I finished the SVG map of Black Rock City. Feels good to get that out of the way. Now I have a place to put location data such as art, events and camps, from the Burning Man API. Further, with the javascript in place, it will be easier to make such maps for future years.Edit: (The original title of this post was Black Rock City map complete) Ah, it's an old truism in software development never to label something as 'complete', 'finished' or 'final'. By 'finished' above, I meant only "I has a map". The project itself is not finished.
I've since added zooming and panning capabilities. To do that, I just grabbed a library (svg-pan-zoom by ariuta)which did the essentials of what I wanted, out of the box.
However, because SVG's coordinate system increases from top to bottom, but real-life GPS increases from bottom to top (i.e. south to north, at Black Rock City, anyway), I had used SVG's transform attribute to reverse the vertical scale. While this allowed an exact mapping between the map's xy coordinates and actual GPS coordinates, this also caused the svg-pan-zoom library's vertical panning to be reversed, as in airplane controls.
In order to get the vertical panning to work properly, I had to do without the easy fix of the reversed vertical transformation and abandon the conceptually convenient x-coordinate = longitude and y-coordinate = latitude scheme. The new GPS => x,y javascript transformation incorporates a vertical flip. It took a while to get it right, but the gain is that the transformation can be any arbitrary size and origin point.