I need some help with edge blending

Hello,

I'm getting ready to do my first show that will require edge blending and I need some pointers. Of course, I couldn't start off with a simple 2 projector blend, I've got to start with 3 4:3 projectors rotated 90* to form one big 16:9 screen... at least it isn't curved too.

Basically, I've been using the mix keystone controls for a while, but never figured out how the aspect ratio setting works. I've just been adjusting the layer aspect ratios to make the images look right again. Is there some formula that converts the actual mix aspect ratio to the decimal value shown on the screen? 1.00 seems to be 4:3 if my memory is correct.

Any pointers on the math to figure out slice sizes and aspect ratios for each slice? I'm going to have a 10 or 15% overlap on both sides of the center, but only on the inside of the two sides, so the math isn't as easy as I'd like... Maybe I'm making this more difficult than it really is?

Also, does anyone have a good test image to use for tweaking blend alignment?

Thanks!

Make your own test image.

I recommend doing something similar to the pattern used on an Axon. It's basically a black background with a horizontal and vertical grid with alternating alphabets in each row. This is how I build all of my test patterns (although somewhat different).

You should also make your test pattern the same size (aspect and pixel count) as your final image. It doesn't need to be complex but it does need to give you a good idea of your distortion and show the scaling of your mixes.

Also, if the math works out well make a second test pattern that includes rasters for your blend areas. This will help you set the corners of your mixes.

Start with the center PJ and work out. But you'll need to keep coming back to each projector to fine tune.

I strongly recommend using the curved screen mix so you can make use of the bezier handles. Try to grab the handles from the mix itself if you can and not from the Mix panel in the hud. Also remember that your offset will adjust slightly as well but should ultimately be mathematically related to the blend region.

I recommend starting with a pow2 curve on your blend fading but don't even worry about that until your image looks good.

Get painter's string and stretch it vertically and horizontally across your screen. Make the distance between the strings the same proportionate distance between your grid in the test pattern.

Get a block of wood and tape it to your Mouse!!!!! This is the big one! For obvious reasons, you'll want your mouse sideways so your brain doesn't have to compute the 90 degree turn.

Also, when you set your default mix size in the curved screen test, set your mix point starting points to divisions of 4 of the screen size. What I mean by this are the starting coordinates of the bezier handles.

So basically, if your projector is 1600x1200 then to maximize the light output, the bezier coordinate start points will be:
(-800, 600) (-267, 200) ( 267, 600) (800, 600)
(-800, 200) (-267, 200) ( 267, 200) (800, 200)
(-800,-200) (-267,-200) ( 267,-200) (800,-200)
(-800,-600) (-267,-600) ( 267,-600) (800,-600)
And would scale inward.

Store these as a user preset and you can recall them again on the next screen. Will save you tons of time.