panorama software,virtual tour software
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Joined: 2011-06-25
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Posts: 1
2011-06-25
#1

Nodal Point

Hi - could someone give me a steer with this please? This is a new NN head, with Nikon 10.5mm - 6 shots at -20 degrees down. From Smooth's fantastic diagrams it's offset a couple of mm to the left - so I can correct that. But why at the 10 oclock and the 4 o'clock is the almost no error but at the other nodes it's fine?

Cheers!

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Joined: 2002-11-23
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2011-06-25
#2

Firstly it is not the "Nodal Point"!

You are looking for the No Parallax Point (NPP), Nodal Points have nothing to do with parallax errors. It's an old common mistake, but we should get it correct because we are all far smarter now. [;)]

I can help, but I will need more information and more images.

You say "new" Nodal Ninja panohead, is it the M1 series? It appears to be. What rotator is attached? (You shouldn't see the blue knobs in shot) this appears to be backwards. At least the Arca-Swiss clamp should have it's tension knob on the same side as the rotator (blue) knobs so that you never take a picture of them.

Because the Arca-Swiss clamp covers the circle of the rotator I would suggest you place a "CD" between the rotator and Arca-Swiss clamp (or under the rotator) so you have a clear circle to aid with finding your left to right "centre" position as explained in my tutorial. Of course it doesn't have the be a CD/DVD it can be a jam tin lid or anything round with a hole in the centre. This is solely for the purpose of setting your NPP position. Once done (proven correct) this will be removed.

Remember when shooting the rotational set of images we never re-level. Set your level at position 1 and leave it alone and shoot all the rotational images.

Your tilt down only needs to be enough to capture a good edge of the circle object. Don't go to far, because too much overlap will give confusing result from the stitcher.

If you can provide a download link for a "good" set of images in .jpg format I'll happily stitch them up and offer an opinion.

Regards, Smooth [8D]


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2011-06-26
#3

After receiving your files I can say that your left to right lower rail setting now appears fairly close as you can see in this stitched nadir footprint looking at the CD edge.

Your upper rail setting though is still out somewhat as you can see in these captures of the same area taken at 60 degrees Yaw.

We need to compare object both near (fence timbers) to far (Cubby/Wendy House and Goal Posts). These should appear in exactly the same positions between Yaw click stop positions.

As you can see clearly the arrows point out the positioning differences between the Yaw shots and what we are comparing it what is visible of the (far) objects when compared to the (near) timber slats. See how much more of the Cubby House window frame can be seen between the left image compared to the right image! (These should be the same). 

You should be able to correct this quite easily by looking through the view finder or using the LCD (with zoom, if you have live view feature) to align these objects by sliding the upper rail fore and aft until eliminated.

Now we need to speak about your panorama shooting sequence. The correct way to shot is 6 rotational shots at -10 degrees and then 2x Zenith shots at +65 degrees (180 degrees opposed). This makes a total of 8 shots only. Shooting more than this is not a good idea. Of course a separate hand-held of tilted tripod Nadir is appropriate if you wish to remove the tripod. 

Regards, Smooth [8D]