Calibrated projecti...
 
Share:
Notifications
Clear all

2022-05-29: APP 2.0.0-beta2 has been released !

Release notes

Download links per platform:

windows 2.0.0-beta2

macOS x86_64 2.0.0-beta2

macOS arm64 M1 2.0.0-beta2

Linux DEB 2.0.0-beta2

Linux RPM 2.0.0-beta2

Calibrated projective registration


(@donkrx)
Brown Dwarf Customer
Joined: 2 months ago
Posts: 13
Topic starter  

I'm trying to understand the different registration options better. I didnt see anything in the quick reference manual. I have the NIKKOR Z 14-24mm lens which at 14mm has a FOV of 115 degrees. First question simply is - what's going to work better for this FOV and why - projective or calibrated projective?

When using calibrated projective, what are the tradeoffs between rectilinear, equirectangular and mercator? Is it speed/quality or is it more about how you want your image represented? The tooltip talks a lot about the algorithm approach but not a lot about the outcomes/use cases.

Maybe I should do some reading on the technical differences.


ReplyQuote
(@mabula-admin)
Quasar Admin
Joined: 5 years ago
Posts: 3158
 

Hi Dane @donkrx,

for that lens I would always use calibrated projective, on a mosaic project it is critical even !

The technical reason is: the normal projection of a normal photography lens (or telescope) is rectilinear. But the rectilinear projection only works okay with Field Of Views smaller than 120 degrees.

If the field of view becomes larger than 120 degrees any image that is rectilinear projected gets distorted big time... it can blow up to infinite dimensions when you have a FOV near 180 degrees.

Calibrated Projective registration model makes APP calculate camera parameters enabling you to use different projections. So in that case, you need to use calibrated projective model and then choose any other projection model than rectilinear. The differences between equirectangular or mercator are well described i think on wikipedia?

Mabula

 


ReplyQuote
(@donkrx)
Brown Dwarf Customer
Joined: 2 months ago
Posts: 13
Topic starter  

Right, well, (using DDC) when I use calibrated projective, the registration RMS is very bad - averaging about 6 over all of my lights with a maximum of 10! Hence this question because it seems to me like you said that this lens might benefit from a different projection model.

I have not tried integrating the equirectangular or mercator projections but the rectilinear was pretty bad with everything out of alignment, even the image center.

When I run with the standard projective option though, the result looks good. Registration RMS ranges from 0.2 to 0.54 and seems to get worse with my later subs so maybe I did a bad job adjusting my camera position (shooting static from tripod).


ReplyQuote
Share: