VFX – Warp Stabilisation & More Tracking

This week with Peter we continued working with tracking footage, however also highlighted on fixing image stabilisation with source footage. These were delivered over three exercises and took up the whole session due to various technical issues. So no logo update this week.

The footage provided this week for all projects was provided in .DPX. This stands for Digital Picture Exchange and we were told it’s a common format for industry VFX work.

Onto the first task!

Warp Stabilisation

Before I get into the process and the tools, something I wanted to post here for my own benefit in future. The computers in the labs have been running terribly with After Effects recently, making 1080p documents almost unusable at times. So we all had a spring cleaning exercise. This would purge the disk cache for AE.

Edit > Preferences >  Media & Disk Cache

From here we clicked on the option to ‘Empty Disk Cache’ and ‘Clear Database & Cache’. This freed up 20GB of cache. Next on the list was something I covered last week, under Previews make sure the enable GPU for Raytracing option is selected. Now we should gain some performance back.

capture2

Oh one last thing, Peter advised us to change the timecode to frames rather than seconds as its easier to work with DPX this way. This option was changed under File > Project Settings > Choose Frames and Frame Count start at 1.

capture1

We were not at a point to import the footage for stabilisation. Once this was on the timeline, the initial fix was a simple case of going to;

Effect > Distort > Warp Stabilise VFX

Similar to the 3D tracking last week, it was advised to turn on the Detailed Analysis option then sit back and let the footage be processed. It might be best if I show a comparison before moving onto the next tool.

As you can see it’s a very good attempt at removing most of the shake from the hand camera. The blur that remains sadly can’t be addressed as its a result of the raw footage itself, AE isn’t perfect but it does its best. There was one more effect added to the above example and that was an Optic Compensation. The original footage had been shot on an 18mm ‘Fisheye’ lens. Using the compensation effect found under Effects > Distort > Optic Compensation, we were able to ‘straighten’ out the footage for lack of a better term.

opticscompensation

One Point Tracking

Okay here is where it all fell apart, After Effects refused to co-operate with at least half of the class. We got there in the end though, a good old restart and some guidance from Peter fixed all issues.So for the sake of making this crystal clear in future you’ll have to bare with me writing this like specific instructions (with comments).

  1. Import footage, graphic(in this case a fish) and create a Null on the timeline.
  2. Set composition to the length of the footage in frames
  3. Select footage on the timeline, go to Tracker > Track Motion > Place the tracking point (Tip: Remember to making the tracking box bigger, there is a balance between losing tracking info when its too small and losing info when its also too large)
  4. Analyse Footage by pressing the play button in Tracker.
  5. Edit Target > Assign to Null > Apply
  6. capture4
  7. Go back to the main composition
  8. Make a solid object the same colour as the side of the building to mask details we don’t wish to see > Effects > Blur > Gaussian Blur edges of box
  9. Shrink the fish graphic to fit into box > Drop fish opacity to 80% to help it blend in.
  10. Parent Fish and Solid Object to Null
  11. Enable MotionBlur > Enable MB in all layers

1pointtracking

Or at least thats as smooth as it was supposed to go. Following instructions three times I had varying results from losing the tracking information, the fish graphic jumping, the fish taking a stroll down the road and the entire footage itself moving. Turns out AE was not happy with Nulls today and was snapping it all over. One PC restart later and the instructions worked smoothly, very odd error.

Two Point Tracking

I won’t recap all of two point tracking, the process is exactly the same except you set (you probably guessed it) two points. You can see an example of this below.

capture6

Both tracking points need to be set in a high contrast area, preferably with some distance between them otherwise it becomes harder for After Effects to figure out scale and rotation. The rule regarding the tracking box size also applies again.

As you can see below, Position, Rotation and Scale are now all selected in the Tracker to accomplish two point tracking.

capture5

The only other difference is that the fish layer was changed to a blend mode of linear burn. While the results from one point were good, I think this has a little bit more of a wow factor.

2pointtracking

 

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