Horizontal Control Points
MHoff
to be effective in leveling my panoramas. Sometimes they have no
impact, other times everything just gets weird. Also in the Editor I
can certainly center the image horizon on the crosshairs, but when I
use control-click on my Macbook, it only makes the image rock on that
center axis. It doesn't allow me to push up and down sections towards
the horizon. Any suggestions? Thanks.
PTGui Support
horizon, not on other horizontal features. Often it's easier to use
vertical control points on buildings' edges.
If leveling doesn't work as expected, this is often caused by either
parallax or by bad lens parameters.
Did you use a panoramic head?
And does the reported focal length (see Project Assistant) approximately
match the focal length of your lens?
Joost
michael crane
On Wed, February 23, 2011 4:48 pm, PTGui Support wrote:
> If leveling doesn't work as expected, this is often caused by either
> parallax or by bad lens parameters.
of course levelling the tripod is quite important.
http://www.mickiwiki.com/?cat=8
PTGui Support
level it afterwards in PTGui.
John Houghton
> I'm new to PTGui and having trouble getting horizontal control points
> to be effective in leveling my panoramas. Sometimes they have no
> impact, other times everything just gets weird.
dependent on the output projection of the panorama. You can use
horizontal line (t2) control points on any feature that would be
expected to be straight and horizontal in the chosen projection. For
an equirectangular projection, the line of the horizon is usually the
only feature that qualifies for t2 points. You would need at least
two pairs of points assigned on the horizon for the levelling to be
effective.
In the case of a rectilinear projection, then it is possible for
features other than the horizon to be flat and horizontal, in which
case t2 points can be used on those too. (You may need to dispense
with an anchor image and optimize yaw on all images to allow the
panorama image to shift sideways. This will be necessary to get a set
of parallel line features horizontal - as in levelling a photograph of
a rectangular painting, say, by putting t1 and t2 points on its
sides).
It may be that the way you are adding the line control points is not
correct. See this tutorial:
http://www.johnhpanos.com/levtut.htm
John
michael crane
On Wed, February 23, 2011 5:19 pm, PTGui Support wrote:
> Not at all. It's perfectly possible to shoot a non leveled panorama and
> level it afterwards in PTGui.
I will have to revisit this then. I did a couple as the example where the
rotation was 30 degrees from horizontal. I seem to remember I failed to
level the equirectangular horizon.
regards
mick
michael crane
On Wed, February 23, 2011 5:37 pm, michael crane wrote:
>
> On Wed, February 23, 2011 5:19 pm, PTGui Support wrote:
>> Not at all. It's perfectly possible to shoot a non leveled panorama and
>> level it afterwards in PTGui.
>
> I will have to revisit this then. I did a couple as the example where the
> rotation was 30 degrees from horizontal. I seem to remember I failed to
> level the equirectangular horizon.
I cannot remember the exact sequence.
The intention was to have a cubeface that contained part of what would
normally be the down face. Now when viewing the result it is turning along
the axes which run through the centre of the faces ( and so is not turning
in the horizontal plane of the actual place).
Is it possible in your viewer to change the axes of the turning ?
regards
mick
Willy Kaemena
the example was shot with a pole against my belly at an angle of about 50º
http://forum.360cities.org/viewtopic.php?f=28&t=370
Regards Willy
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DennisS
into the window from the driver's side. Precise leveling is not
needed, as PTGui does a wonderful job of making things right. I
stopped using a leveler and adjust the tripod legs instead. I use a
bubble level so I can get close, but I do not get the bubble in the
exact center any more.
I have also had very limited success using horizontal control points.
I have, however, had huge success using vertical control points. I
place them in opposing images. If I shot 6 around, I will place two
points in image 1 and two more in image 4. If I shot 4 around, I will
place two points in image 1 and two more in image 3. That is usually
enough to keep the panorama level as I continue working on stitching/
blending errors.
ozbigben
circular plane parallel to the horizon, which is why using straight
lines as a reference may not work
2. You only need 2 vertical lines 90° apart to level a panorama. Yje
[itch for one = the roll for the other and vice versa, so there is
only one combination where they are both vertical
3. Not matter how "crooked" your panorama there are always two
sections of the horixon which will be horizontal. Use a viewer that
allows you to determine the orientation of the current view, zoom out
to an fov of 120° and pan around until your pano looks level. Use the
yaw and pitch angles from this view to transform your panorama. This
approach can be useful where there are no vertical features and the
visible horizon is not level.
John Houghton
> 2. You only need 2 vertical lines 90° apart to level a panorama.
to level a panorama. However, the accuracy of the levelling improves
with larger separations and longer features. Levelling will fail
completely in the case of a separation of exactly 180°.
John
ozbigben
should have specified that the optimum spearation is 90° if you have a
lot to choose from