www.ssontech.com

[evolross]

I was watching both Lens Distortion tutorials that use the football field footage. They make sense and were really helpful.

My question is using the workflow from Example 2, when is the right point to export your track for use in a 3D package? Before or after you've checked "Calculate Lens Distortion"? Does it matter? Is the track changing when you enable this?

[GraphicsKid]

Honestly, I've never had a reason to NOT check "calculate lens distortion". There have been times when I just couldn't get something to solve, I'm screaming at the walls COME ON YOU STUP- oh wait... check... WOW 0.5hpix!

I'm sure a more experienced matchmover can give you a few hypothetical examples of when you wouldn't want it, but honestly, the first thing I do after importing footage into a new shot is check that box.

EDIT: This calculation of the lens distortion happens during the solve, so you need to have it checked before you hit "solve".

[evolross]

My question is, let's say you know you have lens distortion and you have to do a 3D CG shot. So you undistort your footage for use in your 3D app. When you go to export your solve, do you want the version with "Calculate Lens Distortion" checked or the solve without that checked? I noticed that once you undistort your footage, the trackers don't line up any more. This means they also won't line up in your 3D app... this is okay right? I was wondering if undistorting your footage affected how your tracks plays with that footage in the 3D app?

[GraphicsKid]

All "calculate distortion" means is that the solver is going to take into account that it's a REAL lens with REAL distortion, and that you don't have the exact measurements on hand, so IT should do that calculating. You won't ever un-check that box. Solves are more accurate when you either have the correct diistortion values given, or you tell syntheyes (via the checkbox) that there IS distortion present.

In order to get the trackers to line up, you need to go to the image preparation window (p), go to the "output" tab, check the "distortion" box, and click "apply to trackers" BUT SAVE A BACKUP BEFORE YOU DO THIS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I cannot stress this enough. It is modifying the trackers coordinates themselves, not simply giving them an "undistorted coordinates" coordinate. NO it's overwriting the old "distorted" data. CLICK IT ONLY ONCE! If you click it again, your trackers are going to be undistorted twice, which means you'd have to click "remove from trackers" to get it back to normal. But if you click the remove from trackers button more than once, you'll have to click apply to trackers again to get it back to normal. In other words, Syntheyes doesn't know if a tracker has been undistorted or not, but YOU do. If it's been undistorted, DO NOT undistort it again... cause it'll do it!

After the un-distortion has been applied to the trackers, just click solve again.

[evolross]

Okay, I think this makes sense. So using the "Apply To Trackers" will take into account the undistortion and padding you add to your shot?

This is helpful, as I've always wondered if there was a way to get the 3D trackers to line up in your 3D app after you do undistorting, padding, and re-exporting of the undistorted shot.

Good to know. I'll have to try all this and see how it works. I'll report back.

[pscamm]

Export to your 3D app AFTER you have done the lens distortion workflow if your CG renders are to be distorted later.

Also, the undistorted sequence you render out of Syntheyes will need to be manually loaded into the backdrop of you 3D app as your export file will probibly load up the origonal standard sized footage, this will make the trackers in you 3D scene not match up to the background footage.

Could be different for you 3D app but this happens in mine anyway.

[GraphicsKid]

[pscamm]

[pscamm]

evolross,
This is my full lens distortion workflow, Hopefully this may help:

1. Load up your clip, track & solve it while having the 'Calculate Distortion' already selected, Syntheyes will auto calculate any lens distortion if present. You can confirm if there was distortion detected because there will be a figure in the lens distortion box on the lens panel other than Zero.

NOTE: Dont uncheck the 'Calculate Distortion' checkbox from here on in

2. Clean up trackers & do whatever you need to do get a good final solve, once happy with your results make any proxy objects you need for your 3D app......SAVE NOW, this will be your master syntheyes file, if you find any 'glitches' in your camera path at the 3D app stage, here's where you need to correct them.

NOTE: In the camera view everything should look fine & stable if the tracking is good, if you use the Prospective view things may appear to slide a bit because this view is using the lens distortion calculated in the solve but it is still using the origonal distorted footage.

3. Run the Lens Distortion Workflow as highlighted in the 2nd tut video which will undistort & pad up the clip (now things will look nice & stable in the prospective view because it has the un-distorted version of the clip it needs).

4. SAVE NOW (different name from previous save)......This is the file you'll need to load up your CG render(s) into for applying the calculated distortion later.

5. Export for your 3D App now.

6. Output a copy of this new undistorted & padded sequence for use in the background of your 3D App.

----------------------------------------------------------------

7. Open your export file in your 3D app, it'll load up the animated camera, trackers & any other proxies you created.

8. NOTE: When i open my export file in my 3D app with the backdrop video visible it always loads up the origonal 'distorted' clip i origonally matchmoved, the trackers dont appear to line up with their markers because it needs the 'undistorted' sequence produced at Item No 6 above - If the same happens to you then unload the sequence from your background/backdrop and select the sequence you produced at Item No 6 - All should line up correctly now in your 3D app view.

9. Do your CG work and render your sequence(s)

-----------------------------------------------------------------

10. Open the syntheyes file you saved in item No 4 above

11. Once loaded select 'Change Shot Images' from the 'Shot' menu

12. Select 'Re-Distort CGI - Change to Apply Mode' option & hit ok.

13. Select your CG render you produced at Item No 9 above - The 'Edit Shot' dialog box will open up, just click ok.

14. The padding has been removed and the distortion applied to your CG sequence (checking now with Shot->Edit Shot will confirm the resolution back at your origonal size)

15. Now just 'save sequence' to give you your distorted CG clip for compositing with the origonal distorted footage.

16. If you rendered your CG in seperate passes instead of a single render then just undo twice ( 'Save Sequence Settings' and undo 'Change Shot Images' ) and your ready to load up your next pass for distorting, do this until all your passes are done.

Hope this makes sense to you, works for me

Regards
Paul