Port to Java of Cheap Ruler, a collection of very fast approximations to common geodesic measurements. Useful for performance-sensitive code that measures things on a city scale. Can be an order of magnitude faster than corresponding Turf methods.
The approximations are based on the WGS84 ellipsoid model of the Earth, projecting coordinates to a flat surface that approximates the ellipsoid around a certain latitude. For distances under 500 kilometers and not on the poles, the results are very precise — within 0.1% margin of error compared to Vincenti formulas, and usually much less for shorter distances.
cheap-ruler-java is licensed under the BSD 3-Clause License. Copyright (c) 2020, Ian Emmons. All rights reserved.
See the javadocs.
To build from source:
- Clone the repository
- In your working copy, run
./gradlew build(orgradlew buildon Windows) - The jars can be found in
build/libs
Gradle:
implementation 'mobi.emmons.cheap_ruler:cheap-ruler-java:1.0.0'
Apache Maven:
<dependency>
<groupId>mobi.emmons.cheap_ruler</groupId>
<artifactId>cheap-ruler-java</artifactId>
<version>1.0.0</version>
</dependency>
Apache Ivy:
<dependency org="mobi.emmons.cheap_ruler" name="cheap-ruler-java" rev="1.0.0"/>
The following table shows the margin of error for CheapRuler.distance() compared
to node-vincenty (a state of the art distance formula). These results are taken
from the original JavaScript implementation, but should hold for this Java port
given that all of the original JavaScript tests have been ported as well.
| lat | 0° | 10° | 20° | 30° | 40° | 50° | 60° | 70° | 80° |
|---|---|---|---|---|---|---|---|---|---|
| 1km | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% |
| 100km | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0.01% | 0.03% |
| 500km | 0.01% | 0.01% | 0.01% | 0.01% | 0.02% | 0.04% | 0.08% | 0.2% | 0.83% |
| 1000km | 0.03% | 0.03% | 0.04% | 0.06% | 0.1% | 0.17% | 0.33% | 0.8% | 3.38% |
Errors for all other methods are similar.
- cheap-ruler – The original JavaScript from which this library was ported
- cheap-ruler-cpp – C++ port of the cheap-ruler JavaScript library