The basic technique is to to convert the image into a cubic format and then to add the Nadir cap to the "floor" image in the cubic format. There are several methods of doing this;

• Use the "SuperRune" add on for Photo Shop or Paint Shop - http://www.superrune.com/technical/software_supercubic.php
• Use Pano2VR to add a Patch - http://gardengnomesoftware.com/tutorial.php?movid=09
• Use the methods described in this tutorial - http://wiki.panotools.org/Adding_a_nadir_logo_with_text

sometimes i keep a nadir cap in equirect format, i.e. a long stripe which i paste onto the bottom of the equirect pano.

say your equirect is 6000x3000.

1. to make a badge / nadir cap, figure out how big that nadir cap has to be. Let's say, 500 pixels.
2. make your badge.
3. make a new file in photoshop, 6000x6000 pixels.
4. put your 500px badge in the center of this image.
5. go to filters -> distort -> polar coordinates. choose "polar to rectangular".
6. go to "image size" and set the height to 50%.

you now have converted your badge into equirect format. you can now paste this onto the bottom of your equirect panos.

enjoy, jeffrey

http://www.philohome.com/panotutorial/tripodcap.htm

http://www.nyfeler-mueller.ch/TripodCap/Cap.html

http://www.panomundo.com/panos/howto/workflow_nadir.html

and finally one of the best tutorials on the web together with some of the finest technical panoramas.

http://www.fromparis.com/technical.html

the second one is available as actions (just google for tripod cap mirror actions) which you can import in to photoshop then apply to your finished panorama, however you should be aware that 360 cities does not like to see tripod caps, the rules state that you must complete a fully spherical panorama and that any logo you use must be small and technically not promote a business otherwise you must buy a pro account at a cost of €179 per year! Putting a cap in clearly breaks the rules and the reviewer may not pass your panorama, normally i just insert a small logo and it passes, I found using the from paris video helped me a lot but does not solve your problem when you dont have a nadir image.

Perhaps you could clone or patch from other parts of the image to fill in?