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

[jayraj kharvadi]

Dear Blender community,
I have been following the Tomato branch development for quite some time now
and i have to say that its awesome.  :)
However I also found the naming conventions a bit confusing. May be it was
because I am used to other naming conventions.

On Thu, Nov 10, 2011 at 2:43 AM, 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.
>

How about we name it something like :

*trackpoint* instead of a track and marker both.
*track_locator* instead of a bundle?



>
> Here's where the overloading gets confusing:
>
> A track*er* - 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.
>

I agree totally.

>
> 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
>> > _______________________________________________
>> > Bf-committers mailing list
>> > Bf-committers at blender.org
>> > http://lists.blender.org/mailman/listinfo/bf-committers
>> >
>>
>>
>>
>> --
>> ____________________
>> François Tarlier
>> www.francois-tarlier.com
>> www.linkedin.com/in/francoistarlier
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>>
>
>
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>
Thanks,
Jayraj Kharvadi
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