I work in a research environment using projectors to project a virtual environment onto a half dome. I am trying to create a compass that will use the heading coming from the environment as "north". For example, if my soldier is looking at 270 degrees in the dome, looking down at his compass he would see the compass show 270 degrees. As the soldier moves the compass inside the dome, not moving the soldier in the environment, it would offset the yaw of the compass from the "north" being reported from the simulation. The soldier is virtually in a different part of the world. The heading returned from the environment is the magnetic heading for that part of the world. Does that make sense?
see this link to have a better vision of what it looks like MetaVR
My idea would be a accelerometer that would be zeroed with a button press (facing the center of the screen) and then the offset applied based on the values coming from the accelerometer. Is this the right idea or is there a better/easier way.
Also, what kind of parts am I looking for?
Any help going about making this, would be appreciated.
I want to make a compass in the real world to mimic the virtual position of the soldier. If I move the compass in the real world to the left, I want the compass to show that if I were in the middle of the desert in Afghanistan. I.e almost like tracking the movement of the real compass to simulate a compass in the virtual environment. If the real person moves to the left without moving the image, I want the real compass to show that difference.
It doesn't take a huge magnet to overcome the magnetic field of the Earth. You can manipulate the compass with electromagnets placed around the screen.
Your idea with an accelerometer is not workable. The position errors accumulate over time. Even with reasonably good hardware, the errors become kilometers in just a few minutes. If you have a real military budget then nothing's impossible but you're deep in the range of ITAR-protected harware.
Substitute magnetometer for accelerometer. A 9DOF sensor such as a BNO055 includes a magnetometer so it can sense North. A continuous rotation servo can be used as the compass needle which is rotated so it points North, or North +/- offset when operating in virtual mode. Or use an LCD screen to draw the compass.
I would go for an LCD screen. A motor driving the simulated needle will have its own magnetic field which will disrupt any attempt to read an external magnetic field.