Minimizing the appearance of perspective distortion in a 360-degree interior pano

Need a little more direction here on how to continue to improve interior panos.

So far I've had decent success with my 5D3, Rokinon 14mm, and Nodal Ninja; using CS5's automated stitching. However, I'm at a little bit of a sticking point: one of my big clients is asking me for an updated shoot because the interior panorama is too "curvy."

I'm pretty sure the issue is perspective distortion, plain and simple. A re-shoot probably won't resolve it. More photos won't fix it; shooting with a different focal length probably won't fix it - because the curvature is based on the varying distance from the camera to the subject, not due to lens distortion or anything else along those lines. If I shoot the sales counter, it's going to look smaller on the ends because the ends are farther away.

So. Presumably there's some software that will help me subtly straighten out some of these lines, while still maintaining a pretty good looking interior pano. I've downloaded Hugin but haven't used it; I've considered PTGui but don't know if it'll be any better.

Help? Any advice? I don't know if my tongue is silver enough to explain to the client "Look, that's just the nature of a 360-degree pano, there's gonna be some curvature."

Sample image, 6 shots with the 5D3, 14mm Rokinon, Nodal Ninja, stitched with CS5's auto-align. Original (after cropping) is about 13k pixels wide. I might be able to re-shoot it and shove that rack (lower left) out of the way so it doesn't appear in the final image, it's on wheels so I can move it for each shot.

IMAGE LINK: http://www.flickr.com …/nathancarter/8​598192050/

I'd shoot with a longer focal length, one that gives the vertical coverage you need but no more when the camera is held in "portrait" format. 14mm is far too wide and brings its own problems as you are finding.

Can you post up the 6 individual images - I've done this before on a 180 pano but can't remember exactly how I did it - with some source material I should be able to I recreate the workflow.

Lowner wrote in post #15765139
I'd shoot with a longer focal length, one that gives the vertical coverage you need but no more when the camera is held in "portrait" format. 14mm is far too wide and brings its own problems as you are finding.

Can you explain more? I don't think this is a focal length problem.

If I use a longer focal length, I'll just have to shoot more images, but the objects/fixtures that are physically closer will still appear larger in the final result. For a 360-degree pano, I can't simply stand farther away and use a longer focal length to reduce perspective effects. And, I'm already using a pretty good lens profile that nicely cleans up the lens distortion introduced by the lens.

In the Hugin page, there's a stitched result made with 60 images, yet still exhibits the same sort of curvature. The things that are closer to the camera are going to appear larger unless I distort them after-the-fact with software or other trickery.
http://hugin.sourcefor​ge.net/tech/
(scroll down to the one that says "Metapanorama by gadl")

Nightstalker wrote in post #15765145
Can you post up the 6 individual images - I've done this before on a 180 pano but can't remember exactly how I did it - with some source material I should be able to I recreate the workflow.

Yes, I'll put them in a dropbox once I can get to them, probably later this afternoon.

Wide angle lenses are known to distort the image more than longer focal lengths. I'd have stuck with maybe 70mm, or whatever lens would allow me to shoot the full height of the pano. Yes, of course that means many more images are needed, but WAAAY less distortion.

Your issue about fixtures closer or further from the camera will also be eased, as again, the wide angle focal length aggravates the problem.

Try the adaptive wide angle tool in PSCS6: Filter > Adaptive Wide Angle...

kirk

Did you get around to dropboxing the original images?

It's on my list. Had a busy weekend, a couple of shows sprang up.

On the plus side, the client was apparently thinking of some other images that I had delivered, so after we chatted on Friday afternoon about it, she's OK with the relatively small amount of "curvy" perspective distortion in the shot I posted above. I'm building it up into a slightly larger graphic, and will add some callouts and other graphic elements that hide some of the worst of it, like the big rack at the bottom left.

I think this link might work?

https://www.dropbox.co​m/sh/6oshwnocdbj2ol4/I​n9VkN_Ew0

Those are the ones with Lightroom tweaks for WB, lens profile, maybe some other minor things. There's a folder inside there (if you can see it?) that has the originals without such corrections.

It's just the nature of 360-degree panos and how they get remapped to a flat plane. You're basically looking at an unrolled cylinder.

You can try changing the mapping to something slightly less weird, like Panini or Streographic, but it's never going to completely eliminate the curving, because a flat plane basically can only show 90 degrees FoV without any distortion. Hugin or PTGui would both let you mess around with different remappings. Just load the final stitched pano into either one, specify the lens type as cylindrical and the FoV as 360. Then in the preview window, you can switch between the different mappings to see how they look.

My basic recommendation would be to deliver the 360 in an interactive form: QuicktimeVR, Flash, or HTML5-based. The tool here is likely to be Pano2VR. But at that point, you might really want to learn how to do 360x180 equirectangulars.

I'd also recommend hanging out on the panoguide boards. Lots of crazy-mad VR/360-pano shooters over there.

inkista wrote in post #15872819
It's just the nature of 360-degree panos and how they get remapped to a flat plane. You're basically looking at an unrolled cylinder.

You can try changing the mapping to something slightly less weird, like Panini or Streographic, but it's never going to completely eliminate the curving, because a flat plane basically can only show 90 degrees FoV without any distortion. Hugin or PTGui would both let you mess around with different remappings. Just load the final stitched pano into either one, specify the lens type as cylindrical and the FoV as 360. Then in the preview window, you can switch between the different mappings to see how they look.

My basic recommendation would be to deliver the 360 in an interactive form: QuicktimeVR, Flash, or HTML5-based. The tool here is likely to be Pano2VR. But at that point, you might really want to learn how to do 360x180 equirectangulars.

I'd also recommend hanging out on the panoguide boards. Lots of crazy-mad VR/360-pano shooters over there.

Thanks a lot. I had looked at the panoguide forums in the past, but at the time of this post I couldn't remember what they were called, and my google-fu wasn't working.

I understand the part about mapping the 3D space to the 2D image... the old analogy about flattening a globe into a map, and how you can't make an orange peel perfectly flat without tearing it. I was just hoping for some software magic

Since this pano is being printed 20 feet wide for an event, an interactive display wouldn't have worked. I'm pretty stoked, this is the biggest my work has ever been printed.... well, not counting a billboard where a photo was a small component of the overall design.

I think my next steps will be to learn to identify the ideal place to put a tripod for interior panos... and not being afraid to rearrange the fixtures and furniture to make a better final image.