Can't get nadir shot to stitch

[Ryan Bidinger]

Hello. I was wondering if someone could take a look at my project to see what I might do differently to get my nadir shot stitched (even partially). Perhaps my tripod wasn't calibrated properly? I've tried adding manual control points and generating more, re-optimizing & re-aligning but I still can't get it to stitch. I've tried three other panos I have the same problem every time. Viewpoint Optimization doesn't seem to help either. 

Typically I get all my shots except for the nadir to stitch and I can typically do that just fine. Then I try adding the nadir shot and it all falls apart. 

Perhaps I'm also not understanding the difference between to optimize and align? Or when to optimize and when to align? 

Thank you for any help or insight you could provide. Here's a link to my project.

[John Houghton]

Ryan,  If you must use a 15mm rectilinear lens, do yourself a favour and shoot two rows.  As it is, the zeniths and nadirs barely overlap the single horizontal row, making it very difficult to find matching features for control points.  And having a mixture of raw and tiff files in the project is unusual to say the least.  I managed to get the nadirs and zeniths stitched reasonably if not quite perfectly, but you might be able to improve the alignment with some more work.  The complete tiff-only project is available here:  https://we.tl/t-gkw06CEtRJ .

John

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[Ryan Bidinger]

Thanks John.... although this is a 7.5mm rectilinear, not a 15. I double-checked to see if that's what I plugged-in for the lens settings and it converted it to 7.79mm actual, 7.5 theoretical. 

That being said, do I still need to shoot at least two rows? Interesting that a 7.5mm lens requires I need to do this. Totally okay with that but wondering why my situation is different from the norm. Also, what do you mean by shooting two rows?

Yeah, I have a mixture of raw and tiff files because the tiffs were exported from Photoshop after doing some window pulls. 

RYAN BIDINGER

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[Ryan Bidinger]

John how did you do that? I've watched countless tutorials that didn't work for me even after adding manual control points. I think maybe it has something to do with when I click optimize or align images. Either in the wrong order or at the wrong time.

RYAN BIDINGER

[John Houghton]

On Tue, Jan 26, 2021 at 8:11 PM Ryan Bidinger <rbid...@nnu.edu> wrote:

Thanks John.... although this is a 7.5mm rectilinear, not a 15. I double-checked to see if that's what I plugged-in for the lens settings and it converted it to 7.79mm actual, 7.5 theoretical.

Ryan,  PTGui evaluated the focal length as 15.6mm, but this was because I left the crop factor at the default value of x1.  I wasn't aware of the crop factor of your camera, which I now understand is x2 (for the Panasonic  DMC-GH4).  So the real focal length is in fact evaluated as 7.8mm, which is a 35mm equivalent focal length of 15.6mm.  PTGui is really only interested in the angle of view of the lens, which is computed from the focal length and sensor size, so this is the same whether you enter 7.5mm with a crop factor of x2 or 15mm with a crop factor of x1.

John

[John Houghton]

On Tue, Jan 26, 2021 at 8:20 PM Ryan Bidinger <rbid...@nnu.edu> wrote:

John how did you do that? I've watched countless tutorials that didn't work for me even after adding manual control points. I think maybe it has something to do with when I click optimize or align images. Either in the wrong order or at the wrong time.

Ryan, After more than 20 years using PTGui, I have got to know it quite well.  When tackling projects that refuse to stitch ("I've tried everything"!), I simply go about it in manual mode.  The horizontal row stitches just fine to begin with, then I add nadirs/zeniths in turn and usually position each image by dragging into rough alignment on the Panorama Editor window before adding a few control points manually.  After optimizing into more accurate alignment, you can then make use of the "Generate control points here" function to generate more points automatically, followed of course by further optimization.  There's nothing more to it than that, really.

On Tue, Jan 26, 2021 at 1:11 PM Ryan Bidinger <rbid...@nnu.edu> wrote:

That being said, do I still need to shoot at least two rows? Interesting that a 7.5mm lens requires I need to do this. Totally okay with that but wondering why my situation is different from the norm. Also, what do you mean by shooting two rows?

I'm not sure what the norm is - it depends on the focal length chosen to give the resolution required.  Here, I suggest shooting one row with the camera tilted up so as to make the zenith hole very much smaller, and another row with the camera tilted down to do the same with the nadir.

In this case, you could use two rows at +30 and -30, which should work quite well and leave only a small zenith hole to easily be covered by one shot. (You can trial different shooting patterns to see how images overlap by entering y,p,r values on the Image Parameters tab).

John

 

[Ryan Bidinger]

John, this helped me more than you could know! Your instructions worked soooo much better than anything I've tried. I didn't even need to choose the 'align images' option. Thank you so much.

Okay, I will try doing a row of +30 and -30 as well. 

RYAN BIDINGER

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