Vig optimize - Revision history

Thomas at 09:57, 27 January 2013

2013-01-27T09:57:30Z

Jwatters: correct exposure value

2010-09-28T23:00:19Z

correct exposure value

Jwatters: fix the exposure variable in example

2010-09-28T22:52:10Z

fix the exposure variable in example

Aston: calrify

2009-04-22T09:40:33Z

calrify

Bruno: basic page

2009-04-19T22:46:21Z

basic page

New page

With the 0.7.0 [[hugin]] release, photometric parameters such as exposure (EV), [[vignetting]], [[white balance]] and [[camera response curve]] can be optimised in a similar way to [[lens distortion]]. These photometric parameters can be edited in the [[hugin Camera and Lens tab]] or calculated automatically in the [[hugin Exposure tab]].

For this to work, photos first have to be aligned with correct relative positions and lens parameters. hugin will compare randomly selected groups of pixels from matching areas in each of the overlapping photos. Exposure and response curve can be calculated with any kind of overlap, however vignetting calculations require partial overlap, ideally around 50%.

As well as the GUI process of optimisation/calculation in the [[hugin Exposure tab]], photometric calculation can also be performed on the command-line with the '''vig_optimize''' tool. This functionally is configured via 'v' ''variable'' lines in the .pto project file in a similar way to the [[autooptimiser]] tool:

* The [[camera response curve]] is simplified using the [[EMoR]] sensor model which reduces the variation to five numbers, these are the '''Ra''', '''Rb''', '''Rc''', '''Rd''' & '''Re''' image (i) parameters (the default values of 0.0 are equivalent to an 'average' generic sensor).
* The [[vignetting]] model is represented by a polynomial with four parameters: '''Va''' (this is always 1.0 and doesn't need to be optimised) and '''Vb''', '''Vc''' & '''Vd''' (which default to 0.0 - equivalent to no vignetting). The vignetting centre can also be different from the geometrical centre, this is specified by '''Vx''' & '''Vy''' (both default to 0.0).
* Exposure (EV) is represented by a single value '''Ev''' (defaults 0.0, equivalent to no-change).
* The [[white balance]] is represented by two scaling exposure values for the red and blue channels '''Er''' and '''Eb''' (the defaults of 1.0 are equivalent to no-change).

A typical 'v' ''variable'' line configuration would look like this, i.e. optimise camera response curve and vignetting for image ''0'' and exposure for images ''1'', ''2'', ''3'' and ''4'':

v Ra0 Rb0 Rc0 Rd0 Re0 Vb0 Vc0 Vd0
v Ev1 Ev2 Ev3 Ev4

(vignetting centre and white balance are left unchanged)

The .pto project itself can then be optimised with '''vig_optimize''' on the command-line like so:

vig_optimize -o myproject.pto myproject.pto

[[Category:Software:Platform:Windows]]
[[Category:Software:Platform:Linux]]
[[Category:Software:Platform:Mac OS X]]
[[Category:Software:Hugin]]

@@ Line 1: / Line 1: @@
-With the 0.7.0 [[hugin]] release, photometric parameters such as exposure (EV), [[vignetting]], [[white balance]] and [[camera response curve]] can be optimised in a similar way to [[lens distortion]].  These photometric parameters can be edited in the [[hugin Camera and Lens tab]] or calculated automatically in the [[hugin Exposure tab]].
+Photometric parameters such as exposure (EV), [[vignetting]], [[white balance]] and [[camera response curve]] can be optimised by [[Hugin]] in a similar way to [[lens distortion]].  These photometric parameters can be edited in the [[Hugin Photos tab|Photos tab]] or calculated automatically in the [[Hugin Exposure tab|Exposure tab]].
-For this to work, photos first have to be aligned with correct relative positions and lens parameters. hugin will compare randomly selected groups of pixels from matching areas in each of the overlapping photos.  Exposure and response curve can be calculated with any kind of overlap, however vignetting calculations require partial overlap, ideally around 50%.
+For this to work, photos first have to be aligned with correct relative positions and lens parameters. Hugin will compare randomly selected groups of pixels from matching areas in each of the overlapping photos.  Exposure and response curve can be calculated with any kind of overlap, however vignetting calculations require partial overlap, ideally around 50%.
 As well as the GUI process of optimisation/calculation in the [[hugin Exposure tab]], photometric calculation can also be performed on the command-line with the '''vig_optimize''' tool. This functionally is configured via 'v' ''variable'' lines in the .pto project file in a similar way to the [[autooptimiser]] tool:

@@ Line 7: / Line 7: @@
 * The [[camera response curve]] is simplified using the [[EMoR]] sensor model which reduces the variation to five numbers, these are the '''Ra''', '''Rb''', '''Rc''', '''Rd''' & '''Re''' image (i) parameters (the default values of 0.0 are equivalent to an 'average' generic sensor).
 * The [[vignetting]] model is represented by a polynomial with four parameters: '''Va''' (this is always 1.0 and doesn't need to be optimised) and '''Vb''', '''Vc''' & '''Vd''' (which default to 0.0 - equivalent to no vignetting).  The vignetting centre can also be different from the geometrical centre, this is specified by '''Vx''' & '''Vy''' (both default to 0.0).
-* Exposure (EV) is represented by a single value '''Ev''' (defaults 0.0, equivalent to no-change).
+* Exposure (EV) is represented by a single value '''Eev''' (defaults 0.0, equivalent to no-change).
 * The [[white balance]] is represented by multipliers for the red and blue channels '''Er''' and '''Eb''' (the defaults of 1.0 are equivalent to no-change).

@@ Line 13: / Line 13: @@
   v Ra0 Rb0 Rc0 Rd0 Re0 Vb0 Vc0 Vd0
-  v Ev1 Ev2 Ev3 Ev4
+  v Eev1 Eev2 Eev3 Eev4
 (vignetting centre and white balance are left unchanged)