Hi everyone
In my opinion when DJI produced Phantom 4 rtk, it means that company have focused on land surveying affairs. Because of drone's price this is not proper for entertainment or capturing image for documentary or other purposes.

Therefore I don't understand why DJI doesn't complete its new path and cover surveyors' needs.

Fly drone according terrain is preliminary need and I asked DJI adds this ability to GS Pro Rtk.

Sincerely

'In my opinion when DJI produced Phantom 4 rtk, it means that company have focused on land surveying affairs. '

DJI are not focussing on surveying applications, it is just one small area, for every drone sold for surveying, probably 200 are sold for normal consumer requirements.

Fly drone according terrain is preliminary need and I asked DJI adds this ability to GS Pro Rtk.
How would you suggest that DJI might implement this?
Do you know of a lightweight and affordable sensor that they could use?

Labroides Posted at 4-6 17:51
How would you suggest that DJI might implement this?
Do you know of a lightweight and affordable sensor that they could use?

@wrasse man (Labroides): You keep saying things like this in threads about terrain following despite the fact that several autonomous flight apps offer this functionality.
Whether it is via a 3D KML or other flight path generated with respect to a DSM, or an onboard DSM in the flight app (custom or publicly available), the fact is that terrain following (as opposed to simple flight at a single altitude relative to Home point elevation) is totally doable. Especially with the RTK enabled platforms.

You seem to dismiss this need on the basis that what is being asked for is unachievable. The request is not to be able to follow the real terrain with great precision in real time. The goal is not to use this functionality to skim the ground or treetops. Folks just want to be able to program a flight where the drone will stay at a relatively constant (and considerable) altitude over a varying terrain, so that photogrammetry and other use models will function better. Staying within ± 5m of the desired altitude would probably be fine for most needs. And lots of (non DJI) apps have solved this problem. Unfortunately with some DJI platforms, the DJI flight control solution is the only option.

Labroides Posted at 4-6 17:51
Fly drone according terrain is preliminary need and I asked DJI adds this ability to GS Pro Rtk.
How would you suggest that DJI might implement this?
Do you know of a lightweight and affordable sensor that they could use?

Please read @patiam answer carefully and forget all precise sensors or complicated method for following terrain. It's not doable in the way you think about.

It's very simple by using SRTM DEM in flight designing process and I request you to see Map Pilot app in order to get answer all of your questions

Geebax Posted at 4-6 16:08
'In my opinion when DJI produced Phantom 4 rtk, it means that company have focused on land surveying affairs. '

DJI are not focussing on surveying applications, it is just one small area, for every drone sold for surveying, probably 200 are sold for normal consumer requirements.

When a company produce a surveyor related product (P4 RTK) with high price in comparison to usual product(P4), It's not correct to say "DJI has not focused in surveying affairs"

When DJI company steps in this way, It's reasonable to complete the path and make as proper app as device.

jivago Posted at 4-6 21:14
Please read @patiam answer carefully and forget all precise sensors or complicated method for following terrain. It's not doable in the way you think about.

It's very simple by using SRTM DEM in flight designing process and I request you to see Map Pilot app in order to get answer all of your questions

What is the aircraft going to use to measure it's altitude above the terrain?

The signature of kml / Shp File Import has validity for how long?



Grato
Carlos

Geebax Posted at 4-6 21:26
What is the aircraft going to use to measure it's altitude above the terrain?

Stop making it so complicated.
The aircraft doesn't need to know its altitude above the actual terrain. It needs to know its altitude above a model of the terrain, or relative to a programmed absolute flight path, which is also a model. An RTK-enabled aircraft knows its HAE to within at least a meter or so, probably better. In reality given the altitudes most will be flying, ±5m of target altitude would probably be fine. The software just has to use that against whatever DSM or flight path is in use. If a conversion between the vertical datum of the DSM needs to be done, that's easy. Computers are good at math.

Of course the caveat here is that if the DSM is wrong (and they all are) by too much, or the programmed 3D flight path will take the aircraft through something it shouldn't, then bad things can happen. But thats where all the fancy obstacle avoidance sensors and algorithms kick in, just like when RTH is used.

As has been stated dozens of times now, several autonomous flight apps with this functionality currently exist. Are you claiming they don't work? I've personally flown scores of eBee RTK fixed-wing flights using the eMotion ground control software, so I'm talking practice, not theory here.

Geebax Posted at 4-6 21:26
What is the aircraft going to use to measure it's altitude above the terrain?

There is a method in surveying world called "Photogrammetry". This method can produce map by taking images under certain disciplinary from a platform like airplane, satellite, drone or etc. In this method we need to take images from constant elevation above ground in order to have definite scale in all images. In this part, drone need to stay at same altitude relative to ground beneath it.

patiam Posted at 4-7 10:20
Stop making it so complicated.
The aircraft doesn't need to know its altitude above the actual terrain. It needs to know its altitude above a model of the terrain, or relative to a programmed absolute flight path, which is also a model. An RTK-enabled aircraft knows its HAE to within at least a meter or so, probably better. In reality given the altitudes most will be flying, ±5m would probably be fine. The software just has to use that against whatever DSM or flight path is in use. If a conversion between the vertical datum of the DSM needs to be done, that's easy. Computers are good at math.

That's my chance you're in this topic with good information about surveying and completely understand what I said.

As you said eBee RTK in fixed wing category with its own software cover this matter. For DJI's drones, Map Pilot app for iOS platform address this problem and from past year till now I haven't had any problem with that.

@jivago yes as you said photogrammetry works much better when altitude is kept as constant as possible. unfortunately DJI (and some users here) don't appreciate that and/or don't realize than it doesn't take magic to accomplish.

patiam Posted at 4-7 10:20
Stop making it so complicated.
The aircraft doesn't need to know its altitude above the actual terrain. It needs to know its altitude above a model of the terrain, or relative to a programmed absolute flight path, which is also a model. An RTK-enabled aircraft knows its HAE to within at least a meter or so, probably better. In reality given the altitudes most will be flying, ±5m would probably be fine. The software just has to use that against whatever DSM or flight path is in use. If a conversion between the vertical datum of the DSM needs to be done, that's easy. Computers are good at math.

Hmm, I am not making it complicated, but all I get is obtuse answers, and lots of three letter acronyms. I'm not impressed by them, and using them to indicate membership of some secret society does nothing to further your argument.

Geebax Posted at 4-7 21:14
Hmm, I am not making it complicated, but all I get is obtuse answers, and lots of three letter acronyms. I'm not impressed by them, and using them to indicate membership of some secret society does nothing to further your argument.

What is obtuse about my responses? I have fully answered the question more than once, and yet you seem to insist that autonomous flight with varying ATO altitude that follows terrain is some sort of unobtainium.
I explained how it works.
@jivago and I both gave examples of software that does it.
Please explain how that is "obtuse".

Unfortunately, "three letter acronyms" are common usage in many fields, including the one being discussed here, using drones for photogrammetric mapping. Far from being used as secret code, they're used as shorthand so we don't have to spell out  terms we use over and over. I bet you even use a few yourself now and again: GPS? RTK? UAS? Perhaps IMU?
One might argue that if you're going to discuss a topic intelligently then perhaps you should know the vocabulary. But for those terms/acronyms you don't understand,  you could just ask, instead of snarkily accusing the users of elitism. But here, I'll try to help:

HAE = Height Above Ellipsoid. The ellipsoid is a model of the earth's shape. This is the datum against which GPS (really GNSS) measures altitude. In standalone, uncorrected GNSS devices, the accuracy may be as bad as 10's of meters, but RTK can bring this down to sub-meter.

DEM = Digital Elevation Model.  A generic term that encompasses DSM & DTM. A model of the elevation of a planet's surface.

DSM = Digital Surface Model. A representation of a planet's surface. Can be produced via photgrammetry or other means, such as LiDAR. Similar to DTM, but usually includes vegetation, structures, objects, etc.

DTM = Digital Terrain Model. A bare-earth DEM.

SRTM (4 letters!) = Shuttle Radar Topography Mission. A common free DEM with approximatley 30m horizontal resolution. Often used in autonomous flight control software for terrain following/constant altitude flight.

KML = Keyhole Markup Language. An xml format used for geographic data used in Google Earth and many other applications. Created by Keyhole originally, which was bought by Google. Some flight control applications use KML to define 3D flight paths.

Uh, oh, now you're in the "secret society"! You don't get to learn the handshake yet though.

DJI has invested in the surveying community, they have the P4RTK, MT210 and their new software DJI Terra. Terra is similar to DroneDeploy, Pix4D, Agisoft etc.

Look up Drone Harmony and you will see basically what @patiam is talking about. They have flight plans that you can create that allows both horizontal and vertical flight paths. Litchi allows you to set individual heights at each waypoint. As a software developer anything can be programmed.

AVA 2.3 and higher  for the FireFly6 Pro does it as well (as of 2018).

A unicorn, terrain following is not....

I agree with patiam,  DJI is almost the only app now that does not allow for terrain following. Maybe they should download UgCS or MapPilot to see how its done. Mission Planner also does it and allows you to use lidar. Its been able to do it for years! Come on DJI get it done ! You are so close! The drone flies so nice its just a little bit of software programming and you guys will have it well sorted! We dont need precise altitude terrain following just enough so when you are surveying on a hillside you dont have cm pixels at one end and meter sized pixels at the other (ok slight exaggeration but you know what I mean)

I'll just leave this here for @Geebax & @Labroides...

If you are working on flat areas it's ok but in mountainous regions it is not useful drone unless Dji update its software with terrain following functionality.
We bought  Dji Pjantom 4 RTK for surveying projects when it was presented on INTERGEO in 2018 but we are still waiting this update

NIKUSHA Posted at 5-15 04:00
If you are working on flat areas it's ok but in mountainous regions it is not useful drone unless Dji update its software with terrain following functionality.
We bought  Dji Pjantom 4 RTK for surveying projects when it was presented on INTERGEO in 2018 but we are still waiting this update

@NIKUSHA terrain following using a user-supplied DSM in the new firmware (2.01.0009).
Folks are just now struggling to get it to work and test it out. As usual, DJI's lack of documentation for the functionality have left us all fumbling around a bit figuring it out.Also, many users are reporting that the RC device reverts to Chinese characters after the update, which requires you to figure out how to change the langauge settings back to your preferred one.

We updated via Assistant 2 and did not run into this issue.

patiam Posted at 5-15 08:17
@NIKUSHA terrain following using a user-supplied DSM in the new firmware (2.01.0009).
Folks are just now struggling to get it to work and test it out. As usual, DJI's lack of documentation for the functionality have left us all fumbling around a bit figuring it out.Also, many users are reporting that the RC device reverts to Chinese characters after the update, which requires you to figure out how to change the langauge settings back to your preferred one.

Thanks patiam for the information provided.

I have found also this kind of user manual for terrain aware function on this forum:

https://drive.google.com/file/d/17bWIHTD8yI3WI22kNsxWEV7mPys-g0Ww/view?fbclid=IwAR24g21kzNGN3CqVNLkEjn6p4uIyCZaqhCwR3BsXuRzQ0HVfi3VD2KNu-Ds

patiam Posted at 5-15 08:17
@NIKUSHA terrain following using a user-supplied DSM in the new firmware (2.01.0009).
Folks are just now struggling to get it to work and test it out. As usual, DJI's lack of documentation for the functionality have left us all fumbling around a bit figuring it out.Also, many users are reporting that the RC device reverts to Chinese characters after the update, which requires you to figure out how to change the langauge settings back to your preferred one.

Thanks patiam for the information provided.

I have found also this kind of user manual for terrain aware function on this forum:

https://drive.google.com/file/d/17bWIHTD8yI3WI22kNsxWEV7mPys-g0Ww/view?fbclid=IwAR24g21kzNGN3CqVNLkEjn6p4uIyCZaqhCwR3BsXuRzQ0HVfi3VD2KNu-Ds

NIKUSHA Posted at 5-21 00:47
Thanks patiam for the information provided.

I have found also this kind of user manual for terrain aware function on this forum:

Nikusha,

Thanks for this. I was able to do some testing. We were able to successfully use NED to create a DSM and import it to the controller. The flight profile looks correct. Test flying it later this week, will report back.

NIKUSHA Posted at 5-21 00:47
Thanks patiam for the information provided.

I have found also this kind of user manual for terrain aware function on this forum:

@NIKUSHA- thanks for the cookbook, it confirms most of what we've figured out here on the forum (I still have not tried it yet).

@p4pEric- do let us know how it goes!

p4pEric Posted at 5-21 15:19
Nikusha,

Thanks for this. I was able to do some testing. We were able to successfully use NED to create a DSM and import it to the controller. The flight profile looks correct. Test flying it later this week, will report back.

p4pEric,

Thanks for sharing the information.
FYI
Dji have released new remote controller without built in screen for Dji phantom 4 rtk.
I wonder how it works with Litchi and Map Pilot apps.

So it ended up working well. The workflow is a little clunky, you have to use the NED, download the area of the map you want to use, then put that in QGIS and clip that larger area and then use OSGeo4W Shell to create the tfw counterpart to the tif, then put both of those files into the file structure DJI/DSM/(insert project name here folder)/ .tif.tfw folder.

djiuser_FnFhaligjp9M Posted at 5-30 09:14
So it ended up working well. [view_image] The workflow is a little clunky, you have to use the NED, download the area of the map you want to use, then put that in QGIS and clip that larger area and then use OSGeo4W Shell to create the tfw counterpart to the tif, then put both of those files into the file structure DJI/DSM/(insert project name here folder)/ .tif.tfw folder.

This was me on a different account FYI

If you have data processed in agisoft is there a way to export the DEM directly to the required format?

Aerotas published a workflow for using USGS elevation data in order to make the Terrain Awareness feature work.

Go to aerotas dot com / phantom-4-rtk-terrain-awareness

I know that there are GIS applications, like Global Mapper, that can assist in this endeavor. But, the cool part about this workflow is that it is all open source and completely free.

Steps for leveraging free USGS elevation data in order to use the Terrain Awareness feature:
- Get elevation data from USGS web-viewer
- Convert and clip the data using QGIS
- Use OS4Geo4 Shell to create a TFW for the clipped TIF
- Load the TIF and TFW on the SD card
- Put the data in the DJI controller
--- Tap three lines
--- Tap the SD card icon
--- Select the DSM file
--- Select Terrain Awareness Mode
--- Select the right DSM
--- Plan Task (aka Plan Flight Path)

Trey Swann Posted at 6-4 14:44
Aerotas published a workflow for using USGS elevation data in order to make the Terrain Awareness feature work.

Go to aerotas dot com / phantom-4-rtk-terrain-awareness

dont know if this is required, but i have read that you should put the files (*.tif and tfw)  in the following structure on the SD Card:

DJI --> DSM --> Name of project ---> Put files here

Knertiz Posted at 6-4 22:17
dont know if this is required, but i have read that you should put the files (*.tif and tfw)  in the following structure on the SD Card:

DJI --> DSM --> Name of project ---> Put files here

That’s what I do. You're right, you need the tif and tfw in the same folder for the controller to recognize it as a DSM.

Hello,
It does not work and yet I follow the instructions.
See an explanation please?
Thanking you.

Thanks for sharing, I think DJI covers both the enthusiast and the budding professional with its line drone products. Mavic series is capable of just for fun and some semi-commercial work. The professional work is in the Inspire line of drones ($$$$).

Hello All,

With the introduction of terrain following, I finally purchased the Phantom RTK . So far I am totally unimpressed with the terrain following feature. For reference, I've been using map pilot for years, which is seamless and very easy to use.  It's a great app that leverages readily available SRTM data. It also supports x-grid missions and KML overlays. It doesn't seem like I can do either with DJI terrain following. Not to mention its a very cumbersome process to bring the data in to the DJI ecosystem. I do like that I can use custom DSMs but seamless integration of SRTM needs to be included in future releases.  As it is now, terrain awareness doesn't proved the tools I need to make it useful.  Bummer!

Hello All,

With the introduction of terrain following, I finally purchased the Phantom RTK . So far I am totally unimpressed with the terrain following feature. For reference, I've been using map pilot for years, which is seamless and very easy to use.  It's a great app that leverages readily available SRTM data. It also supports x-grid missions and KML overlays. It doesn't seem like I can do either with DJI terrain following. Not to mention its a very cumbersome process to bring the data in to the DJI ecosystem. I do like that I can use custom DSMs but seamless integration of SRTM needs to be included in future releases.  As it is now, terrain awareness doesn't provide the tools I need to make it useful.  Bummer!

fans6a2d4df1 Posted at 6-10 05:22
Hello,
It does not work and yet I follow the instructions.
See an explanation please?

fans6a2d4df1,

I had a similar problem. I wasn't creating the tif file correctly so it wasn't showing up in the directory. How are you creating the tif?

We performed a flight at an altitude of ca. 2300 m. We have generated our own DSM from a first flight and have planned the final flight with a flight altitude of 70 m. The drone then made the flight at a height of over 200 m. The altitude was relatively constant but due to the height error, the GCP can hardly be selected in the software.
Does anyone have a solution to the problem with the wrong altitude?

AUTPhantom4RTK Posted at 10-23 01:57
We performed a flight at an altitude of ca. 2300 m. We have generated our own DSM from a first flight and have planned the final flight with a flight altitude of 70 m. The drone then made the flight at a height of over 200 m. The altitude was relatively constant but due to the height error, the GCP can hardly be selected in the software.
Does anyone have a solution to the problem with the wrong altitude?

I am trying to figure this out, which is why I am rereading this thread. I was hoping someone had a solution.

The Phantom RTK is consistently flying 50 m too high, leading to a GSD higher than desired and an abundance of images (the mission was planned for 90 m)

I suspect the altitude difference is due to a datum issue.

Here is my workflow:

I start with a DSM from Pix4d. The DSM is in SPCS NAD27 with vertical datum of EGM 96, so the DSM is MSL altitude.

I know NAD 27 is an archaic coordinate system but that is what my clients use and want.

I convert the DSM into WGS 84 with MSL elevation data and create a GeoTIF

I import the GeotTIF into GSRTK and plan a mission at an altitude of 90m.

The drone is flying a relative and absolute altitude approximately 50 m too high.

A few questions  for the group:

Does the PRTK fly absolute or relative altitude? If is absolute is the based on ellipsoidal or orthometric altitude?

What vertical datum should be used for GEOTIFF creation? Ellipsoidal or orthometric?

Any insight is greatly appreciated,

Thanks,

Dave

PS: Just got off the phone with a good buddy. He suspects this is related to barometric pressure. The P4P flies relative altitude based on home point barometric pressure.  If the user wants to fly 300 ft, the Phantom 4 converts 300 ft to a differential pressure, adds  that to home point pressure and then flies constant pressure. Maybe the RTK doesn't work the same way?

Dear all,

I hope you are fine. My company have a Matrice 210 rtk v2 + micasense altum.
I would like to have the terrain awareness flight option. Our Dji pilot doesn't have the same option as the Phanthon rtk. Can you help me to solve this problem?

Thanks,
best regards,

André Duarte

patiam Posted at 2019-4-6 19:59
@wrasse man (Labroides): You keep saying things like this in threads about terrain following despite the fact that several autonomous flight apps offer this functionality.
Whether it is via a 3D KML or other flight path generated with respect to a DSM, or an onboard DSM in the flight app (custom or publicly available), the fact is that terrain following (as opposed to simple flight at a single altitude relative to Home point elevation) is totally doable. Especially with the RTK enabled platforms.

Well stated!