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J. Wallace

Importing 3d data from drone

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Hi Everyone

I have a question here that I'm hoping someone can help me with. I'm starting a project on a piece of agricultural land (creating a agri-tourism concept) which is about 10-15 acres in size. I'm in need of some accurate elevation data as well as some high definition images (overhead), a drone is one obvious choice. I have contacted a company that will fly a drone and collect data for me at a pretty reasonable price when compared to traditional surveying.  This drone pilot uses a web based software to share this information with his clients, which I think is a pretty sensible approach.

http://resources.dronedeploy.com/getting-started?utm_source=hs_automation&utm_medium=email&utm_content=53288874&_hsenc=p2ANqtz-_927kOLGu-YsnBPuK3o_rF3UYgKfKJDm-bqgdqx-OeoY2-BxDVCjceb-C95fCtwxhrm-e-HsgQ5CZfc_qSIOoGzBh1OQ&_hsmi=53288874

My question is whether I can this exported data and make it useful within VW. I have provided a couple of shots from the drone Deploy website and I'm pretty sure that importing .dxf will give me some contours that I can work with. Can anyone confirm this? The service is $750+ 100/month for access to this online software which I imagine I'll use only once. 

I don't see the high definition image being an issue, but I'm unsure of the 3d data.

Thanks in advance for any assistance.

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Edited by J. Wallace
Added drone2.png

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Provided that the data are accurate enough, a simply point cloud should work fine in the DTM to generate a 3D terrain model. What accuracy are they claiming ?

 

Speaking of drones, has anybody used one in combination with a photo modeling program (such as PhotoModeler) to extract terrain data ? I assume a decent drone model such as the Phantom 4, having a good camera 4K video and is able to extract decent stills. I have used PhotoModeler and GoPro cameras to extract data used for creating boat covers (well over 200) and it seems to work fairly well, so that's why I am curious.

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DSM = Digital Surface Model  which shows elevations at the heights of e.g. top of buildings, trees etc.

What you probably need is a DTM = Digital Terrain Model , i.e. elevations without the objects as trees etc.

 

So the big question is whether the contours would be useful for your purposes anyway.

 

Assuming you still want to use the data and you need contours, then by all means do select shapefile as it will contain the georeference information and should reproject to your desired coordinate system better than a dxf. (BTW, AutoCAD Civil 3D can import shapefiles so the argument for DXF is a bit inaccurate in this case, it only applies for CAD programs that don't support georeferencing. Because VW does support this in Landmark and Architect my suggestion would be to always use shapefile over dxf if possible if georeferencing is used)

 

The other option is to use the XYZ points to create the site model instead of contours, but the Z value will most likely be the top of the trees, buildings etc. and not of the ground given their comment they are providing a DSM and not a DTM.

 

So again usability of this data is the big question to answer first before spending the money.

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2 hours ago, Claes Lundstrom said:

Provided that the data are accurate enough, a simply point cloud should work fine in the DTM to generate a 3D terrain model. What accuracy are they claiming ?

 

Speaking of drones, has anybody used one in combination with a photo modeling program (such as PhotoModeler) to extract terrain data ? I assume a decent drone model such as the Phantom 4, having a good camera 4K video and is able to extract decent stills. I have used PhotoModeler and GoPro cameras to extract data used for creating boat covers (well over 200) and it seems to work fairly well, so that's why I am curious.

 

Coincidentally I happened to be at a user day of GlobalMapper (a GIS program) earlier this years where one of the workshops was from a company using drones and Agisoft Photoscan to create terrain models.

One thing they use are ground beacons to determine accurate elevations as these points serve as a reference for how far above the ground the drone is flying at any given point in time for improved accuracy.

It worked really well but it does take some time to render the features etc., but it is far more cost effective and faster than satellite data for relatively small areas to get an overview of the current situation (i.e. as of the of flying the drone) compared to commercially available options which usually have some delay between photographing and updating imagery.

 

So in this case it really depends on how they did the photographing and georeferencing, i.e. only use the drone's GPS or also ground beacons to reference for elevations etc?

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7 hours ago, Art V said:

DSM = Digital Surface Model  which shows elevations at the heights of e.g. top of buildings, trees etc.

What you probably need is a DTM = Digital Terrain Model , i.e. elevations without the objects as trees etc.

 

So the big question is whether the contours would be useful for your purposes anyway.

 

Luckily the site is open as it's agricultural. Some trees on the property boundary but for the most it's open.

 

7 hours ago, Art V said:

Assuming you still want to use the data and you need contours, then by all means do select shapefile as it will contain the georeference information and should reproject to your desired coordinate system better than a dxf. (BTW, AutoCAD Civil 3D can import shapefiles so the argument for DXF is a bit inaccurate in this case, it only applies for CAD programs that don't support georeferencing. Because VW does support this in Landmark and Architect my suggestion would be to always use shapefile over dxf if possible if georeferencing is used)

 

The other option is to use the XYZ points to create the site model instead of contours, but the Z value will most likely be the top of the trees, buildings etc. and not of the ground given their comment they are providing a DSM and not a DTM.

 

So again usability of this data is the big question to answer first before spending the money.

 

This makes sense, thanks @Art Vfor that. A few weeks back I had some Lidar data sent to me (after it was manipulated a bit) and this was in a shape file. It was great to see all objects associated with an elevation, so this would be great. The drone app that I would have to use to access the information does produce 3d DTM but I'm not sure I cold actually utilze these in VW. It's going to be a bit of a wait and see with this service I think.  Based on your comments I feel confident that I'll be able to extract some useful information.

Thanks again.

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7 hours ago, Art V said:

 

Coincidentally I happened to be at a user day of GlobalMapper (a GIS program) earlier this years where one of the workshops was from a company using drones and Agisoft Photoscan to create terrain models.

One thing they use are ground beacons to determine accurate elevations as these points serve as a reference for how far above the ground the drone is flying at any given point in time for improved accuracy.

It worked really well but it does take some time to render the features etc., but it is far more cost effective and faster than satellite data for relatively small areas to get an overview of the current situation (i.e. as of the of flying the drone) compared to commercially available options which usually have some delay between photographing and updating imagery.

 

So in this case it really depends on how they did the photographing and georeferencing, i.e. only use the drone's GPS or also ground beacons to reference for elevations etc?

Not sure of their claims on accuracy other than they claim to produce 1' contours.

 

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1 hour ago, J. Wallace said:

Not sure of their claims on accuracy other than they claim to produce 1' contours.

 

I took a look at the website for some more info, these are the things you may want to read for info and have some idea what to look for in the provided data or to ask if it has been used (this sort of refers back to the ground beacons I mentioned in one of my previous replies):

https://support.dronedeploy.com/v1.0/docs/gcp-request-checklist

https://support.dronedeploy.com/v1.0/docs/working-gcp-step-by-step

https://support.dronedeploy.com/v1.0/docs/gcp-csv-checker-tool

https://support.dronedeploy.com/v1.0/docs/elevation-toolbox

 

If those ground control points have been used they might be able to provide DTM info for the "flat" agricultural area depending on the software capabilities.

 

From their website:

"The rule of thumb is that absolute Vertical Accuracy will be around 3 times worse than the horizontal so we would expect around 3 meters.

GPS Corrections and Ground Control Points
You can radically improve your Absolute (or Global) GPS accuracy by using Ground Control Points (GCPs) or Differential GPS systems (RTK, PPK, etc.). More on this below, but these can increase your Absolute accuracy to maximum of around 2-5cm horizontally, and 4-8cm vertically.

Note: SenseFly eBee imagery with embedded RTK is also compatible with DroneDeploy on all Business, Premier, and Enterprise plans. This typically is within 1 to 3cm of horizontal accuracy. Read more about our compatibility with eBee RTK here."

 

From this page: https://support.dronedeploy.com/v1.0/docs/accuracy

This is probably the page that contains the info that is the most relevant for you to get an idea of how accurate the (elevation) data is that you are being provided with (or to ask if these features were used or not).

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Thanks @Art Vsome great info. Looks like I wrongly assumed good accuracy given they were generating up to 1' contours. Thanks for that.

I've sent along some questions to the drone pilot that I'll pass along once I hear back.

Take care and thanks again Art V

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@J. Wallaceyes please do pass along the answers as I'm interested to hear what they have to say. Drone images will become more common in the near future so knowing how they do things and what information they put in by default and what should be requested specifically will be useful information.

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