Wide angle lens vs. software stitching

Started Jun 27, 2013 | Discussions thread
DWMurf
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Re: Wide angle lens vs. software stitching
In reply to james laubscher, Jul 7, 2013

james laubscher wrote:

When you shoot wide angle, inevitably the image will show distortion. In fact our eye's visual field is distorted but brain software straightens it out for us. So when we look at a wide angle picture, we would like to see it the way our brains have perceived it i.e. no conscious distortion.

One benefit I have found in decent stitched images is that the image does not show distortion thus matching what we perceive in real life - wide angle lenses on the other hand always show distortions.

But it turns out that making a decent stitched image is not as easy as it looks - ideally you need a camera/tripod mount that rotates your camera around the focal point in the lens barrel, not around the tripod mount point on the base of the camera. You need a clear day as shifting clouds can throw your exposure balance out from shot to shot and you need some time to check that you have aligned the different images

Long range landscapes are the easiest to do because the horizontal curvature of the image field is not noticeable. Shooting in interiors is very tricky even using the vertical format as you can effectively only still do a horizontal pan - the moment you try to do overlapping vertical shots, the field curvature distortion becomes evident and then it is up to perspective correcting software to save the day.

I have used such software - one version simply stretched one part of the image while compressing another - the effect is visible in an enlargement (due to interpolated content) and some part of the image has to be cropped to retain a rectangular format. I found that it was better to allow a slight 'natural' distortion e.g. slight receding lines than to straighten out all lines into strict parallel alignment.

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jamesza

This is a very interesting subject to me. Thanks for sharing your insight here.

I've had some success with landscape panoramas, or at least I'm getting better at it, but as you say, shooting interiors is very tricky. I'm been looking into getting a pano head to try to avoid parallax errors in the stitching. I see Panosaurus on Amazon, I'm not sure which one is best, if you have any experience with that.

Do you recall the name of the software you used to adjust the distortion of wide angle images? It sounds like it's just what I'm looking for.

My in-camera sweep panorama is limited to the wide end of the zoom in my compact camera, and yielded this fish-eye like barrel distortion:

in-camera sweep panorama

Using continuous shooting at telephoto end of the zoom, and post process stitching, resulted in this, which has only slight barrel distortion:

post process stitching

The difference in the amount of distortion between these seems to be a function of the focal length of the lens used. If I try to de-fish the first one the results are not good, at least not with Paint Shop Pro which I just tried.

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David

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