Working in the video game industry

This week a Queens’ CompSci alumnus, Ben Nicholson, gave us a talk about his journey in the video game industry.

Ben started life at Oxford, graduating with a degree in Mathematics. However, he quickly saw the error of his ways and decided to read the Computer Science Diploma at Queens’. This was a postgraduate course run until about 2007, that was intended as a one year crash course in Computer Science.

Like many CompScis, Ben had grown up playing video games. He wanted to combine his knowledge of maths and physics with computer science to make games a lot more realistic when it came to the laws of nature.

Ben took us through his life in the most creative way possible. His presentation was a video game (made in Unity3D) with a metaphorical hill of life. As we climbed it, we saw more and more of what he’d done.

He left Queens’ and started work at Sony on the game “This is Football” series of games. This was his first taste of working in AAA game studios and he shared valuable insights on the experience. He walked us through one of the first problems he had to solve: making goal nets move when they come in contact with a football. There was a trade-off here between how realistic the physics was and how fast the computation, and he showed us some cool physics hacks and approximations.

He then moved to Rocksteady Studios where he worked on the Batman: Arkham series of games. As the physics developer on the games, he was in charge of Batman’s cape and funky physics on ropes/explosions/hair etc. We all left with a much greater knowledge of point masses.

Ben also worked on destruction physics at Frontier Developments, leading the development of the destruction tech engine for Scream Ride. This is a game where you get to build a city, put a rollercoaster around it and then watch the ride smash through your creation.

After his 11 years working on large AAA games, Ben decided to form his own indie games studio. Inspired by his work on Batman, it’s called Cape Guy!

A lot of us, especially final year computer scientists, trying to figure out what we want to do, have thought about starting our own companies. So a game studio sounded like the perfect opportunity. However, while Ben is loving the experience, he did provide a little bit of reality check on the indie life. He talked about how things he hadn’t considered in AAA games were suddenly important – such as PR and marketing. He weighed the pros and cons of being on your own versus a big studio and spoke about how we should proceed if we wanted to join the industry. The games industry certainly provides a whole host of roles based on your interests – from game mechanics, to graphics, physics engines or high level animation.

Personally, I can’t wait for Ben’s next game – check out his twitter and website to find out more!

The annual dinner

We had the annual Computer Science dinner last Sunday. This our annual event for current students, supervisors and alumni.

First point of celebration was that all the Part II students successfully completed their projects and handed them in on time: well done everyone!

I’d like to thank the companies that sponsored us this year: Improbable, Palantir, Microsoft Research, Jane Street and Coherent Graphics. Your support is really appreciated.

This year we were lucky to have Eben Upton and Liz Upton of Raspberry Pi fame as our guests of honour. Eben gave us a really interesting talk about things that (almost) went wrong when they were getting Raspberry Pi of the ground. The moral of his story was that its never plain sailing in a startup. Imagine a swam: calm on the surface and paddling like mad underneath.

It was great to see so many people there. See you all next year.

20160515_191505

I forgot to take any more photos than this one so if anyone has any good ones then please do send them to me!

Boundary Detection in Natural Language

Does it often happen to you when you get a text “Let’s eat Eduard” and start wondering whether your friend has joined University of Cambridge Cannibalism Club? Well, worry no more, because Andi’s project is going to put all the missing punctuation in and eliminate your worries. This Wednesday he gave us a presentation on the topic.

We now (hopefully) see that missing punctuation, or in more scientific terms, missing segment boundaries, can be harmful. However, why is this problem important? Surely, if a human omits crucial piece of punctuation from the written text, it’s his own fault. However, there is another type of obtaining text, apart from writing, which has grew really popular recently. I’m talking about speech recognition. Whether you use Siri, Cortana, Alexa or “OK, Google”, they largely have the same challenge – from an infinite stream of words they want to break them down to segments to obtain original meaning. Of course, the other way to obtain punctuation is to carefully consider pauses in speech, but we’re going to assume we do not have that information available.

The project is split into four stages as shown below:

process

First, we need to gather data. For this purpose, British National Corpus was used, containing over 100 million of segments with annotated words. Some extra processing was required to remove some noise, unhelpful to the project. Finally, the corpus was filtered down to include only written text; omitting some other types of text, like meeting minutes, which were not verified and could contain grammatical and linguistic errors.

Then, we move on to training a model. For this purpose, the n-gram model was used. As Andi explained, it is a type of probabilistic language model for predicting the next item in such a sequence in the form of a (n − 1) order Markov model. In other words, we use the previous (n – 1) words to predict the next one.

Now, we can perform classification in this model. We can now estimate the probability of whether the next word or punctuation follows (n – 1) words based on the training set. After that, we can use that information to predict the punctuation by using the beam trees. Essentially we want to consider all possible branches (punctuation or next word) pruning branches with very small probability. This is beneficial, since it allows us to delay the decision point if the probabilities are similar, and only prune when the continuation of the branch was deemed to be improbable. You can see the example of this in the Figure below, when we delay the prediction whether “cat” is followed by “eats” or by a punctuation in a bi-gram model.

beamTree

Finally, we perform evaluation of the model. There are two commonly used metrics – recall and precision. Recall measures how many actual punctuation we have identified. Precision measures how many punctuations we identified were actual. However, neither of these metrics is good on its own – it’s easy to get a perfect recall by having punctuation everywhere and it’s easy to get a perfect precision by generating only really obvious punctuations. To solve this, the F-score is introduced, which combines these two metrics into a single one.

Screen Shot 2016-03-11 at 13.41.23

Easter Revision Planning: 2016

In a departure from the previous theme, we focused this week on Easter revision. Eduard collected everyone’s plans and classified them as either focusing on when to revise, or what to revise. Some of us were chosen to present our plans to everyone else. Here’s the selection of the more memorable moments from the presentations.

When, Middle Level of Detail:  Ben

Ben planned to do eight hours of work per day… on his dissertation alone. Not to mention revision for his final year exams and a three-day rowing trip. While he sketched out a rough work schedule – in sufficient detail to identify daily targets – he retained enough freedom to juggle sessions around as necessary.

When, High Level of Detail: Andy

Andy planned in great detail each hour of his day, segmenting it into blocks of exactly 1 hour 35 minutes. Andy’s plan should ensure that he stays on track, and can just run on autopilot from this stage onwards.

Image: Andy’s incredibly detailed plan.

Screen Shot 2016-03-11 at 13.45.54.png

When, Low Level of Detail: Alex no. 1

Alex started off by asserting that he was a great “believer in freedom”, and so it’s no surprise that his plan left plenty of room for improvisation. This should allow him to vary his schedule on a day-to-day basis, as per his mood.

What: Alex no. 2

Everyone was dazzled by his three page plan written in LaTeX — until he mentioned that “none of this is the actual plan.” Fortunately, he did seem to have a good alternative plan, relying heavily on tripos questions (“Java questions are jolly useful”) to revise. This is a good strategy to get to understand the style of tripos questions and cover the material at the same time.

Image: An extract from Alex’s plan written in LaTeX.

Screen Shot 2016-03-11 at 13.42.13

What: Henry

Henry emphasised the importance of taking a break, planning in a week of gliding. Cambridge can be lot of hard work, and it’s vital to take some time off to be able to focus fully during term-time.

What: Radu

Radu used fancy fitting algorithms to slot his study sessions into his timetable. Wisely, he prioritised the courses he needed by assigning them the most number of sessions. The Part II dissertation was also once more a running theme.

How it can all go wrong: Eduard

To finish off, Eduard gave a demonstration of how a plan can go wrong, even for the best of us. Overall, the message was “be honest with yourself,” and keep a realistic set of goals in mind while revising over Easter.

Image: Eduard’s example (of what not to do) plan, including travel to Japan, FIFA, meeting with friends, and a worryingly small amount of time to work on his project.

Screen Shot 2016-03-11 at 13.43.07.png

Compiler Optimisation and Automatic Loop Parallelisation

This week the Queens’ Computer Scientists were given a fascinating talk by Katie regarding her Part II project on Compiler Optimisation and Automatic Loop Parallelisation.

The project looks at exploiting parallelism automatically through compiler optimisations and distributing work across multiple cores. The benefits of which are quite remarkable: if 50% of a program is parallelizable, the speedup from parallelisation can be as much as 2x, but a program with a parallelizable code fraction of 95% could see a speedup of up to 20x!

To begin with, we were told about the basics of compiler optimisation.

Compiler optimisation aims to make code:

  • Smaller E.g. Dead code elimination, Unreachable code elimination
  • Faster E.g. Auto-Vectorisation, Auto-Parallelisation
  • Cheaper E.g. Register colouring, Cache management

 

Screen Shot 2016-03-06 at 20.14.08

There are many types of optimisation, and each type corresponds to the stage in which the compiler should be optimised. In the image above, we can see that it is possible to optimise the parse tree, intermediate code or target code. Katie chose to run her optimisations on the program’s intermediate code, because in doing so, the intermediate representation is translated from the original source code and so should have obvious basic blocks, meaning a block of code without control flow. As such, distinct units of execution are created, upon which optimisations can be carried out — this saves time and space compared to if the optimisation had been run and stored per individual instruction. Intermediate code also has a smaller number of instructions than the original source code and so it reduces the number of instruction combinations and structure that the optimisation needs to look for.

Optimisation is carried out by analysis and transform passes. The transform pass changes the code written by the programmer, and the analysis pass prevents these changes being dangerous, e.g., leading to unexpected behaviour or segmentation faults.

Unreachable elimination is one property that can be checked when optimising code, it allows for transforming the code to optimise the size of the program. However, with this comes the issue of the transform being safe; will any code be broken?

When the analysis searches for a particular program property that cannot be decided, the optimisation approximates cautiously. One example is overestimating reachability:

Screen Shot 2016-03-06 at 20.41.33

Katie adopted a similar approach in her project to implement a way of optimising a compiler to parallelise loops. The aim was to gain program speed up by utilising many cores.

It is possible to take a risk and try to parallelise code that is non-parallelizable, but the safer option is to underestimate parallelizability.

Screen Shot 2016-03-06 at 21.23.08
After carrying out safety checks in the analysis of the above loop: checking that there are no inner-loop dependencies, ensuring later iterations are independent of earlier ones, checking that arrays don’t alias to prevent dependencies between loops, bounding the loops with known constants, ensuring there are no unexpected breaks or returns, and omitting loops with reduction variables that occur on a per thread basis, Katie was able to optimise the code, extract loops and run them as separate threads distributed across multiple cores:

Screen Shot 2016-03-06 at 21.23.12
To finish her presentation, Katie talked about how she  ran a Mandelbrot set calculation with a maximum iteration of 1000 to test the compiler optimisations she had created to spread the iterations across multiple cores. The graph below shows the data from the test:
Untitled

Procedurally generating closed-circuit racetracks

In this week’s talk we had another 3rd year student, Jamie, explain his project to us and why he chose to spend his time on this subject.

Jamie started out by giving some examples of procedurally generated content. The example he used was Minecraft and how 2D Perlin Noise was used for the terrain generation. However, he explained that different methods are used in procedural generation depending on the required properties of the result. He illustrated this by explaining that Perlin Worms are used to generate the caves in Minecraft in order to increase the connectivity of the caves.

image.CN0VCY

He then went on by briefly touching upon the uses of procedural generation in audio, L-systems and city layout generation (as seen above), before going on to the main part of his talk: “Procedurally generating closed-circuit racetracks”.

Jamie started out by giving us some definitions that were necessary to understand the process. Firstly, he needed to define a racetrack, which was required to be a closed circuit and needed to have a start and a finish. Then, he talked about the different constraints one could put on the racetracks. He chose to have a number of “hard constraints”, which were properties the generated racetrack had to have, and also a number of “soft constraints”, which were properties which would be preferable but not necessary. The “hard constraints” were represented by a set of (in)equality constraints, so they had to have a certain exact values. Each “soft constraint” was represented by an Energy Function, which gave a certain racetrack a value based on its properties regarding the constraint. The total “value” of a racetrack was then found by summing all the Energy Functions.

In order to write his code and generate racetracks, he needed a way of representing the racetracks, which he did by using an ordered list of “d quadratic bezier curves”, which are a way of representing a piece of the racetrack, where each bezier curve can at most have one type of curvature.  The racetracks themselves were generated by using something called Voronoi Diagrams (as seen below).

image.0NATCY

Voronoi diagrams are represented by a group of points, with the edges being defined as the locus of points where the distances to each of the 2 closest points are equal. Jamie then created racetracks from these by selecting a collection of these edges. Each racetrack is first checked to conform with the “hard constraints” and is then optimised by minimising the sum of the energy functions of the “soft constraints” using gradient descent, which works a bit like rolling a ball down a slope (see picture below).

image.V0KZCY

Jamie finished his presentation by giving us a demo of his code and explaining that, to finish off his project, he would do a user study to see if the racetracks he generated are truly as good or maybe even better than the content that is available so far.

Parallelization, Convolutional Neural Networks and other buzz-words

Last Wednesday we were given a talk by Ben, one of the third years at Queens’. His talk introduced us to some very recent popular computer science topics and a way to combine them under his Part II project “Parallelized Deep Learning for Convolutional Neural Networks on the Intel Xeon Phi”.

He started his talk by explaining how neural networks work. We’ve seen how they aim to process information in a way similar to how biological systems, such as the brain, do it. Their structure gives the impression of a brain, by having multiple interconnected layers, each of them composed of multiple neurons. Neurons are just processing units that apply a predefined function to a set of inputs. Convolutional Neural Network are a particular case in which the function applied in each neuron is a convolution. The following picture represents the structure of a neural network, and it shows how one neuron applies its function.

Presentation.7-page-001

Ben then explains that you can train such networks to make different “intelligent” decisions – his example was understanding handwritten digits. The training can be done by minimizing the error for each training sample – in a way similar to letting a ball roll down a hill.

The theory behind all of this is as old as 1980, but requires quite high computational power. Due to recent advances in technology, using such a structure has become a feasible thing. For his project, Ben uses the Intel Xeon Phi co-processor, specialized to do parallelized computing. By splitting and parallelizing the calculation, Ben showed us how you can reduce the training time to mere seconds, compared to several days.