View Full Version : shadow over a stadium

12-09-2004, 06:28 PM
Hello everyone,

I have footage of a football stadium and I want to cast a moving shadow over it and make it look real, so that the shadow creeps over the stands and field and actually looks like it goes up and down the relief portions of the footage.
Possible in LW?
I don't have alot of time to pull this off.
Any suggestions?

12-10-2004, 05:45 PM
yea theres a way...im not good explaining such things...well, i would set the stadium as the target item for the light, and then put the light at start point in frame 1 and push enter twice to set it there, then roll all the way to the last fram and move it where you want, and push enter twice to set it there, or mebe make more of a circular path to simulate a sun...you were trying to get sun right?..i hope that helps at least some, i may be completely wrong..., im not too good at animation :rolleyes:

~best of luck :D

12-10-2004, 10:44 PM
Actually, I'm trying to simulate the sun being covered by a huge shadow, like in "Independence Day", moving slowly across the stadium.
The animation itself will be easy. It's the way it travels across such things as benches and small structures.
I need to somehow composite a shadow and a shadow receiver and make the shadow receiver invisible to the eye, but not the shadow.

12-11-2004, 05:47 AM
Have you given a quick trial to this:
Put the stadium footage in a compositor (i.e. After Effects) and put a mask above it. The mask should be dark but not opaque of course. But make the mask so that it has serrated edges. You might have to experiment with the size of the serrations. The serrations give the effect of the shadow crawling across the horizontal surfaces and quickly rising across the vertical surfaces--maybe. Experiment with different speeds to see if this produces the desired effect.

12-11-2004, 09:09 AM
A few years ago there was a TV commercial here in Denver for a radio station which had a huge eagle's shadow flying over local monuments (all shot from a helicopter). Whoever did it did a great job.

I've never tried this, but I can only assume that they modeled the local monuments in LW (or whatever app they used), matched the camera movement to the helicopter shots, rendered out just the eagle's shadow (more in a second), and composited the shadow over the real footage (I think you can crowbar LW into doing the compositing, but it would be easier using an external compositing package if you have access to one).

To get just the shadow, I'm guessing that they modeled everything as low poly objects (just need to get the major geometry right, not all the details), and surfaced it as flat white. (You might have a bit more work than that, if you want it to look like it's going over each seat etc. But real shadows are a bit fuzzy at the edges, so don't go too nuts). Then if you also have a flat white background, everthing in the frame should look flat white except for the menacing shadow from your spacecraft. (There are likely other details in here, like playing with the self-shadow and luminosity settings, and there may be easier ways to extract the shadow; maybe there's a buffer especially for that).

One of the hardest things was probably matching the movement of the helicopter; if you can do a locked-off shot, it will save you a lot of grief. (If you do want some camera motion, one way to do it is to render the frames larger than you need, and then "pan around" within the big frames as a separate step.)

Again just guessing at a lot of this, but hope it gives you some ideas. Experiment and have fun! -MG.

12-11-2004, 03:09 PM
Both wonderful answers and I'm going to play with these and see what happens.
Luckily, the footage is not moving....only the shadow.
I shot the footage yesterday and I observed the existing shadows of the light poles and the pressbox etc. and noticed that the shadows weren't detailed in tiny increments when they lay across the bleachers. As long as I have the general shape of the stadium and yes MG, I think making it a flat white will make a good render pass for DFX+, which is what I will be comping on. I've never done render passes and I just hope I get it right.
Thank you both for your help. I really appreciate it!