[X] My Assistant

[Nirgal]

Hi all,

I first thought that the problem of uneven horizons in navcam stitches must have been discussed a lot previously but to my surprise the forum search in the Tech&Imagery-board with key-word "horizon" did not yield that much relevant results ...
So far, for autostich one "solution" seems to be to try-and-error estimate the correct "greek" orientation
parameters (phi,psi,..) However I would like to know if there is a better and more deterministic way.
I also played with PTGui/hugin and manual control points on the horizon but this seemed even more cumbersome than getting the right orientation in autostitch.
The other problem ar the "edges"/"bumps" along the horizon exactly at the transition zones between individual panorama frames ...
Now I am not that an expert in the stitching part of the image processing (jut use Autostitch which does a sufficiently good job, except for the horizon-problem ) so the question goes to the real "stitching Gurus (->Nico, Tman and others ??) how to cope with the horizon :-)
Any recommendation for other pano programs that do better with flattening the horizon ?
One idea qould be to use some JPL Metadata about the actual rover orientation.
I understand that Micheal's MMB program does something like this but was unable to exploit this
horizon-information for deriving orientation parameters for external panorama programs.
Also, does anyone know if there is already a specification of the lens geometry of the MER navcam
available in the form to be usable for a panorama program like hugin etc. ? this would certainly also help
to yield undistorted horizons ...

Maybe this thread could serve as a collection of useful tips & hints specifically with respect to the
"horizon problem"

[Tesheiner]

I'm quite happy with autostitch; sure the lack of control is a negative point but the results usually are very nice, specially for pancams. But let's do an example with a navcam mosaic.

Here is the 5x1 navcam mosaic taken after driving on sol 958.


And this is the process I almost always do to obtain such a mosaic:
1) Process all images with MichaelT's antivignetting tool.
2) Calculate the rotation angle (psi) to be applied on the first image in order to get a level horizon:
2.1) Use IrfanView (or any other tool) to measure the sides (dx, dy) of a rectangle whose opposite points are coincident with the horizon. In the above example, dx=820, dy=47
2.2) The rotation angle psi=atan(dy/dx). Psi=3.3º (aprox.)
3) Execute autostitch with the following non-default parameters:
- Scale: 25%
- Gain compensation: yes
- SIFT Image Size: Scale: 100%
- RANSAC Parameters: Max Iterations: 1500
- Auto Straighten: no
- Phi: -15º (*)
- Psi: 3.3º
4) If the result is acceptable, change scale to 100% and redo stitch.

(*) Note: Use -15º for navcam mosaics and -3º for pancam.