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Author Topic: Importing IMU  (Read 6803 times)

Krish

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Importing IMU
« on: December 18, 2013, 07:40:33 AM »
Hi
How to import IMU in Agisoftphotoscan professional

Krish

Alexey Pasumansky

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Re: Importing IMU
« Reply #1 on: December 19, 2013, 04:01:43 PM »
Hello Krish,

IMU data can be imported along with the camera positions from the text file using Import button on the Ground Control pane.
Best regards,
Alexey Pasumansky,
Agisoft LLC

osima

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Re: Importing IMU
« Reply #2 on: January 03, 2014, 04:57:16 PM »
Hi Alexey,

How are the IMU data used in Photoscan? I cannot find any info about using IMU data in the documentation.

best regards,

Ola

JMR

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Re: Importing IMU
« Reply #3 on: January 04, 2014, 03:23:02 AM »
Hola Ola:

the IMU log contains recordings of all sensors that provide data to the flight controller. You may find them in many formats but you probably can have a parsed ascii file with a sequence of records formed as a selection of fields. If your system boasts a very good positioning system (gnss dgps) and you have accurate information about the offset between the camera center and the IMU origin then you could better estimate the photo-centers and use them as true ground control for the whole project.

But  even if it was inaccurate by some meters,  this a priori information can speed up considerably the alignment step if you import the photo geo-tags as ground control for pair preselection.

If your system has been well designed ("well" here stands for "for photogrammetric missions") probably your camera is commanded by the flight controller itself and is likely to exist a way to obtain an specific record for the shutter actuation along with the corresponding XYZ and camera attitude descriptors. This log is easily matched to a photo folder if the number of files and photo action records are coupled. So you just need to build a text file with photo names and positions

If this is not the case; I mean, your aircraft does not control the camera but is a time-lapse or the user who presses the shutter, the matching task becomes sometimes hard if not impossible to do, because you have to be able to know exactly when the photo was taken prior to know where was taken from, and time-stamp in photos is usually of poor time resolution (seconds in best case).

PD. According to the last information I can remember, Photoscan just makes use of camera coordinates and dismisses pose information so don't waste your time with that
Regards

Geobit

osima

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Re: Importing IMU
« Reply #4 on: January 04, 2014, 03:59:21 PM »
Hi Geobit,

Thank you for your extensive info about how IMU works. I appreciate the time you spent on replying but this is not an answer to my question.

By using the position and orientation of images  the number of image combinations used in matching could be significantly reduced and this is a long awaited feature in PS, at least from my point of view.
I thought that if the IMU data can be now imported to PS (it seems to be a new feature), maybe they are also used in the processing workflow. Are they?

Best,

Ola

JMR

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Re: Importing IMU
« Reply #5 on: January 04, 2014, 07:39:05 PM »
It is actually used since long time ago.
Add photos
select the coordinate system of your IMU data (likely Geographic WGS83)  import a file with photoname.jpg, lat,lon, elev (I'm not sure if yaw, pich and roll are also considered)
goto align step and choose "ground control" as method for preselecting pairs
this actually helps PS to skip photo pairs that are unlikely to overlap, but this is not a new feature.

In further processes, like orientation refinement, camera coordinates may also be used. In the ground control pane, you can see the photos with their coordinates that can be checked for the absolute orientation if you consider them good enough to participate in the external orientation. See that in the settings dialog you can fix the camera accuracy which is set to 10m by default, so even if checked, camera positions are usually low weighted in the bundle adjustment calculations.

I guess no new role for the IMU in this version

Alexey Pasumansky

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Re: Importing IMU
« Reply #6 on: January 05, 2014, 02:34:05 PM »
Hello Ola,

Camera orientation angles imported to the Ground Control pane are not utilized in the processing. This data can be only used if Camera Correction section is enabled in the Ground Control pane settings dialog.
Best regards,
Alexey Pasumansky,
Agisoft LLC

simon_29

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Re: Importing IMU
« Reply #7 on: August 09, 2016, 08:14:32 PM »
Hi,

I am currently working on a dam inspection. I have mounted 2 DLSR ( Pentax K3II - Pentax K50 ) for the aerial part  and 4 GoPros ( 2 Hero 4 and 2 Hero 2) for the underwater part,  on a bar fixed to a boat. During the acquisition I have recorded IMU data and I would like to import them in PhotoScan. In attachment you can find a drawing that shows how the cameras and the IMU are installed. The Position and IMU data that I am trying to import are referenced at my cameras location. Up until now, I haven't been able to import them correctly. I know I should put some angular offsets in the "Camera Calibration" menu, but I don't know what are the suitable values.

From what I have understood the Photocan Manual  (see the attachment "PhotoScan_Sing_Convention.png"), the PhotoScan frame is the same as the one from my IMU. However, my cameras are  "looking" perpendicularly to my boat's heading ("Mounting.jpg").

I hope someone can shed some light about this. If I am not clear don't hesitate to contact me.

Thank you in advance !