360 sky replacement

[Terry Bean]

I enjoy creating 360 photospherse using my drone. The obvious problem is that I end up with a panorama that has little sky above the horizon due to the camera location and this has to be created using either a stock sky or edited in using photoshop.

I saw a tutorial where one could take a single photo of the sky using a wide angle lens such as a 9mm fisheye and just load that into ptgui. The resultant panorama was a thin strip that covered about 50% of the pano. I do recall that the finished rectangular image showed the sky in the power half. Try as I might I cannot now find that tutorial.


This pano section could be overlaid using photoshop onto the drone 360 pano that was missing the sky. What I cannot work out is the settings required to convert that single fisheye photo into a segment of a panorama. Hoping someone here may be able to help?

[John Houghton]

Terry, To find the correct settings for a fisheye sky shot, I suggest you shoot a test panorama consisting of a horizontal row of shots and one shot with the camera pointing upwards to capture the sky.  The lens type should be specified as either circular fisheye (if the edge of the image circle is visible in the shots) or fullframe fisheye.  For a circular fisheye, set the crop circle just inside the image circle in the shots.  Note that all of your images should be presented to PTGui in the same orientation (all landscape or all portrait).  The camera's auto rotate sensor does not give reliable results when the camera points directly up or down, so images can be produced in either orientation.

When the images have been aligned with PTGui and a satisfactory 360x180 panorama has been produced, all you need do is generate an output with only the sky shot present.  To do this, enter Advanced mode via the button on the Project Assistant tab and select the Create Panorama tab.  In the Include Images list, uncheck all the images except the sky shot.

John

[Terry Bean]

Thanks for that.. Could create using a series of photos no problem. I am sure that the demo I saw used only a single photo taken upwards using a fisheye (which I have) and this single image was loaded into ptgui to create a band of sky in a rectilinear pano.This image could then be stretched a little if required to complete the other drone panorama.

[John Houghton]

On Thursday, August 18, 2016 at 6:17:21 PM UTC+1, Terry Bean wrote:

Thanks for that.. Could create using a series of photos no problem. I am sure that the demo I saw used only a single photo taken upwards using a fisheye (which I have) and this single image was loaded into ptgui to create a band of sky in a rectilinear pano.This image could then be stretched a little if required to complete the other drone panorama.

That is certainly possible if you know the appropriate lens parameters to set in PTGui in order to get an decent output.  The purpose of shooting a single row of images is to enable PTGui to work out the parameters accurately for you.  Of course you might use whatever lens parameters PTGui supplies by default, which may or may not be good enough.  All you need to do then is set the pitch of your sky image to +90 degrees on the Image Parameters tab and set the output to 360x180 equirectangular..

John

[Terry Bean]

Thankyou John!

It was the 90 deg [itch that I was missing in the image parameters>

Will run a few test panos now but recon that has solved it!