Abstract

Sketch 2 Graybox is a tool for 3D game designers to automatically generate a graybox prototype level from an image of a top-down level layout drawing. This approach for level prototyping aims to speed up game development by removing the bottleneck of modeling 3D graybox levels. It allows the designer to control wall and floor geometry, as well as the placement of gameplay actors based on the contents of their sketch. This is acheived through computer vision techniques such as edge detection and contour finding, as well as drawing classification through a multi-class non-linear SVM classifier trained on the Google Quickdraw Dataset

Intro

To build a level for a 3D video game, the game designer first draws a sketch: a top-down level layout on paper to fulfill a set of gameplay objectives. Next, the designer models a 3D prototype level, often called a blockout or graybox level, which matches the 2D layout. This prototyping process allows the designer to playtest the level and get feedback to assess if the level fulfills its objectives. Oftentimes, the level fails and the designer returns to the drawing board to iterate on their initial sketch or start over. The designer repeats this process until the level design fulfills its objectives.

The modeling of graybox levels can be a bottleneck in the level design process. It slows the designer’s ability to iterate because with every unique layout the designer has to reconstruct the level in 3D. This discourages significant changes due to the extra work generated. The designer may prefer to tweak a level they have already modeled over starting from scratch. Additionally, this can be a costly process for a game studio as an art department may be waiting for a completed level design to begin their work shaping the final level.

Example of Sketch 2 Graybox results automatically generating level grayboxes from sketches. This approach aims to boost creativity by allowing the designer to instantly playtest their designs and iterate without 3D modeling slowing down the process. It can also save money by speeding up the level design process and allowing artists to begin working on levels earlier in production.

An image of a top-down level layout drawing is converted to a graybox level as such. First, relevant data is extracted from the image such as level contours and instancer object bounding boxes. Secondly, 3D static level geometry and instance points are generated from that data. Thirdly, static level geometry is processed and actors are transformed to the instance points and scaled appropriately. This whole process is packaged into the game engine such that the level designer only needs to specify a filepath to their input image and tune relevant parameters such as wall and floor thickness to generate a graybox level.