Fwd: New type of control point?

[Rogier Wolff]

Hi all,

I'm stitching a few panos taken on the Mediterranean sea. Visually
they end up all bad, because the horizon is not straight. Luckily
there are a few islands so that I can put a few control points on
them, but still the horizon comes out crooked. I've added bunches of
"horizontal line" points as well, and still it doesn't come out
straight.

I was thinking.... Would it be possible to define a new type of
control point: near a single line. The difficult part is probably that
then there are no longer two control points and one type, but LineX
with unlimited number of points which should lie on that line.


Slightly less difficult to implement would be to associate a weight
with each control point. If I'm very sure about this control point,
and I really really don't want any seams near there, I can bump the
weight up a lot.

What do you think?


On short term: Does anybody have any hints and tips on how to get that
sea to look straight?



        Roger.

--
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[Carl von Einem-2]

If the sea shows a horizon then just set a pair of horizontal CPs.
That's what they are usually used for. The horizon should be straight
even in the Mediterranean sea from a normal viewpoint, i.e. I assume you
didn't shoot from a very high elevation or didn't shoot during a storm.

http://wiki.panotools.org/Horizontal_control_points
"In cylindrical, equirectangular and fisheye projections only the
horizon itself stays horizontal."

see also
<http://wiki.panotools.org/Straight_line_control_points>

Carl

ps.
As long as the images stitch fine it's absolutely no problem to level
the panorama in a second step:
<http://wiki.panotools.org/Leveling_a_Finished_Panorama>

Rogier Wolff wrote:

>
> I'm stitching a few panos taken on the Mediterranean sea. Visually
> they end up all bad, because the horizon is not straight. Luckily
> there are a few islands so that I can put a few control points on
> them, but still the horizon comes out crooked. I've added bunches of
> "horizontal line" points as well, and still it doesn't come out
> straight.
>
> I was thinking.... Would it be possible to define a new type of
> control point: near a single line. The difficult part is probably that
> then there are no longer two control points and one type, but LineX
> with unlimited number of points which should lie on that line.
>
> Slightly less difficult to implement would be to associate a weight
> with each control point. If I'm very sure about this control point,
> and I really really don't want any seams near there, I can bump the
> weight up a lot.
>
> What do you think?
>
> On short term: Does anybody have any hints and tips on how to get that
> sea to look straight?

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[Jim Watters]

Rogier Wolff wrote:
> Hi all,
>
> I'm stitching a few panos taken on the Mediterranean sea. Visually
> they end up all bad, because the horizon is not straight. Luckily
> there are a few islands so that I can put a few control points on
> them, but still the horizon comes out crooked. I've added bunches of
> "horizontal line" points as well, and still it doesn't come out
> straight.
>  
Add pairs of horizontal points to the same image (to make each image
level).  And use straight line points joining all the images at horizon
( to join the images together to make sure the horizon makes one
straight line).
> I was thinking.... Would it be possible to define a new type of
> control point: near a single line. The difficult part is probably that
> then there are no longer two control points and one type, but LineX
> with unlimited number of points which should lie on that line.
>  
How is that different than the straight line points?

> Slightly less difficult to implement would be to associate a weight
> with each control point. If I'm very sure about this control point,
> and I really really don't want any seams near there, I can bump the
> weight up a lot.
>
> What do you think?
>  
It would be just as easy to add an additional set of points next to the
spot that is important to give that area more weight.
> On short term: Does anybody have any hints and tips on how to get that
> sea to look straight?
>
>
>
> Roger.
--
Jim Watters

jwatters@...
http://photocreations.ca


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[Tom Sharpless]

HI All

I don't know if fussing about control points is justified here.  All I
ever need to do to get a straight horizon is set the projection center
at the right level, and sometimes rotate the pano a little -- a couple
of clicks in the preview window.  The projected horizon is fully
determined by the zenith point -- put that at the top of the
panosphere and the horizon is automatically straight and level.

If the basic image alignment is actually wrong, I suppose that would
bend the horizon, among other visible defects, and the cure would
certainly involve editing control points.  But that is not a "horizon
problem".

Regards, Tom


On Oct 13, 12:00 pm, Jim Watters <jwatt...@...> wrote:

> Rogier Wolff wrote:
> > Hi all,
>
> > I'm stitching a few panos taken on the Mediterranean sea. Visually
> > they end up all bad, because the horizon is not straight. Luckily
> > there are a few islands so that I can put a few control points on
> > them, but still the horizon comes out crooked. I've added bunches of
> > "horizontal line" points as well, and still it doesn't come out
> > straight.
>
> Add pairs of horizontal points to the same image (to make each image
> level).  And use straight line points joining all the images at horizon
> ( to join the images together to make sure the horizon makes one
> straight line).> I was thinking.... Would it be possible to define a new type of
> > control point: near a single line. The difficult part is probably that
> > then there are no longer two control points and one type, but LineX
> > with unlimited number of points which should lie on that line.
>
> How is that different than the straight line points?
>
> > Slightly less difficult to implement would be to associate a weight
> > with each control point. If I'm very sure about this control point,
> > and I really really don't want any seams near there, I can bump the
> > weight up a lot.
>
> > What do you think?
>
> It would be just as easy to add an additional set of points next to the
> spot that is important to give that area more weight.> On short term: Does anybody have any hints and tips on how to get that
> > sea to look straight?
>
> >    Roger.
>
> --
> Jim Watters
>
> jwatt...@...://photocreations.ca

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