that the drone is visible at all times during flight.

So once the survey has been flown,

data from sorties can be imported individually

or in batches.

The UAV extension has input templates

for single sensor magnetic data

from commonly used UAV systems,

mainly the Mag Arrow and drone mag.

It does also have the ability

to utilize other ASCII import templates.

There is a full suite of processing tools

included in the extension.

These are for removing data discontinuities

or masking data that is acquired why the UAV is stationary.

You can also do base station corrections,

Idera for removal

and correct for lag and heading.

Repetitive tasks could be scripted

using the record functions.

So from this point,

you can easily merge data from individual sorties

into one master database,

and then apply leveling

and grit the total magnetic intensity.

So this near real-time processing means

you can QA QC really quickly,

and you can adjust survey parameters

whilst you’re out in the field.

Once I’ve merged each individual sortie

into one master database,

printed the TMI and leveled the data,

what tools are available in Oasis Montaj

to improve the subsurface understanding?

So under grid and image, there are a couple of options.

We can locate and plot the grid peaks.

So this is a target picking tool.

It uses Blake Cliff’s method to find peaks in a grid.

So I’m going to find peaks in my level TMI grid.

I’m not going to apply a smoothing filter.

This applies a hunting filter

to remove low amplitude high frequency noise.

Increasing this number reduces the number of peaks found.

I’m going to leave the level of peak detection to normal.

So the surrounding grid values in

all directions must be a lower value

for it to choose that point as a peak.

And I’m going to save the results as an extra line D 10

in my merged database.

This adds an extra column called grid value

and makes an extra line in my merged database.

I’m now going to plot these grid value points

on my level TMI grid.

So this is now highlighted all of the peaks

in my level TMI grid.

Another option is to calculate

and display the analytical signal.

This is done in the grid and image filters option.

So the analytical signal is useful for locating the

edges of magnetic bodies,

particularly why a remanence

and or low magnetic latitude complicates interpretation.

So I’m going to use my leveled TMI,

it’s my input.

You can choose to use the fast forward transform

or the convolutional methods.

This traits and analytical signal grid,

which you can close and then display the grid on your map.

Once you are happy with your results,

you can share your findings with your team members

by connecting to essential server.

You can see which server you’re connected to

in the top right of your Oasis Montaj window.

And then you can use the data services to upload to central.

We have a wealth of information

available online at,

where you can find out more about Seequent Solutions,

including case studies and blogs.

You can find self-learning content


You can also see what webinars and workshops are coming up

by going to

or by contacting a member of your local Seequent team.