Re: [Lensfun-users] Lens calibration looking for help

[Torsten Bronger]

Hallöchen!

junkyardspar...@yepmail.net writes:

>> Matthias Andree writes:
>>
>>> I also looked through the older materials on calibration and
>>> have been scratching my head over the illumination of vignetting
>>> test images, how do you get good ones.
>> 
>> [...]
>
> I found another interesting possibility for this recently, in the
> form of OLED mobile device screens. [...]

I haven't had an OLED screen in my hand so far but evenness is only
one thing.  The other thing is independence of direction.  If you
tilt the screen, it must have the same brightness, with a tolerance
smaller than what could be evaluated with the naked eye.

Therefore FWIW, I would not accept images taken with an OLED screen.
If you put a sheet of paper inbeween, it might be okay, though.

> Anyway, I'll try to get to some of the calibration chores too,
> pending updated hugin instructions.

So I should send you access credentials?

Tschö,
Torsten.

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Re: [Lensfun-users] Lens calibration looking for help

[junkyardsparkle]

On Tue, Jul 19, 2016, at 21:56, Torsten Bronger wrote:

> Matthias Andree writes:
>
> > I also looked through the older materials on calibration and have
> > been scratching my head over the illumination of vignetting test
> > images, how do you get good ones.
> 
> It is less critical than it seems.  A diffuser in front of the lens
> is always necessary, but in contrast to earlier texts of mine, I now
> think it can even be paper (if absolutely level of course).  The
> actual ilumination should not cast a visible gradiant of the
> diffuser but unless somebody points a laser pointer to it, I think
> this will work in all practical cases.

I found another interesting possibility for this recently, in the form of OLED 
mobile device screens. As mentioned in the existing tutorial, backlit displays 
don't make good sources of even lighting, but the OLED display on my current 
phone does a great job of this, as it turns out, when set to display an 
all-white screen[1]. Of course, it helps that my micro four-thirds lenses have 
fairly small front elements... and you would want to make sure your device 
screen is actually flat...

Anyway, I'll try to get to some of the calibration chores too, pending updated 
hugin instructions.

[1] handy android app for full-white screen: 
https://f-droid.org/repository/browse/?fdid=org.bc_bd.mrwhite

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Re: [Lensfun-users] Lens calibration looking for help

[Torsten Bronger]

Hallöchen!

Matthias Andree writes:

> [...]
>
> Is there a list of lenses/cameras contained in those uploads?
> Just to prevent someone taking more calibration images of a combo
> that someone already uploaded...

That's a good point, but I don't have that.  On
, you can review the
content of the uploads directory.  The names are already changed by
writing EXIF data into the filenames.  But still, this list is of
limited use, and I don't like to advertise it.  Note that 40% of all
uploads eventually turn out to be unusable.  Mostly I get better
ones from the original uploader, but not always.  Besides, in some
cases, the actual lens model is found out only during the
calibration.

My goal is to have so few uploads pending that a collision is very
unlikely.  It used to be like that.

> I also looked through the older materials on calibration and have
> been scratching my head over the illumination of vignetting test
> images, how do you get good ones.

It is less critical than it seems.  A diffuser in front of the lens
is always necessary, but in contrast to earlier texts of mine, I now
think it can even be paper (if absolutely level of course).  The
actual ilumination should not cast a visible gradiant of the
diffuser but unless somebody points a laser pointer to it, I think
this will work in all practical cases.

Tschö,
Torsten.

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Re: [Lensfun-users] Lens calibration looking for help

[Matthias Andree]

Am 18.07.2016 um 23:39 schrieb Torsten Bronger:
> Hallöchen!
>
> After some 400 lens calibrations, I currently don't have the time
> for doing further calibrations in time.  New job.  58 uploads have
> to be processed still, therefore, I am looking for help.
>
> Here is the plan: I set up an ownCloud server and a GitHup repo.
> People interested in helping get access to both.  Every upload
> creates an issue in the repo.  The details of the workflow are
> outlined here:
> https://github.com/lensfun/lensfun/blob/master/tools/calibration-webserver/workflow.rst
>
> I hope to get the calibration business on track again with that.
> Besides, a single point of failure never is a good idea.  I will
> continue to calibrate myself, I just hope to do it not alone.
>
> Over the next days, I will write an HOWTO for calibrators.
> Moreover, I will create a new screencast showing how to use the
> latest Hugin for this.  And of course, I will be responsive in the
> issues.
>
> If you are willing to help – much or little – send me an email.

Is there a list of lenses/cameras contained in those uploads?
Just to prevent someone taking more calibration images of a combo that
someone already uploaded...

I also looked through the older materials on calibration and have been
scratching my head over the illumination of vignetting test images, how
do you get good ones.


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consuming the most bandwidth. Provides multi-vendor support for NetFlow, 
J-Flow, sFlow and other flows. Make informed decisions using capacity planning
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[Lensfun-users] Lens calibration looking for help

[Torsten Bronger]

Hallöchen!

After some 400 lens calibrations, I currently don't have the time
for doing further calibrations in time.  New job.  58 uploads have
to be processed still, therefore, I am looking for help.

Here is the plan: I set up an ownCloud server and a GitHup repo.
People interested in helping get access to both.  Every upload
creates an issue in the repo.  The details of the workflow are
outlined here:
https://github.com/lensfun/lensfun/blob/master/tools/calibration-webserver/workflow.rst

I hope to get the calibration business on track again with that.
Besides, a single point of failure never is a good idea.  I will
continue to calibrate myself, I just hope to do it not alone.

Over the next days, I will write an HOWTO for calibrators.
Moreover, I will create a new screencast showing how to use the
latest Hugin for this.  And of course, I will be responsive in the
issues.

If you are willing to help – much or little – send me an email.

Tschö,
Torsten.

-- 
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consuming the most bandwidth. Provides multi-vendor support for NetFlow, 
J-Flow, sFlow and other flows. Make informed decisions using capacity planning
reports.http://sdm.link/zohodev2dev
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