Flying rigs and digital erasing
by MB of http://www.darkstrider.net/main.html

There are several ways to create the illusion of a puppet or object flying through the air (useful for running and jumping shots as well as flying).... for this tut I'll focus on using a flying rig and digitally erasing it in photoshop. In some cases this might not even be necessary.... Starevitch used to get away with all kinds of crazy tricks with wires hidden behind the puppets and invisible threads. You can also strategically place foreground objects to hide the wire if you want. The other method I'm aware of is to place a sheet of glass in front of the set, and maybe tilt the set on it's back so you can just lay a puppet on the glass and slide it around, or leaving it upright and tilting just the glass you can use some sticky wax or fun tack to stick him to the glass. A rig can be bare bones simple... Nick has used a sharpened wire jabbed right into a small foam latex puppet. I used my mini tabletop rigging with a thick aluminum wire clamped to it. With the joints as tight as I could get them barehanded, I could swing the arm up or down and it stayed right where I put it, and the wire allows for fine tuning. I drilled several holes in the chest and pelvis blocks of this puppet so I could choose the best location. The picture above shows a difficult setup... that extra piece of wire would mean a lot of work to erase. I chose to hide it behind his head, which in retrospect wasn't the best idea. I probably should have had it emerge from behind his right shoulder, as far as possible from his shadow! But more on that later. I also indicated the wire's shadow, which sometimes needs to be erased. In fact, I learned there can be a lot of shadows you were completely unaware of until you watch the clip after thinking you've got it all cleaned up. You can watch the clip below frame by frame by pausing it and using your left and right arrows. Note the first frame is empty... that's what's known as a clean plate... the background with no puppet in place. It's important to shoot a clean plate with the camera and lights exactly where they'll be during animation. I just lifted the puppet out of frame and snapped off a pic in Framethief that can be edited out later. Ok, now for the nitty gritty on digital erasing.... Click here for larger version When you've got your shot done, you have a series of consecutively numbered image files in a folder, or a movie file. If your software creates a movie file, then open the movie with QTPro and Export as an Image Sequence. Now open Photoshop (any image manipulation software that supports layers will work) and from the File menu select Automate and then Batch. This lets you select the source folder to open. Make sure to go to the bottom of the Batch window and set it to Log Errors to File and create a folder to save them in... otherwise you'll need to click a little box before each frame opens... and you don't want that! It will take a while as all the images open on your desktop. Once that's done, click on the first frame (the clean plate) and look at your Layers window. You'll see that by default the image is set as Background. Now click on the second frame (first actual frame of animation). What you want to do is end up with this frame pasted into the original image as Layer 1, and the way to do it is with good ol' Cut and Paste. Well, actually make that Copy and Paste. Go to the Select pulldown menu and choose All, which puts a dotted line around the entire picture. Then go to the Edit menu and choose Copy. Now click on the original clean plate image to highlight it, and from the Edit menu choose Paste. The first frame should appear in the clean plate image, and your Layers Window should look like this: Note the little thumbnail images... you can see the tiny puppet in Layer 1. Note also that Layer 1 is highlighted in blue, meaning it is the currently active layer, and the little paintbrush icon next to it. The paintbrush means this is the layer any drawing or painting (or erasing) will take place on... it's important that it be on layer 1 rather than the BG layer... but by default this is the way the layers will come up, so you don't need to mess with these settings. I just want to explain what some of this stuff means. See the little eyeball icons next to each layer? They just mean that layer is visible. Click one to shut it off and that layer disappears. Both eyeball icons should be there. Opacity should be set on 100%, and it should say Normal in that long box in the upper left. Actually, just for fun, try a few different settings here... you can get some very interesting effects that might suggest other techniques. Some of the settings will make the top layer transparent in different ways, and I can easily see how you could do a ghost effect like this. But that's for another tut! Anyway, back to it... Here I'm using the eraser tool to make the wire disappear. What it actually does is cut a hole right through Layer 1 and reveal the BG layer, which is identical except there's no wire and no puppet, so the wall (or whatever is there in your shot) will show through. I'm new to this... I was learning even as I did this demo, and now I would use a much bigger eraser. To see why, look at the processed clip below... I thought I had got the entire shadow of the wire, but I missed some faint parts that I couldn't even see until I watched the clip in motion afterwards. On the right I've demonstrated another possible error. If you're not careful, you can take a bite out of your puppet. Here I had enlarged the image to see a magnified view... a good strategy when you're working up close to the puppet. If you reduce your eraser tool to a small enough size you can take out those pixels individually. But if you slip and take a chunk out of your puppet's head like this, just hit Undo or Step Backwards and take another stab at it. You'll find these commands under the Edit menu. Here's the shot after processing: You can't see it in this tiny, heavily compressed version below, but click on the larger one, and there are parts of the shadow I missed with the eraser. It's the kind of thing that's all but impossible to see in a still image, but as soon as there's some movement it jumps out at you. So that suggested to me a way to combat it. Remember in the Layers Window, the little eyeball icons that make a layer visible or invisible? You can easily check each frame before saving it by just clicking the top eyeball icon a few times, which will turn Layer 1 on and off, so any shadows will flash like a strobelight. I haven't tried it, but I know it will work. Another thing I thought of only after finishing up is to make the eraser really really big, so that one swipe will clear the entire top portion of the frame instantly... no shadow can escape it! Then enlarge the view and switch to a smaller eraser for the detail work right up close around the puppet, and maybe even have a tiny four-pixel brush for ultrafine detailing. Click here for larger version The biggest problem I had was because of the diffused lighting I used and the fact that the shadow of the wire goes right into the puppet's head shadow. When I tried to erase there, I kept ending up with a hard edge I couldn't disguise. I asked Nick about it, and he said he's done similar shots where he had to go back and do a lot of cleaning up. I thought about it, and I suppose I could set the eraser as an airbrush tool with a low flow rate, so it makes a soft edge rather than cutting a clean swath. But it would be a lot of work and might not come out satisfactorily anyway... I think in a situation like this (if this was part of a film rather than just a test) I'd probably just shoot it over and place the wire on the left edge of the frame, emerging from behind his shoulder so it's nowhere near his shadow. Live and learn, eh? And while I'm on the subject, another good strategy would probably be to not have him right in front of a wall where his shadow will fall! A little planning can save you loads of work and make for a great shot. One point I'd like to mention is the necessity for using tie-downs when the puppet is grounded. I arrogantly thought I wouldn't need them, since the wire would hold him in place... not so. In my first attempt (the one in this tut is my second) poor Buster kept sliding back away from the camera! I didn't even notice it, but I must have been pushing him back slightly each frame. Toward the end I did notice, when he had moved form midshot to way back near the wall, and I still couldn't stop it. So I just started over and broke out the tie-downs. I don't know much about Photoshop, and anyone who does can doubtless find a better way to do this, but I had to save each image individually after processing them. And one problem that could conceiveably wreak havok is this... since you're essentially using only the first image - your clean plate - for every frame, with the individual frames simply pasted in as Layer 1, every frame will try to save as frame 0001. Very annoying! I had to manually change the number each time, by looking at the frame I had just processed to make sure what # I needed. A mistake here would mess up your shot pretty good. I'm sure there are ways to get around it... you can probably set it up to batch-close and save the images while automatically numbering them, but that's beyond my current skill level. At any rate, when you're all done, you once again have a folder with a series of consecutively-numbered image files in it... known as an Image Sequence. To turn it into a movie, open QTPro and from the File menu select Open Image Sequence and navigate to the folder to select the first numbered file. It will find the rest and create a QT movie. Now just Export it and choose whatever settings you want as far as compression, frame rate, size, etc. I want to leave you with this thought... the best way to learn is by doing. -- Mike Brent

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