Stereographic Projections (little planets)?

• petercox

  Member

  May 21, 2009 at 11:16 am

  Hi folks –
  I came across this technique recently and was intrigued. Known variously as photospheres or panoplanets (or technically as a stereographic projection), I gave it a quick and dirty trial yesterday. I’m pretty pleased with the results, and with the right location, this looks like it could be an interesting direction to take.

  

  Anyone else playing with this? Note, this is a true stereographic projection, rather than a simple polar coordinate mapping in photoshop.

  Cheers,
  Peter
  fig

  Participant

  May 21, 2009 at 4:18 pm

  What’s the difference? I think I tried the later awhile back from a stitched 360.
  petercox

  Member

  May 21, 2009 at 11:41 pm

  Polar mapping distorts quite a bit more, and specifically stereographic will not compress spheres. Also polar mapping gives a squashed sky effect, and maps to a circular image. Stereographic will give the nice sky and square image you see there.

  Cheers,
  Peter
  Allinthemind

  Participant

  May 22, 2009 at 7:07 am

  That’s super Peter. Do you have a link to a technique?

  Si
  petercox

  Member

  May 22, 2009 at 12:31 pm

  Si –
  I’ll probably do a complete article once I’ve ironed out the workflow for myself. It’s fairly time-consuming (mainly in terms of computer processing time – even on a speedy machine the rendering can take quite a while).

  Basically, you take enough shots to get yourself a full 360×180 degree panorama (a complete sphere). Ideally this should be done with a proper panoramic head that lets you rotate the lens about the nodal point, although people have and do shoot these hand-held – parallax errors aren’t as big of an issue with this sort of thing as they would be with a virtual tour.

  Once you have your shots, stitch them into an equirectangular (spherical) projection in the stitching application of your choice. Once you have that, change the shape to a 2:1 aspect ratio (if it’s not there already). I use a tool called ‘Hugin’ (hugin.sourceforge.net) to do the stereographic mapping – just open your image in that, set the pitch to 90 degrees and hit ‘stitch’, and you’re done bar the normal post-processing.

  Cheers,
  Peter
  Allinthemind

  Participant

  May 23, 2009 at 9:45 am

  Thanks Peter, something new to play with :)

  Si
  carstenkrieger

  Participant

  June 27, 2009 at 2:10 pm

  Nice one. I am intrigued…

  Cheers,

  Carsten

  Carsten Krieger Photography – http://www.carstenkrieger.co.uk
  NEW BOOK “THE WEST OF IRELAND – A PHOTOGRAPHER’S JOURNEY” OUT NOW
  carstenkrieger

  Participant

  June 27, 2009 at 2:11 pm

  Nice one. I am intrigued…

  Cheers,

  Carsten

  Carsten Krieger Photography – http://www.carstenkrieger.co.uk
  NEW BOOK “THE WEST OF IRELAND – A PHOTOGRAPHER’S JOURNEY” OUT NOW