Match Move newbie

[Aneks]

Go and buy this book :

http://www.amazon.com/Matchmoving-Invisible-Art-Camera-Tracking/dp/0782144039

read it.

Basically there a bunch of good match move apps out there and shooting it all bluscreen is fine AS LONG AS YOU HAVE MARKERS OR REFERNCE POINTS PLACE PROPERLY ON SET.

I swear to god if one more 'vfx sup/vfx dop' comes to me with a bunch of chroma key stuff with like two makers on the back wall and tells me that I can track it I will commit murder.

[Studev]

Yeah, i just quickly run to the bookstore and place an order. I surprised to see this title actually.

"I swear to god if one more 'vfx sup/vfx dop' comes to me with a bunch of chroma key stuff with like two makers on the back wall and tells me that I can track it I will commit murder."

This is exactly what we want to avoid. I'm facing the same situation frequently but on different task. I do think we need a marker, otherwise, there's no way we can track it. Looking at software right now. 3D Equalizer seems to be on top but is running on Linux and OSX. Boujou seems to be an option.

Any ideas for windows base ?

Regards

[dprgb]

If you're doing chroma work, something like Matchmover might work well. If you have the ability to get some goot survey data on-set, you can create a simple model, import it into Matchmover, and use the survey points as 'elastics' to help solve the camera.

Also, if you get it now you can get Imagemodeler, which you can also use to set up survey points with multiple photos of the set.

[Studev]

The test shoot is starting next week.

Before reading ur post. What i've in mind in quiet simple. Placing a marker on a bluescreen wall, corner of the wall and floor. Shoot in on HDCAM Sony Cinealta. We've created a simple building ready to try it on.

Now, regarding ur approach.

"you can create a simple model, import it into Matchmover, and use the survey points as 'elastics' to help solve the camera."

Since the marker on bluescreen is help to identify camera movement. How will this survey points help in adding the information in ? And if you don't mind. Would mind explaining what elastics is ? I've no idea about this. I believe image modeler is only help in recreating building that is matching to the photograph. How does this fit into match moving process ?

I'm very curious in ur experience in doing this task. Mind to share ?

Thanks so much

[Aneks]

I am shocked that they killed eqaulizer off windows. but I still belevie it to be the best racker out there. On PC I thnink Syntheyes, Pftrack or Matchmover are the best for serious work, boujou is the easiest to use but can be a little unrealiable !

[beaker]

I am shocked that they killed eqaulizer off windows.3de has never ran on Windows in the first place. It has always been a unix only app. Even the osx version only runs through X11.

[Aneks]

my bad, I just assumed it was windows because all the guys had it running on their PC's.... I will just retreat back in to my dark corner and continue shouting ...

[Hegs]

Ok, well im only a beginner, but I have read a good deal of that book mentioned. Matchmoving works due to a scientific principle called paralax. When looking through a camera, (or your eyes!), you'll notice that when you move, objects up close move much more than objects in the distance. The computer uses this phenomena to calcaute the camera in 3D (note 2D tracking does not require this). Ok, so if you wanna track in 3D, you'll need the following when shooting:

At least 8 visible markers/trackable items in shot. Most matchmoving programs require at least 7 markers VISIBLE AT ANY GIVEN TIME to acheive a solution for a 3D camera (2d tracking requires far less markers). That means if an actor walks in fornt of a marker, you need to have an extra one somewhere else which you can switch to while the other marker is obscured.

The markers should be a good variety of positions such as up close, at the back, and spread across the shot, otherwise not enough paralax is present for the calculations.

The markers should be easily trackable. Square/ cross markers are good cus sharp corners are easier to track than circles.

Make sure your markers are in a position where you can paint them out easily enough in post.

And take AS MUCH measruments and diagrams as you can. Distances of all markers to the lens (not the end of camera but the distance to the actual lens in the camera), prop dimensions, etc.

Finally make sure you matchmove on an uncompressed/ highest-quality-possible version of your shot.

Ok well thats all I can think of now..I havent actually done much matchmoving but I do know a fair bit about it! Hope that helps :)

[azkuene]

Hi, interesting thread.
Can the markers be coplanar? or Does it be preferable to position them at different planes??

[Studev]

Ok, i can see ur approach now. eg. using square marker instead of circle marker, i can try to use a masking tips paint it with gray or someother color like green so i can key it out easily. It's only that i have to find out the difference between 2D track and 3D track. It looks like what i have in mind all the time is 3D track. No idea what is 2D track.

Just got the matchmoving book. Just starting on the first chapter and quiet amaze how they do it back in the past before the matchmove software came in.


Hegs, you are right about paralax, it does mention inside the book as well. Thanks a lot for sharing ur experience. Appreciate it very much

Regards

[Aneks]

At least 8 visible markers/trackable items in shot. Most matchmoving programs require at least 7 markers VISIBLE AT ANY GIVEN TIME to acheive a solution for a 3D camera (2d tracking requires far less markers). That means if an actor walks in fornt of a marker, you need to have an extra one somewhere else which you can switch to while the other marker is obscured.



There is really a bit more flexibility in the main. the '8 marker rule' etc is a good guide, but things can be a lot more adaptable. Basically fill the set with markers as best you can. Basically its a question of which is more work ? removing the markers in 2d or trying to mannually track in 3d ? I often find that marker removal is easier than manaual matchmoving.

The markers should be easily trackable. Square/ cross markers are good cus sharp corners are easier to track than circles.


Depends on which tracker you are using. Some actually prefer circualr markers (weird I know).

Can the markers be coplanar? or Does it be preferable to position them at different planes??

You had better position then on different planes. Co-plananr tracker error is the most common problem in tracking green/blue screen shoots. a very common trick is to use c-stands and tripods and other objects with markers on them to place marks and indicator in different planes. also putting stuff on the floor is a good idea too !

[Hegs]

Thanks aneks for clearing all that up. Like I said, Im pretty much a novice so its good to get feedback like that. One thing Im a bit confused about is that you say the 8 marker rule is not absolutely critical. But I thought that if you didnt have 8 markers at any given point you simply wont be able to get a solution in 3D (boujou aside). Btw, when I say "marker" I just mean trackable object, not necassarily tape etc.

As for co-planar markers, yeh i forgot to mention that. It is very important! Correct me if Im wrong aneks, but I believe it is also good if you can have at least 2 parrallel markers on each plane, so that you can define the axis.

Studev, the difference between 2D and 3D tracking is that in 2D tracking the computer does not calculate depth, thus it is a MUCH more simple method of tracking..it simply tracks a marker in terms of its X&Y position on the screen. So you can do a 2D track with only one marker if need be...however a 2D track is useless if you need to insert 3D/CG elements INTO the actual scene (as opposed to mattes, which - again correct me if im wrong aneks! - could be composited successfully with 2D tracking).

hope that helps :)

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