[Bf-vfx] [Bf-committers] Camera tracking UI

[Daniel Salazar - 3Developer.com]

The problem is not the names, i bet the are alright, but don't slap
them between totally unrelated UI controls with absolutely no
separation from the rest, how is anyone going to even understand what
relates to tracking and what not if there's no separation?

Take another look at the screenshot
http://www.pasteall.org/pic/show.php?id=20350

Show reconstruction of shading? bundle quad view? it's simply not
organized. Start by actually making a new panel for tracking options,
that will get you far. I'd be interested to hear what matt or william
think


Daniel Salazar
3Developer.com



On Wed, Nov 9, 2011 at 3:13 PM, Keir Mierle <mierle at gmail.com> wrote:
> +bf-vfx
> On Wed, Nov 9, 2011 at 4:40 AM, François T. <francoistarlier at gmail.com>
> wrote:
>>
>> yeah I kind of agree with all that. So far all those naming as been chosen
>> based on a technical naming side (ie bundles means something to a computer
>> vision developer, doesn't mean a thing to an artist)
>
> What do you propose instead? There has to be some name, either "point" or
> "track". The problem with "track" is that it's highly overloaded. Same with
> marker. It's not an issue of computer vision, it's an issue of simply
> deciding on names. It IS important to have a way to refer to each of the
> different concepts so that there is no confusion.
>
> The naming we've chosen for Blender at the moment is:
> A marker - a 2D coordinate on a single image. Literally, a struct of (x, y,
> image#, track#)
> A track - A collection of markers, one per frame, that point to the same
> physical location in the scene. In other words, a collection of {(x, y,
> image#)}. There is a 1-to-many relationship between a track and markers.
> A bundle - The reconstructed 3D point for a track. Called a "bundle" because
> if you visualize a ray from the camera to each marker, they (should)
> intersect at a single point for a good reconstruction. The word "bundle" is
> used to distinguish a reconstructed point from any regular point. There is a
> 1-to-1 correspondence between a track and a bundle.
> Here's where the overloading gets confusing:
> A tracker - The algorithm that tracks a marker from frame A to frame A+1. In
> libmv right now, this is KLT and SAD. Ok, there's a few KLT variants but
> they're similar. This is pattern matching across frames. There needs to be
> documentation about why you would use one over the other (SAD is faster but
> less accurate, KLT is very accurate but sometimes slow)
> A tracker - Also the name used for general matchmoving software, e.g.
> syntheyes, boujou, etc. Confusing! But there you go.
> Feature detector - An algorithm to identify "good features to track" in the
> image, for automatic tracking. Again, the best algorithm depends on the
> scene. I wish there was One True Feature Detector To Rule Them All but there
> isn't.
>
>>
>> Same confusion with, markers, trackers, ....
>> Same with algorithm FAST, SAD, ... all technical stuff that doesn't mean a
>> thing if you havn't done any computer vision dev in your life
>
> I don't think we can avoid having good documentation.
>
>>
>> But in another hand, matchmove is something you have to get interest in as
>> well. it is a discipline and not just a camera to move around :p. There
>> are
>> terms you got to know as well. Reconstruction is a common one for
>> instance.
>
> The difficulty is that if everything is made automatic with no choices, then
> the tool is less useful since in many situations the difference in whether
> you can track a shot or not depends on which algorithm you pick.
> Welcome to computer vision, where the pixels don't care what you want :)
>>
>> So yeah on the overall, lots of cleaning stuff to do, and lets drop the
>> geeky dev side. This is a tool for artist and not for devs as far as I'm
>> concern
>
> Do you have concrete proposals to do so?
>
> Keir
>>
>>
>>
>>
>> 2011/11/9 Daniel Salazar - 3Developer.com <zanqdo at gmail.com>
>>
>> > Hi, i see that camera tracker related UI is spread all over the place
>> > with no clear definition. Camera tracking is a corner case use of
>> > Blender, I'd suggest that UI elements belonging to it get clearer
>> > names *and* get pulled together in boxes or their own panels
>> >
>> > ie: follow track constraint
>> >
>> > http://www.pasteall.org/pic/show.php?id=20349
>> >
>> > why would any regular user of know that this is camera tracking stuff,
>> > or what is a Bundle?
>> >
>> > it's worst in the N Panel
>> >
>> > http://www.pasteall.org/pic/show.php?id=20350
>> >
>> > Shading, Textured solid.. reconstruction? reconstruction of what??
>> > bundle, bundle, bundle and then the old quad view!
>> >
>> > Daniel Salazar
>> > 3Developer.com
>> > _______________________________________________
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>> >
>>
>>
>>
>> --
>> ____________________
>> François Tarlier
>> www.francois-tarlier.com
>> www.linkedin.com/in/francoistarlier
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