Hello,

I am Kirat, MA Digital Effects student at Bournemouth University, UK.I would like to have a little help from you guys in achieving an effect that I am attempting.In my project, I am trying to replicate an effect from Skyfall Title Sequence.Please see the video below from 02:27 to 02:47:

http://vimeo.com/53372914 [vimeo.com]

I am not attempting a full kaleidoscope sequence but the effect where silhouette of the woman is emitting smoke from the body edges.In this effect of the smokey woman, I think Framestore shot the model on green screen, keyed her in Nuke and used Nuke to generate motion analysis.The vector motion path generated from motion analysis was then used to drive smoke simulations in Houdini.

Recently I have been also experimenting with Nuke's Point Cloud Generator to check if I can track the cam and generate point cloud in Nuke and then export it as Alembic to use those points as emitters of smoke in Houdini.I did some tests on a plate where the cam was moving but the object was stationary.

https://dl.dropboxusercontent.com/u/42878955/1.png [dl.dropboxusercontent.com]

https://dl.dropboxusercontent.com/u/42878955/2.png [dl.dropboxusercontent.com]

https://dl.dropboxusercontent.com/u/42878955/3.png [dl.dropboxusercontent.com]

In the first two images I generated PC in Nuke and in the 3rd photo I imported it as alembic in Houdini.

But I think this will not work for my project because the cam will be still and the model will be making physical motions against the green screen.Since the model will be moving, PC generator in Nuke will not work.

Another option is to body track, which I guess is to create dummy geometry and use the surface geo to emit smoke.

I have no clue how to do what framestore did, which is to generate motion vector path in Nuke and use that in Houdini.

I will be choreographing the model's movement so that is something which can be adjusted depending on the technique I wish to employ.For example if it is body tracking, then I may have small and subtle movements of hands so that it only needs a cylinder with some minor modelling to act as a dummy for her hand.

Could you kindly guide me on how to achieve this effect?A few pointers will be absolutely fine.I would love to learn more about the Framestore technique.

Your help will go a long way.Thank you.

Best,
Kirat

Hi Kirat,

Hope you are well and enjoying the MA!

I'm a bit busy at the moment so sorry if this is a bit of a brief reply….

How I would go about the effect you are producing is to take a key of your actor in nuke and import it into Houdini via a trace SOP, Scatter some points along the edge of the result and use those points as emitters.

Hope this is what you are after, you can probably do some VOP wizardry to get the initial velocity moving away from the silhouette shape, but I don't have a chance to bash that out until this evening.

Say hi to Phil and Mel for me!

Chris

Hi Chris,

Thank you for your reply.This is brilliant.Thank you!Yes this is a nice technique and shall work, I tested.But what if say the model rotates or her hand movements change in z axis, then I guess the point scatter will fail as it is very 2D and alpha/key doesn't have depth info.Kindly correct me if wrong.But I think it will be useful if I have 2D like movements, for example the side profiles as seen in Skyfall and not movements like rotation, hand intersection, etc.

I also tried ‘test’ motion analysis in PFTrack.I did get vector motion, but I am not quite sure how to interpret the colors I see and how will they affect the simulations.As you can see in the images, the green arrows and directions especially on her arms are correct.But how do I know that the color pattern of motion I see in Nuke is the correct one?

Any info on how to import vector into Houdini to drive simulation would be greatly appreciated.

Thank you Chris once again.I will definitely say hello to Mel and Phil on your behalf.

Best,
Kirat