Lighting a massive (6'x4') canvas using RGB LEDs

[kriista]

I want to create an RGB LED setup that can light up a large (6feet by 4feet) canvas somewhat evenly.

I'm thinking a strip of LEDs along the top of the canvas with some diffusion would do most of the work with maybe some more underneath (along the bottom) so shadows wouldn't be so heavy.

I'm not really looking for perfectly even lighting, just enough so that a white canvas, in a normally lit room, would appear to be different colors (red, blue, purple etc..).

All of the LEDs would be the same color, so I wouldn't need to address each one differently. Just one master color control to rule them all.

Is this controllable from a single Arduino + a power supply?
Or would I need as many outputs as I have LEDs?
How many LEDs would it take to color an area of wall in a lit room?
Is going one main strip above and a secondary (less LEDs) strip below a reasonable way to go?

It would basically be lighting a canvas that will be painted on in a performance situation, so the painters hands would be on the canvas. So a single source would cast big shadows underneath them (which could be nice some of the time, but not all).

[CrossRoads]

take a look for stuff like this
http://www.blackanddecker.com/power-tools/9074CTN%20A.aspx
rgb led strip light.
amazing # of options our there.

[kriista]

Um, is that a cordless screwdriver you linked?

[kriista]

Right, I found some RGB light strips.

I take it those are hackable/controllable with an Arduino?
Powering them with their own PSU and instead of the control unit, using the Arduino.

Would have to figure out how big/many would be needed to adequately light something like that, then fabricate a little hood so it aims towards the painting and gets diffused a bit.

[CrossRoads]

Um, yeah, sorry about that, that was meant for another topic. Guess I didn't copy the link I wanted.
Glad you able to find some.

What about backlighting it instead?

Please explain, what is the purpose  of the different colored lights on the screen with handpainting at the same time?

Post a link to the LEDs you found.  Am sure there are multiple suppliers in the UK to be able to find something workable.

[kriista]

I've thought about backlighting too but primed canvas is fairly opaque and although it would shine through a little bit, it wouldn't be suitable as the sole source of light, or as an accent.

This is what one of the performances is generally like:

http://www.youtube.com/watch?v=wTwhnUM8xdk

It's mainly black on white, so the LEDs would serve two purposes. One would be that hopefully while in 'white' mode, they could replace the clunky/hot workslights we often use to perform with.
They work well as most places we perform in are dark, so having a bright painting is a must. The worklights, as mentioned, are very hot and uncomfortable to look at, and also cast shadows (even with two of them).

The other thing would be to shift the mood/color of the light to red or blue (or whatever) based on manual control and/or eventually some accelerometer/gyro type setup on the artist's wrists.

Just to add another dimension/element to the performance.

We'd have to be very careful for it not to become a disco show, but I think colored light could be very effective.

[CrossRoads]

Take a look at something like this
http://www.led-tape.com/

Ok, I appreciate the need for lighting above and to the sides.

The engineer in me isn't in tune with the guy making all the scracthy noises going along with the 'painting' style tho.

[CrossRoads]

This might be more cost effectve
http://www.ledlightdepot.co.uk/21-rgb-smd-5050-flexible-led-strip-300-led-1m-strips-lights.html

[kriista]

The engineer in me isn't in tune with the guy making all the scracthy noises going along with the 'painting' style tho.

The sounds are all (well 98%) coming from contact mics on the canvas. Those sounds are being sampled/captures/processed in realtime. There is an iPad in play too, but the bulk of it is sample/playback based.

We'll probably get something like the low cost version just to experiment with and to see if it's an avenue that's worth testing, then maybe move onto a more powerful system if needed.

At the moment we're also trying to expand (actually reduce) the sound processing by having accel/gyro on her wristbands that would control the sample/playback/processing by feeding data to MaxMSP running on a laptop.
This could eventually inform the lighting decisions too.

[macegr]

LED strips are probably not able to light up a canvas evenly, or at all beyond the edges. You need something more like an RGB PAR can or two, aimed at the canvas from above and back. Or an RGB wall-washer, aimed at the canvas from the floor. They can be found on eBay or American DJ pretty easily.

[kriista]

That certainly kicks the price up a bit. And would probably be more difficult to control from an Arduino.

I might do some testing with the LED strips as it's cheap, and see if it's aesthetically worthwhile and go from there.

LED strips are probably not able to light up a canvas evenly, or at all beyond the edges. You need something more like an RGB PAR can or two, aimed at the canvas from above and back. Or an RGB wall-washer, aimed at the canvas from the floor. They can be found on eBay or American DJ pretty easily.

[CrossRoads]

Maybe this then:
http://www.coolstrip.co.uk/pdf/Powerled_3_RGB.pdf

Have to find out what MR16 fitting is. Maybe make a frame around the canvas supporting these.

[kriista]

I just ordered one of those 30LED 1meter strips to test with. If it works alright I'll try more powerful solutions (or just getting more LEDs if those work OK).