Ideal shooting sequence for 10mm lens on 1.6x crop dSLR and BLUE skies!

[neilp]

Hi all,

I'm sure this might have been discussed before, if so I'm sorry for bringing it up again and please send me a link to other threads, I'm new :001_smile:

I've been taking 360x180 panos with my Canon 40D, Canon 10-22 at 10mm, T20 and NN3 over the last 4 weeks while on vacation but haven't started stitching yet (wasn't possible to do on the road). The sequence I used was the following:

{zenith (at a shorter setting on upper arm), 8 pictures at +30, 8 pictures at -30, nadir at 0/90/180 on the rotator and a handheld nadir}

For the one sequence I have stitched this seems to have worked well, lots of overlap between the +30 and -30, and the -30 has the advantage that it includes people from head to toe for city scenes in a single frame. Also at 8 frames in a row there is plenty of horizontal overlap, which is again useful if people move around in the scene etc. Also the advantage of doing the zenith first is that it catches clouds that may be moving quickly and would have completely changed if you took the picture after the horizontal rows.

I wanted to ask if anyone else uses this same setup for this kind of focal length or if there are other recommendations? I once tried two rows at +45 and -45 as it includes the zenith/nadir but has poor horizon quality and little overlap for control points. Do some users add a 0 degree row for extra quality? Maybe a +45, 0, -45 is effective or is it overkill.


One other related question which I don't have the answer to yet is how due you stitch a zenith of a perfect blue sky which has no features other than the sun? The sun might give me control points but is that enough? (I will be using PTGui 8 ). Any advice appreciated, it seems there's so many different ways to get to a result with this technology.

Thanks again,

Neil.

[neilp]

On further research, I think I may have found the answer on here, thought I'd be interested in comments from other users. I'm currently using the "alternative" below but it sounds like the "recommended" might solve my blue sky problem.

http://www.vrwave.com/ --- Canon EF-S 10-22mm f/3.5-4.5


* 1.6x=16-35mm, HFOV: 97¬? - 54¬? | VFOV: 74¬? - 38¬? | DFOV: 107¬? - 63¬?

* EF-S lens- exclusively for EOS 20D and Digital Rebel bodies

* Min. shots: N, 6 images every 60¬? at -30¬? pitch, 6 images every 60¬? at +30¬?, Z. Output resolution: 11600 x 5800 pixels - Canon 20D (8mpx)

* Recommended: N, 4 images every 90¬? at -60¬? pitch, 8 images every 45¬? at 0¬? pitch, 4 images every 90¬? at +60¬? pitch, no zenith image required

* Alternative: N, 8 images every 45¬? at -30¬? pitch, 8 images every 45¬? at +30¬? pitch, Z

* This lens might cause problems with older Realviz Stitcher versions, unless the images are pre-corrected. Stitcher 5.1 can handle the lens correctly.

[John Houghton]

One other related question which I don't have the answer to yet is how due you stitch a zenith of a perfect blue sky which has no features other than the sun?

You don't need any control points to position the zenith correctly. The optimizer uses control points to work out the camera angles for each shot so the stitcher can be told where to place the shots on the spherical stitching surface. But you already know the camera angles from the detent positions and scale markings. The zenith will probably have been taken at the same yaw position as the last horizontal shot. You tilted the camera to point straight up, so pitch=90. Roll will be 0, (or the same as the other shots at least). So all you need do is enter these values for the zenith on the Image Parameters tab. For optimum results, you can start by optimizing one row of images in Advanced mode with pitch and roll linked. This will force the pitch and roll values to be the same for the images and straighten the row. Then anchor one of those images and optimize all the other images into position around it (i.e. uncheck y,p,r for the anchor). Then place the zenith into position. The whole panorama can finally be levelled, if required, by assigning vertical/horizontal line control points and using the Level Panorama option on the Edit menu of the Panorama Editor window (NOT the optimizer).

Instead of pointing the zenith shot up at 90 degrees, you might tip it down so that one edge was low enough to overlap an area with features for control points. Pitch=60 is as far as you could go and still cover the zenith hole (just!).

John

[neilp]

Excellent reply John, thanks for spending the time to right this up. I'll experiment with those settings you mentioned. As much as the tools are capable of auto stitching (for the most part) it sounds like a good knowledge of the parameters tab and knowing when to optimize can really help tune the positioning of the photos and get the horizon level etc.

You're right, I should be able to work out the exact pitch and roll etc for the Zenith. I found today the "Align Panorama" window also allows youto drag the image without control points into the approximate position at the top. You can then disable optimizations to prevent the warnings. Of course your suggested method should give much more accurate results.

Thanks again,

Neil.