Fixing nadir parallax errors - Revision history

Erik Krause: 1 revision(s)

2007-03-21T18:09:02Z

1 revision(s)

Bruno: fisheye nadir doesn't really work, use rectilinear instead

2007-03-21T18:07:00Z

fisheye nadir doesn't really work, use rectilinear instead

Bruno: fisheye nadir doesn't really work, use rectilinear instead

2007-01-21T21:32:55Z

fisheye nadir doesn't really work, use rectilinear instead

WikiSysop: fixed the Pano-name... Mediawiki always capitalizes the first letter...

2006-12-15T00:37:23Z

fixed the Pano-name... Mediawiki always capitalizes the first letter...

Bruno: note on image loaction

2006-12-15T00:16:38Z

note on image loaction

Bruno: new tutorial on stitching parallax errors

2006-12-15T00:01:59Z

new tutorial on stitching parallax errors

New page

Here is a set of source photos for a [[spherical]] panorama:

[[Image:npx-uncorrected-originals.jpg]]

They were taken using a one second exposure without a [[tripod]], the camera
was stabilised by jamming it against the sides of a palm tree. This means that
they don't stitch easily because of the large (approximately 60cm) [[parallax]]
error:

[[Image:npx-uncorrected-equirectangular.jpg]]

Particularly, the [[nadir]] doesn't work at all. This is an extreme version of the
usual problems caused by failing to rotate the camera around the [[No-parallax point]]:

[[Image:npx-uncorrected-nadir.jpg]]

However the nadir can be stitched by taking advantage of another technique generally
used for stitching a [[linear panorama]]. The way this works is that if you assume
the ground forms a ''plane'' just like a mural on a wall; a series of
[[rectilinear Projection]] images taken from different locations can be assembled by
optimising [[roll]], [[pitch]] & [[yaw]], [[Field of View]] and ''d & e'' lens
correction parameters separately for each image.

So the first step is to create a series of [[defish|defished]] rectilinear images
from the [[fisheye Projection]] originals. You can do this in any of the
[[GUI front-ends]], but you do need to [[calibrate your lens]] first:

[[Image:npx-rectilinear-extracted.jpg]]

These can then be stitched together into a single [[nadir]] image with minimal errors,
in this case I chose a fisheye projection, though a rectilinear or equirectangular
projection would work just as well:

[[Image:npx-corrected-nadir.jpg]]

This image can then be reinserted into the original panorama project as another
source photo with a different lens and stitched as normal. Here is the result as a
[[QTVR]], the buildings in the distance are a bit wobbly, but this could have been
corrected with [[vertical control points]]:

<pano file="npx-corrected.mov" width="600" height="450" scale="tofit" controller="true" cache="true" />

[[Category:Tutorial]][[Category:Tutorial:Specialised]]

← Older revision		Revision as of 18:07, 21 March 2007
Line 42:		Line 42:
	in preparation for UAE national day.		in preparation for UAE national day.

−	~~[[Category:Tutorial]]~~[[Category:Tutorial:Specialised]]	+	[[Category:Tutorial:Specialised]]

@@ Line 39: / Line 39: @@
 corrected with [[vertical control points]]:
-<pano file="npx-corrected.mov" width="600" height="450" scale="tofit" controller="true" cache="true" />
+<pano file="Npx-corrected.mov" width="600" height="450" scale="tofit" controller="true" cache="true" />
 This scene is of the Abu Dhabi corniche, 30th November 2006.  The buildings are decorated

← Older revision		Revision as of 00:16, 15 December 2006
Line 40:		Line 40:

	<pano file="npx-corrected.mov" width="600" height="450" scale="tofit" controller="true" cache="true" />		<pano file="npx-corrected.mov" width="600" height="450" scale="tofit" controller="true" cache="true" />
		+
		+	This scene is of the Abu Dhabi corniche, 30th November 2006. The buildings are decorated
		+	in preparation for UAE national day.

	[[Category:Tutorial]][[Category:Tutorial:Specialised]]		[[Category:Tutorial]][[Category:Tutorial:Specialised]]

@@ Line 28: / Line 28: @@
 [[Image:npx-rectilinear-extracted.jpg]]
-These can then be stitched together into a single [[nadir]] image with minimal errors,
+These can then be stitched together into a single [[rectilinear Projection]] image of the [[nadir]] with minimal errors.
-in this case I chose a fisheye projection, though a rectilinear or equirectangular
+Effectively this is ''plan view'' of the ground surface:
-projection would work just as well:
 [[Image:npx-corrected-nadir.jpg]]
-This image can then be reinserted into the original panorama project as another
+This ''plan'' image can then be reinserted into the original panorama project as if it was another
-source photo with a different lens and stitched as normal.  Here is the result as a
+source photo with a different lens, and then stitched as normal by optimising [[roll]], [[pitch]], [[yaw]], [[Field of View]] and ''d & e'' lens correction parameters.  Here is the result as a
-[[QTVR]], the buildings in the distance are a bit wobbly, but this could have been
+[[QTVR]]:
-corrected with [[vertical control points]]:
 <pano file="Npx-corrected.mov" width="600" height="450" scale="tofit" controller="true" cache="true" />