Topics

1

Camera Calibration / Quick Question - RTK/PPK precision, drone image position accuracy

« on: September 14, 2021, 11:59:45 PM »

Hello,

For my use case, I will not do any 3D reconstruction, but I COULD do it with the images that I acquire. But I need an accuracy of the camera locations of better than 3-4cm in all directions. Now I'm reading all sorts of stuff how people are improving their "precision", by putting just a few ground control points into their scan.

So here's my question for you pros:
Does this use of GCPs improve only the precision of the SCAN DATA, or also the precision of the CAMERA POSITIONS (my area of interest)?

I'll be using a rtk/ppk drone (probably DJI P4.pro.RTK), so the proclaimed camera location precision is a few cm. I'm just wondering if that is marketing speech and I really should use the scan data, to ensure that the camera positions are ALWAYS at this level of accuracy.

Thanks for your wisdom.

2

General / set region & co.sys from markers

« on: October 08, 2017, 11:36:01 PM »

Hello everybody,

I found this supergreat script for scaling and rotating a scanned model into a usable coordinate system, written by Richard on his site:
http://www.pi3dscan.com/index.php/instructions/item/agisoft-how-to-process-a-scan-with-projection
The script looks for some markers, builds a coordinate system from them and rotates the scan-model to lay flat & scaled properly in the origin of the Photoscan coordinate system. Or maybe it scales & rotates, the PS-co.sys - either way, you can export your model to a next CAD system afterwards and have your model sit perfectly on the ground, with the right scale. Super useful and great, as I said

Now, I have changed his script it a little, to fit my purpose of scanning small objects on a sheet of paper with some targets on it. Unfortunately I don't really speak python, so a lot of the code is based on guessing and copy+paste from the forum.

So my script worked fine until a while ago, but now not anymore. I'm not even sure if it has to do with a current update. Maybe the syntax has changed, so now the rotating/scaling of my model does not work anymore? From all I found on the forum, it looks like some crucial things changed regarding the rotation of the Photoscan Region, but I cannot figure out what's the current way to solve this. 

I have attached the marker-template and my script. Could anyone with some python/agisoft-superpowers take a look at the script and look for some obvious mistakes or changes in the syntax?

Thanks a lot!

3

Feature Requests / align photos - sequential matching

« on: February 18, 2014, 03:15:31 AM »

Hello,
I'm having a few struggles with chunks aligning perfectly at first attempt, but when i add some more photos to fill the missing gaps, suddenly many others won't align anymore and new holes pop up. weird.

As far as I learned about the photo alignment, it is looking at all possible pairs of a chunk. Is this correct?

Well, at least for my case, when scanning small objects, I have the option to deliberately create a large overlap from one photo to the next (which I'm already doing, still not good enough it seems  ).

In case I understood this right, it might reduce the computational time significantly, if one could select some sort of "sequential alignment", where PS only looks at the overlap of two successive images in the list of the chunk.
Also, this might reduce alignment errors, where PS might (not sure if this is the case) be unsure where a certain image belongs.

Thank you for your consideration