Eric Alba Blog
The blog of Eric Alba, Visual Effects Supervisor in Brooklyn, NY.
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How to: Adjustable-Height #VFX Tracking Marker Poles
Sometimes, you don’t have complete control of your shooting location, you might not get a grid above your set to hang lights or any gear.
On a recent project, we were scheduled to be shooting weeks of bluescreen that required us sometimes to be low and shoot looking upward, high into our bluescreens. We would need tracking markers visible in these shots and our bluescreen was a hanging cloth, not a wall where you could affix semi-permanent markers.
I would usually hang blue or green painted dowels with tracking markers on them from the lighting grid or a Truss. Our problem is that we are constantly moving all over the floor and have multiple cameras, we simply couldn’t have a big rig like that for the sake of speed.
We came up with a cheap solution to have adjustable-height tracking markers that we could layout on different planes for 3D tracking. We concluded 10 feet was the max height we needed for all our setups over the shoot.
This post will show you how we build a bunch of these things on the cheap.
Materials you need:
Each Tracking Marker Pole needs:
1 x 3/4” x 5’ CPVC Pipe / Price $ 1.30
1 x 1/2” x 5’ CPVC Pipe / Price: approx $ 1.00
You can usually buy 10’ lengths of both pipes (it’s usually cheaper and you can have it cut down to 5’ at the store).
Before you buy the pipes, make sure there is some kind of space between the pipes when the 1/2” is inside the 3/4” pipe, a millimeter is enough, you need some space for the primer and paint later.
1 x Genova 1/2” x 3/4” CPVC Male Adapter / Mfr #: 50475Y / Price: $ 0.72 each
1 x Genova 1/2” CPVC x 1/2” Female Pipe Thread Wing Elbow / Mfr #: 53055 / Price: $ 1.15
http://www.google.com/products?q=Genova+1%2F2%22+CPVC+x+1%2F2%22+Wing+Elbow+53055&aq=f
1 x Genova 3/4” x 1/2” CPVC Reducing Coupling / Mfr #: 50175 / Price: $ 0.39 each
2 x screws for each Elbow, not too long since they’re going into 1” wooden base.
Pack of 10 x 5/8” I.D. x 13/16” O.D. O-Ring / Price $ 2.35 (23.5 cents each ring)
http://www.idealtruevalue.com/servlet/the-67684/Detail
1 x Can of All Purpose Cement / Price $ 5.47
Velcro Clear Hook &Translucent Loop 15’ x 3/4” Fastener / Model #: 91325 / Price $ 21.83
Velcro Black Universal ONE-WRAP Straps (50 straps) / Model #: 90924 / Price $ 4.91
Assembling the pieces:
Cement the Male Adapter to the 3/4” pipe, the adapter will connect to the base that you’ll build later.
Cement the Reducing Coupling to the 1/2” pipe, this acts as a stopper and “top” for the 1/2” pipe.
Let it all dry.
If you you want to help the Art/Scenic department out, sand the interior edge of the 3/4” pipe to smooth it out a little, this helps reduce the chance of scarring the paint off the 1/2” pipe when it’s sliding in and out of the 3/4”. If not, whoever is doing the painting of the pieces should do this for you.
Controlling the height:
We need something around the 1/2” pipe that you can slide up and down that acts as a stopper on the 3/4” pipe top.
At first we were going to use plastic CPVC clamps on the 1/2” but it was too tight and it scarred the paint right off the 1/2”.
We ended up using a simple O-Ring with 5/8” interior size, not too tight, can’t scratch and you can move it up and down easily.
Consult your Art or Scenic Department but i suggest primer on all the parts before painting them with the final color paint.
You’ll also need a wooden base for each marker pole, we asked construction to cut up a 1” x 4’ x 8’ plywood board into 12” squares, they’ll be painted the same time you have the pipes done. The board costs about $35 and will give you 32 bases.
Break out your Rosco Super Blue paint or whatever you’re going to use. Spraying is best, again consult with your Art or Scenic department.
So now you’ll have painted 1/2” top pipes, 3/4” Bottom pipes and wooden bases.
The last thing to do is screw 1 FPT Wing Elbow into the center of each wooden base. You can then screw the male adapter end of the 3/4” pipe into the base.
Put one O-Ring on each 1/2” pipe and then put it into the 3/4” pipe.
The Magic of Velcro:
I cut up a roll of Clear Velcro and stuck the teeth part at the top of each pipe because I know I’m usually always going to have a marker at those positions.
I then stick the furry piece on the back of the tracking marker. (more info on making tracking markers here http://www.flickr.com/photos/alba/2505310839/)
I use Velcro cable ties wrapped around the poles as a way of easily adjusting the tracking markers on them. Remember to make sure the teeth part of the velcro ties are on the outside of the pole, so they’ll grip the tracking marker’s velcro (it also avoids scratching up the paint). If you don’t wrap the ties too tight around the pole, you can simply slide the marker up and down without adjusting the velcro and wherever you stop it will stay. This is helpful when you need to adjust markers quickly between takes.
That’s pretty much it, now you have a tracking marker adjustable height pole that goes from 5’ to 10’.
Cost per Pole:
- under $3 for the 2 CPVC pipes, fittings O-ring, cement, velcro
- approx $1 for 1 x 12” base (not counting the labor to cut it up)
- the most expensive part of this is your paint (which could be hundreds of dollars for one gallon) and the labor to paint all the pieces.
Some notes/caveats:
CPVC pipe is light and durable but can warp in heat so keep them upright or lay them flat when storing or transporting. Also, If you’re not careful, you can scrape the paint easily off. so be careful not to scrape or bump equipment with the poles. And just be careful when you’re sliding the 1/2” pipe up and down to not scratch or take off paint.
With heavy use everyday, our poles needed paint touchups only once in 2+ weeks, keep a pint of paint on standby when using the poles.
These were used always indoors, because they’re fairly light, we had to be careful not to hit them with big fans or they might sway. I’m guessing outdoors these things would move around as well with a gust of wind.
P.S. I found all our materials at Lowes hardware store (in Shreveport, Louisiana where we were on location filming) but it seems online they don’t have everything, so you’re local store might vary in stock. Check to make sure everything fits, etc.
Hope you find this useful. Contact me if you have any questions.
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