Image Credit: Common Sense

Participants at the first ever Offline Camp had diverse backgrounds and interests, ranging far beyond the Offline First approach that we came together to discuss. Through short Passion Talks, campers shared with us some of the hobbies, projects, and technologies that excite them. Here’s a taste of that passion for you as a preview to Offline Camp California (November 4–7, 2016).


Calvin Metcalf is passionate about maps. But by their nature, maps require tradeoffs. In attempting to represent a spheroid on a flat surface, cartographers always create distortion. (If your grade school science teacher ever asked you to draw a globe on an orange and then flatten the orange peel, this problem will seem familiar.) However, different map projections work to minimize distortion of different properties (area, shape, direction, distance, etc.), as Calvin shared in his passion talk at Offline Camp:

As passion talks were presented off the cuff at Offline Camp, Calvin has since tracked down a few more precise details for you:

  • The State Plane Coordinate System (SPS or SPCS) has 124 zones.
  • The difference between the 2 axes of the earth is ~21km.
  • You weigh more at the poles because you are closer to the center of the earth. The spinning of the earth also contributes to this. Whether the pear shape of the earth would lead to you weigh more on one pole versus the other is an exercise left to the reader, as Calvin has no clue. 
    ¯\_(ツ)_/¯

Calvin works for AppGeo, a company specializing in Geographic Information Systems (GIS) and geospatial Information Technology (geospatial IT).

He also helps maintain Proj4js, a JavaScript library to transform coordinates from one coordinate system to another, including datum transformations.

Campers like Calvin spent a lot of time at Offline Camp pondering how to best apply Offline First principles to mapping functionality within apps. Fellow camper Julian Simioni summarized those discussions on offline maps here:

Another favorite topic of Calvin’s is security, and he wrote a great article for us recapping our unconference discussion on the security challenges of Offline First applications. Check it out!