360 degree panoramic projects

[James Hooey]

I've seen some tutorials recently that create a virtual 3D environment from stitched together photos created using principles of 360 degree panoramic photography.

From another thread a fellow DVinfo member (Jim Andrada) made mention of a little bit of his tools/workflow creating the photos for projects like this...

Jim said..."Taking the photos is really pretty simple. I got a Manfrotto panorama head and leveling base and a fisheye lens for my Canon 5D and the rest is up to Stitcher. I don't know that I really like the app all that much, but it is capable of producing good results. The French company that did it (RealViz) was bought by Autodesk a few months back."

I'm sure there is a good amount of information on the net for creating this sort of work, but a few quick questions came to mind.

Why a fisheye lense? There are some obvious benefits like the wide field of view but is a fisheye lense necessary? What about just a wide angle lense say in the 24mm range?

I'm not familiar with panorama photographic heads. Would that be similar to something like a Manfrotto 503 head with 50mm ball? (not size wise but adjustment capability) I would surmise that it is best to remain level while taking the series of shots, but do you also have to consider degrees of rotation?

Finally Photoshop Extended CS4 can apparently stitch together photos. I've seen some examples of this on the net. Does anyone have any first hand experience working with this function within PS?

[Giroud Francois]

if you limit your panorama to a narrow vertical field of view, regular lens is ok.
if you want the sky(ceiling) and floor in the picture, fisheye is mandatory.
fishey also allow to take 2 or 3 pictures for a full view, while a dozen of picture will be needed wth a 24mm for example.
with my 8mm lens , i can do a full "bubble" , in only 2 pictures (while 3 are better).
the average of convering you need for a good stitching between 2 pictures, is about 30%.
so it means that only 30% of the field of view change between each picture (you need 30% at left and right).
This means a lot of picture to take. More picture means more work for stitching, plus the risk to have a bad exposed picture, or object moving between pictures that makes stiching more difficult.
Ideally , you have to rotate the camera at the nodal point, that is somewhere near inside the front of the lens. this prevent parallax of object (misalignement of close and far object in a different perspective.) http://www.panoguide.com/howto/panoramas/parallax.jsp
For this, a standard tripod dos not fit, since the rotation is usually somewhere under the body of the camera.
There was a "cheap" accessory called NODAL Ninja http://www.tawbaware.com/nodalninja_review.htm that help to mount the camera to have the nodal point of the lens aligned with rotation of the tripod.
you can do without it, but stitching will be less perfect.
idally when doing panorama, you will use bracketing (taking three shot at different exposure (-2, 0 +2 for example) so you can build HDR picture or panorama.
This is very nice because most of time, panoramic view includes some shot with sun or sunny window directly in the field of view.

The pope of panorama stitching is called Helmut Dersch and he developped some free tools to build panorama. You will find some graphical interface (GUI) using these tools as shareware like PTgui giving VERY professional results. http://www.ptgui.com/

[Jim Andrada]

This is a really quick and dirty spherical pano I shot in front of the house and into which I plopped a couple of 3D objects which I had fly around. One was a "glass" ball and the other a mirrored ball so you could see reflections of the sky in the mirrored ball and the inverted image in the glass ball.

You'll also notice a black mechanism reflecting in the mirrored ball, which is the rail of the Manfrotto pano head. Keeping the camera support out of the picture is pretty much impossible

As Giroud said, I use an 8mm fisheye and take 3 pictures at 120 degrees. I probably should take one straight up as well but haven't done so out of either laziness or the belief that I would never really aim a camera straight up in the virtual world.

If you use the 8mm Sigma which puts a circular image on a full frame, you sort of luck out because there is a gold colored ring around the lens and the nodal point is almost exactly inside the ring. I'm a Canon user and they have a nice 15mm fisheye which covers 180 degrees on the diagonal, so you need a few more photos to stitch, but you get a lot bigger/higher resolution image to work with. You will also probably need a fancier pano head that lets you swing the camera vertically around the nodal point.

This talk about "nodal point" means that you want the camera to rotate around the point inside the lens where the light rays would "cross" if you looked at a lens diagram. Otherwise you will get small errors in the stitching process, as the image will sort of "swing" slightly as you rotate the camera and the stitching program will have more work to do and the stitch may not be quite as clean as you would like.

The web site Giroud referenced is a good one

This little video is purely a "five finger exercise" of no artistic or technical merit other than to show that it works. And to give a nice tour of the Arizona desert around our house!

www.j-e-andrada.com/Balls.mov