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How do you convert flat image (sky for example) to fit inside of sphere?

scott_4e0b772ae4scott_4e0b772ae4 Posts: 50
edited December 1969 in The Commons

How do you convert flat image (sky for example) to fit inside of sphere?
But without strange warping and pinching at the poles?
I see examples of this all the time but cannot find a tool or plugin or such to do it.
I have PaintShop Pro6 (so can use Photoshop plugins), Gimp, Dogwaffle - in case any of these have tools I'm not aware of.
Thanks!

Comments

  • prixatprixat Posts: 1,588
    edited December 1969

    The way I've done that in the past is with the "Rectangular to Polar" and "Polar to Rectangular" filters in Photoshop.
    Does PaintShop have those?

  • scott_4e0b772ae4scott_4e0b772ae4 Posts: 50
    edited December 1969

    Yeah, I tried it but no luck. Maybe I didn't have the proper ratio for image size. Is it like 2:1 or 3:1, or even 4:1 ? Will look at images that already work and check out the size ratio on them.

    Thanks.

  • prixatprixat Posts: 1,588
    edited December 1969

    Yes, its always 2:1

    ...but there's a technique to it:

    Do the top half first, when its Polar, use the blur, smudge etc to get rid of the seams, switch it back to Rectangular

    Now rotate the image 180 to work on the other 'top half', go to polar and repeat the process to get rid of the remaining seam, back to rectangular.

    rotate back 180, so its right way up again and that should work.

    If you can wait a bit I'll make some examples when I get home from work.

  • HavosHavos Posts: 5,361
    edited December 1969

    Gimp also has a polar conversion filter

  • wizwiz Posts: 1,100
    edited December 1969

    And if you get tired of those toys, hugin is free, open source, and does this stuff right.

  • scott_4e0b772ae4scott_4e0b772ae4 Posts: 50
    edited October 2014

    Thanks Prixat and Wiz.
    Still not sure I'm clear but will keep trying - why do some 360 panoramas, when flat, have an almost S curve to their imagery?
    Wiz, Hugin seems pretty interesting but no clue what to do with it. Any good tutorials that I may have overlooked?
    Thanks again.
    I did find a tutorial on creating 360 panoramas but a bit more complex than I think I'm ready for - includes all sorts of stitching of images and such - mostly just want to take a high res sky photo and make it the sky in a 3d space. Will work with the Prixat method some more and see what I come up with.

    Post edited by scott_4e0b772ae4 on
  • MistaraMistara Posts: 38,675
    edited December 1969

    can't remember what it was called, pretty sure it was this page i found a free utility here, several years ago
    http://www.hdrlabs.com/tools/links.html

  • WendyLuvsCatzWendyLuvsCatz Posts: 38,204
    edited October 2014

    Microsoft ICE will stitch panoramas and is free
    http://research.microsoft.com/en-us/um/redmond/groups/ivm/ICE/

    Post edited by WendyLuvsCatz on
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