motion track, problem.

Support Compositing and Post Processing
1

Hello, all.
I’m busy with motion tracking but i have a problem.
I’ve maked a movie with my samsung Nexus S, but i can’t find the sensor width.
How can i fix this?
Does someone know a site i can find that specs or someone that knows it.
Ty, already.

2

I could find it
Try solving the camera with the default sensor width and have refined “focal length and K1” on

3

focal length is 3.36 MM, but i don’t know what K1 is?
What number should i put their?

4

if you have refined “focal length and K1” on, Blender will try to find an approximate focal length and K1(lens distortion)

5

Ok, ty
Blender is tracking now.

6

I’ve tried to get the camera motion.
And this is the result, it gave me an error of: 198 (average), that’s pretty much.
So i took my other camera it’s this one: casio EZ-Z80.
But again i can’t find the lens width.
How can i fix this?
Ty, already.

7

is the error rate 198 or .198?
because if its .198 that’s good enough

8

No it was 198.572

9

You can also try to manually set the focal length and then solving the motion. Repeat this until you get a reasonable error rate.

EDIT: Phone cameras are rather small, thus resulting in a smaller focal length. I couldn’t find the specs for your phone, but I did manage to find them for the iPhone 4. It might not be the same type of camera, but it’s a start.

iPhone 4 main camera:

  • 5.0 Mpixels (2592 x 1936)
  • 1/3.2" back-illuminated CMOS sensor
  • 4:3 aspect ratio
  • 35 mm film camera crop factor: 7.64
  • Low ISO 80 (or better)
  • 3.85 mm lens focal length
  • f/2.8 lens aperture
  • Autofocus: tap to focus

http://falklumo.blogspot.se/2010/06/apple-iphone-4-camera-specs.html

10

Ty, my phone has a focal length of: 3.36 mm.
only 1 problem is what is the width of the sensor is it right it’s from the Iphone 4: 3.2 mm?
Or is that back-illuminated CMOS sensor number at the front another number?

11

Well, that is actually 1/3.2" (inch), which corresponds to 7.9375 mm. It’s not really my area of expertise, but yes, I believe that would be the size of iPhone’s CMOS.

12

A 4:3 aspect? Does that mean that the iphone crops it’s sensor for 16:9?

13

Oke, i’ve tried a lot of things and this is the result:

blender motion track problem1.jpg1920×1080 311 KB


I’ve put a screenshot of blender with this post.
The average error is quite much.
Can someone help me?
Maybe someone can help me now better, (you guys already helped me a lot, especially ldh1109)
Ty, already.

14

I tried tracking with my samsung galaxy before and even got the error range very low (0.4 I think it was), in the end I still got this; http://www.youtube.com/watch?v=jgQMCO9uUEA&list=UUYSBxohiBmCsiGBRTqkG7tA&index=2&feature=plcp, I have gotten much better at tracking since then but have not updated this for a long time, when using a canon 7D I got much better results.

From looking at your picture you might not be using the best frame range (I can’t really tell), you need to choose a range where there is perspective shift.

15

So my movie with not that much perspective changes isn’t that great?
It’s better to have much perspective then less?

16

I think he means parallax change that’s where foreground stuff moves more than mid ground or back ground stuff when the camera moves. The software can establish distances based on that info and lens length etc.

17

So let the paper with the black dots on it move to the front and to the back?