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Messages - patcarbon

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General / Re: V1.1 lens distortion equation
« on: June 02, 2016, 07:03:46 PM »

General / V1.1 lens distortion equation
« on: June 02, 2016, 06:21:00 PM »

I'm having a debate with a reviewer on an upcoming Phantom 3 photogrammetry paper.  Could someone please clarify the exact form of the distortion correction used in the old V1.1?  If we assume no tangential effects and neglect K4, which of these 2 forms would be correct

(1) K1*r^2 + K2*r^4 + K3*r^6
(2) r*(K1*r^2 + K2*r^4 + K3*r^6)

Obviously the key diffference is that r factor at the start of (2) and whether or not Ks ultimately work in even or odd powers of r


Bug Reports / Tiled model preprocessing stalled
« on: March 13, 2016, 05:57:45 PM »
I recently upgraded to 1.23 and the tiled model isn't processing.  I'm only processing a small model with 126 cams and a dense cloud built on lowest.  But it stalls on the preprocessing has and is hardly using the CPU.  DEM export was easier in 1.0!

General / Optimisation from camera stations
« on: February 26, 2015, 07:34:44 PM »
Is there any point in optimising from camera stations alone?  From experimentations with UAV imagery I get the impression that yes but I'm not sure about the maths.  How can the X0Y0Z0 position of cameras model radial distorsion (and others) of a tie point?  What exactly does PS do when you hit the optimise button with only camera stations?


Python and Java API / Re: Acessing calibration parameters
« on: June 17, 2014, 07:37:12 PM »
Aha, Thanks!!

Python and Java API / Re: Acessing calibration parameters
« on: June 16, 2014, 06:56:23 PM »
Minimal progress but I'm still struggling!

I have a psz file and multiple calibration files in the same folder.  I want to apply each calibration file to the psz file, create a new psz file then process the lot.  So far I can:
- Batch generate all the calibration files
- Load the calibration files
- process multiple .psz files

My problem is that I can't seem to apply a calibration file once it's loaded.  user_calib.load(CalibFile) doesn't seem to do much.  This:
Code: [Select]
user_calib = PhotoScan.Calibration()
sensor = PhotoScan.Sensor()
sensor.user_calib = user_calib

Doesn't seem to do anything.  But I checked in the console and print (user_calib.fx) does give me the right number.  This has to be a simple error...


Python and Java API / Acessing calibration parameters
« on: June 13, 2014, 04:10:25 PM »
I have a basic .psz file and I'd like to create slightly modified versions of this project where only the camera calibration parameters change.

In this forum I've found leads on how to script and load calibration xml files.  But can a script directly access one of the calibration parameters (e.g. fx,fy,k1,k2, etc..)? 


P.S. I'm a python ultra-newbie

General / Re: Automatic GCP identification
« on: October 24, 2012, 03:42:59 PM »
I'm doing exactly the same thing!  I did see somewhere that you could printout targets for automatic ID, but I was under the impression that the pattern match relied on shape and texture.  So they would have needed to be huge for un-ambiguous ID.  But there is a semi-automated approach.  I've figured this out with trial and error so I might not be 100% right:

1-In a spreadsheet, create a 4 column text file.  the first column should be 'point N' and the other 3 the X,Y and Z
2- If possible, give a rough georefecence to your model.  Camera positions from the UAV GPS are perfect for this.
3-Import this into photoscan (version 0.9+) and it should create a set of flags with estimated positions
4- From here I'm less certain but here's my best guess: Click on a GCP in the ground control panel
5-  View photos, and sort by marker. 
6- When you click on each photo and display it in the main window, you'll see at least 1 grey flag with the estimated position.  Hopefully, it'll be close to your GCP.  Drag it into place.  It should go blue or green (Not sure about what the difference between blue or green is)
7- go through all the photos, then choose a new GCP and repeat!

PS actually updates the georeference as you go along.  It's somewhat slow, but I remember the days where photogrammetry projects over 500 images required thousands of man/hours so I'm not coomplaining!

If you're attending the big meeting of the AGU in San Francisco in December, I'll have a session on topography generation and some UAV/photoscan stuff will be present.

Patrice Carbonneau
Geography, Durham University, UK

Feature Requests / Manual update: markers
« on: October 24, 2012, 11:47:31 AM »
The manual seems to have nothing on 'pinning' and 'unpinning' markers.  So the difference between green and blue markers is ambiguous.  Please update and see my post in the general section.  Anybody in the earth sciences or surveying who will use dGPS to control a set of photos needs to know this.


General / Green vs Blue markers and their impact on geocorrection
« on: October 24, 2012, 11:41:11 AM »
I've seen mention of blue markers in the forum, but what about green ones?  I know that you can pin a marker, then it goes green, you can unpin it, then it goes blue and you can remove it to go grey.  None of these things seem defined in the manual!

So what is the difference between a blue and green marker?  How, exaclty, are the different markers (grey, blue and green) used in the initial 7-parameter transform and then in the optimise stage.  what I mean here is will bleu and green markers be treated differently.  Are there weights associated?

I have 25 markers to place in 2000 images.  In some cases, the images are a bit blurry and I'd rather not use the marker.  Should I leave it grey?


General / Best way to optimise a multi-chunk model?
« on: October 22, 2012, 05:17:53 PM »

I've not got a 6 chunk model with a total of 1973 images.  I have about 400 low accuracy (10m) GPS camera positions (2 chunks) and about 20 high accuracy (5cm) ground control points. I've processed all the chunks (align: high, build geom: med) and I've aligned them all (point based, high).  Everything looks pretty good so far.

Now I want to optimise this model.  Since I only have 20 GCPs, there are only 2-3 per chunk.  Should I merge all the chunks before I optimise?   I have 16 gig RAM so according to the Photoscan wiki, I can re-build the geometry on medium just like I already did.


Bug Reports / Error reporting in 'Align chunks' batch job
« on: October 22, 2012, 11:52:29 AM »

Very minor bug:

I tried to align chunks as a batch job over the weekend.  When I arrived this morning, the batch display said that it had done the job with no failures.  However, nothing had happened.  There was a bug because I had changed a folder name by mistake after a chunk had been processes.  So photoscan could not find the image in the designated path.   So somehow, the fact that it did not find the images and aborted the alignment was not recorded as a failed alignment.  Nothing major but needs to be fixed.


General / Aligning chunks in steps?
« on: October 16, 2012, 04:22:08 PM »
I'm processing a 2000 image project.  The surface is quite self-similar and aligning the entire project in 1 chunk was a disaster (see below). So I'm having to use several chunks.  I'm now on 7 chunks (which correspond to 7 UAV flights) and I'd like to end up with 1-2 chunks before I optimise.

Is it possible to use markers to performa an initial chunk alignment and then have a point-cloud match to reffine this alignement?  Does the 'points' align option just delete any previous alignment?


General / Build Geometry subsampling
« on: October 16, 2012, 04:14:17 PM »

I can't find this in the wiki or older posts.  What level of subsampling occurs at Ultra high, high medium and low geometry builds?

I think Ultra uses the raw image resolution and high uses a 2X2 pixel average.  but what about medium and low?  These things should go in the wiki.  It's quite usefull to know if you have an idea of the raw image resolution and you have an idea of the final average point cloud/DEM resolution you need.

General / Re: The mysterious 'bowl effect'
« on: July 27, 2012, 04:49:19 PM »
Thanks Alexey

Do you think optimisation will perform well if I use about 150 camera positions from a small, non-corrected, GPS?  Again this is from the SmartPlanes UAV.


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