Map projections; it’s always a fun topic…if you are a map geek like us. When you make a map, you have to project from a round earth to a flat piece of paper or a screen. Projections are mathematical formulas to take lat/long values and project into a new coordinate system, like feet or meters. I know this stuff is a real yarner. But from our side of the app, it’s a big deal.
When we first developed OnScene Xplorer we used a “localized” projection. The “State Plane” projection was used and localized for each area. There is a “Pennsylvania North State Plane”, and a “Pennsylvania South State Plane” and so on. When we wanted to create a new data set, for example in Camden County, NJ, we had to process the data for the New Jersey flavor of State Plane. As you can imagine, as we brought on more customers, this became a big task and it became difficult to manage the base county datasets in Esri Shapefile format.
When we designed OnScene Xplorer 3.0 we decided to store all of the mapping data in once seamless dataset in a very robust database engine. So we have to move everything to a single map projection before loading into the database. We choose the “World Mercator” projection as it would suite well for any location we mapped. We re-projected and uploaded the mapping data into our master database. From that point forward we could have many people editing our one master database at the same time. No tripping over each other!
But as fate would have it, the web mapping industry gravitated over time to a new map projection created by Google Maps. The “Web Mercator Auxiliary Sphere” is now accepted as the standard. So if any app wants to take advantage of services, like satellite imagery, to include in their app, it’s best to use the “Web Mercator” projection.
For OnScene Xplorer 4.0 we will be using the “Web Mercator” projection. So do we have to re-project our master database? Nah, the tools we use to deliver data to OSX 4.0 will re-project the data on-the-fly. Therefore, with an available internet connection, users will be able to view satellite imagery or other web available layers without the performance penalty of re-projecting the data on the users’ devices.
Isn’t technology great? When we first built OSX, most of today’s tech was just a vision. We live in great times, well at least for map geeks like us.