Can PTgui stitch two fisheye (spherical) photos from Garmin VIRB360?

[J. Ramirez]

I am wondering if PTgui can stitch two fisheye (spherical) photos from Garmin VIRB 360?

I have tried a couple of times, but no success. I am on a Mac. Any suggestions?

[PTGui Support]

Hi,

It's possible to stitch two circular fisheye images but it's a bit
complicated. This is mainly because the overlap area between the two
images is very small: only a small outer ring of the circular images
overlap. Often there's too little overlap for PTGui to automatically
detect control points in, so you would need to place control points
manually. Also, accurately determining lens distortion requires more
overlap.

Assuming you have two separate circular images, this should work:
- switch PTGui to Advanced mode by clicking the Advanced button in the
Project Assistant
- load your two circular images
- go to the Crop tab and set the crop circle
- set the lens type and estimated field of view / focal length, e.g.
circular fisheye, 200 degrees fov
- try Control Points -> generate control points to see if PTGui is able
to find any control points automatically
- go to the Control Points tab and place control points between the two
images. Try to have some control points all around the edge.
- go to the Image Parameters tab, set the yaw of the second image to 180
degrees
- go to the Optimizer tab and choose 'Optimize lens Field of View: yes'
and 'Minimize lens distortion: medium'
- press the Run Optimizer button
- go to the Panorama Editor and press Ctrl+Shift+H (windows) or
Command+Shift+H (mac) to switch to 360x180 equirectangular projection.
You should now see a proper spherical panorama
- go to the Create Panorama tab, click on Set Optimum Size and render
your panorama.

Keep in mind that you won't get a perfect stitch from two back-to-back
fisheye images, the parallax will cause stitching errors.

If you have a single image containing two fisheye images, a trick you
can use is to load the same image twice and use Individual Crop settings
to set a different cropping circle for each image.

Kind regards,

New House Internet Services BV
Joost Nieuwenhuijse

-----------------------------------------------
PTGui - Photo Stitching Software

www.ptgui.com
For support see: http://www.ptgui.com/faq/
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[John Houghton]

On Monday, September 25, 2017 at 3:26:32 AM UTC+1, J. Ramirez wrote:

I am wondering if PTgui can stitch two fisheye (spherical) photos from Garmin VIRB 360?

I have tried a couple of times, but no success. I am on a Mac. Any suggestions?

It should be possible to stiitch a pair of the raw fisheye images, though the result will be compromised by the very limited degree of overlap of the images.  For best results, two shots should be taken with the camera panned through 90 degrees of yaw to yield four circular fisheye images.  Stitching all four images together will enable the lens distortion correction parameters to be evaluated accurately.  You then eliminate one pair of images from the project to produce a template that can be used for future stitches of single image pairs.  If you care to provide some sample images to download from somewhere convenient (eg sendspace.com ), we should be able to do a stitch for you.

John

[Luis Ferrans]

How do you generate the template? Thanks for any insight.

[John Houghton]

On Sunday, November 12, 2017 at 7:13:07 PM UTC, Luis Ferrans wrote:

How do you generate the template? Thanks for any insight.

Luis, Any PTGui project file (.pts) can be used as a template.  See FAQ:  http://www.ptgui.com/support.html#2_14 .  If you create the project with 4 circular images (one for each 90 degree yaw position), just remove one pair of images. Then you can use that as a template.  In applying the template to a project with another pair of images, the lens parameters will be copied in.  Then add some control points as best you can.  Optimize including the fov parameter but not the other lens parameters (a,b,c).  This should give a much improved alignment with more accurate correction of the fisheye distortion.

John