panorama software,virtual tour software
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2008-09-23
#1

Zoning in on perfect (NPP) via Nadir view

Optimal Stitching Position (OSP)

The OSP is not necessarily what people mistakenly call the Nodal Point, nor is it necessarily the point of No Parallax. The position we are after is the Optimised Stitching Position (OSP) where the images stitch together with the lowest possible adjoining control point errors after eradicating erroneous wayward strays and any control points that have been automatically place on object that may have moved between shots. This is highly likely on Clouds, Trees, Cars, Shadows or any non solid structure.

Note: This method is designed around a round rotator/panohead footprint. The method doesn't work with panoheads that leave a square footprint like the Manfrotto range of 303 series panoheads.

LOWER ARM ADJUSTMENT

This is an aid in perfecting your (NPP) No Parallax Point position to find your OSP using your panohead/tripod footprint in the nadir area of your stitched panorama. It will clearly show when you have found the correct centre position and demonstrate how being off as little as 2mm either side of "centre correct position" displays via the panorama nadir footprint.

In this case the Nikkor 10.5mm Fisheye Lens is being used on a Nikon D300 (this will be the same for equivalent 6x 60 degree solutions such as Canon with Tokina or Sigma 10mm etc) on a quality panohead. But it really doesn't matter what the Camera or lens is, you just must be able to see at least some of the "outer edge" of the panohead in the shots but never "all". As this is captured with the Sigma 8mm there is no reason to tilt the camera but I advise you shoot 6 rotational shots at 60 degree click stops for the purpose of finding the NPP and OSP. The first thing is to position your camera on the upper rail and lower rails as close as perfect as you know. Rotate the camera down (15 degrees in this case) "but no tilting required with Sigma 8mm" using the markings on the upper arm rotation markings and lock off tight. Level your panohead at position (1) the 0 degrees starting point. Shoot image (1) and rotate 60 degrees (in this case) to shooting position (2) and shoot - and so on until you have shot all 6 images (because in this case 6 images is the correct number for a set of images using the above mentioned equipment). Do NOT ever re-level between shots. Once done, go ahead and stitch your images and then view the Nadir tripod/panohead footprint area. What we hope to see is a "perfect circle" of the panohead. But most likely it will be out slightly either to the left or to the right showing what looks like a circular saw blade like you see in the images below.

I chose a "tiled floor" for this demonstration because this is many peoples worse nightmare and to prove that once you have followed this mini tutorial that tiles should be of no fear to the panographer.

The above image shows that vertical arm on the lower rail needs to be moved to the right a little.

The above image shows that vertical arm on the lower rail needs to be moved to the left a little.

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2008-09-23
#2

Thanks for the detailed post Smooth.  I look forward to trying to perfect my camera's position on the pano head this weekend!

Robert


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2008-09-24
#3
Quote: Originally posted by Rob63 on September-23-2008

Thanks for the detailed post Smooth.  I look forward to trying to perfect my camera's position on the pano head this weekend!

Robert


I look forward to seeing your results.

Please show us your tripod/panohead footprint once completed.

Regards, Smooth


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2008-09-24
#4

Thanks Smooth,  Stitching issues do occur in the bottom and top  20 % of the image height

It appears that even if you are 2mm L or R... floor tile looks great.  Agreed.. gotta get the calibration correct.   


/s/
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2008-09-24
#5

UPPER ARM ADJUSTMENT

Taking this a step further below are the results when adjusting the upper arm backwards and forwards of the correct (NPP) No Parallax Point.

When the camera/lens is too far forward your will get lack of nadir tripod/panohead footprint. A long way forward and you will not even see the round panohead circle we are aiming for.

Note: You should always remember that the "Gold Ring" of the lens will always be near enough to the X & Y Axis of the tripod centerline. This is NOT the correct position but in general the Gold Ring of the lens is a good starting point.

The above shot is +15mm forward of the (NPP)

The above shot is +5mm forward of the (NPP) and you can now see the nadir tripod/panohead circle footprint and minimal parallax errors. (This clearly shows that there is some acceptable allowance when setting up for nil parallax).

Here we show the correct alignment of the both the "X" & "Y" upper and lower arms "The No Parallax Position" and this is obviously our aim.

Now going the other way "Backward of the NPP" in the above shot it is -5mm

Now the above shot is at -10mm of the NPP and you can see the start of the "Flower" shape of our panohead footprint.

and here above at -15mm where the "Flower" shape is clearly evident. This introduces bad parallax errors. (well bad by the definition that the lower arm in this case is already 100% correct)

Note: Obviously if you have both the "X" & "Y" upper and lower arm offset to the correct (NPP) your Nadir Tripod/Panohead footprint will be much uglier than any of the examples I have posted. Meaning you really do need to work adjusting your positions in both directions.

Hope this helps.

Regards, Smooth

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2008-09-24
#6

Yes  I agree.  Those images are GREAT !

Just noticed that if you are off -10 or -15 behind the NPP.. only starts displaying miss aligned tiles.  See tiles upper left and lower right.

Not really sure what miss alignments are occuring in other parts of the panorama


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2008-09-25
#7

Hi Dave,

None of the tiles show significant misalignment in these images because in either set at least either the "X" or "Y" axis is perfectly aligned. Should both ("X" or "Y") be out of alignment things really get ugly. Maybe later I will demonstrate this with another set of images. But I'm sure people are aware of how bad it can be! The stitching alignment or misalignment will follow the "segment/join" if each image from what you see at the bottom/nadir all the way to the top/zenith. The blender if being used will help somewhat disguise these through the middle section (if your lucky). It is best to follow the tutorial and correctly align your camera/lens around the No Parallax Point (NPP) on both axis.

Regards, Smooth 


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2008-09-25
#8
True
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2008-10-01
#9

I am using a Canon 5D + Sigma 8mm 3.5 EX DG Lens.

I shoot 3 circular fisheye images.

I can't point the camera down 15 degrees and get a proper stitch with only 3 images.

I did the above image, shooting normally, then rotated the image down and did a screen image capture.

Is this the only way for me to do this with my camera lens combination?

It appears as though I'm still off a bit on my camera position.

Thanks,

Robert


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2008-10-01
#10

You clearly need to move to the left on the lower arm about 1 or 2mm and to set a better footprint you should shoot 4 images in rotation at 90 degrees stops for the purpose of zoning in on the NPP. You are still looking for a perfect circle.

Things will become much clearer with a 4 shot nadir footprint. But I do suggest you shoot 6 rotation shots  1 every 60 degrees for setting up your NPP OSP.

Regards, Smooth


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2008-10-01
#11

Thanks for the advice. I'll try moving the camera position a bit.  How do I stitch 4 circular fisheye images with Panoweaver 5.0.  I don't see an option to input 4 cirular fisheye images.  Maybe I'm just not seeing it, or should I choose Full Frame Fisheye from the drop down list?

Thanks.