Quadruped Walk [Animal and Creature Animation - Unit02]

 Quadruped Walk - Horse

12/02/24

Introduction

So this is pretty exciting! One of the reasons I wanted to start this course was due to the creature animation element. I’m pretty excited that we are ramping up the difficulty quickly but also focusing on a loop - as a game animator I love a good loop! Right before I got my first job in industry I did actually animate a tiger, however, I kind of just downloaded the rig and started animating with a bit of reference and the outcome was pretty mediocre. In this unit I wanted to really work on achieving a quality outcome that was smooth and free of glitches. These rigs tend to have a lot of controls so I wants to make sure I used the most relevant ones and controlled their motion in the graph editor to achieve accurate and flowing motions.

I was really enjoying the theory lectures based on the horse and was all ready to go with animating the horse and then the technical lecturers flipped over to a leopard which I found a little jarring. I was pretty geared up to animate a horse and there were several rigs identified to use so I thought that I’d move forward with that approach. I organised my Trello board, as show below, to focus on the horse walk to achieve the learning outcomes but added the leopard walk into my board as a stretch goal. Again I knew I needed to focus on quality over quantity to help me catch up and then once I am back on track I might have more flexibility to explore quality and quantity. 

Preproduction and Research

There were some key points that resonated with my from the theory lecturers : 

• Herbivores will have a less flexible spine and move less due to having larger stomachs to hold lots of grass.
• Carnivores are more flexible in the spine areas to allow them to bend and stretch more.
• Upper joints in animal legs will run parallel to the lower leg bone
• Front legs in particular will remain pretty straight as weight is transferred across them and they support the front half.
• The rear legs are the driving force and the front legs are the steering mechanism
• As the back right leg goes forward so will the front left one and vice versa (Generally with some overlap)

This was a great starting point but I wanted to start by gathering some reference, including the thumbnails from the lecturers, to further support this animation. As mentioned in a previous blog post I tend to have my iPad open in front of me as I work so that I can study my reference - keeping my large computer monitor clear for animating!

I liked the above thumbnails created by ‘Horse walk test 2D' Cook, N (2013) as they were similar to the thumbnails from the lecturers however used colour to make it a little more readable and identify the different parts of the animal easier. There is also annotations to make it really clear where the up, down, passing and contact poses are.

I found the above thumbnails by ‘Animal Anatomy - The Horse’ Hernandez A. (2014) interesting as it was starting to show some of the underlying bone structure of horses. I thought this might help me understand how the joint on the rig should fall.

These thumbnails from (Horses and Us, 2021) had a little more detail to it visually, however, identified the feet with colours. I know there’s only 4 legs but its easy to get confused when you’re animating and trying to understand where each foot should be.

I then felt I had enough imagery and wanted to gather some video reference to support. This video by HORSE GAITS PART 01 - WALK CYCLE ANALYSIS (2020) was similar to the last image reference, however, animated! This wasn’t the only thing that was useful in this piece - it broke down the foot striking sequence really clearly in the bottom left. This enabled me to see which feet should be in contact at any one point. This is particularly useful for me to understand how the feet would be supporting the main mass so that it was believable.

This video reference Horse Walk Cycle Reference (2023) seemed to be the closest I could find of a ‘normal’ walk where the horse was moving at a standard speed and was facing forward. There were a fair few videos I found where the head was focused elsewhere rather than the direction it was heading. I felt it important to have a piece of key video reference of a horse to refer and compare back to when animating. Thumbnails are great and will help me get 90% of the way there but the actions observed from real reference will help me make a believable animation and push that final 10%. This did seem to be a pretty stocky male stallion rather than an agile horse therefore its motions were a little weighty. However, I particularly liked the head motion in this one as you get a feeling for how the horses hold their heads when they walk - something I found harder to observe on the thumbnails.

I found some stunning reference from Muybridge (1887) that I thought would be useful to again compare against the drawn thumbnails and the poses I create with my rig as a way to check the motion.

Next I reviewed my copy of the 'Animator's Survival Kit' (Williams, 2009) to understand the key theory here from a trusted source. Needless to say this was very similar to the theory explored in the lecturers from Alex Williams (Quadruped Locomotion, 2012), unsurprisingly so given that Alex is Richard's son. You can see the key breakdown of the horse walk acting as 2 people walking offset from one another. There is the key up and down motion of the hips and chest offset from one another and a really useful breakdown of key poses such as contact, passing, up and down poses to help me understand key poses across the walk. It also reflects the key theory of the rear legs being the driving force and the front legs acting as support structures.

I had also been reviewing the 'Timing For Animation' (Whitaker & Halas, 1990) to deepen my understanding of timing and came across this section analysing timing for horses. This echoes a lot of the theory I have already explored and includes a good visual of the horizontal line across the horse to show up and down poses across a walk. It also refers directly to frame numbers which I will be able to use to help with my timing of my walk!

Lastly I grabbed the thumbnails from the video (Quadruped Locomotion, 2012) as I mentioned earlier. The breakdowns of frame numbers on this were particularly useful and there was just the right amount of detail to make the poses easily readable. I think it’s images like this that show just how powerful thumbnails really are in helping you understand the key poses. As highlighted in my ‘cartoon fox hop’ blog post - this is something I want to explore I’m more detail using ProCreate Dreams to test out poses and motion before you get bogged down in Maya. Proper planning prevent poor performance after all!

Animation

Right so I had a load of static and video reference to support me - it was time to start creating the key poses in Maya. I couldn’t get the Rhett the Clydesdale rig, however, I found another rig that was recommended on the Animation Apprentice blog page that seemed really good! It was a little slow initially but seemed to be fine after it had cached and loaded. 

I started creating the pose for frame 1 and frame 17. Below shows how I was posing the legs and trying to embed the theory I learnt about keeping the upper and lower bones parallel. I was using the rotation manipulator in side view to draw and imaginary line to check that is was parallel to the one below. This was the rotate Y axis line - as you can see in the image below it enables me to see the direction the bone is facing.

After tweaking the rig and just focusing on the hips, chest and all legs I achieved the pose shown in the image below. It was relatively tricky to manipulate all the controls but after fiddling around with them all I only really needed to use the upper bone joints, hips, pelvis and feet to get the majority of the poses I needed. I knew that I could use the extra controls later to refine the poses if need be but I would make more progress if I kept things simple. I was happy with this first pose in the sequence, it resembled the the thumbnail sketches and felt like a good first step!

However, this is where it went a little wrong! When trying to create further poses I was getting slow downs and regular crashes. I was starting to lose a lot of time on this and it became apparent that this rig wasn’t going to be viable moving forward. I tried optimising the scene size and a few other clean up techniques, however, I was getting regular and consistent crashes - very frustrating given that the first pose had gone well! I did manage to get a second pose created so that I had frame 1 and frame 17, this is the playblast I managed to capture:

It is difficult to comment on quality at this point as there is so little information in the poses, however, the more important thing was the ability to make further progress which was being hindered by the crashes. The hip and chest motion didn’t feel very believable. I knew that it should feel quite inflexible but with this first animation pass it felt a little too stiff for an animation at least. This is something I planned to address on the next rig and rather than focus on the full poses I thought I’d get the hip and chest moving in an overlapping action first to set the key positions. This way I’d be able to poses the legs and control the ‘popping’ and amount the legs can stretch from those positions set from the hips. If I posed the legs and then tweaked the hips I could end up with more problems with popping or over extended hips. 

I did a little more wider research and came across this wonderful rig. This horse was modelled by Hung Vodinh and rig produced by Anderson, J. (no date). It was responding well and actually had slightly less and easier to read controls that I thought would be useful in simplifying the animation process. There also seemed more than enough to achieve all possible fidelity I needed - so I started the process again!

It was slightly frustrating to have to restart, however, quickly playing around with the rig to stress test the performance alongside saving, closing and opening again it was apparent that this rig was going to be significantly easier to work with and more reliable. I took a slightly different approach with this rig as whilst using the thumbnails and my researched reference was good I had ran into an issue getting the hips adn chest flowing nicely moving up and down. This time I started with the hips and chest - focussing on getting their Y translation moving up and down in an overlapped fashion. This would give me a strong base to begin posing the legs. I mentioned this earlier but the hip position drastically affects the range of motion and leg IK snapping you can get. If you start with the legs and then edit the hips you might find that you get popping. So as the video below shows I got the hips working and overlapping nicely with smooth curves in the graph editor. I then focuses on posing the rear legs with the view to pose the front legs after.

This process was significantly easier and less confusing. You can see the curves of the hips and chest below that showed the overlapping action. Initially I thought it would make sense to pose the full horse rather than working on the rear and then moving to the front but this was significantly easier. Once I focused in on a particular area I was able to focus on the motion of just that area (e.g. the rear legs) then afterwards I can give the same attention to the other. Once I had that working I could then turn my focus to reviewing it together and tweaking things from there. This enable me to get a higher visual quality of motion faster than the previous method I was using with pose to pose on the previous rig.

The below video shows the progress I made with the front and back legs working together. Annoyingly I forgot to extend the timeline on this one so it’s a bit of a shorter loop! I was using infinity and cycle actions on the curves to work with on these loops - again really powerful particularly when it comes to offsetting keys that I do a lot of later. At this stage I was feeling pretty confident the base of the animation was starting to take shape and the feet motion was starting to feel believable and in line with my reference. I was making sure to keep the front legs straight as they supported and steered the motion and the back legs I made sure to keep the upper bone parallel to the lower bone in the legs as the theory lecturers described - this was helping with the believably of the anatomy and kept the rig looking natural - this was making a huge difference to the overall quality of the motion!

Below shows how I was using the upper and lower sections of the leg and the rotate handle to keep the upper and lower bones inline. I described this process earlier on the rig that was crashing - by using the centre line on the rotate tool as a imaginary guide to keep these bones working together!

The below video shows my first blocking pass of animation on this locomotion complete! I’ve got all the key frames in based on the theory lectures - my poses mirror the key pose breakdown. This was important as I knew I had a good base. What I didn’t have at this point was a smooth transition and blend between the key poses. I’d not looked at the graph editor yet and instead was focusing on the visual accuracy of the key poses compared to my reference breakdown. Therefore, my in-betweens weren’t looking good and it felt a little jerky. None-the-less this was an important milestone in this animation as the base was complete! I’d also left the tail and head and would focus on these in their own animation pass - once I’d improved the quality of this main body and leg motion I’d move onto these.

The below video shows my first pass on the graph editor to smooth out the foot motion and allow each pose to flows into one another. I’ve also added a slight rotation to the hips and chest in an over arched pattern as the legs are lifted and placed. This is only a few degrees as I knew that herbivores would have a more static spine, however, having no rotation here made it feel too mechanical so this enabled the hips and chest to feel a touch more natural in my opinion.

I went on to add a slight twist on the hips and chest as the images showed below so that I now have rotation happening in 2 axis on the hips and chest to create a slight rolling action here, but again only a few degrees. Again I feel this really helps the animation overall to feel less mechanical and whilst it is probably slightly exaggerated over a real life horse’s motion I find it still feels more believable than if I weren’t to add it. Almost going for a ‘hyper real’ approach. Another reason for this is that this horse model feels a little more agile than some of the stallion’s I’d seen in my research, therefore I felt there were some creative liberties that could be taken place to help find this horse’s personality through its motions!

I was happy with the progress I was making, however, there was one thing that was really standing out to me that I didn’t like - shown in the image below. The back right leg seemed to stretch pretty far and looked unnatural! This was from the upper bone right to the position of the foot - it was just moving a little bit too much! It was accentuated when it was in motion and although it wasn’t popping - the amount it extended made it feel like it was popping and it didn’t look good! It was time to leave the project for the night so this was my first plan of action when I return to it the next day. It actually got me thinking about all the feet and the paths of motion they were taking. I had smoothed the curves, however, I hadn’t really analysed and optimized them to get them moving naturally. For example, focusing on translate Z so that feet were moving backward at a constant rate to give the illusion this was moving forward. Also the feet were coming down softly with an ease out and they should land a bit more impactful so I wanted to break some of the translate Y curves to get those hoofs snapping or should I say ‘clopping’ down!

13/02/24

I actioned the feedback I set myself from the previous day and the legs were really starting to take shape now. This really shows how you can build up quality over time. I remember my BA(Hons) lecturer saying that 90% of the animation takes 10% of the time and that last 10% of polish takes 90% of the time. This is definitely true but it is that last 10% of polish that really helps sell the animation. The feet are flowing together naturally and the transfer of weight on the horse is feeling believable. I was really happy and wanting to keep working into this to get it feeling even more believable - my next action was to experiment with the breaking of tangents to get the feet impacting the ground a bit more firmly rather than softly as they are now.

The below images shows the translate Y curves of all feet and you can see how I have a softer motion upward as the hoof is being pulled up and then I’ve broken those tangents to land the impact.

The below curves show the translate Z curves of the feet - the goal here was to improve the consistency with the hooves as they travelled forward and backward. Previously with non smooth curves you’d either inconsistent motion and in reality it should be pretty consistent as the horse is pushing itself forward. However, if you get things too perfect it then starts to look a bit too mechanical and perfect again so eyeballing and tweaking these things loosely helps to get a bit of natural variation in!

Below shows the improvements I discussed in the last couple of paragraphs to improve the motion of the feet. I’m pleased with the motion of the hips, chest and feet as these small tweaks are helping with accurate, natural and believable motions. The hooves rolling were feeling a little off and weird in places so this was the next area that I wanted to turn my attention to.

I decided to add a slight bit of hoof roll ease in, as the image below shows. You can see that as the legs are moving backward the hoof will ease into its roll so that the action isn’t so snappy which is what would happen as the horse pushed backwards and prepared the next step. This actually reduced some of the popping on the foot and this small subtle action went a long way to improving the motion of the legs as a whole. Now I’d made a lot of tweaks to the feet and I was worried that either the upper leg bones had fallen out of parallel with the lower leg bones and I wasn’t sure how smooth the translation and rotation of the upper leg bones was. These upper bones should also be flowing into one another smoothly rather than jacking backwards and forwards. Essentially the whole leg needed to work in harmony in a natural motion so now that the feet were feeling more complete I would turn my focus to the upper leg bones!

The below video shows the improvements made to the upper leg joints across all bones. I methodically went though them all focusing first on the translation curves to ensure these moved in a natural motion and then on the rotation to make sure that the curves flowed smoothly but that the upper bone rotation mirrored the lower bone rotation. I also was conscious that the front legs needed to remain straight as they supported the chest whilst the rear was pushing. With these things in mind I went through and tweaked and watched back the animation to check the tweaks I was making in the graph editor wasn’t having a negative visual impact - balancing the smoothing of curves with the actual poses themselves. 

I feel that this again made a big different to the visual quality of the motion. The legs were looking more and more natural with each improvement. The tweaks were subtle but the upper bones were feeling really on point. I was at the point now where I was happy with all the motions that were happening on the legs, chest and hips and it was time to start of the elephants in the room - the tail and the head!

Below shows my first pass on the head. I knew that as the chest went down the head should come up and when the chest came up the head should go down. I also went back and watched the reference videos I’d found of real horses. To understand what I was aiming for. I noticed a lot of horses kept their head in the same space and facing the direction they were going - generally quite stiff. I knew I wanted mine to feel a little looser but I also wanted to stick with this general idea and not get it feeling too loose and silly. I studied the curves I created for the chest and got the head moving in the opposite direction. It was looking okay but a little weird and I wasn’t happy with it. I tried some overlapping action and offsetting the key frames. I tried exaggerating the end point motion on the head. I tried reducing the range of rotation to make it stiffer but nothing was really making it look any better.

I did a little more research into horse animation to try and understand the head a little better and came across this video Animating Horse Walk Cycle (2009) . It was actually pretty similar to the thumbnails I was using, however, it was animated. Here I noticed that the chest goes up and down twice in one walk loop - the same way I’d animated it! However, for some reason I only had my head moving up and down once - this was why it looked off because essentially the poses were incorrect. It was starting to get a bit late and I now knew what I’d done wrong but wanted to revisit it at another point - I wanted to flesh out a bit of animation on the tail to essentially get all parts moving and start on the head again with a fresh outlook tomorrow rather than reset everything at this point.

I used what I learnt about the head to make sure that the tail was swinging up when the hips came down and swinging down when the hips came up - just like the tail on the cartoon fox! I started by posing the tail and then adding the rotational values in as I described. I then offset the key frames as it went down the tail to achieve the successive breaking of joints overlapping action. I then increased the amount of rotation  so that the further you went down the tail the more the tail rotated. I hoped this would make it seem floppy! It did make it seem floppy but a little too floppy! I loved the motion in isolation as the tail whipped back and forth, however, it didn’t feel too believable and looked more like the horse was whipping its own tail for some reason.

At this point it was time to call it a night, however, I had two clear actions for the next day :

1. Reset and reanimate the head to get it moving in a realistic and natural motion
2. Reduce the amount of swish on the tail to make it feel more believable

14/02/24

The plan was to hopefully finish the animation today! It felt achievable and would mean I could start the next unit tomorrow - this would align with my plan to get back on track of things as I outlined at the beginning! I’ve been super enjoying this animation and I’ve been proud of my skills so far - I don’t think I’ve ever animated a rig of this complexity to this quality for a creature before and feel like I’ve learnt a lot! I’ll expand on this in the conclusion.

Below shows me actioning the tail to reduce the amount of swish on the rotate Z. I actually used the scale tool on the keys vertically in the graph editor to keep the proportions of the rotation in sync with one another but reduce them all overall, with then a few bespoke adjustments after. 

The below video shows these improvements visually in video form. As you can see the range of motion is a lot less, however, it still retains that swish-like motion that looks appealing. I kept it a little stiffer towards the top and looser towards the bottom. I think this looks pretty awesome and really helps enhance the full animation by creating believable and natural actions. I think its the overlapping action and successive breaking of joints that is helping this look particularly appealing. Next steps are to revisit the head and and create the overlapping actions with the chest.

Below shows the curves of the rotation on the head moving in the opposite direction to the chest to create that overlapping action. I did this by decimating the existing key frames and resetting the head and neck control curves transforms to 0 and starting from scratch! I studied my reference footage again and tried to find the ‘pose’ I wanted the head positioned in and then adding the up and down motion from there. You can see I’ve got quite a determined pose as the horse confidently walks forward. I then offset each control curve to create the successive breaking of joints to create the overlapped action.

This was vastly improved from my first attempt - it looked a lot more natural and was a lot close to my reference. The rotation is subtle but it feels like the body motion is now having an effect on the head. I also like now that the head stay facing forward, maintaining its gaze, this in itself helps the action look more natural whilst not being static. The horse was now almost feeling complete! The final touch I needed to make was on the ears so that these weren’t so static - these again needed to move in an overlapped fashion from the head.

Below shows the rotation curves for the ears. These took a little bit to get feeling natural, however, I adopted a similar approach to the tail. When studying reference I noticed that these didn’t move a lot and tended to be posed facing the direction the horse’s attention was - so I kept them facing forward. I spent a good amount of time getting the general rotation range right so that it wasn’t too broad or too stiff. Once I’d got the range I increased the range of motion slightly toward the tip of the ear to get these a bit looser, however, I did this quite subtlety so that they didn’t look too floppy. They would be cartilage so bend by not as flexible as cloth. I used successive breaking of joints again and I offset the left ear from the right to prevent twinning and create some further overlap.

The effect of the ear motion was pretty subtle and again more exaggerated than real life but was adding a little more appeal to the character through the overlapping action. I was happy with the outcome - when they didn’t move it looked odd so this added a small touch to make it feel more natural. I did notice that horses tend to flick their ears as they move and if this was a longer study I would have tried to incorporate elements like this, however, I really wanted to focus on a core believable loop. Another thing I noticed when studying reference was that horses would shake their neck and raise their head ever so often. Something that would add personality but would look odd in a loop happening repeatedly!

Final Outcomes

Finally the quadruped walk of the horse was complete! This was a really fun project where I learnt a lot about animating a horse but also the concepts of animating a quadruped in general. The theory lecturers have imprinted on me an array of key concepts that I can use when animating any quadruped generally in addition to studying specific reference to understand the anatomy and flexibility of other creature skeletons. The key general theories I learnt were : 

1. Key poses to break down a walk - How contact, passing, up and down poses work with 4 legs
2. Upper leg bones should be parallel to the lower leg bones
3. Overlapping actions and successive breaking of joints in relation to the chest and hips.
4. The flexibility of skeletal structures of herbivores and carnivores

I was really happy with the quality of this cycle. I feel like I’ve said it a million times but I feel that my level of study of horses and key poses in a walk has enabled me to make natural and believable animation which is no easy feat for a creature walk cycle. I feel I have learnt a lot about creature animation generally that I will be able to apply to other creatures or future animation to make them more believable and engaging. I’m really happy with the level of polish I managed to achieve - looking back through the work in progress images I made you can see how much all the small tweaks I made are leading to outcomes of increasing quality. The videos below show the final animation from a range of angles. In the interest of time I’ve decided to just focus on a simple playblast rather than rendering, however, this is something I’d like to come back to in order to prepare for a portfolio piece.

Perspective View

Side View

Animation Turn Around

The following videos experiment with translating the horse forward with the walk cycle looping to understand how the animation looks when moving forward. These come out generally well, although I feel there is a little bit of foot slide in places, although fairly minor. It took a little bit of time to get the correct amount of translate Z for the main body. In order to improve this I would need to investigate the translate Z on the feet in relation to the translate Z overall. Despite this I do think it looks good and shows that the work I put into the loop works as the horse is moving forward and transferring its weight between its 4 legs.

Walk Forward - Side View

Walk Forward Perspective

Render

I began development of my showreel for this module so that it was easy to share and presented more professionally. I used a simple 3 point lighting setup and rendered in Arnold from multiple camera angles. I then brought these into Premiere Pro and arranged it in a pleasing way to show the perspective render looping in full followed by multiple angles. I felt multiple angles were better than a turn around so that you could study the angles and look at the quality of work easily whilst also not taking forever to render a large number of frames that a turn around would need. Due to doing this a bit later I just rendered one video that included the walk, trot and gallop, however, moving forward I plan to get a render for each cycle and then allow the showreel to slowly develop. I will add updates to the showreel on the module contents page that collates all my work together.

Conclusion

It feels incredibly good to tick off another Unit and complete another project! I’ve updated my Trello board below to show this task moving to completion and leaving 2 tasks in my weekly backlog. I am still a little behind, however, with my plan to catch up I am on track! The plan is to tackle Unit 03 the quadruped walk next and complete by the end of the weekend; move onto Unit 04 by which point Unit 05 will be added, however, I have time off work next week which should give me enough time to tackle these tasks and be back on track! I’ve moved some tasks into the back log and tagged them as stretch goals. These are things I would like to explore but are not a priority due to my overall progress through the module. All in all I am feeling really good about my progress and the quality of outcomes being produced.

I feel I have achieved the learning outcomes, listed below, through this project! I have : 

• Understood animal anatomy through animating the horse, including elements like transfer of weight between feet; parallel upper and lower bones; keeping front legs straight and how overlapping action integrates into the range of motion occurring across different body parts.
• I feel my workflow has been efficient by gathering a range of appropriate research to support me in generating key poses and using video reference to understand how a horse would move in real life.
• I’ve created a believable quadruped walk by implementing the theory I learnt and creating natural and believable motions.
• I didn’t use the leopard rig but I’ve applied equal understanding to the Joel Horse rig through experimentation and use of controls to create key poses that implemented the theory I explored.
• Again whilst I didn’t animate a leopard I have focused on creating a quality animation of a horse instead to create realistic and dynamic animation!

Learning Objectives

1. Animal Anatomy Deep Dive: Explore animal anatomy, focusing on the major differences between various quadrupeds. Understand how anatomical variations impact movement and behaviour, providing a solid foundation for realistic animation.
2. Planning Quadruped Animation: Learn the essential principles of planning and executing quadruped animation. Develop a reliable workflow that ensures efficiency and consistency in bringing your animated creatures to life.
3. Quadruped Walk Fundamentals: Delve into the basics of quadruped walks, uncovering the common principles that underlie the movement of all four-legged creatures. Gain insights into the nuances of gait and posture that contribute to the realism of quadruped animation.
4. Introduction to the Leopard Rig by Truong: Familiarize yourself with the free and versatile Leopard Rig by Truong, a powerful resource tailored for animating quadrupeds. Learn where to find and download the rig, and explore its features and controls designed to optimize your quadruped animation workflow.
5. Hands-on Tutorial – Leopard Animation: A practical tutorial where you'll animate a leopard in motion using the Leopard Rig. Apply the principles learned in quadruped walks to create a realistic and dynamic animation, highlighting the fact that all quadrupeds share fundamental walking patterns.

Reference List

1. Anderson, J. (no date) Horse rig, Models and Maya Rigs by Joel Anderson. Available at: http://www.joel3d.com/horseByHungVodinh.html (Accessed: 27 March 2024).
2. Animating Horse Walk Cycle (2009) YouTube video, added by animan1999  [Online]. Available at https://www.youtube.com/watch?v=INQx-Lzs8mU&t=4s [Accessed 27 March 2024].
3. Cook, N (2013) ‘Horse walk test 2D’, 3D Animals in Motion, 8^th November 2013 [Blog], Available at https://naomicookyear3.blogspot.com/2013/11/horse-walk-test-2d.html (Accessed 27 March 2024).
4. Hernandez A. (2014) ‘Animal Anatomy - The Horse’, Anatomi Artistica 3402, 24^th February 2014 [Blog], Available at https://anatomiartistica3402.blogspot.com/2014/10/blog-post.html (Accessed 27 March 2024).
5. HORSE GAITS PART 01 - WALK CYCLE ANALYSIS (2020) YouTube video, added by Horses and Us [Online]. Available at https://www.youtube.com/watch?v=ZwKdHJdCMgg [Accessed 27 March 2024].
6. Horse Walk Cycle Reference (2023) YouTube video, added by Alice [Online]. Available at https://www.youtube.com/watch?v=W1eRaKNO1uA [Accessed 27 March 2024].
7. Horses and Us (2021) The ‘ambling’ horse gaits - complete guide, Horses and Us. Available at: https://www.horsesandus.com/ambling-horse-gaits/ (Accessed: 27 March 2024).
8. Muybridge, E. (1887) A Half-Stride Photographed Synchronously From Two Points of View, [Online]. https://www.alamy.com/muybridge-race-horse-image6078449.html [Accessed 27 March 2024].
9. Quadruped Locomotion (2012) YouTube video, added by Alexander Williams [Online]. Available at https://www.youtube.com/watch?v=5sc8JbO1sRs&t=4s [Accessed 27 March 2024].
10. Whitaker, H. and Halas, J. (1990) Timing for animation. London u.a.: Focal Pr.
11. Williams, R. (2009) The animator’s survival kit. London: Faber and Faber.