Convert 3D world space coordinates to SVG viewport coordinates

Question

I've been attempting to display the positions of players in a 3D game, on a web page, from an overhead view perspective (like a minimap). I'm simply superimposing markers (via SVG) on a 1024x1024 image of the game's level (an overhead view, taken from the game itself). I'm only concerned with the x, y coordinates, since I'm not using z in an overhead view.

The game's world has equal min/max coordinates for both x and y: -4096 to 4096. The 0, 0 coordinate is the center of the world.

To make things even more interesting, the initial position of a game level, within the game world, is arbitrary. So, for example, the upper-left world coordinate for the particular level I've been testing with is -2440, 3383.

My initial confusion comes from the fact that the 0,0 coordinate in a web page is the top-left, versus center in the world space.

How do I correctly convert the 3D world space coordinates to properly display in a web page viewport of any dimension?

Here's what I've tried (I've been attempting to use the viewbox attribute in svg to handle the upper left world coordinate offset)

scalePosition: function (targetWidth, targetHeight) {
    // in-game positions
    var gamePosition = this.get('pos');

    var MAX_X = 8192,
        MAX_Y = 8192;

    // Flip y
    gamePosition.y = -gamePosition.y;

    // Ensure game coordinates are only positive values
    // In game = -4096 < x|y < 4096 (0,0 = center)
    // Browser = 0 < x|y < 8192 (0,0 = top-left)
    gamePosition.x += 4096;
    gamePosition.y += 4096;


    // Target dimenions
    targetWidth = (targetWidth || 1024),
    targetHeight = (targetHeight || 1024);

    // Find scale between game dimensions and target dimensions
    var xScale = MAX_X / targetWidth,
        yScale = MAX_Y / targetHeight;

    // Convert in-game coords to target coords
    var targetX = gamePosition.x / xScale,
        targetY = gamePosition.y / yScale;

    return {
        x: targetX,
        y: targetY
    };
},