Frame of FMV in ArcGIS Pro is wrong or....

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04-28-2021 05:06 AM
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VassilisTrigkas1974
New Contributor III

Hi, I try to use FMV butI have a problem. Please check the image I attach.

I did a fly with Phantom Pro v2.0 with Site Scan App (not LE). I used the Inspection fly type with video mode. I downloaded the video and flights Metadata and then I followed the procedure in ArcGIS Pro. As you can see the camera is straight forward to the ground, not 90 degrees but it is looking towards the ground. But when I choose FMV the area that covered the frame is completely wrong. The frame covers a huge area which is far away. Any idea what is going wrong?

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5 Replies
SarahPC
New Contributor III

What did you use for elevation in the processing and how high are you flying above ground

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VassilisTrigkas1974
New Contributor III

Hi and thank you for your reply,

I don't remember the height of the flight, but it's not more than 50-60 meters.

I didn't use any file for elevation.

Do you think that is the problem?

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CodyBenkelman
Esri Regular Contributor

Vassilis - 

My first question would be to ask you to verify that you processed the correct GVL file to go along with the video - but presuming the answer is "yes" I expect that the problem here is that many drones report incorrect altitudes.  If your altitude values are incorrect and too high, the apparent video footprint will be too large.  Then, if you have any forward look angle (not directly down at Nadir?), the footprint may incorrectly indicate that the view is above the horizon.

Would it be possible for you to send me your Geospatial Video Log (GVL) file?  If you don't want to upload it publicly you can send me a private message.  (I don't need the video)  Please let me know your expected/planned flight altitude above ground.  I should be able to determine if your altitude values are incorrect, and show you a method to correct them.

I have not seen any cases where the pitch angle of the gimbal is recorded incorrectly, but it is possible there is an error in the metadata (and it may be possible to apply a correction).

Another question - is this your one and only video flight?  Have you done others that succeeded?  If you have no other samples, could you try recording another test video?  You should only need 15-30 seconds of video for a test.  

Cody B. 

 

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FlavioFurukawa
New Contributor

Hello! I had the same problem


In my case, I am using SiteScan LE with a Phantom 4 RTK.

The first photo the drone takes before takeoff shows an altitude of around 178 meters, but on the Geospatial Video Logs file, the "SensorEllipsoidHeight" shows 48.7 meters

The area altitude according to another RTK device shows that the altitude of the place is around 180m

I flew the drone at 30 m


thank you

 

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CodyBenkelman
Esri Regular Contributor

Flavio

sorry I couldn't respond sooner.  The vertical values from most drones can have large errors - up to 100 meters.   the RTK corrections are applied to the single images, but unfortunately the DJI API does not allow us to access the RTK corrections in realtime, so the GVLog files do not include corrected values.

We have a draft tech support article written that describes how to apply a correction to the GVLog file using MS Excel.  I can send you a copy of that draft article if you need it.  We hope to publish the article soon.

Cody B.