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Thread: NN3 Calibration and potential problem

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weiyan

Posts: 41
Location: Hong Kong
Registered: 31 Oct 2013
Re: NN3 Calibration and potential problem
Posted: 22 Nov 2013 at 0:02 GMT
Understand how this thood work.

Fewer guess work. Use the magnifier function of mirrorless camera and adjust visually. Then take these pair of shots. It still not perfect. If this is useful than its ok.

www.flickr.com/photos/woweiyan/10986019274/
www.flickr.com/photos/woweiyan/10985860605/
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weiyan

Posts: 41
Location: Hong Kong
Registered: 31 Oct 2013
Re: NN3 Calibration and potential problem
Posted: 22 Nov 2013 at 0:27 GMT
Upper arm calibration.

It still not perfect. If its useful is OK lol.

www.flickr.com/photos/woweiyan/10986248196/
www.flickr.com/photos/woweiyan/10986370283/
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John Houghton

Posts: 3934
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: NN3 Calibration and potential problem
Posted: 22 Nov 2013 at 7:31 GMT

weiyan said:

Why cannot done with mirroless camera?

It is the method of observing the entrance pupil directly that cannot be used for mirrorless cameras. The entrance pupil can be seen when you look into the lens of a DSLR camera when the aperture is illuminated from the rear by light entering the camera via the viewfinder and reflected down and forwards by the mirror system. Without a mirror, this is obviously not possible. Hence you have to observe the parallax effects caused by the change in position of the entrance pupil rather than directly check for the shift of the entrance pupil itself by viewing it.

John
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John Houghton

Posts: 3934
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: NN3 Calibration and potential problem
Posted: 22 Nov 2013 at 7:51 GMT

weiyan said:

Upper arm calibration.

It still not perfect. If its useful is OK lol.

Your calibration appears to be quite good enough. The proof of the pudding is in the eating: waste no more time and shoot a panorama to see if everything works as it should.

John
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weiyan

Posts: 41
Location: Hong Kong
Registered: 31 Oct 2013
Re: NN3 Calibration and potential problem
Posted: 22 Nov 2013 at 12:39 GMT
Yes, your are all right.

Hope this weekend has time to shoot some panoramas.
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DennisS

Posts: 1787
Location: Los Anglels, United States
Registered: 1 Sep 2007
Re: NN3 Calibration and potential problem
Posted: 22 Nov 2013 at 22:54 GMT
The way I do the initial setting for the lower arm is to point the camera straight down then turn the pano head round and round. The lens should not move as you rotate the pano head round and round. Adjust the lower rail left/right until there is no lens movement. You are now centered over the axis of rotation. As mentioned before the real proof is the final stitch.
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John Houghton

Posts: 3934
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: NN3 Calibration and potential problem
Posted: 23 Nov 2013 at 8:12 GMT

DennisS said:

Adjust the lower rail left/right until there is no lens movement.

It might be necessary also to adjust the mount of the camera to the upper rail to correct any lens movement at right angles to the lateral shift. i.e. twist the camera round a bit. Getting this adjustment right is seldom mentioned, though it's usually not necessary or possible when the camera position is fixed by a locating pin or plate.

John
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DennisS

Posts: 1787
Location: Los Anglels, United States
Registered: 1 Sep 2007
Re: NN3 Calibration and potential problem
Posted: 23 Nov 2013 at 13:19 GMT
I have not seen a pano head where you can precisely adjust the camera on the upper arm left/right or circular, only fore/aft. I have not found a way to reliably dial out parallax when tilting up/down. Even with the NN R1 type pano head I have had to mount the base in my machinist vise and give the upper arm a good twist in order to center the camera over the center of the base. The R1 provides only fore/aft, no left/right. A twist in the camera mount is also why you cannot rely on centering the pano head logo in the center of the view finder when pointed straight down. I always rely on the final stitch to tell me if my rig is calibrated.
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weiyan

Posts: 41
Location: Hong Kong
Registered: 31 Oct 2013
Re: NN3 Calibration and potential problem
Posted: 26 Nov 2013 at 5:24 GMT
A test

-45 x 14
0 x 14
+45 x 14
zenith x 2, rotated 90 degree
NADIR x 3: -90, opened NADIR adapter, opened nadir and shifted tripod. Still a hole on the floor. The line in the NADIR also not straight. Removed control points in mask. Tried add vertical line control points. Heave + Lens Shift optimization.

Optimization report:
Average control point distance: 1.121531
Minimum control point distance: 0.023914
Maximum control point distance: 25.577542

Exposure is a problem. 47 x 3 HDR seems not possible. Is it possible to use auto exposure? EV is not same but the brightness is averaged.

www.flickr.com/photos/woweiyan/11061705955/

Tried Hugin, stitched a messed pano. It has contradictory control points.

If use a Samyang 8mm solve the problem with Hugin? For I only have budget to buy either one.
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weiyan

Posts: 41
Location: Hong Kong
Registered: 31 Oct 2013
Re: NN3 Calibration and potential problem
Posted: 26 Nov 2013 at 6:07 GMT
Finally, find out control points in tripod of last two nadir images. Removed and hand stitched.

Is the calibration come to a conclusion now?

www.flickr.com/photos/woweiyan/11062520093/
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John Houghton

Posts: 3934
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: NN3 Calibration and potential problem
Posted: 26 Nov 2013 at 7:49 GMT

weiyan said:

Is the calibration come to a conclusion now?

I sincerely hope so. The nadir is not perfect, though. I would expect better alignment with the use of viewpoint correction.

John
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weiyan

Posts: 41
Location: Hong Kong
Registered: 31 Oct 2013
Re: NN3 Calibration and potential problem
Posted: 26 Nov 2013 at 8:03 GMT
Thank you.
Notice the problem in nadir, it even has a hole! The narrow fov makes -90 useless.

I mean is nodal point calibration ok?
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Smooth

Posts: 4310
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
Re: NN3 Calibration and potential problem
Posted: 26 Nov 2013 at 11:02 GMT

weiyan said:

Notice the problem in nadir, it even has a hole!
The hole appears to be caused by a mask.

weiyan said:

The narrow fov makes -90 useless.
Because of the FOV you will likely need to shoot multiple images to cover the nadir footprint. Be mindful of shadows and positioning. You then should use PTGui (VPC) View Point Correction on your nadir images. Control points only of flat surfaces/ground and re-optimize F5.

Also be sure to remove control points from your panorama on any object that may have moved between shots. I.E: People/Cars/Clouds/Trees etc. This will likely require manual removal. But you also have the option of Delete Worst Control Points: Ctrl+Shift+W

weiyan said:

I mean is nodal point calibration ok?
First is not the "Nodal Point" it is NPP (No Parallax Position) it is an old mistake and should not be used. Each of the lens two nodal points is not relevant to parallax. For us to know if you have a good calibration involves you sharing the photos involved so we can stitch and compare. You can make them downloadable via a service like www.ge.tt and post the download link.

Regards, Smooth cool
www.omnipix.com.au
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Smooth

Posts: 4310
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
Re: NN3 Calibration and potential problem
Posted: 26 Nov 2013 at 11:07 GMT

weiyan said:

Exposure is a problem. 47 x 3 HDR seems not possible. Is it possible to use auto exposure? EV is not same but the brightness is averaged.
Each image exposure set is expected to have the same Shutter Speed, Exposure F/Stop, White Balance and ISO. 47x3 HDR is no problem for PTGui Pro.

weiyan said:

If use a Samyang 8mm solve the problem with Hugin? For I only have budget to buy either one.
Buy PTGui Pro if you can only afford one. Save for a Samyang for when you are sick of taking so many images.

Regards, Smooth cool
www.omnipix.com.au
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weiyan

Posts: 41
Location: Hong Kong
Registered: 31 Oct 2013
Re: NN3 Calibration and potential problem
Posted: 26 Nov 2013 at 23:42 GMT
Developed the image set to jpeg. Following is the link.

app.box.com/s/zflm7lueag5yl9yzqmqz

Already sick for shooting 3 x 47, but if no choice have to master it. Yesterday take hours to stitch 3 x 2 rows x 17, it align well in preview, hanged in mid-night. Don't want to spend too much time with software.
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