Category: Technical

Technical stuff on panorama shooting and on photography in general.

Spherical pano stitched from sweep panoramas, an experiment

This post also deals with the answer to Huck’s question whether it is possible to make a full spherical panorama from sweep panoramas made with the Sony NEX-5:

The camera can pan vertically 185 degrees. It can catch the nadir and zenith. It would have more than 45 degrees horizontally so about 5 shots should get you everything. If these could be stitched you could have a spherical panorama with 5 shots. Have you ever tried this? Do you know if it could be done?

As an introduction to the subject please read my answers to Huck’s question here before you continue.

Sweep Pano Head Setup

I mounted the camera on a weird looking panorama head. The setup may not have been perfect in the NPP, but good enough because there were no objects near the setup. I switched the camera to the panorama mode “Vertical Up” in “Wide” mode. One resulting sweep panorama has 2160×5536 pixels. To get enough overlap I took eight of them, starting from the bottom to the top. I locked the exposure for every stripe around the horizon by pressing down the shutter half way. The finished panorama was about 12000×6000 pixels in size.

Here is the best result I could achieve with the source material. You find my PTGui project for the panorama for starting your own stitching experiments here.

[pano file=”https://www.panotwins.de/wp-content/panos/MMatern_20101008_1188_PanoramaSmall.xml” preview=”https://www.panotwins.de/wp-content/panos/MMatern_20101008_1188_PanoramaSmall.jpg”]
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The result may not look that bad at first sight, but when looking closer you will see heavy distorted parts (due to the really weird a, b and c parameters from the optimizer) and moving poeple cut in parts:

To make a long story short: The poor result does not warrant the huge effort!

I got a much better result taking individual shots from the panorama head. With the 16mm pancake lens in portrait mode you can make a complete sphere with a final size of about 20000×10000 pixel: You need three rows: 6 shots tilted 60° up, 8 shots at the horizon and again 6 shots tilted 50° down. This closes the hole at the zenith and leaves one at the nadir. However this can easily be fixed by removing the tripod and making a down shot using the view point correction technique described here or here.

When you download the sample sweep panoramas and try it for yourself, please let me know when you were able to stitch a better result from the source material. And what’s most important: Try to describe the process in detail!

Spherical pano combined from sweep panoramas

Huck asked me whether it is possible to make a full spherical panorama from sweep panoramas made with the Sony NEX-5:

The camera can pan vertically 185 degrees. It can catch the nadir and zenith. It would have more than 45 degrees horizontally so about 5 shots should get you everything. If these could be stitched you could have a spherical panorama with 5 shots. Have you ever tried this? Do you know if it could be done?

My short answer is: No!

You may ask why? I don’t think you get the results you expect, or hope to get!

I try to make this more clear with the following statements.

  1. When using the camera in landscape mode five shots cover 360 degree, however there is almost no overlap of the shots. So you need at least 6 shots. But this is only true for normal single shots, not for sweep panorama stripes (see the next statement)!

  2. Rectilinear Panorama Detail

    Sweep Panorama Stripe Detail

    When using the vertical sweep panorama mode you get stripes that are only 2160 pixel wide, compared to the 4592 pixel of a normal landscape shot. The image is scaled down inside the camera and furthermore it is cropped on the sides! Thus you need at least eight stripes to cover the full sphere! See the different scale of the following two images showing the same spot of the result panorama.

  3. Some panorama stripes just don’t stitch! In my living room I was not able to get a sweep panorama done, because the camera just was not able to find features for stitching! I tried some of the stripes for about ten times. Always at the same point towards the end I got an error message from the camera. This was usually when the ceiling started, where only few features can be found.
  4. You can’t control the quality in the sweep panorama mode, because the following settings get disabled:
    • ISO
    • JPG Quality
    • Shutter
    • Aperture

  5. Sweep Pano Head Setup

    When using a pano head it gets really complicated, due to the fact that you are shooting in landscape and not in portrait mode (however it would be less complicated, when using an L bracket designed for the NEX-5).

  6. There is no matching lens type available for stitching! I tried my best to stitch a panorama using PTGui Pro but failed. At the moment I’m quite sure that none of the available lens types is the right one! I tried all of them, even the ones, that don’t make real sense. I got the best results using the fish eye lens setting, but somehow this is still wrong.
  7. When shooting handheld you may make curves, that will be straightened in the finished panorama stripe. No stitcher will ever be able to correct this.
  8. The exposure is taken from the start of the panorama, unless you point the camera to a different part of the scene, press the shutter half way down and return to the start.
  9. It’s not easy to hold the shutter all the way when sweeping the pano head.

I hope to get some more information online over the next weekend.

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