PDA

View Full Version : Advanced compositing workflow question in LW9.2



vazy
08-11-2007, 12:49 PM
Hey Everyone,
Just received LW9.2 and loving it so far!

I wanted to pick ya'lls brains as far as what different types of workflows I could consider. Any and all are greatly appreciated!

I have some video footage of a guy being stabbed (not greenscreened or bluescreened) in a shack.

I want to create blood spurts from the wound and the knife as it's coming out of the body. This is part of a dream sequence, so it doesn't have to be 'super-real looking'. But the more realistic the better.

So obviously I have to 'make' the blood and 'animate' it.

This is where my workflow brain stops working.

Do I import the video image sequence in Modeler to create the blood? If so, how do I advanced the images in the sequence?

Or do I just first make the blood and NOT care about the footage at all?

Then do I import the image sequence into Layout and start deforming and animating the blood? I can import the image sequence into Layout, but I'm having to render out each frame or the whole scene to see the blood results in respect to image sequence? Is there a better way?

Finally, should I just export only the blood sequence into AE and composite there with the video? (remember no blue or green screen was used) or should I just export the image sequence w/ the blood?

Is this what most of ya'll are doing as far as workflow? Or are there alternative methods?

Thanks in advance! :D
VAZY

SplineGod
08-11-2007, 01:00 PM
The hardest part is going to be tracking the footage so that the blood lines up with the wounds. You would do this in layout.
You can do the comping in layout or later in AE.

Maxx
08-11-2007, 01:03 PM
Personally, I'd forgo Modeler all together and look at using a particle emitter with HVs in Layout. But - as Larry said - the tracking is going to be a problem. I think there's a free version of Icarus out there on the World Wide Interwebs somewhere that could help in that regard.

iconoclasty
08-11-2007, 01:13 PM
Later versions of AE have pretty good camera tracking options for this type of scenario. You could just make a stationary blood spurt then comp and track it all in AE.

Here's a tute on how it's done
http://videocopilot.net/videotutorials/blood/

vazy
08-11-2007, 01:30 PM
Thanks for the quick responses.

And that's a good point - tracking.

I know how to track in AE7 and I was initially going to do it there, but after asking many people, I was told 3d was the way to go b/c the blood will be landing in many places (forward, backward, etc) and would look more real in 3d (specularity, etc)

So I'm guessing LW doesn't have a 3d tracker. eh?

I don't mind going frame by frame and animating the blood. It is a 5 second shot. (and yes, I know it'll take a while) so it's not 'that' bad

If I were to go this route, how do I import the image sequence so I can see the image sequence advance as I scrub through? I imported the sequence, but can only see it if I render out a frame?

Maxx
08-11-2007, 02:04 PM
*snip* how do I import the image sequence so I can see the image sequence advance as I scrub through? I imported the sequence, but can only see it if I render out a frame?
Load the sequence into Image Editor and set it as Image Type "Sequence". Then set the image sequence as your Background Image in the Composition tab of the Effects window. Now, make sure that Camera View Background option in the Camera View tab of the Preferences window is set to "Background Image". You should then see the frame in the background of the camera view - as you scrub the time line, the view should update.

RedBull
08-12-2007, 03:49 AM
You would track the footage in something like Voodoo
http://www.digilab.uni-hannover.de/docs/manual.html#download

Which is a free Matchmoving application, which spits you out a .lws with a camera motion that matches your plates..

From there it basically becomes fairly easy.....

Note: LW support is now included out of the box, which means people don't need to PM me for the script... :)

G M D THREE
08-12-2007, 03:59 AM
Even you got very good advice from everybody above, it raises the question to me if this will really help you. As it depends very much on what your shot really is. Is the camera moving, is the guy moving or is he static on a floor or bad, is he stabbed from behind or from the front. Do you want blood shooting out or is it just spilling/leaking out of him.

As liquid shooting out of a moving object behaves to gravity and it would look very fake if it was done in 2d compositing.

See some examples of work we had to struggle with:
[its all rated R] and you will need quicktime 7+ to play.

http://www.urbanpolygon.com/ua/0029_V2_H264.mov
http://www.urbanpolygon.com/ua/0032_V_1_h264.mov
http://www.urbanpolygon.com/ua/0106_3_h264.mov

///

warrenwc
08-12-2007, 01:30 PM
Thanks RedBull !
I lucked into a discounted version of Boujou Bullet a while back but a free one is worth a try.

vazy
08-12-2007, 02:57 PM
Wow great job! I especially like the frontal one. What apps did you use? Any tutorials posted? Keep up the great work!

To anser your questions: Yes, the camera has a slight jiggle (handheld) b/c it was a POV shot in a dream. The guy being stabbed repeatedly in his back. The victim is lying on his stomach and is barely moving b/c he's almost dead. I don't want blood spilling out of him, I just want blood thrown from the knife as the killer pulls out the it out of the victim's body each time. I want the effect to be very subtle but want the audience to definitely know it's blood.

I agree that the 2d route would look fake. In LW, I have hand-tracked the position of the knife with a null. Obviously it's only in 2-d. So this isn't any better than tracking in AE7.

I definitely want to try that match-moving S/W above but my PC is down (I'm on my mac now) Is there any mac matching-moving S/W out there?


Even you got very good advice from everybody above, it raises the question to me if this will really help you. As it depends very much on what your shot really is. Is the camera moving, is the guy moving or is he static on a floor or bad, is he stabbed from behind or from the front. Do you want blood shooting out or is it just spilling/leaking out of him.

As liquid shooting out of a moving object behaves to gravity and it would look very fake if it was done in 2d compositing.

See some examples of work we had to struggle with:
[its all rated R] and you will need quicktime 7+ to play.

http://www.urbanpolygon.com/ua/0029_V2_H264.mov
http://www.urbanpolygon.com/ua/0032_V_1_h264.mov
http://www.urbanpolygon.com/ua/0106_3_h264.mov

///

RedBull
08-12-2007, 07:02 PM
Thanks RedBull !
I lucked into a discounted version of Boujou Bullet a while back but a free one is worth a try.

No worries, Choices are good!

Boujou simply rocks! (Not sure about Boujou Bullett)
It's the closest thing to a magic "make not suck button" I've ever used CG.

Shhhhh it's a secret.... :)

It's one of the few software packages that made me say "WoW"
The extra realism that added to my CG and Live action shots was incredible...

But failing that, Voodoo is a good free Icarus replacement...
Thanks to Thorsten for finally getting the LW support done.

Mr Rid
08-12-2007, 10:07 PM
Ive done many versions of the type of effect/track/comp it sounds like you are describing. You definitely need to use particles for the blood as it sounds like you are maybe considering something strange about animating objects frame by frame (?). Sometimes you can get away with no camera tracking in a shot with a brief, quick-moving spatter and little camera jitter. But tracking the movement of emitter to the knife is to be done in Layout.

Personally Ive often found it easier to track camera motions manually in LW, and on several occasions with complicated shots that even Boujou and SynthEyes could not handle. I could describe some tricks for this but it requires an experienced eye, and sounds like your situation is easily tracked in 2D.

One technique is to first stabelize any camera motion in your plate (AFX or Fusion), then animate to the stationary version of the plate, then reverse the stabelize in comp on your CG element to perfectly match the motion in the jittery plate.

Another cheap trick is to add even more X/Y camera motion in post to cover subtle camera motions.

Also, to make your background sequence scrub faster, you might convert the footage into jpegs compressed 50%, at video rez (dont know what your source rez is) and maybe crush the levels/contrast or otherwise process (I usually desaturate) to exaggerate what you need to see clearly (the knife, etc) in Layout. You could also first generate a preview of the background image sequence, then instead select 'preview' for your background which will then scrub realtime as you diddle in Layout.

Some cartoonish Sin City spatters I generated in RF and LW (hand tracked the skull split), 3.4mb-
http://www.box.net/shared/static/8ra92b65vm.mov

I just love this shot done (I recall in one day, for Epoch in 2000) by one Al Villagomez, an AFX guru, where he shot some karo syrup on a piece of white paper and comped this all post gore and self-healing wound effect (256kb)-
http://www.box.net/shared/static/5ahei09isb.mov

G M D THREE
08-14-2007, 04:23 AM
Excellent response Mr Rid. Exactly what I would have suggest as well.

Just to recap:
Track or stabilize camera. (for camera tracking: Bouju good but highly overpriced, SynthEyes good and very affordable, both exist for mac)
For 2D stabilizing (AE or even better Shake if on mac)

Manual tracking of knife should be very simple in Layout, as knifes stabbing move usually fast. I would attach a particle emitter to the tracking null and do the blood with HP in Layout. With the right gravity and velocity seatings you should get good results.

If you need any presets for the HP set up, feel free to hit me up I wont mind handing out what ever old scenes we have. As long as it gets put to good use.

You can use the e mail of the site in my profile.

By the way the shoots I posted above used Real Flow for the blood, but that is so much more headache.

Good luck. ///