Hello everybody, I'm Casey Bentley.
I'm an applications engineer for
Bentley Systems in our reality modeling
team and today I'm going to discuss.
How to master the art of complex and
challenging reality data acquisitions?
The big takeaway here is that
higher quality data will always be
easier to work with than poor data.
High quality acquisitions will
have higher degree of automation
when you're using the software
annual get much better results.
If you have borderline data something
that's a little more of a lower quality,
you might take more extensive work.
Or if its soap or it might not even work at
all context capture is very good at working.
When did acquisition is very thorough
but complex sites have a higher risk of
failure as there's a lot more going on.
In the site itself,
so the best way to mitigate this risk
is to have a strong project management.
And planning phases.
So let's start with looking at a
terrestrial project such as this bridge.
A couple questions you need to start
with asking yourself when you're
planning is is the site accessible
in house inside iaccessible.
What are the rough dimensions of the site?
Is there a specific area of interest
in the site that you want to?
Focus on an would be the right Camera choice.
That's going to include type of
Camera whether it's you know.
DSLR or little point and shoot.
Or even a cell Phone to even questions like
what kind of lens would you use on a DSLR?
And things like that.
A good starting point.
Is to use some online
Maps such as Google Earth?
Um that allow you to look at the site
without actually having to be there.
So here we can take a look at
our bridge and we can see we
have access along this road way.
We can zoom in we can get a
rough measurement. Of the span of
sidewalk that we're looking at.
This will give us a rough dimension,
so we know what we're working with later.
So as we can see the site will be
accessible from the north and will be
free of vehicles because will be on the.
Sidewalk here.
The sites around 1200 square meters
and the central part is the key that's
where we want to focus the most.
We can estimate that this will
take roughly 500 to 800 images.
To achieve a robust capture of this.
And while the Structure is fairly high,
we shouldn't have issues capturing it
because we can see it very clearly.
And there's not a whole
lot going on behind it.
So. 1st we can do and next
week and do a on site review.
We can actually visit the site.
And we can walk around it determine
exactly what capture path,
we would have and we're going to
want to identify any potential.
Difficulties that we might not have seen
while we were looking on Google Maps.
This could be.
Things that weren't visible when whatever.
Uh you know map source captured that area
temporary setups and stuff like that,
or just you know specific.
Areas of the subject that
might be difficult to capture.
We can then determine some exact ground
control points or areas to measure
for going to use scale constraints.
And it's also a good chance to do some
early testing on your settings to see.
For example, what kind of focal
length is going to be needed.
Or perhaps.
Shutter speeds if there's a
dark area that you're going to
be capturing things like that.
And we can take a look
on if we were going to.
Walkthrough capture here.
We have a starting point
that we have marked so we
know where to come back to.
And we can just start
walking along capturing.
From the Top of the bridge.
You want to be especially careful
around the corners of the shoot.
Anytime you make a turn.
Uh these areas need to be captured.
Extensively, in order to have a
clear an automatic processing.
As we go under the bridge here.
You're going to see the
scene get a lot darker.
It's important to pay attention
to lighting conditions. Because.
If it changes significantly it
can cause issues for the automatic
registration of the tie points.
You also want to identify your
relevant points for measurement here,
we can see it's that bottom of the bridge.
Make sure those areas are well captured.
And then we can head back
to our starting point.
To close the loop?
Now to look back at what we just captured.
You can see you can follow the
path the whole way around.
It goes back to where it started.
You can see that there are few or
small breaks in between any of the
image is a good way to check It is,
you should be able to just.
Speed through the images real quick
and it will look like a movie.
Just as if you know consecutive
frame goes by.
You're going to want to make
sure that you focused on the key
areas so here we focused on the.
Underside of the bridge,
there, which we can see as we
walked along underneath it.
If we look at the.
Capture through the 80 we can see
our splats and our photo positions
do see they're all very consistent,
especially around the corners.
No breakages there.
And this is what a good capture
should look like it should be very
consistent the whole way through.
Now we do a final checklist
before leaving the site.
It's always important to remember that
going back to the site is generally
more expensive than to shooting
more images while you're there,
so when in doubt.
Always over capture you can just
delete the images at a later time.
So the checklist before you want to
leave you want to make sure that
your path is complete and robust.
You want to make sure that you
focused on the areas that are
important so as we said before.
Under the bridge here around
those main supports.
I'm going to make sure that you have
any Geo registration any control points
that information has been written
down and collected somewhere same
with any measurements if you're using?
Scale constraints and then you're
not going to get anything that
you might have there if you
have targets or something.
Set out or whatever you use to mark
the starting point things like that
are important to bring with you?
So to process the data you'll then
head back to your work station and
take your images and copy them.
Onto your computer?
You can then import all those
images into context capture.
And start defining any.
Constraints such as TCP
scales if you have any.
QR targets things like
that April tags chili tags.
Those sorts of things and then
you can just submit an error
triangulation either using the?
Desktop or our cloud processing
service to get the ball rolling.
After processing we can
take a look at what are?
Finish mesh looks like.
As we can see this is the important
part under the bridge here.
If it looks pretty good.
Here we can see that mesh itself
with the texture turned off.
And again we can confirm
that it looks pretty good.
With that extra turn back on we
can see a little more detail.
So if we review our.
Whole project here, we can see we
spent a good bit of time on planning
a good half an hour on getting a plan.
Um 10 minutes walking around the site
men about an hour on the actual shooting.
For processing the manual
processing because this is a good
acquisition was very quick 'cause.
It's a couple minutes to put.
In those gal constraints.
Uh on the bottom side of bridge
automatic processing that's going
to be rarer triangulation annual
reconstruction was about 240 minutes.
And then you can do a quick project analysis.
Afterwards, that's about 20 minutes
for a total time of 6 hours.
5 minutes,
so important to look back and
review the time you spent under
capturing the automatic processing
and your manual processing.
If you're spending a lot of
time on manual processing.
It might be a good idea to start
spending more time on the planning
and that way you can cut down.
On the manual and hopefully use
more of the automatic processing.
So comparing this to a poorly Matt got
managed capture we can see the manual
processing time is significantly longer.
Um. Where is there good captures 5 minute
it becomes 60 minutes for a bad capture
so while you spent 3 save some time.
Not planning you end up wasting a
lot more time running additional
error triangulations and.
Having to do manual tie points
and stuff like that,
which can be rather tedious.
So let's look at a another example.
Let's look at capturing from a drone.
So for this example, we're going to look at.
Microsoft Redmond campus,
we wanted accuracy at this site of somewhere
around 5 centimeters better if we can.
Um. We're going to merge this
reality mesh with an existing lower
resolution mesh so in order to do that.
We're going to use a drone that
can fly over the whole site.
We're going to have.
Lots of ground control points throughout
the site so that it will be very
accurately located and can be easily.
Merged with a lower resolution mesh.
So again let's start.
By looking at our online map of the site.
Here we can get a rough idea of
how big the overall site is so
you can see it's rather large.
Has a highway that runs
through the center of it?
2700 meters long.
By 1600 meters wide.
And these are all the ground control
points that will be using as you can see,
there are lot of them.
Because the site this large is
going to need them in order to
have that high degree of accuracy.
So we can merge it with
a lower resolution mesh.
So let's start our planning here from
the office as we looked at our map.
We can try to think of an area.
Or we can take off and land.
We can you know if you're flying a drone
you're going to have to check to see
if there's any controlled airspace.
Or airports around that you're
going to need to coordinate with
in order to fly the site.
You're going to need to identify
your drone path and the GCPSPCP
is going to obviously be placed.
Like we just saw in something like Google
Maps drone flight path can be calculated.
Considering that we want a 5 centimeter
or better than 5 centimeters.
Accuracy.
Is that will be the flight altitude?
Which will determine the criticize?
When you go to the site to review
you're going to want to check out
that planned landing and takeoff.
Area and make sure there's no
unexpected obstacles that you
didn't see maybe you couldn't see if
there are power lines from the map.
Or things like that,
you're going to want to also
check for potential obstacles.
Across the whole campus.
Again, things like power lines or perhaps
trees that have changed or even new
construction things that haven't been.
Included on the map data.
You can then set an survey your
targets for your ground control again.
Another thing you're going to
want to make sure is that?
Those ground control targets are
going to be visible from the drone.
Maybe there's not so many some
obstacle that you couldn't see.
Before blocking them.
Put actual capture.
You're going to want to execute a
vertical and oblique predefined
flight path for something like this,
you might not fly the whole thing.
With a oblique flight plan,
you might just want to look at specific
areas, so for here we can see.
Orbitz were done around specific buildings.
And for everything else that
consistent oblique excuse me
consistent vertical image was taken.
Again, you can also see the highway that
goes through the middle of the site.
You cannot fly over that so you have to.
Split the site into 3 areas essentially.
So here we can look at the
overall capture after being arrow,
triangulated, we can see all of our.
Vertical images in their grid pattern as
well as the oblique's with their orbits.
If we look at just a single area.
These are the obliques or excuse
me these are the vertical images.
Over Top of the.
This specific area in a grid pattern.
In fact, this is if you look at 2
grids that overlap slightly you
can see where the images are.
Roughly on Top of each other.
Then to get Higher detail on the
sides of buildings on the facades,
we can add the oblique imagery,
which are these.
Orbitz that were just added.
As you can see the drone flight,
the obliques.
We're done from the same and
differing altitudes as the.
Vertical shots and again,
it's much like the shooting around
corners of a captured there's lots of
photos in between the two altitudes.
To tie them together,
so that context capture could
automatically stitch them.
So for the processing again,
you'll.
At home,
you'll copy your images to your work
station and then you can import
your images and all your ground
control points that you have.
You can start manually
registering those jeeps.
And then you can submit an error
triangulation again to the cloud
or to a local desktop version.
Again, if we look at our time
spent here planning for a
project like this was one hour,
the on site checking was.
10 minutes to make sure there
weren't any potential problems.
Image shooting is a more substantial
time because we have such a large area.
So again if we look at our
time spent on our project.
We could see our planning took about an hour.
For on site check was 10 minutes
or image shooting was 8 hours,
which is pretty impressive
considering the overall size.
Of this area. A drone can capture
a lot of area very quickly.
I'm very thoroughly.
The manual processing was about 45 minutes.
That's the time it takes to import and
Mark all those G CPS in several images.
The automatic processing is 20 days.
That's the actual 80 time as well
as the overall processing time.
And for the reconstruction.
And then we can do our knauss
afterwards for 20 minutes to give
you a rough estimate of 20 days,
10 hours in 15 minutes or
something like this.
Now, if we compare this to a poorly managed
capture the big difference again BR manual
processing on a well managed capture.
You don't be about 45 minutes
put on a poorly managed capture
with lots of manual tie points.
I can easily go up to 20 hours.
It could possibly even go higher than
that and then automatic processing.
Time will again be higher as well because
of additional 80s that have to be run
to ensure that the manual tie points
are working as they are supposed to.
Um can easily add another 10
days to your processing time.
Finally let's look at a
complex hybrid capture.
This is going to involve lots of different
types of imagery both from a drone.
Inground Dimitry as well as
a laser scan being used this
example is Cambridge University.
And the point of interest is a
single building that's going to be
captured both indoors and outdoors.
So again. Would start by looking at
our scene. Through an online map.
Here we can see the overall area
of interest for A. Low resolution.
We have 600 meters by 930 meters area.
So it's not nearly as big as
Microsoft but still. A sizable area.
Is it going to be captured by both
oblique orbits as well as a grid?
The critical shoot vertical
images while the orbits will shoot
oblique and so they interlock.
This building in the centre here is
going to be our high resolution.
Area of interest. And that area
is 85 meters by 73 meters.
Again, this area will be captured with some.
Oblique orbits. They have that
interlocking grid so that they will
all automatically tie together.
So let's start planning from the office.
Um again because we're working with the
drone. We're going to need to define
a takeoff and landing area in any.
Play clearances that might be necessary
began coordinating with any airports
or any air traffic control if you're
in any sort of controlled. Airspace.
Oh, you're going to need to identify how
to access the site and the main building.
And then you're going to need to
define your flight path and any GC PS.
Not including this,
you're going to want to think about
what kind of drone you're going
to use for something like this?
What kind of Camera in between.
The drone in the ground.
So if we look here, we can see our main
area is 556 square meters with an expected.
Accuracy of 2 centimeters so that's fairly
low resolution for the high area and it
is being captured by both the oblique.
The deer grid. Which gives you an
estimate images of about 1400?
You can estimate capture time with that
for about 2 hours and that's going to
require a couple operators a drone.
The total station, etc.
The focus building.
Is considerably smaller but it's going
to be captured in much higher accuracy
so while we have a smaller area?
We do have a much larger number of images.
As well as our.
Total number of scans.
So we do our on site review.
We're going to be looking for many of
the same things that we did for our.
Drug capture anything that drone might
hit or things that we couldn't see
making our takeoff landing area unsafe.
Any potential obstacles things that
are blocking our focus building and
or things that might be blocking
our ground control points.
So we're also going to do a
review of the building itself.
We want to determine our exact Camera
path that we're going to be capturing
any potential difficulties things that.
Or uh not conducive to good
capture such as blank walls.
Highly reflective surfaces.
Glass things like that,
and this is a good time now to.
Test any Camera setting.
We're also going to review the inside of
the building again defining our exact.
Capture path and again looking for any
of those potential difficulties such
as shiny surfaces again angles going
around corners needs to be captured.
Extensively and entrances are
potential difficult areas.
For the scan we're going to want to
define our scanner positions that can
cover the entire area and we're going
to make sure that the laser scanning
activity is not going to interfere.
With imagery capture because people are
going to be moving as photos are taken
they will end up not being present.
In the final model,
but because a laser scanner on a tripod is
going to be stationary for several images.
It's possible that that could be an
artifact in your mesh that you're
not going to want to you want to.
Time that so that laser scans
aren't being done at the same time.
Or at least not in the same area.
Next we'll start our capture
of the overall area.
We're here, we're just flying
are predefined flight plan.
And we're going to make sure the
TCP czar set before flying and
then just flat a constant height.
And execute was already planned.
For the imagery capture of the outdoor
buildings is the ground Camera again.
We're going to want to follow
the capture path that we?
Did well with our on site review?
We're going to check that this capture
is robust with no breaks again.
It should appear that it's like a movie.
If you just look through all
the images really quickly,
like they're just frames.
Uhm you shouldn't be getting sick from
the Camera jumping around or anything,
it should all be very consistent.
When were capturing the
indoor building again.
We're going to follow that capture
path that we planned out before. Um.
To ensure that you can get some automatic
stitching between the two sections.
You don't want to take extra
care with the entrances.
I'm going to take photos outside
the entrance as you go in and
go through them from both ways.
So that way you can automatically
stitch the two together.
I'm going to want to pay attention
to lighting conditions inside,
especially because it's very
easy for it to become very.
Dark in a room with perhaps
no windows or with.
Oh, just some you know standard
lights in a room.
You're going to need to make sure
that the exposures are fairly
consistent throughout the whole thing.
So as we can see looking
through our entrance here.
We're looking through it as we go.
And as we go inside it
gets a little bit darker,
but not noticeably so.
And then we go back outside.
To do your laser scan inside?
Where is going to set the laser scan
on our predefined positions that we
determined during our on site review?
And then you will run your acquisition.
What's all the acquisition is done,
we can start the processing,
which will again import your laser scan
and you're going to import all your?
Images from the drone from the ground Camera.
All your GC PS you'll import that
all in start marking your TCP's.
Are going to line the ground
and the indoor images and then
fit them to the point cloud?
And you can run your 3D Reconstruction.
So here we can see our overall site
with these smaller site merged in.
Then we can look at our
finished results here.
As we can see we have our
overall site a lower resolution.
But as we Zoom in here and
look around our focus building.
We can see it becomes much sharper.
Things you can really see the
added detail that you get from the.
Ground photos, especially when
you're looking at just the
mesh without the textures.
You see how sharp the actual geometry is.
Of course, because this was
captured on the interior
going to look on the inside.
And we can see our.
And I sharp geometry coming
from our laser scans as well
as the interior photography.
The combination of the two giving
us a full. Capture of the building.
Right now we can look back and
review our time as we can see are
planning for this was about an hour.
Um focus building tour is about
half an hour that's you know
looking around the actual building.
Image shooting an laser shooting were
2 hours and 4 hours for the image
shooting that's the ground an the drone.
And then the laser scan was 4 hours.
Manual processing takes about an hour
that's merging everything together
and adding any control points, etc.
So they can all be merged.
And then the automatic processing
your 80 and reconstruction again
are 6 days and one hour.
And then we could do a quick
project analysis afterwards.
Take about 20 minutes for
a total time of 6 days,
13 hours and 50 minutes.
So comparing this to a poorly
managed capture we can see again,
you can save some time on planning
if you don't want to do it.
But you will end up doing more on the.
Manual processing and on the
automatic processing as you
have to troubleshoot things.
This ends up giving us a almost twice
as much time for a poorly managed
capture versus a well planned out one.
So conclusion here is that a robust
capture is going to give you the most
consistent reality match a lot of planning.
Is going to definitely have
you and you will have much?
Ferber results will be much
easier to process? Um.
If you do you're planning right can
easily reduce your processing time in
any issues that you have by up to 80%?
And here we can just look
at some estimated costs for.
But the good captures an the bad
catchers as you can see it's almost
twice as much for all of the.
Poorly managed captures as you
end up doing spending much more
time in the manual processing.
Yeah, for instance,
is we had the terrestrial manual processing.
We can see it goes from 5 minutes to 2
hours for the amount of manual processing.
Oh, so anytime you can minimize that.
Will certainly Reduce the overall cost.
And here we can see our.
Comparison to graph here
for the trust real project.
We have our good capture
on the left and are.
Put image on the right.
Same for AR drone.
And finally for our. Hybrid project.
Thank you everybody for attending I
hope you learned a good bit on how to
plan out complex captures. And uh.
Thank you for joining us today.