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everlite
02-17-2007, 05:57 PM
Hey guys,

I'm trying to learn a little about match moving and doing what i can with my little digi cam, results are less than great and i'm thinking that maybe i need to figure out a few of the camera i'm using.

The front of the lens says:

f=2.45~24.5mm 1:1.8

10x optical zoom (strange symbol) 37mm

You can also see the camera and specs here:

http://audiovisual.kelkoo.co.uk/b/a/ps_16051342/123501.html

So looking at the above information what is important to know when trying to set up a match move?

I've noticed that the camera settings in MM ask for the film back width and height, is this the same as the video width and height?

It also asks for the focal length, so in my case would this be 24.5mm?

Cheers - Dave.
RiKToR
02-17-2007, 08:20 PM
It is really difficult to track, or least for an accurate track if you dont know the film back and focal length. In your particular camera I believe the film back would constitute the size of the CCD chip. And then your focal length would be 24.5, unless you zoomed. MM has calculate the focal length variably which has to be turned on and given a starting point, I would use the 24.5 MM there. And it says your chip is 1/6th of an inch so I have no idea where to go from there, whether thats measure width, length, or diagonal.

Im not much of a tracker Im just remembering a gnomon DVD for doing camera tracks in MM and Boujou.
everlite
02-17-2007, 11:18 PM
1/6 inch equals 0.42cm or 4.2mm, that sounds a little small, though could be correct as know very little about the subject.
RiKToR
02-18-2007, 09:40 AM
I wouldnt be suprised that its that small.
Hugh
02-18-2007, 01:21 PM
That sounds about right for the sensor size... Video sensors are pretty small....

Semi-pro cameras usually have a 1/3" sensor, and pro cameras usually have a 2/3" sensor...
everlite
02-18-2007, 01:43 PM
So would that be the width of the film back?
JshuFX
02-18-2007, 08:52 PM
first things first...if your shooting video with a digital camera you already have one hit against you in terms of getting an accurate solve. The quality just isn't going to be good enough for automatic tracking to be very accurate and will even make it difficult if doing hard tracks by hand.

2nd - you do not need to know both the filmback size and focal length in order to do a track. In fact if you leave both blank programs such as Boujou and matchmover pro will just calculate it for you. also, a general rule of thumb is if you only know one value and not the other it is generally better to not input anything and let the program calculate both for you.

3rd - matchmoving is never a one shot deal. often times you will have to do multiple solves and just see which one has your cg sticking to the plate the best. sometimes you will get a better solve with more tracks, sometimes with less, sometimes it will be better to input the known focal length - sometimes not.
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