Tracking a particle emitter to an object

[ryan3d]

k....im trying to add smoke to a CG ciggarrette ive tracked in maya to a mans hand......the cigg is tracked perfectly to the hand, i bring it into combustion and its on a seperate layer....i track the cigg so i can get its transforms.....then when i copy and paste the transform keys to the particle emitter its sticks the emitter way up in the left hand corner of the screen(nowhere near the ciggarrete) how come it does this? shouldnt the transforms from the track tell it that it should be on the cigg and not way up in the corner?....please help me, ive had this problem before in different situations and havent been able to solve it

[user_deleted]

Try this;
Make a New Solid ( black, additive layer mode,) that is the same size as the clip you want the smoke tracked to and paste the emitter to it instead of the actual cigg footage. Or...
Stupid question, but did you try dragging ( with Animation OFF,) the emitter to where you want it to be-presumably the smoke emitting from the end of the ciggy-and playing it back? If the coordinates relative to the cigg are correct, despite being incorrect relative globally, they should line up.
Or...
You could nest your cg smoke with your BG and track the smoke emitter right to the tip of the Death Stick.
Or...
next time shoot the actor with smoke in hand.

Save frequently, particles are dodgy at best!
Hope this helps,
jon a

[ryan3d]

well its weird...see I have 3 layers.....the cg cig layer, the man layer, and a particle layer.....when i track the end of the cigg and copy those keyframes it makes and place them on to the transfroms for the smoke particle it puts the particle emitter up in the top left corner at 0,0 coordinates.....if i apply the keys to the particle layers transforms it obviously is wrong cuz i dont want the layer to move just the emitter.....why does it put it up in the corner? shouldnt the keys from the track tell it to go on the end of the cigg?

[dlm]

Hi,

You need to pay close attention to your X and X postion coordinates. In the compositor, when X and Y = 0, this is the center of the composite. However when working within a layer, the X and Y value of 0 equals the top left corner of the image. This is by design.

What I would suggest that you track your layers as normal then instead of copying and pasting the keyframes, rather save the tracker data and re-load it when it's needed. This will then allow you to keep the same motion although you might need to offset the X and Y of all the keyframes before applying it to the emitter.

Regards
Grant

DISCREET UK