[Basilisk]

Many thanks for this Dan – I think it is looking good – I think I need to get my head round the trigonometry to sort out the bugs, but it is great to have pointers on correct usage on “toWorld” and “linear”. This is my first multiline expression, and although I am familiar with ActionScript in Flash, I am finding the Adobe documentation (by comparison) a bit poor and lacking in examples of usage. Maybe I am looking in the wrong place!
Is there anyway of tracing variables easily? I can see the final effect of an expression, but if there is something wrong in the middle it is quite difficult to find it.

thanks
James

[Basilisk]

Thanks Dan – that would work if I was just rotating the AE camera round the object. What I want to do is some fairly complex camera moves where the angle between the object and camera is detected automatically. I have worked out that I need to put the script in the time remap channel of the rotated object layer. Something like this

v=(position)-(thisComp.layer(“Camera 1”).position) //gives vector between camera and layer
a = radiansToDegrees(Math.atan2(v[2], v[0])) // deduces angle between camera and layer in x/z plane
a // need to do some maths to convert this to the correct value for the time remap amount

I have a new problem – if I parent the camera to some nulls to help with animating the camera the “.position” value is not the actual position of the camera in 3D space. I have tried to use the “toWorld” expression but it doesn’t seem to give the results I expect. Am I using the correct expression here?

thanks
James

[Basilisk]

Thanks Dan – that would work if I was just rotating the AE camera round the object. What I want to do is some fairly complex camera moves where the angle between the object and camera is detected automatically. I have worked out that I need to put the script in the time remap channel of the rotated object layer. Something like this

v=(position)-(thisComp.layer(“Camera 1”).position) //gives vector between camera and layer
a = radiansToDegrees(Math.atan2(v[2], v[0])) // deduces angle between camera and layer in x/z plane
a // need to do some maths to convert this to the correct value for the time remap amount

I have a new problem – if I parent the camera to some nulls to help with animating the camera the “.position” value is not the actual position of the camera in 3D space. I have tried to use the “toWorld” expression but it doesn’t seem to give the results I expect. Am I using the correct expression here?

thanks
James

[Basilisk]

Thanks Mylenium
Yes – the layer is auto-oriented towards the camera. The problem is that the layer is a video of an object rotating on a turntable. Let me try and explain more clearly:
1. I film a complete rotation of the object in 360 frames
2. the AE camera rotates around my 3d set.
3. the object layer is auto oriented to the camera.
4. If the angle between the object layer and the AE camera is 78 degrees I need to go to frame 78 of the object layer movie, which is the frame at which the object is at 78 degrees to the real camera.

My expression needs to do two things – it needs to measure the angle between the object and camera – and it needs to tell a layer to play a particular frame.

Thanks
James

[Basilisk]

Thanks Mylenium
Yes – the layer is auto-oriented towards the camera. The problem is that the layer is a video of an object rotating on a turntable. Let me try and explain more clearly:
1. I film a complete rotation of the object in 360 frames
2. the AE camera rotates around my 3d set.
3. the object layer is auto oriented to the camera.
4. If the angle between the object layer and the AE camera is 78 degrees I need to go to frame 78 of the object layer movie, which is the frame at which the object is at 78 degrees to the real camera.

My expression needs to do two things – it needs to measure the angle between the object and camera – and it needs to tell a layer to play a particular frame.

Thanks
James

[Basilisk]

Hand matting a character in full motion video will be a major task – if you have a lot of time and no money it maybe an option. The best way is to film your character on greenscreen and then composite him on the background – it is then simple to switch the background. I would guess this is how the effect is done in the example you are thinking about. You need a good camera and lighting team to pull it off convincingly
The most recent examples on my website have all been done with greenscreen footage – basilisk.co.uk
James

[Basilisk]

Sounds like you were lucky with your actor – we did a music video with walking on the spot and it looks a bit wierd. I think the problem with the Argos walking machine is that, as it is unpowered, you need to hold the handles to get the belt to move. I suppose the other option would be to attach a wire to the actor to give him something to pull against. I am trying to get a powered machine on ebay, but they seem to go for

[Basilisk]

Might be worth rendering the sequence at 4 times the frame rate (100 or 120 fps) then reimporting it and turning on frame blending. A bit tedious but if nothing else works…

[Basilisk]

If you have the Pro version with SA Color Finesse you can do some pretty fancy stuff with colour processing. If you click on the “secondary” tab, you can select a number of colours with the eye dropper. If you check the “invert” button you can then use the sliders to desaturate all the unselected colours. The problem is that this plugin takes a lot of practice to get the best out of it, but I would say it gives the best results.

[Basilisk]

If you have colorFinesse you can use the “secondary” tab to select a bunch of colours to tweak in a particular way. Probably the most powerful way of doing it.