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nadir point pano straightening   Topic List   < Prev Topic  |  Next Topic >
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#36179 From: Erik Krause <erik.krause@...>
Date: Wed Dec 30, 2009 4:25 pm
Subject: Re: nadir point pano straightening
ekrause2003
Send Email Send Email
 
Am 29.12.2009 07:43, schrieb matt_nolan_uaf:

> But what I can do in all cases it find my nadir spot to the pixel (at
> least before I stitch out the tripod mount or monopod spike mark).
> It seems to me that if I was able to select my nadir pixel in a
> stitching program (before or after stitching the nadir image), that
> the panorama would straighten perfectly (or at least as well as my
> nadir image is stitched compared to the rest) with no other fuss or
> muss with eyeballs or vertical control points. Isn't this correct?

No, sorry. The point you can find is the rotation axis of your tripod
head. But that says nothing about the orientation of this axis. Imagine
a vertical pole pano. Your "nadir" point will be 90° off...

--
Erik Krause



#36163 From: Ken Warner <kwarner000@...>
Date: Wed Dec 30, 2009 12:04 pm
Subject: Re: Re: nadir point pano straightening
kwarner000@...
Send Email Send Email
 
Yes, and if you use a compact camera with the tripod hole off center
and no centering pin (as I do) it gets even harder to get the first
image or any image exactly level. You just do the best you can and
then try to eyeball the pano level in the editor.

I can get roll values of 2 or 3 degrees on some images and that can
be very hard to level. Yaw and pitch are easier to work through.

Hans wrote:
>
> --- In PanoToolsNG@yahoogroups.com, Ken Warner <kwarner000@...> wrote:

>> But the original idea was to target the center of the pano head and
>> use that as the ultimate reference point -- and that is not easy either.
>
> Really,
> If you should be able to use the centre point of the panohead it has to be
leveled in the first place. So whats the point.
> The important is that you take one single image in level. If you use the first
or any other image as the anchor for that is not important.
> As long as you have one image in level you should have no problem.
> But remember you also have to make sure that the camera is not rotated on the
head.
> Even a 360 precision can have a rotation of 0.5 degrees which has to be
accounted for when you use the anchor image as reference.
>
> This rotation is usually what will give an error which increases all the way
around even if the panohead is perfectly leveled.
>
> Hans
>



#36158 From: "Hans" <hans@...>
Date: Wed Dec 30, 2009 9:48 am
Subject: Re: nadir point pano straightening
panoramicsdk
Send Email Send Email
 


--- In PanoToolsNG@yahoogroups.com, Ken Warner <kwarner000@...> wrote:
>
> I guess we are disagreeing about something but I'm not sure what.
>
> If you are shooting architecture, you probably will have a lot of
> vertical and horizontal lines available -- even if it's the Sydney
> Opera House.
>
> Leveling the head helps but is not a complete fix -- I agree. It's just a
> preparation -- you still have to use skill to get a pano visually
> pleasing.
>
> And while it should be possible to use a foot and a string and a weight
> and or whatever, I don't think it's any better than leveling the pano head
> and it's not an easy thing to do in every condition especially outdoors.
>
> But the original idea was to target the center of the pano head and
> use that as the ultimate reference point -- and that is not easy either.

Really,
If you should be able to use the centre point of the panohead it has to be
leveled in the first place. So whats the point.
The important is that you take one single image in level. If you use the first
or any other image as the anchor for that is not important.
As long as you have one image in level you should have no problem.
But remember you also have to make sure that the camera is not rotated on the
head.
Even a 360 precision can have a rotation of 0.5 degrees which has to be
accounted for when you use the anchor image as reference.

This rotation is usually what will give an error which increases all the way
around even if the panohead is perfectly leveled.

Hans

Hans





>
>
> Sacha Griffin wrote:
> > No, the method has nothing to do with the head.
> > You do not need to shoot level in order to level a 360.
> > Trying to shoot level almost never yields usable results no matter how well
> > you do it.
> > Half a degree is enough to need correction, for architecture, something
> > not easily done with a bubble level.
> >
> > The point we've been making is that you only need a frame of reference which
> > you make level. Thats a lot easier that relying on a bubble level on a 360
> > head.
> >
> > It should be possible to use a foot and a string and weight to achieve a
> > stable plumb.
> >
> > s
> >
> > On Tue, Dec 29, 2009 at 7:40 PM, Ken Warner <kwarner000@...> wrote:
> >
> >>
> >> I use a monopod with a level all the time -- in even a slight breeze, it's
> >> not so easy. When it's more than a breeze, it's very hard plus it's a
> >> whole bunch of other gear to carry around in my pack.
> >>
> >> I prefer to spend a few more seconds leveling the pano head then I know
> >> I have a solid reference for image 0 and that seems (to me) to be a way
> >> that works well.
> >>
> >> So thanks for the additional help but for me -- having tried it
> >> several times -- that method is not practical.
> >>
> >> By the way, I'm not the person who is having the leveling problem...
> >>
> >>
> >> Sacha Griffin wrote:
> >>> In the event you need additional help figuring out a suitable method for
> >>> breeze.
> >>>
> >>> I offer you this.
> >>>
> >>> Straight pole that you level with a "ahem" level.
> >>>
> >>>
> >>>
> >>> Leveling a panorama shouldn't be all that high tech, just a simple
> >> thought
> >>> "How do I get OR create something that is level in the scene?"
> >>>
> >>> Once you reach the proper thought or question, the solutions are usually
> >>> simple.
> >>>
> >>>
> >>>
> >>> I usually go overboard and set 3 or 4 vertical points, but I think two
> >> will
> >>> suffice most situations.
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> Sacha Griffin
> >>
> >>
> >
> >
> >
>





#36154 From: Ken Warner <kwarner000@...>
Date: Wed Dec 30, 2009 1:59 am
Subject: Re: Re: nadir point pano straightening
kwarner000@...
Send Email Send Email
 
I guess we are disagreeing about something but I'm not sure what.

If you are shooting architecture, you probably will have a lot of
vertical and horizontal lines available -- even if it's the Sydney
Opera House.

Leveling the head helps but is not a complete fix -- I agree. It's just a
preparation -- you still have to use skill to get a pano visually
pleasing.

And while it should be possible to use a foot and a string and a weight
and or whatever, I don't think it's any better than leveling the pano head
and it's not an easy thing to do in every condition especially outdoors.

But the original idea was to target the center of the pano head and
use that as the ultimate reference point -- and that is not easy either.


Sacha Griffin wrote:
> No, the method has nothing to do with the head.
> You do not need to shoot level in order to level a 360.
> Trying to shoot level almost never yields usable results no matter how well
> you do it.
> Half a degree is enough to need correction, for architecture, something
> not easily done with a bubble level.
>
> The point we've been making is that you only need a frame of reference which
> you make level. Thats a lot easier that relying on a bubble level on a 360
> head.
>
> It should be possible to use a foot and a string and weight to achieve a
> stable plumb.
>
> s
>
> On Tue, Dec 29, 2009 at 7:40 PM, Ken Warner <kwarner000@...> wrote:
>
>>
>> I use a monopod with a level all the time -- in even a slight breeze, it's
>> not so easy. When it's more than a breeze, it's very hard plus it's a
>> whole bunch of other gear to carry around in my pack.
>>
>> I prefer to spend a few more seconds leveling the pano head then I know
>> I have a solid reference for image 0 and that seems (to me) to be a way
>> that works well.
>>
>> So thanks for the additional help but for me -- having tried it
>> several times -- that method is not practical.
>>
>> By the way, I'm not the person who is having the leveling problem...
>>
>>
>> Sacha Griffin wrote:
>>> In the event you need additional help figuring out a suitable method for
>>> breeze.
>>>
>>> I offer you this.
>>>
>>> Straight pole that you level with a "ahem" level.
>>>
>>>
>>>
>>> Leveling a panorama shouldn't be all that high tech, just a simple
>> thought
>>> "How do I get OR create something that is level in the scene?"
>>>
>>> Once you reach the proper thought or question, the solutions are usually
>>> simple.
>>>
>>>
>>>
>>> I usually go overboard and set 3 or 4 vertical points, but I think two
>> will
>>> suffice most situations.
>>>
>>>
>>>
>>>
>>>
>>> Sacha Griffin
>>
>>
>
>
>



#36153 From: Sacha Griffin <sachagriffin@...>
Date: Wed Dec 30, 2009 1:36 am
Subject: Re: Re: nadir point pano straightening
sachagriffin
Send Email Send Email
 
No, the method has nothing to do with the head.
You do not need to shoot level in order to level a 360.
Trying to shoot level almost never yields usable results no matter how well
you do it.
Half a degree is enough to need correction, for architecture, something
not easily done with a bubble level.

The point we've been making is that you only need a frame of reference which
you make level. Thats a lot easier that relying on a bubble level on a 360
head.

It should be possible to use a foot and a string and weight to achieve a
stable plumb.

s

On Tue, Dec 29, 2009 at 7:40 PM, Ken Warner <kwarner000@...> wrote:

>
>
> I use a monopod with a level all the time -- in even a slight breeze, it's
> not so easy. When it's more than a breeze, it's very hard plus it's a
> whole bunch of other gear to carry around in my pack.
>
> I prefer to spend a few more seconds leveling the pano head then I know
> I have a solid reference for image 0 and that seems (to me) to be a way
> that works well.
>
> So thanks for the additional help but for me -- having tried it
> several times -- that method is not practical.
>
> By the way, I'm not the person who is having the leveling problem...
>
>
> Sacha Griffin wrote:
> > In the event you need additional help figuring out a suitable method for
> > breeze.
> >
> > I offer you this.
> >
> > Straight pole that you level with a "ahem" level.
> >
> >
> >
> > Leveling a panorama shouldn't be all that high tech, just a simple
> thought
> > "How do I get OR create something that is level in the scene?"
> >
> > Once you reach the proper thought or question, the solutions are usually
> > simple.
> >
> >
> >
> > I usually go overboard and set 3 or 4 vertical points, but I think two
> will
> > suffice most situations.
> >
> >
> >
> >
> >
> > Sacha Griffin
>
>
>



--

Sacha Griffin
Southern Digital Solutions LLC
http://www.southern-digital.com
http://www.seeit360.net
404-551-4275


[Non-text portions of this message have been removed]




#36151 From: Ken Warner <kwarner000@...>
Date: Wed Dec 30, 2009 12:40 am
Subject: Re: Re: nadir point pano straightening
kwarner000@...
Send Email Send Email
 
I use a monopod with a level all the time -- in even a slight breeze, it's
not so easy. When it's more than a breeze, it's very hard plus it's a
whole bunch of other gear to carry around in my pack.

I prefer to spend a few more seconds leveling the pano head then I know
I have a solid reference for image 0 and that seems (to me) to be a way
that works well.

So thanks for the additional help but for me -- having tried it
several times -- that method is not practical.

By the way, I'm not the person who is having the leveling problem...

Sacha Griffin wrote:
> In the event you need additional help figuring out a suitable method for
> breeze.
>
> I offer you this.
>
> Straight pole that you level with a "ahem" level.
>
>
>
> Leveling a panorama shouldn't be all that high tech, just a simple thought
> "How do I get OR create something that is level in the scene?"
>
> Once you reach the proper thought or question, the solutions are usually
> simple.
>
>
>
> I usually go overboard and set 3 or 4 vertical points, but I think two will
> suffice most situations.
>
>
>
>
>
> Sacha Griffin



#36150 From: "Sacha Griffin" <sachagriffin@...>
Date: Wed Dec 30, 2009 12:29 am
Subject: RE: Re: nadir point pano straightening
sachagriffin
Send Email Send Email
 
In the event you need additional help figuring out a suitable method for
breeze.

I offer you this.

Straight pole that you level with a "ahem" level.



Leveling a panorama shouldn't be all that high tech, just a simple thought
"How do I get OR create something that is level in the scene?"

Once you reach the proper thought or question, the solutions are usually
simple.



I usually go overboard and set 3 or 4 vertical points, but I think two will
suffice most situations.





Sacha Griffin

Southern Digital Solutions LLC

http://www.southern-digital.com

http://www.seeit360.net

GMAIL IM: sachagriffin007@...

404-551-4275







From: PanoToolsNG@yahoogroups.com [mailto:PanoToolsNG@yahoogroups.com] On
Behalf Of Ken Warner
Sent: Tuesday, December 29, 2009 5:54 PM
To: PanoToolsNG@yahoogroups.com
Subject: Re: [PanoToolsNG] Re: nadir point pano straightening





Unless there is a breeze. Then it's not so easy.

PanoToolsNG.10.m8@...
<mailto:PanoToolsNG.10.m8%40spamgourmet.com> wrote:
> Gosh, so obvious 'now', and so simple.
> Thanks for that!
>
> Darren.
>
> )-----Original Message-----
> )From: Sacha Griffin





[Non-text portions of this message have been removed]




#36144 From: Ken Warner <kwarner000@...>
Date: Tue Dec 29, 2009 10:54 pm
Subject: Re: Re: nadir point pano straightening
kwarner000@...
Send Email Send Email
 
Unless there is a breeze.  Then it's not so easy.

PanoToolsNG.10.m8@... wrote:
> Gosh, so obvious 'now', and so simple.
> Thanks for that!
>
> Darren.
>
> )-----Original Message-----
> )From: Sacha Griffin
> )
>
> )
> )You could also, shoot 2 calibration images during acquisition. Take two
> )offset photos of someone with a plumb. A set of car keys hanging from a
> )string for example.
> )
> )With that method, it's a real no brainer.
> )
> )
> )
> )
> )
> )Sacha Griffin
> )
>
>
>



#36140 From: PanoToolsNG.10.m8@...
Date: Tue Dec 29, 2009 9:19 pm
Subject: RE: Re: nadir point pano straightening
grant_1947
Send Email Send Email
 
Gosh, so obvious 'now', and so simple.
Thanks for that!

Darren.

)-----Original Message-----
)From: Sacha Griffin
)

)
)You could also, shoot 2 calibration images during acquisition. Take two
)offset photos of someone with a plumb. A set of car keys hanging from a
)string for example.
)
)With that method, it's a real no brainer.
)
)
)
)
)
)Sacha Griffin
)





#36134 From: "yuval_levy" <yahoo08@...>
Date: Tue Dec 29, 2009 5:49 pm
Subject: Re: nadir point pano straightening
yuval_levy
Send Email Send Email
 


--- In PanoToolsNG@yahoogroups.com, "matt_nolan_uaf" <web@...> wrote:
> if I was able to select my nadir pixel in a stitching program
> (before or after stitching the nadir image), that the panorama would
> straighten perfectly

if everything else is perfect.

> does this feature already exist?

open your stitched, not straightened equirectangular with a 2009 version of
Hugin. Go to the Fast Preview (CTRL+SHIFT+P). Make sure the projection is
Equirectangular 360x180. Click on the Drag tool in the Toolbar. Move the mouse
to the point of the equirect that is your nadir. Drag it exactly to the middle
of the cross grid markers (if you are sure about your mouse movement, you can
drag it to the bottom of the vertical grid marker and skip the next step). Use
numeric transform to pitch it -90°.

that should prove your concept.

now all is left to do is to turn your idea into code.

Yuv




#36118 From: crane@...
Date: Tue Dec 29, 2009 2:09 pm
Subject: Re: Re: nadir point pano straightening
m_c_r_a_n_e
Send Email Send Email
 
Quoting panostar <j.houghton@...>:

> --- In PanoToolsNG@yahoogroups.com, "matt_nolan_uaf" <web@...> wrote:
> >
> > It seems to me that if I was able to select my nadir pixel in a
> > stitching program (before or after stitching the nadir image), that
> > the panorama would straighten perfectly.
>
> This is true, but I don't know how you would identify the nadir pixel. It
> isn't necessarily the centre point of the panorama head, which may not be
> exactly level. No matter, what you can do in PTGui is to click with the
> centre point tool on the nadir pixel in the Panorama Editor window. That
> will bring the nadir to the centre of the output area. Then apply pitch=-90
> using the numerical transform feature and that will position the nadir point
> correctly at the nadir.
>
> An alternative approach that gives a similar result is to optimize the main
> horizontal row with pitch and roll linked. Since constant pitch and roll
> settings were maintained as the head was rotated, the panorama will be
> automatically straightened and therefore levelled, again with the proviso
> that the panorama head was level.
I guess if there are no straight lines at all to be seen and levelling is
important one could take 2 photos of one view.
one holding a plumb line in the picture and one without.
use the plumbline as a vertical line and then replace it with the other.

regards

mick

----------------------------------------------
This mail sent through http://www.ukonline.net



#36113 From: "panostar" <j.houghton@...>
Date: Tue Dec 29, 2009 1:51 pm
Subject: Re: nadir point pano straightening
panostar
Send Email Send Email
 
--- In PanoToolsNG@yahoogroups.com, "matt_nolan_uaf" <web@...> wrote:
>
> It seems to me that if I was able to select my nadir pixel in a
> stitching program (before or after stitching the nadir image), that
> the panorama would straighten perfectly.

This is true, but I don't know how you would identify the nadir pixel. It isn't
necessarily the centre point of the panorama head, which may not be exactly
level. No matter, what you can do in PTGui is to click with the centre point
tool on the nadir pixel in the Panorama Editor window. That will bring the
nadir to the centre of the output area. Then apply pitch=-90 using the
numerical transform feature and that will position the nadir point correctly at
the nadir.

An alternative approach that gives a similar result is to optimize the main
horizontal row with pitch and roll linked. Since constant pitch and roll
settings were maintained as the head was rotated, the panorama will be
automatically straightened and therefore levelled, again with the proviso that
the panorama head was level.

John




#36110 From: "Sacha Griffin" <sachagriffin@...>
Date: Tue Dec 29, 2009 1:33 pm
Subject: RE: Re: nadir point pano straightening
sachagriffin
Send Email Send Email
 
You'd have to pick both the nadir and the zenith exactly to set the axis of
the sphere of course. And do it better than 1 degree.

I feel that any more than 0.5 degrees off, I must fix the leveling before
I'm happy.

The best method is

1. Good acquisition: Shoot Level (Most heads have bubble levels, and
some tripods too)

2. Use the editor window and numerical transform and output small
resolution jpgs until you get it right.



Or if it's a massively layered hdr, just output 1 version, reimport it, use
your numerical transform, save the numbers, input them on your full project.

You could also, shoot 2 calibration images during acquisition. Take two
offset photos of someone with a plumb. A set of car keys hanging from a
string for example.

With that method, it's a real no brainer.





Sacha Griffin

Southern Digital Solutions LLC

http://www.southern-digital.com

http://www.seeit360.net

GMAIL IM: sachagriffin007@...

404-551-4275









From: PanoToolsNG@yahoogroups.com [mailto:PanoToolsNG@yahoogroups.com] On
Behalf Of matt_nolan_uaf
Sent: Tuesday, December 29, 2009 2:08 AM
To: PanoToolsNG@yahoogroups.com
Subject: [PanoToolsNG] Re: nadir point pano straightening





Roger,

Yes, that's the idea I have in mind. One way I judge how well I did was to
look down and spin the pano, and it should rotate around the mark left by
the monopod or the center mark on my pano head. While messing with this, I
thought "rather than mess with the horizon, why not mess with the nadir
point directly?" But when the horizon seems level and the nadir point spins
off center, I'm not sure whether that's due to poor leveling, poor
acquisitions, or poor stitching, or all of the above.

In terms of acquisitions, I center my camera to better than a millimeter on
the tripod, and I would imagine this to be good enough to use that mark on
the head to pick the nadir point. I dont think the lens has to be
perpendicular exactly, since it isnt usually when we do things the standard
way. That is, the nadir point doesnt have to be dead center in the nadir
image, I dont think, it just needs to be identifiable in the software. This
could be done on the flat image before stitching, to make coding easy. At
least that's my idea.

-Matt



.


<http://geo.yahoo.com/serv?s=97359714/grpId=18227848/grpspId=1705006496/msgI
d=36100/stime=1262070757/nc1=4025291/nc2=3848642/nc3=5898816>





[Non-text portions of this message have been removed]




#36106 From: Ken Warner <kwarner000@...>
Date: Tue Dec 29, 2009 12:12 pm
Subject: Re: nadir point pano straightening
kwarner000@...
Send Email Send Email
 
I've had the same thought and I have tried it but with limited success.
What you've described should work but I found it hard to do. I'm not sure
why. And I finally ended up just rotating and shifting the pano until
it "looked right". And I can't really say that when it looks right it's
level. This is especially hard when there is no real horizon to judge
against.

Like this pano --
http://www.pancyl.com/Overlook.htm

The trees are all tilted because of the wind. The valley is just tilted
because it is. The mountains are in an arc.

I just moved it around until I felt like my head was level when I looked
at it.

matt_nolan_uaf wrote:
> I have an idea for straightening panoramas. I have trouble straightening my
panoramas, not sure why, my eye just isnt good at it, and I rarely have level
horizons or buildings to help. But what I can do in all cases it find my nadir
spot to the pixel (at least before I stitch out the tripod mount or monopod
spike mark). It seems to me that if I was able to select my nadir pixel in a
stitching program (before or after stitching the nadir image), that the panorama
would straighten perfectly (or at least as well as my nadir image is stitched
compared to the rest) with no other fuss or muss with eyeballs or vertical
control points. Isn't this correct? Or is it just an optimistic day dream at
the end of a long day? Or does this feature already exist and I'm the only one
trying to do this by eye?
> Thanks,
> Matt
>
>



#36103 From: "Hans" <hans@...>
Date: Tue Dec 29, 2009 8:22 am
Subject: Re: nadir point pano straightening
panoramicsdk
Send Email Send Email
 


--- In PanoToolsNG@yahoogroups.com, "matt_nolan_uaf" <web@...> wrote:
>
> I have an idea for straightening panoramas. I have trouble straightening my
panoramas, >not sure why, my eye just isnt good at it, and I rarely have level
horizons or buildings to >help. But what I can do in all cases it find my nadir
spot to the pixel (at least before I stitch >out the tripod mount or monopod
spike mark). It seems to me that if I was able to select >my nadir pixel in a
stitching program (before or after stitching the nadir image), that the
>panorama would straighten perfectly (or at least as well as my nadir image is
stitched >compared to the rest) with no other fuss or muss with eyeballs or
vertical control points. >Isn't this correct? Or is it just an optimistic day
dream at the end of a long day? Or does >this feature already exist and I'm the
only one trying to do this by eye?

For landscapes or other subjects with no visible horisont or vertical lines the
only usable way is to level your first image properly.

Hans





#36101 From: PanoToolsNG.10.m8@...
Date: Tue Dec 29, 2009 7:37 am
Subject: RE: Re: nadir point pano straightening
grant_1947
Send Email Send Email
 
The theory is good.

...provided you are able to determine the true downward point.

This requires that the axis that you are rotating your camera around, to be
truly vertical(eg. with a spirit level) And then I am guessing you are then
using a known regular point on your tripod to then calculate/determine the
centre point of the axis.

If the axis is not truly vertical(eg. some of Roger Berry's shoots from his
monopole can, and I suspect often are, at angles of 45 degrees and more) the
downward point will not then give you a useful guide to level your panorama.

Cheers,
Darren.



)-----Original Message-----
)From: matt_nolan_uaf
)
)Roger,
)
)Yes, that's the idea I have in mind. One way I judge how well
)I did was to look down and spin the pano, and it should rotate
)around the mark left by the monopod or the center mark on my
)pano head. While messing with this, I thought "rather than
)mess with the horizon, why not mess with the nadir point
)directly?" But when the horizon seems level and the nadir
)point spins off center, I'm not sure whether that's due to
)poor leveling, poor acquisitions, or poor stitching, or all of
)the above.
)
)In terms of acquisitions, I center my camera to better than a
)millimeter on the tripod, and I would imagine this to be good
)enough to use that mark on the head to pick the nadir point.
)I dont think the lens has to be perpendicular exactly, since
)it isnt usually when we do things the standard way. That is,
)the nadir point doesnt have to be dead center in the nadir
)image, I dont think, it just needs to be identifiable in the
)software. This could be done on the flat image before
)stitching, to make coding easy. At least that's my idea.
)
)-Matt
)
)--- In PanoToolsNG@yahoogroups.com, "Roger D. Williams"
)<roger@...> wrote:
)>
)> On Tue, 29 Dec 2009 15:43:28 +0900, matt_nolan_uaf <web@...>
)> wrote:
)>
)> > I have an idea for straightening panoramas. I have trouble
)> > straightening my panoramas, not sure why, my eye just isnt
)good at it,
)> > and I rarely have level horizons or buildings to help.
)But what I can
)> > do in all cases it find my nadir spot to the pixel (at
)least before I
)> > stitch out the tripod mount or monopod spike mark). It
)seems to me that
)> > if I was able to select my nadir pixel in a stitching
)program (before or
)> > after stitching the nadir image), that the panorama would
)straighten
)> > perfectly (or at least as well as my nadir image is
)stitched compared to
)> > the rest) with no other fuss or muss with eyeballs or
)vertical control
)> > points. Isn't this correct? Or is it just an optimistic
)day dream at
)> > the end of a long day? Or does this feature already exist
)and I'm the
)> > only one trying to do this by eye?
)>
)> If I understand you aright, you are assuming that you can identify a
)> true vertical from the precise location of the central nadir spot, as
)> this would define an axis about which the entire panorama
)should rotate
)> and therefore necessarily specify the "horizon."
)>
)> That seems a good assumption to me, but are you sure you can identify
)> that spot accurately enough? Doesn't your camera have to be precisely
)> centered over that nadir spot with the lens axis equally precisely
)> vertical? It seems to me that that might be just as difficult as
)> identifying the straight line corresponding to the horizon... and so
)> subject to the same kinds of error.
)>
)> Roger W.
)>





#36100 From: "matt_nolan_uaf" <web@...>
Date: Tue Dec 29, 2009 7:08 am
Subject: Re: nadir point pano straightening
matt_nolan_uaf
Send Email Send Email
 
Roger,

Yes, that's the idea I have in mind. One way I judge how well I did was to look
down and spin the pano, and it should rotate around the mark left by the monopod
or the center mark on my pano head. While messing with this, I thought "rather
than mess with the horizon, why not mess with the nadir point directly?" But
when the horizon seems level and the nadir point spins off center, I'm not sure
whether that's due to poor leveling, poor acquisitions, or poor stitching, or
all of the above.

In terms of acquisitions, I center my camera to better than a millimeter on the
tripod, and I would imagine this to be good enough to use that mark on the head
to pick the nadir point. I dont think the lens has to be perpendicular exactly,
since it isnt usually when we do things the standard way. That is, the nadir
point doesnt have to be dead center in the nadir image, I dont think, it just
needs to be identifiable in the software. This could be done on the flat image
before stitching, to make coding easy. At least that's my idea.

-Matt

--- In PanoToolsNG@yahoogroups.com, "Roger D. Williams" <roger@...> wrote:
>
> On Tue, 29 Dec 2009 15:43:28 +0900, matt_nolan_uaf <web@...>
> wrote:
>
> > I have an idea for straightening panoramas. I have trouble
> > straightening my panoramas, not sure why, my eye just isnt good at it,
> > and I rarely have level horizons or buildings to help. But what I can
> > do in all cases it find my nadir spot to the pixel (at least before I
> > stitch out the tripod mount or monopod spike mark). It seems to me that
> > if I was able to select my nadir pixel in a stitching program (before or
> > after stitching the nadir image), that the panorama would straighten
> > perfectly (or at least as well as my nadir image is stitched compared to
> > the rest) with no other fuss or muss with eyeballs or vertical control
> > points. Isn't this correct? Or is it just an optimistic day dream at
> > the end of a long day? Or does this feature already exist and I'm the
> > only one trying to do this by eye?
>
> If I understand you aright, you are assuming that you can identify a
> true vertical from the precise location of the central nadir spot, as
> this would define an axis about which the entire panorama should rotate
> and therefore necessarily specify the "horizon."
>
> That seems a good assumption to me, but are you sure you can identify
> that spot accurately enough? Doesn't your camera have to be precisely
> centered over that nadir spot with the lens axis equally precisely
> vertical? It seems to me that that might be just as difficult as
> identifying the straight line corresponding to the horizon... and so
> subject to the same kinds of error.
>
> Roger W.
>
> --
> Business: www.adex-japan.com
> Pleasure: www.usefilm.com/member/roger
>





#36099 From: "Roger D. Williams" <roger@...>
Date: Tue Dec 29, 2009 6:52 am
Subject: Re: nadir point pano straightening
roger_d_will...
Send Email Send Email
 
On Tue, 29 Dec 2009 15:43:28 +0900, matt_nolan_uaf <web@...>
wrote:

> I have an idea for straightening panoramas. I have trouble
> straightening my panoramas, not sure why, my eye just isnt good at it,
> and I rarely have level horizons or buildings to help. But what I can
> do in all cases it find my nadir spot to the pixel (at least before I
> stitch out the tripod mount or monopod spike mark). It seems to me that
> if I was able to select my nadir pixel in a stitching program (before or
> after stitching the nadir image), that the panorama would straighten
> perfectly (or at least as well as my nadir image is stitched compared to
> the rest) with no other fuss or muss with eyeballs or vertical control
> points. Isn't this correct? Or is it just an optimistic day dream at
> the end of a long day? Or does this feature already exist and I'm the
> only one trying to do this by eye?

If I understand you aright, you are assuming that you can identify a
true vertical from the precise location of the central nadir spot, as
this would define an axis about which the entire panorama should rotate
and therefore necessarily specify the "horizon."

That seems a good assumption to me, but are you sure you can identify
that spot accurately enough? Doesn't your camera have to be precisely
centered over that nadir spot with the lens axis equally precisely
vertical? It seems to me that that might be just as difficult as
identifying the straight line corresponding to the horizon... and so
subject to the same kinds of error.

Roger W.

--
Business: www.adex-japan.com
Pleasure: www.usefilm.com/member/roger



#36098 From: "matt_nolan_uaf" <web@...>
Date: Tue Dec 29, 2009 6:43 am
Subject: nadir point pano straightening
matt_nolan_uaf
Send Email Send Email
 
I have an idea for straightening panoramas.  I have trouble straightening my
panoramas, not sure why, my eye just isnt good at it, and I rarely have level
horizons or buildings to help. But what I can do in all cases it find my nadir
spot to the pixel (at least before I stitch out the tripod mount or monopod
spike mark). It seems to me that if I was able to select my nadir pixel in a
stitching program (before or after stitching the nadir image), that the panorama
would straighten perfectly (or at least as well as my nadir image is stitched
compared to the rest) with no other fuss or muss with eyeballs or vertical
control points. Isn't this correct? Or is it just an optimistic day dream at
the end of a long day? Or does this feature already exist and I'm the only one
trying to do this by eye?
Thanks,
Matt




 
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