Matchmoving footage advice

[jonyeahyeah]

Also posted this in matchmoving forum but as its a real beginners question I think it may also be suited to this area of the forum

Hi guys, i'm new to matchmoving and am looking for just some basic advice as a few things i've read kinda contradict eachother

Anyway I have a Panasonic DMC fz150, It has a 1/2.33" live MOS sensor, am I right in thinking this would be a filmback of 0.613 x 0.4884 for an 16:9 aspect ratio for 1080p

My main question however is how to shoot the footage, would tracking software (using 3de) be better suited to progressive or interlaced footage, how would you guys go about preparing the footage in a compositing software like after effects.

I imagine this is all fairly basic stuff to you guys so sorry in advance but i've always found the info on this site helpful so thought it might be a good idea to make a post.

Thanks

Jon

[adamghering]

it amazes me that noone replies to these posts.

1. not sure about film back, you can look it up for your specific camera. it is not based on the fps or the aspect ratio of the footage but on the camera itself (also known as sensor size). couple of notes on this: digital cameras have what is called an active sensor size. on this web page http://www.dpreview.com/news/2011/8/..._gallery...you will find the sensor size for your camera. 1/2.3 which if you look at the table for sensor sizes on wikipedia ohttp://en.wikipedia.org/wiki/Image_sensor_format#Sensors_equipping_compact_digi tal_cameras_and_camera-phones you will note the size of you sensor in mm. ( under the table for sensors and format sizes) on the first website you will also find the full total pixels of 12.8 million and the effective pixels of 12.1 million. so there is an "active sensor" size. how do we find that. well, in working with film, plates, different viewing sizes it is often necessary to work in percentages. so, the 12.1 million effective pixels of your camera is 94.5% of the full 12.8 miilion pixels. if your stated sensor size is 1/2.3(6.17mm x 4.55 mm) you only need to multiply each by .94 (5.8mm x 4.3 mm). now it may be that your camera is servicing the entire pixel range and then cropping it which would mean the first height width in mm is correct. at any rate try both. this will work for all formats shot with your camera. fps, aspect ratio doesn't matter because that is only taking place on the full range of pixels on encode. which will not affect the sensor film back size, or the way the matchmove software will calculate features and paralax. its like taking a piece of 35mm film and cutting it down to a smaller size, but it doesn't mean it was shot with a different camera.

thats the hard part. for preparation of the footage progressive is always better. if you have interlaced then you will want to de-interlace using the proper cadence. then render out progressive full non-interlaced frames for your tracking software. then track, solve and do all your vfx on non-interlaced frames. if you need sound sync or are delivering in standard def then you may have to reverse the interlace removal before final render.

something else to watch out for with a cmos sensor is rolling shutter. you can google this. it will have to be taken care of before you match move. also, it is better to remove any strong lens distortion before matcmove.

so workflow would be
1. de-interlace or shoot progressive
2.render to frames
3.remove lens distortion
4. remove any rolling shutter if necessary (should only be an issue on faster pan shots)
5. matchmove using proper filmback dimensions, lens size would be good to but if you don't have it make sure to set this propertie to unknown, depending on your software.

cheers

[jonyeahyeah]

Wow Thanks!, Lucky I decided to check vfxtalk recently, but that is exactly what i needed thanks a lot! Will maybe try to update with my progress!