Resource Efficient and Accurate Altitude Conversion to Mean Sea Level

In this paper we present a novel approach to efficiently and accurately convert altitudes to Mean Sea Level in real-time on resource limited devices, such as phones and wearables. The conversions are valid worldwide and do not require a network connection. We first discuss using a composite image to store on disk a spherical projection of an equirectangular map provided by the National Geospatial-Intelligence Agency. We then discuss creating an optimal image for our application, followed by using a least-recently-used cache to reduce volatile memory usage. An implementation of our work will be open-sourced and natively part of upcoming Android framework releases. It will also be available as a Jetpack library to support applications running on older API levels.