  Map-based methods for autonomous racing estimate the vehicle's location,
which is used to follow a high-level plan. While map-based optimisation methods
demonstrate high-performance results, they are limited by requiring a map of
the environment. In contrast, mapless methods can operate in unmapped contexts
since they directly process raw sensor data (often LiDAR) to calculate
commands. However, a major limitation in mapless methods is poor performance
due to a lack of optimisation. In response, we propose the local map framework
that uses easily extractable, low-level features to build local maps of the
visible region that form the input to optimisation-based controllers. Our local
map generation extracts the visible racetrack boundaries and calculates a
centreline and track widths used for planning. We evaluate our method for
simulated F1Tenth autonomous racing using a two-stage trajectory optimisation
and tracking strategy and a model predictive controller. Our method achieves
lap times that are 8.8% faster than the Follow-The-Gap method and 3.22% faster
than end-to-end neural networks due to the optimisation resulting in a faster
speed profile. The local map planner is 3.28% slower than global methods that
have access to an entire map of the track that can be used for planning.
Critically, our approach enables high-speed autonomous racing on unmapped
tracks, achieving performance similar to global methods without requiring a
track map.
