Sunday, 27 July 2008

Panoramic and virtual reality photography

I like taking panoramic photos. Some of the header photos on our very slowly developing website (www.thompsonz.net) are early attempts. More recently, I have stumbled into virtual reality photography.

Panoramas

Often with my panoramic photos, I simply take a sequence of photos hand held and without restricting the camera to manual exposure or focus settings. This works fine provided you align the horizon appopriately. This image of Edinburgh comprises three photos taken with my canon EOS300D is an example. The focal length was 34 mm for all of the original photos but the exposure was 1/250 sec at f/13, 1/320 at f/14, and 1/400 at f/14. They were stitched together with Canon's PhotoStitch software. In this case, it is difficult to see the seems between the images.


Original photos:



Stitched result:


Not all attempts are so clean. Here the merge is of two images of the Rimutakas taken from near Featherston in the Wairarapa, New Zealand. On my first attempt, I changed the focal length so the two photos would stitich. But these two photos have the same focal length of 200 but there is enough difference in the exposure (1/500 sec at f/9.0 and 1/800 at f/10) to cause problems in the stitching.

Here are three different attempts. The first with the Canon PhotoStitch, the second with Photoshop Elements 2.0, and the final one with Hugin. Hugin has compensated for the differences in exposure to produce a well blended image.


Original photos:



Canon PhotoStitich image:



Photoshop Elements image:



Hugin image:



VR 360 cylindrical image


With virtual reality photography, you don't simply take a panoramic image in which three or four images are stitched together. Instead you take a set of images that encompass the full spherical view. My reading suggests that most of these are made using a fisheye lens (extremely wide angle). Unfortunately, I don't have such a lens so I am having to experiment with my standard lens. Just to get a full 360 degree horizontal image takes 16 photos so to ensure it aligns you really want a good tripod and a head like Manfrotto's 303SPH.

I decided that I needed to check my locations before taking all the camera gear, tripod, and head. So I took my Canon SX100 IS camera with me and checked the location on one of my bike rides. I then went back as the sun was about to set with all of my gear and set up to take the image.



Initially I viewed it with Canon PhotoStitch Viewer in 360 mode to give the impression of a cylindrical image. The same effect can be achieved by using a Flash or Quicklime if the image is converted to the appropriate format. The following links show the trials in creating a view for the web. Have a look.


Image viewed with Flash viewer
Image viewed with Quicktime viewer

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