Walk Cycles. We love them, we need them and yet we still fear making them!
Yes, getting your characters to walk is a time consuming and often frustrating exercise, but I also find it to be the most rewarding. Animations can be brought to life in a much more engaging and relatable way with the potential to shape and define a character's personality or mood.
Whether your character is is being playful, aggressive or seductive; suggestive motions and actions can be used to influence that perception. Think of it like harnessing an animated body-language, which we can use to indicate emotions to the viewer. For example, long bouncy strides will evoke a sense of joy whilst rigid-marching steps might convey a more serious or aggressive approach.
Before we delve 'feet-first' into these complex animation walk cycles, we need to be competent in the basics. This blog outlines the principles of walk-cycle animations and how to apply that knowledge within Adobe's After Effects.
Creating a natural walk will often require lots of experimentation and patience, but the more time you invest the more convincing your characters will be. To help speed up the process, we are going to be using the Rubber Hose plugin from Battle Axe. I find this to be one of the best tools for quickly generating basic walk cycles. If this plugin is new to you, you can read about its capability here. If you are using other rigging tools, the method for posing your character might differ, but the theory is the same.
What's a walk cycle?
Let's start with the basics, because after-all you need to learn to walk before you can run! An animation walk cycle is a sequence of frames or illustrations that create the illusion of a walking character when they are continuously looped. It's one of the quickest techniques to generate an animated walk and helps the movements to look consistent.There are limitless variations of walk cycles, which can all be tailored to the character you are animating. For example. the walk cycle for a female may differ from that of a male, but there is a general guideline which we can bear in mind. Human walk cycles are built up from 4 main poses:
- The contact
- the low
- the passing
- the high.
Take a look at each pose which I've roughly sketched out below, I've removed the arms so you can focus on the legs.
- At the 'contact', the heel of the foot in front (leading foot) will start to reach the ground, whilst the leg behind begins to bend and prepares to lift up.
- At the 'low', the leading foot is now flat on the ground, whilst the leg behind bends as its foot leaves the ground. During this pose the body will lower into the movement, so by squashing the body we can exaggerate the motion.
- At the 'passing' the legs are pulled in level to the body, as they prepare to cross over and switch positions.
- At the 'high' the position switch is complete and the leading leg is swapped. The front leg straightens out as it reaches the back whilst the back leg bends and raises as it prepares to make contact at the front. The body will rise into this movement so it is a good idea to exaggerate some stretching on the body.
After the high pose is reached, the cycle will return to the contact pose, with the other leg now in front. Just by playing these 4 poses in succession you can begin to see how a walk cycle takes shape.
Now let's add in the arms. The arms and legs work in opposing actions; when a leg is stepped forward, the arm on the same side will be back and visa versa. The sketch below shows a complete walk cycle. You'll notice there are 8 poses in total; the second 4 are the same as the first 4, except the 'leading' leg and arm changes.
When these 8 poses are played in succession the result is a complete walk cycle. If you were hand drawing your animation you would now fill in 'between poses' which would help to smooth the movements out. But as we are going to be using After Effects for our cycles, we will finish this example here.
The first step to creating your walk cycle is to create your character. You'll need to break this into parts that can be animated separately, so whether you're using Illustrator or Photoshop, make sure you illustrate body parts in separate layers. For this basic animation we are going to break up the head, torso and hair. It's really important to get into the habit of naming your layers, something designers are told time after time. That's because it really does help improve your work flow, especially when you'll be switching layers so frequently. Naming layers can quite literally stop you losing your head!
We will create the arms and legs in After Effects using the Rubber Hose plug-in but if you're using another rigging tool, you'll want to separate out the arms and legs beforehand. For complex walk cycles, you could separate additional details such as eyes, feet, hands, fingers etc. The more elements you separate, the more control and movement you can express in your animation.
Once you've illustrated your assets, you'll need to import them into After Effects, make sure you chose 'retain layer size' when importing. Create a new composition, and drag your assets into the scene and arrange them in place.
You'll need to organise the parenting of the body parts to connect them together. Use the pickwhip or the parent drop down menu, and select the parent that it should connect to. The hair will be parented to the head, and the head will be parented to the body. The body will have no parent. Now you'll see if you move the body around, the head and the hair will move with it.
Now let's adjust the anchor points. Select each layer in turn, and use the 'pan behind' tool to move the anchor point to a natural pivot point. The head would pivot from the neck of the torso, and the body will pivot from the hip. Once you've moved the anchor points, changing the rotate value will pivot the parts from the right place. You won't need to adjust the anchor point for the hair as we will come to animating this later.
Now your anchor points are set, let's use Rubber Hose to create some arms and legs. From the Rubber Hose work panel use the drop down menu to choose the 'Hip/Ankle' option and then click 'new hose'.
This will give you a default grey hose, and three new layers in your composition (Ankle, Hip and Hose). The 'Ankle' layer controls one end of the hose, the 'Hip' controls the other and the 'Hose' layer controls the styling options. By selecting the Ankle layer and opening up the effect control panel, we can begin to adjust the properties such as bend direction, length etc.
Lets drag the three hose layers beneath the torso layer, then adjust the hose length in the Ankle layer to suit the leg. You can adjust the stroke weight from the 'Hose' layer if you need to make your legs thickness. I'm going for a 'Chibi' illustration style, so I'll be making short stubby legs for my character. Once you're happy with your leg, align the Hip control layer with the Torso and parent it to the Torso layer. Now if you move the torso, the leg will remain attatched at the hip.
Animating the legs
Let's refer back to our walk cycle poses and start shaping our walk. It's important to remember there is always one foot on the ground, as we need to create the illusion the foot is supporting the mass of the body.
Set a position keyframe at 0 seconds for the Ankle layer and use the walk cycle diagram to pose your leg into the 'contact' pose. You can use page up/page down on your keyboard to navigate one frame forward or backwards. Skip ahead 5 frames and set another position key frame, this time bending the leg into the 'low' pose. Repeat this for passing and high poses until you have 8 poses spaced equally 5 frames apart, then copy and paste a 9th keyframe that is the same as the first (contact) key-frame. This will enable the cycle to loop smoothly.
Now we're going to use a loop expression, which tells After Effects to continuously loop the existing key-frames. Hold the alt key and click on the position stop-watch, this will open up the expression input. In this box we will need to type loopOut("cycle") and then deselect the layer.
Now your leg is looped in motion, we'll use it to create the other leg. Select one of the hose layers, hold alt (or Option ⌘ for mac) and click the 'new-hose' in the rubber hose panel shown below.
This will duplicate the selected hose with the same position key frames. As the legs are currently moving in sync, we will need to adjust their timing slightly. Click the position property of the new hose 'Ankle' to select all the keyframes, then drag them to the left until the fourth keyframe becomes the first keyframe.
At this point you'll have a basic cycle of walking legs, which you can go ahead and stylise to match your character using the options within the 'hose' layer. If styling hoses is new to you, you can read more about it here.
Animating the arms
This is where things get a little bit easier, the process to creating the arms is almost identical to the legs. Create a new hose but this time select Shoulder/Wrist from the drop down menu and parent it in place to the torso. Now go through and add a position key-frame for the wrist layer at every pose, with 5 frames between each one. You'll need to add the loop out expression and duplicate it just like the legs to create the other arm, this time layering it beneath the torso.
Now you've got a basic walk cycle, but it's looking very rigid. Let's add some movements to exaggerate the high and low points of the animation. Using the Torso layer (or a parented null), set a position key frame at the low pose and adjust the Y value until the hips are sunk into the pose. Create another key frame at the 'High' pose, but this time use the Y value to raise the hips up and stretch into the pose. Use the loopOut("cycle") expression as before, to loop between the two poses. I like to add some additional high and low key frames for the head layer too, but delay them by 1 frame to create a drag effect.
Now it's time for some final touches, and one of my favourite walk cycle tricks is to add some drag to the hair. This can really add some bounce into to your step. Grab the 'puppet tool' from your tool panel, create some pin points along the hair (shown in yellow below). When you move a pin on the fringe you should be able to do so without deforming rest of the hair. If this is happening, you'll need to add more pins to anchor the base of the hair down.
Select the pin point of the end of the hair and add key frames to give it a flick at the high point of the walk. You can loop pin positions with the same loopOut("cycle") expression.
And there you have it, a functioning walk cycle! It's important to remember that walk cycles are a time consuming process and can be complex to get your head around. Using plugins like Rubber Hose will definitely speed things up for beginners but there is still a steep learning curve. If you didn't get it looking as smooth as you hoped for first time round, keep practicing and always refer back to the 4 key poses.
To take your walk cycles further, you can rework motions to interact with your scene or objects, see below where I've tailored the arm to pull along a Katapult kite. I also added background elements that move in reverse to the character to further the illusion of travel. Keep practicing the technical aspects of walk cycles and you'll open up new doors for your creative potential!
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