Distance Calculation Using Reticle Binoculars

Presentation for the Developing Data Products course

One of the main tasks of marine mammal observers (MMO) is to estimate the distance to the marine mammals they detect during the surveys. To that end, they usually use retical binoculars, that

• allow them to measure a relative angle between their target and the horizon
• however, it does not provide the estimate of an actual distance

If the observation height is known, we can construct the distance profile (shown in the next slide) and, given the angle measured using the reticle binoculars, calculate the exact¹ distance to target.

We have developed a Shiny app, located at http://graywizard.shinyapps.io/DataProducts, that provides a user-friendly way to accomplish that.

^1. Not correcting for refraction

1. Navigate to http://graywizard.shinyapps.io/DataProducts
2. Speciy the height of the observation platform and the eye-hight of the observer
3. Select the unit of the reticle grid for your binoculars
4. Specify the tide height at the observation time
5. Align the zero reticle mark on your binoculars with the horizon
6. Specify the reticle mark that overlays the target
7. The distance profile graph for the specified heights and the distance to target would be shown in the window below

For example, for the observation height of 10 m and the target at the 10 mil reticle, the distance to target will be 1027.55 m