www.ssontech.com

[doka15]

I got SynthEyes last week and finally have time to play with it. I have a piece of footage, which I want to do a track to. I picked this as a sample footage that is 3 seconds long. It was shot with my HVX-200 wide open. It has lines running down the wall to help better find out what the distortion is for my camera. Once I find that it is always the same number I am guessing.

How do I find out what the distortion is? I read a post in here about a Lens distortion tool but it was not available for OS X

Here is the footage.

http://www.sbtraveler.tv/flicks/china_shot.mov

Thanks,

-Lars

[LFGabel]

Since you have straight edges, use the line tool to find the distortion factor. Then plug that number into your distortion field in the image preparation window so you can track an undistorted plate. Solve, and use to create your CG. Then you need to redistort the CG to match the original CG plate.

It's all in the manual. Just search for "lens distortion".

[doka15]

I did alot of reading today about that part. I added a line at the top edge and then at the middle and found that -0.01600 was the right number. So I did do what you said and went into the Image Preperation and punched that number in for the Distortion amount. It ended up really distorting the image even more. So I ended up trying to apply it as a positive number 0.01600.

That seemed to cause the line to be more straight. Did I do that right by converting it to a positive number?

Thanks,

-Lars

[LFGabel]

I just tried your value on your shot, and -.016 is about correct. I put this into Image Preparation, just as it is (-0.016) and it worked fine.

What you probably did was check "Apply", which applies the distortion value, not remove it.

You whould check "Apply" if you were redistorting your CG to match your original plate.

[doka15]

Yes that is exactly what I did by pressing apply.

My work flow is SE to Cinema 4D to After Effects. I know After Effects pretty well and I would think I could apply 'Optics Compinsator' to the CG elements to match what the background distortion is. But. Is there a way to translate the SE numbers to AE numbers?

I'm guessing I don't need to undistort the footage in SE and let it track normaly if I can get the right distortion in AE, is my thinking right?

Thanks again for all the help whle I am learning this program.

-Lars

[LFGabel]

It is my understanding that you should always track an undistorted plate.

[doka15]

So if I correct for the distortion in SE and then track it for export to Cinema 4D, I would have to have a way to undistort the actual QT movie to match the to camera move in Cinema 4D.

Can you export from SE a QT movie that has the distortion adjustment or how is this done?

The SE numbers don't match the Optics Compinsator in After Effects which I have been using what would you recommend for that?

On a side note for lens distortion I have a box that sits in front of my Video camera that allows me to add 35mm lenses. here is a photo.

http://s111.photobucket.com/albums/n159/larswik/?action=view&current=DSCN2220.jpg

Are there other things that I need to worry about or is the back plate still the same since it is the same camera?

Lots of questions sorry, but it is helping me get a better understanding.

-Lars

[LFGabel]

The CG should be distorted to match the source plate after its rendered.

You can undistort the QT, but I would suggest you do that to your CG. I believe you need to go through the perspective camera, locked to current view. The complete workflow is all in the manual.

I'm not familiar with AE's optic compensator. I'd distort the CG either back in SynthEyes (check "Apply") or use Shake (there's a script for this).

Not sure about your back plate question.

[doka15]

Thank you for your help. I breezed through the important parts of the manual to get me to this point. I did see Perspective but didn;t look at that to much. I will go back over it.

Thanks very much.

-Lars