Projector Calibration 6dof MP

[sagrada737]

Hello Folks,

As planned, I have finished calibrating the display on my Sim Project with its 6dof Motion Platform.   As you might imagine, I am anxious to get the Sim up and running.  Getting the display calibration completed is another step in that direction.

For a quick review...   I am using a three (3) projector setup to accomplish a 210 degree wrap-around display, using a single GTX1080Ti GPU on a Win10 PC running P3Dv4.5x   I am using the Optoma GT1080HD projectors.  These have a throw-ratio of 0.5, which makes it convenient to achieve such a display by "direction projection".   The lense to screen distance is 62.5".  The projectors are hard mounted up-side-down on a support plate.  I used 0.60" think Russian Baltic Birch, as it is cheap, lightweight, stable, and very strong.  That said, I have aluminum right-angle cross braces on the top side to further stabilize the mechanical support of the projectors.

Since the projectors are mounted up-side-down, I 3D printed a three leg mounting bracket using PLA-CarbonFiber filament.  For added mechanical security, I also used a stainless steel threaded rod through the length of each leg, such that it is fail-safe.  That said, the three legged brackets act a bit like a dampener, having a minor degree of flex, thus it has some shock absorbing capability, yet quickly returning to its fixed mounted position.  Photos next post...

Previously, I was use to performing a screen calibration with PixelWix (the OEM for Immersive Display Pro) without having the Nose Section blocking my view during calibration.   Having the Nose Section on top of the 6dof Motion Platform adds a whole new dimension to this calibration process.

Fortunately, I have a really nice tool to aid in the screen calibration process.  It is a X-Y Laser Level made by Bosch, Model GLL 2-20.  This little guys is worth its weight in gold, making it easy to establish the necessary grid point alignment.    Since it is "auto-leveling" and has a magnetic mounting plate, I can easily locate it in any location on the screen support structure/Nose Section for convenient projection of the red laser lines onto the curved screen.  The laser lines are adjusted simply by rotating/sliding the entire level to line up with the registration marks on the top and side of the projector screen.  The Grid Pattern I am using is 6 vertical and 28 horizontal.

Anyone who has worked with PixelWix or Immersive Display Pro knows that there is a bit of a learning curve to doing a full projector calibration.  Since we only need to do a screen calibration rarely, it is easy to forget the process, which can be frustrating. So it is best to make good notes on the calibration process that you can refer to when you to do it again. 

In the next post, there are some photos showing the completed Grid Pattern, the "Tunnel" calibration view, and my finished calibrated display from P3D (showing KSAN).  Notice in the Tunnel View, that I have set the Frustum setting such that the "Eye Point" is for the CA side of the cockpit.  Since this is NOT a collimated display, you have to choose the eye point that you want for the resultant display.  I have found that for me...  It is best to have it at the CA's position in the cockpit.  Of course, this results in an "offset" display view for the FO, but I have found that this is negated by the FO simply looking to the left of FO's forward view by about 30 degrees, which then eliminates mentally the "visual crab effect".  I have found that if this viewing technique is explained upfront to the person in the FO seat while taxiing straight or lined up on the runway, they will easily adapt their visual awareness, so they can see what the CA is seeing.  In my case with the 6dof Motion Platform in operation, this will be especially important to help the FO from getting "Sim sickness".

The great thing about Direct projection wrap around display, is that it adds greatly to the Sim immersion experience, while not being too expensive.  The down side is that it takes up a lot of space in the Sim Room, and as I mentioned above, that it is not a collimated display.  As they say...  "You can't have everything!"   

Anyway...   Now that the Screen Calibration is complete, I am able to proceed to fitting the major Sim modules inside the Nose Section and work on mounting and wire harness considerations.   More to do, but I'm making incremental progress.  I'm shooting for an initial flight in the Sim with 6dof MP in a couple of weeks or so...   No big rush under the current circumstances...

Mike

[sagrada737]

I forgot to add the photos...   Here they are...

[fsaviator]

Looks great Mike.  I use the same Bosch Level.  Probably one of the best tools I've ever bought and I use it for a ton of stuff.

[Shaft]

That's a fantastic setup. We're did you get your motion setup from? And more to the point what was the cost and the head hight required above the sim?

[sagrada737]

Thanks for the comments...   Regarding the 6dof Motion Platform setup...  I designed and fabricated the mechanics myself.  Metal fabrication and welding were required.  The approximate cost of the Motion Platform (minus my time) breaks down as follows:

- Steel Platform structure, including Actuators and Levers was $2,500.
- Grove Gear custom dual reduction gearboxes and mounting plates were $9,500.
- Motion Cue Controller $350.
- Servo Controllers and 2.6KW Servo Motors and cabling $3,500
- Electronics enclosures, wiring, EMI Filters, and Contactors $2,800
- Special Motion Platform concrete foundation and weldments (~14,000 lbs.) $2,500

So...   For less than $25K I was able to build my own 6dof Motion Platform.  This was an aggressive project for me to tackle, but because I am able to do welding and fabricate my own parts it was a viable project to tackle.  There are myriad ways to design a motion platform, with some better than others, and all of them having their own pluses and minuses.  I chose the Gearbox/Lever approach because it was simple and low cost, easy to mount, and very robust for the physical load I wanted to move around.   The Servo System is simple as well, very smooth control, very powerful, and interfaces nicely with the Motion Controllers.  I am using the BFF 6dof motion software, which is fairly inexpensive, yet very capable for generating complex motion cues from the flight sim.  For those sources that are "single source" items, I purchased backups in case the supplier could no longer provide product or support.

As far as vertical clearance above the Sim...   In my case, I designed the room to have 3 feet of vertical clearance between the ceiling and the top of the Sim structure.  As they say, "An inch is as good as a mile.", but I wanted a good margin in case I need to modify the Platform Actuators in the future.

Keep in mind that I am not trying to duplicate a commercial motion platform, which cost in the millions of dollars.   This is a beer budget project to challenge my design/building skills, and to have fun adding to my 737-800 Sim Project, the intent of which is to help increase the sense of immersion in the Sim experience.  From what I can tell thus far, it accomplishes that.   Further refinement of Motion Cue settings will only serve to improve the 6dof Motion Platform performance.

Mike

[Shaft]

😯 wow👍

[fsaviator]

That's a hell of a lot of beer.... ;-)