How to Build a Wiremap

Step 12 Calibration

Now all that hard work starts to pay off.

Find out where your projector should go by measuring it out form your construction.

When you find this spot, take your camcorder or digital camera and put it in that spot (image 1 & 2). If you're precisely where you need to be, you'll see all your wires equidistant from one another. Anywhere else, and they'll overlap. Find that hot spot, and put your projector there.

Fire up your projector and set your computer to match it's native resolution. Get to those files you downloaded and run the calib program with your wire count attached to the end of it.

Once you get that running, you should see a series of vertical strips of light. This program has your wire positions memorized, and it shines a color of light depending on how distant each wire is. The wires that are closest are red, the ones that are furthest are blue, and the ones in between are green.

The first thing you'll want to do is to drop a piece of paper about half way through your strings (maybe even a tad bit closer) to focus your image on it (image 3).

Once you're focused, your wires will probably look something like image 4 below - with each wire having bands of light and darkness. This is because your projector is out of tilt. Fix this by tilting your projector right and left.

Then, you'll probably that one side is out of tilt while the other side is lining up. This is due to the projector being out of tilt in the forward and backward dimension. This is called a keystone distortion, and it can be fixed by tilting your projector up and down. If your image is too fat on the bottom, you need to tilt your projector upwards. If it's too fat on top, tilt it downwards. Use your shims (image 5).

Now, fix the zoom on your projector. You'll want the left side of the image to just be hitting the left-most string, and the right side to be hitting the right-most string.

Try to find that hot spot - & you'll know when you hit it. Keep an eye out for when all the strings closest to you turn red. If you're having trouble, temporarily block the light coming from your projector and pull out your camcorder and try recentering the projector. Play with zoom and projector location. Keep playing with your zoom and location, and you'll find it soon. (image 6)

**tip - the projector's focal point is usually 2 - 3 inches behind the lens.
**tip - also remember that you can make micro adjustments to the foam core - this is very useful especially in the end of the calibration process.

Once you get partially calibrated, it's just lots of small fudging from there. Go up to the wire field and push on a thread in both directions to see which way the light needs to go (images 7 and 8). Take notes, and make a quick diagram:

If the strings need to be pushed this way to resolve:
_ _ _ _ _ _ _ _ _ _
\. .-->. . . . . . . .<--. . /
.\. . . . . . . . . . . . . . . /
. \. . . . . . . . . . . . . . /
. .\_ _ _ _ _ _ _ _/

... then the light needs to go this way:

_ _ _ _ _ _ _ _ _ _
\. .<--. . . . . . . .-->. . /
.\. . . . . . . . . . . . . . . /
. \. . . . . . . . . . . . . . /
. .\_ _ _ _ _ _ _ _/


If the light needs to get wider in the back but is perfect in the front, this means you need to move your projector forward and widen the focus.

Keep making these micro adjustments. This is a very time consuming process, but it's well worth is and pretty much the final step.

And lastly, I've found from experience that I'll get to this point and realize that everything is perfectly aligned except for one or two threads in the middle. This is because their holes are just off center. If you find any of these, just cut those strings, remove them, and move on.

When you're all done, it should look like image 9, below..