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Author Topic: Tetracam adc multispectral camera processing AGAIN  (Read 5939 times)

Dvo

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Tetracam adc multispectral camera processing AGAIN
« on: May 05, 2015, 09:48:50 PM »
Hi

It would be most helpful if detailed instructions for processing Tetracam ADC aerial images (latest Photoscan Pro version) could be posted.

I have the same problems reported by others on this forum (images not aligning, and the plane of the model built from those that do is oriented about 90 degrees from where it should be) and I have tried following instructions posted in several places on this forum as well as other methods.

None of these work:

(1) Batch export RAWs to TIFs using PixelWrench2 and using these in Photoscan
(2) Batch export RAWs to multi-page TIFs using PixelWrench2  (setting NIR channel 1 as master channel in Photoscan Pro).
(3) PixelWrench2/TifExport the above created multipage TIFs as per instructions in this forum -- PixelWrench2 creates 16 bit images (images have one channel only, makes no difference if use default or channel 1 as master).

Like others have lamented, (3) is not working, and similarly wondering 'what am i doing wrong?´

Note: locations are available for all images and there should well be sufficient overlap (about 65% lateral, 80% longitudinal).

p.s. I have been looking to purchase Agisoft Photoscan Pro as an alternative to a rival orthomosaicing software that we have been using to date but where we are unsatisfied with the quality of mosaics for NDVI calculations (as verified by field scouting) - but that depends on being able to use Photoscan to process TTC images (which the other product can do). Photoscan os doing a good job with images from digital cameras (including modified ones), but TTC processing is proving a bummer.

GPC

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Re: Tetracam adc multispectral camera processing AGAIN
« Reply #1 on: May 10, 2015, 07:53:25 AM »
Would it be possible for you to share a sample of the images?

Image quality has a lot to do with your results.. and I think a 3.2 megapixel sensor is borderline for expecting results, especially at several hundred feet away.

When things get weird, the weird turn pro.

jmgc

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Re: Tetracam adc multispectral camera processing AGAIN
« Reply #2 on: September 09, 2015, 12:56:31 PM »
Same problem here.

I'm using a Tetracam ADC Snap.

I've done a 150m AGL flight over a smooth terrain and I could process the dataset with no problems, using GPS/IMU data.
I just saved the original photos in .JPG using "Run Folder Batch" using IndexTools in Pixelwrench, then a normal processing in PS and the results were OK.

On other hand, I have another 150m AGL flight over a more changeable topography area and I just can't align the photos, exported from Pixelwrench in the same conditions.
I've tried to follow the Agisoft Tetracam multispectral imagery processing and didn't get to results.

It would be very helpfull is someone could post a walkthrought to use the Tetracam photos in PS.
« Last Edit: September 09, 2015, 03:15:06 PM by jmgc »
José Miguel Campos
Geospatial Specialist
UAS Operations Manager

HyperFox

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Re: Tetracam adc multispectral camera processing AGAIN
« Reply #3 on: September 09, 2015, 03:11:05 PM »
Hello,

I used that camera and even got bad results. I think it's due to the global shutter of that camera. (Cheap cameras like GoPro have no mechnaical shutter). And also that ADC Camera has no mechanical shutter.

Sit down on a revolving chair (perhaps you already sit on one).
Take the ADC and prepare to take some shoots.
rotate the chair while sitting on it
take some pictures
stop after a few rotations  ::)

take a look to the photos.
Things (like your monitor) with perpendicular lines will not have vertival line in the image.
Everything will be distorted between the vertical lines of the image, because the sensor is read line by line (this means: rolling shutter).

Perhaps you can send us such a photo to the forum as a nice example for "cameras the world doesn't need".

I put away my ADC to the garbage a few week ago. My vendor in Germany say "it's a feature".


And - NO - theres no chance to compensate the effect, your UAV will always move in some kind of direction, it's not a matter of microvibrations (take a revolving chair, make the test....)

stihl

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Re: Tetracam adc multispectral camera processing AGAIN
« Reply #4 on: September 09, 2015, 03:42:09 PM »
My vendor in Germany say "it's a feature".
:o ::)

jmgc

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Re: Tetracam adc multispectral camera processing AGAIN
« Reply #5 on: September 10, 2015, 11:58:49 AM »
I supposed the ADC Snap had the rolling shutter "problem" solved.
Might be field of view issues, lack of overlap?
I had the exact same problem at the same place, at two different moments.
José Miguel Campos
Geospatial Specialist
UAS Operations Manager

jmgc

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Re: Tetracam adc multispectral camera processing AGAIN
« Reply #6 on: September 11, 2015, 06:37:34 PM »
Finally I could have the dataset aligned and working.
There was a problem with the GPS/IMU data (time sync error).

The dataset was processed ok, at the end I was able to export orthophoto and dsm.
I've used JPG image format, extracted from the .RWS format file, via Pixelwrench.
I've just saved the original files to JPG.
José Miguel Campos
Geospatial Specialist
UAS Operations Manager