David Churchill

A Survey of Real-Time Strategy Game AI Research and Competition in StarCraft

This paper presents an overview of the existing work on AI for real-time strategy (RTS) games. Specifically, we focus on the work around the game StarCraft, which has emerged in the past few years as the unified test bed for this research. We describe the specific AI challenges posed by RTS games, and overview the solutions that have been explored to address them. Additionally, we also present a summary of the results of the recent StarCraft AI competitions, describing the architectures used by the participants. Finally, we conclude with a discussion emphasizing which problems in the context of RTS game AI have been solved, and which remain open.

Real-Time Strategy Game Competitions

In recent years, real-time strategy (RTS) games have gained attention in the AI research community for their multitude of challenging and relevant real-time decision problems that have to be solved in order to win against human experts or to effectively collaborate with other players in team-games. In this article we motivate research in this area, give an overview of past RTS game AI competitions, and discuss future directions.

Portfolio greedy search and simulation for large-scale combat in starcraft

Real-time strategy video games have proven to be a very challenging area for applications of artificial intelligence research. With their vast state and action spaces and real-time constraints, existing AI solutions have been shown to be too slow, or only able to be applied to small problem sets, while human players still dominate RTS AI systems. This paper makes three contributions to advancing the state of AI for popular commercial RTS game combat, which can consist of battles of dozens of units. First, we present an efficient system for modelling abstract RTS combat called SparCraft, which can perform millions of unit actions per second and visualize them. We then present a modification of the UCT algorithm capable of performing search in games with simultaneous and durative actions. Finally, a novel greedy search algorithm called Portfolio Greedy Search is presented which uses hill climbing and accurate playout-based evaluations to efficiently search even the largest combat scenarios. We demonstrate that Portfolio Greedy Search outperforms state of the art Alpha-Beta and UCT search methods for large StarCraft combat scenarios of up to 50 vs. 50 units under real-time search constraints of 40 ms per search episode.

Homing in scale space

Local visual homing is the process of determining the direction of movement required to return an agent to a goal location by comparing the current image with an image taken at the goal, known as the snapshot image. One way of accomplishing visual homing is by computing the correspondences between features and then analyzing the resulting flow field to determine the correct direction of motion. Typically, some strong assumptions need to be posited in order to compute the home direction from the flow field. For example, it is difficult to locally distinguish translation from rotation, so many authors assume rotation to be computable by other means (e.g. magnetic compass). In this paper we present a novel approach to visual homing using scale change information from Scale Invariant Feature Transforms (SIFT) which we use to compute landmark correspondences. The method described here is able to determine the direction of the goal in the robotpsilas frame of reference, irrespective of the relative 3D orientation with the goal.

An Orientation Invariant Visual Homing Algorithm

Visual homing is the ability of an agent to return to a goal position by comparing the currently viewed image with an image captured at the goal, known as the snapshot image. In this paper we present additional mathematical justification and experimental results for the visual homing algorithm first presented in Churchill and Vardy (2008). This algorithm, known as Homing in Scale Space, is far less constrained than existing methods in that it can infer the direction of translation without any estimation of the direction of rotation. Thus, it does not require the current and snapshot images to be captured from the same orientation (a limitation of some existing methods). The algorithm is novel in its use of the scale change of SIFT features as an indication of the change in the feature’s distance from the robot. We present results on a variety of image databases and on live robot trials.

StarCraft Bots and Competitions

Definition Real-Time Strategy (RTS) games is a sub-genre of strategy games where players need to build an economy (gathering resources and building a base) and military power (training units and researching technologies) in order to defeat their opponents (destroying their army and base). Artificial Intelligence (AI) problems related to RTS games deal with the behavior of an artificial player. Since 2010, many international competitions have been organized to match AIs, or bots, playing to the RTS game StarCraft. This chapter presents a review of all major international competitions from 2010 until 2015, and details some competing StarCraft bots. State of the Art Bots for StarCraft Thanks to the recent organization of international game AI competitions fo-cused around the popular StarCraft game, several groups have been working on integrating many of the techniques developed for RTS game AI into complete bots, capable of playing complete StarCraft games. In this chapter we will overview some of the currently available top bots, and their results of recent competitions.

Lithography for robust and editable atomic-scale silicon devices and memories

At the atomic scale, there has always been a trade-off between the ease of fabrication of structures and their thermal stability. Complex structures that are created effortlessly often disorder above cryogenic conditions. Conversely, systems with high thermal stability do not generally permit the same degree of complex manipulations. Here, we report scanning tunneling microscope (STM) techniques to substantially improve automated hydrogen lithography (HL) on silicon, and to transform state-of-the-art hydrogen repassivation into an efficient, accessible error correction/editing tool relative to existing chemical and mechanical methods. These techniques are readily adapted to many STMs, together enabling fabrication of error-free, room-temperature stable structures of unprecedented size. We created two rewriteable atomic memories (1.1 petabits per in2), storing the alphabet letter-by-letter in 8 bits and a piece of music in 192 bits. With HL no longer faced with this trade-off, practical silicon-based atomic-scale devices are poised to make rapid advances towards their full potential.Manipulation at the atomic scale comes with a trade-off between simplicity and thermal stability. Here, Achal et al. demonstrate improved automated hydrogen lithography and repassivation, enabling error-corrected atomic writing of large-scale structures/memories that are stable at room temperature.

Heuristic Search Techniques for Real-Time Strategy Games

Real-time strategy (RTS) video games are known for being one of the most complex and strategic games for humans to play. With a unique combination of strategic thinking and dextrous mouse movements, RTS games make for a very intense and exciting game-play experience. In recent years the games AI research community has been increasingly drawn to the field of RTS AI research due to its challenging sub-problems and harsh real-time computing constraints. With the rise of e-Sports and professional human RTS gaming, the games industry has become very interested in AI techniques for helping design, balance, and test such complex games. In this thesis we will introduce and motivate the main topics of RTS AI research, and identify which areas need the most improvement. We then describe the RTS AI research we have conducted, which consists of five major contributions. First, our depth-first branch and bound build-order search algorithm, which is capable of producing professional human-quality build-orders in real-time, and was the first heuristic search algorithm to be used on-line in a starcraft AI competition setting. Second, our RTS combat simulation system: SparCraft, which contains three new algorithms for unit micromanagement (Alpha-Beta Considering Durations (ABCD), UCT Considering Durations (UCT-CD) and Portfolio Greedy Search), each outperforming the previous state-of-the-art. Third, Hierarchical Portfolio Search for games with large search spaces, which was implemented as the AI system for the online strategy game Prismata by Lunarch Studios. Fourth, UAlbertaBot: our starcraft AI bot which won the 2013 AIIDE starcraft AI competition. And fifth: our tournament managing software which is currently used in all three major starcraft AI competitions.

Seismic Tomography as a High Performance Application

In this paper we present a dipping layer, gridded cell, ray trace tomographic system built at Memorial University for determining seismic velocity tomograms need for processing reflection and vertical seismic profiles. Based on Java, the JRAY system is portable and the code is open source which allows for modifications for research purposes. Our system design allows for parallel computing of individual shot ray paths and we have developed a natural mapping (domain decomposition) into a multi-processor computer. During the presentation we will illustrate the raytracing aspects of the three dimensional tomographic problem using the Landmark Visualization Laboratory Deep Computing Visualization system in the Earth Sciences Department at Memorial University.