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Author Topic: Oriantation after processing  (Read 5445 times)

anvi

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Oriantation after processing
« on: April 14, 2014, 12:57:56 PM »
Hey together!

i worked a lot with Agisoft DEMO in the past weeks for processing our Aerial Photoscans with UAV's.
It works fine, it's easy and the results are good - But now i have these problem:

We have no flight plan of the Scan, no GPS Dates in the picure only the calibrate Camera - How is it possible to set the Coordinate-System to the right place after processing for compatible measurement Software ?

After the picture alignment my coordinate System is totaly distorted. If i want to use the pointcloud for measurements in the "quick terrain reader" for example, the whole scan is one the opposite. So all mountains are holes and i cant determine it.

I have the same problem if i scan a wall with some bottom - i cant do any measurements because in the software after, the wall isn't the wall, it's the roof.....
(I set the position frame right after aligment)


It would be great to get some ans reply - THANK YOU VERY MUCH :)


Alexey Pasumansky

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Re: Oriantation after processing
« Reply #1 on: April 14, 2014, 02:45:57 PM »
Hello anvi,

If you need to perform measurements on the model or scale/orient the model according to its' real world orientation and dimensions, you need to input coordinates of reference points to the Ground Control pane. It could be coordinates of camera locations or any control points located on the models' surface. Otherwise PhotoScan would not be able to guess how the object or scene is oriented in the real world.
Best regards,
Alexey Pasumansky,
Agisoft LLC

anvi

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Re: Oriantation after processing
« Reply #2 on: April 14, 2014, 04:46:06 PM »
Hey Alexey,

thanks for your fast and clear reply!
This was what i guess...

How important is the precision of each point?
Is it enough, when i take 5-8 GCP's with a normal GPS-Tagger like "Garmin eTrax", for an 300x300m area?

Or which affordable equipment do i need for good results?

Thanks a lot!

Alexey Pasumansky

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Re: Oriantation after processing
« Reply #3 on: April 16, 2014, 11:06:24 AM »
Hello anvi,

The accuracy of the final result will depend on the measurement accuracy for control points coordinates.

Usually we recommend to have 10-15 GCPs regularly spread on the area of interest.
Best regards,
Alexey Pasumansky,
Agisoft LLC

gatsri

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Re: Oriantation after processing
« Reply #4 on: April 16, 2014, 11:23:39 AM »
when you use a "Garmin eTrax", your accuracy of the GCP ist aprox. +- 10m...
maybe its good enought, otherways you should use a DGPS (http://en.wikipedia.org/wiki/Differential_GPS), a totalstation ore something like this.

The accurancy of the ortophoto or DEM will be as accurate as your GCP's are...

anvi

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Re: Oriantation after processing
« Reply #5 on: October 02, 2014, 05:33:05 PM »
We worked with several DGPS devices from stonex and the upside down probleme was history.
Now we did one project and used a trimple DGPS but the coordinate systeme is the same like the stonex DGPs.

After alligning the photos the model is upside down ( z-axis points down). If I optimize with the GCP´s it doesn´t swtich to the right side.
As the coordinate systeme i chose WGS 84/ UTM Zone 32S. The .txt file is attached.
The measurements are right, but its just upside down.

What could be wrong with this workflow?
Does anybody could help me with this?

Thanks very much :)

Alexey Pasumansky

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Re: Oriantation after processing
« Reply #6 on: October 02, 2014, 05:38:02 PM »
Hello anvi,

Could you please post the screenshot of the model view where we can check the GCPs distribution and coordinate system orientation?
Best regards,
Alexey Pasumansky,
Agisoft LLC

anvi

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Re: Oriantation after processing
« Reply #7 on: October 03, 2014, 11:47:28 AM »
Hey Alexey,

thanks for your fast reply.
I attached you two screenshots with the settings of the coordinate systeme and the view on the screen.

In one the oriantation is not parallel to the bottom of the model, in the second I tried and swopped the X and Y data of the GCP´s. I got the oriantation parallel to the bottom but the z axis is pointing down.

It would be great if you got some ideas to resolve the problem.


anvi

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Re: Oriantation after processing
« Reply #8 on: October 03, 2014, 11:48:26 AM »
Second version

Alexey Pasumansky

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Re: Oriantation after processing
« Reply #9 on: October 03, 2014, 12:28:51 PM »
Hello anvi,

It seems that X and Y columns have been mixed. Could you please re-import marker coordinates with the different column order.
I think that if you convert current data into WGS84 you'll get completely wrong coordinates.
Best regards,
Alexey Pasumansky,
Agisoft LLC