How to Build a Wiremap

Step 5 Determining the Depth

The first step to plotting out your wiremap is to figure out your project's depth. Your Wiremap's depth is the distance from the projector to your mapline. Here are the two guidelines for figuring this out.

1 - Throw Ratios: In the image below there are two angles of projection - the wide zoom and the tight zoom. Because the your mapline length is fixed, the length of the projection is determined by your projector's throw ratios.

2 - Closest Focus: The center of your wire field must be further than your closest focus measurement. Or, in other words, your depthline must be longer than closest focus + 10"

Then, if you have any choice in the matter - a smaller depth tends to make calibration easier.

Example please!

So, for my construction, I went with 128. My mapline length is 32".

My widest ratio is 1:2. With a fixed mapline of 32", the depth for this throw ratio would be:

depth = x
1:2 = 32": x corresponding ratios
1 * x = 32" * 2 cross mutiply
x = 64"

My tightest ratio is 27:72.

depth = z
27 : 72 = 32" : z corresponding ratios
27 * z = 32" * 72 cross multiply
z = (72 * 32") / 27 divide
z = 85.333

To fit my projector's throw ratio, my depth must be between 64" and 85"

Closest zoom

My projector's closest focus distance is 45". The center of the wire field must be greater than 45" away from my projector. Because the wire field is 20" deep (as is everybody's), the center of the wire field is 10" shorter than the depth. So, as long as my map line is greater than 55" out (45" + 10"), then I'll be okay.

For my case, I can just disregard this because my throw ratios are more limiting than that anyhow.

I ended up settling on a 68" depth from my projector to the mapline. This gives me a 4 inch margin of error (I'd always give myself at least a 2" margin of error, just for good measure).