#22: The Scale Model (3/19)

This week I’ve successfully printed the scale 3D model, and set up and run several lighting tests. Printing took a little over 9 hours, using a fairly high (.2mm) layer height. I’d have loved more detail (especially since this printer can do much better), but even a .15mm layer height would’ve taken a whole day to print. The Ultimaker S5 I’m using has a number of excellent qualities – it’s robust, reliable, can handle just about any material and is very stable – but speed isn’t one of them. If I were to have another go at it, I’d love to cut the sides down and scale the whole model up, run it at a .1mm layer height to get more detail, and plan to have it spend 2 days printing. What I’ve got is just fine for this project, though.

I’ve now done several lighting tests on the scale model, and it has been a little challenging to get everything lined up, but the process has been getting quicker, and results are at least functional. Doing this at a small scale makes it a challenge to get enough precision in the projector setup, and I’m hopeful that the full-scale setup will make that much easier.

The first time, I got everything roughly set up and did some trial-and-error to get the projector in the right place, but that was never particularly effective. I had much more luck setting measurements for everything I could – an inch on this scale model is about 341 “Unreal units,” and using that and a measuring square I’m able to position the projectors in exactly the right location and with roughly the right left-right angle (i.e. about the z-axis) this is much more effective, as it leaves me with the FOV and x-axis angle as the main variables.

The FOV is, unfortunately, really imprecise in this system, for two reasons. 1) while the camera is set to the same FOV and aspect ratio as the projector, it isn’t quite able to go properly full-screen. This means I need to “guess” a little wide and eyeball it. 2) the projector includes a vertical shift, and so I’ve tilted the projectors down to center them on the model, but this means that I really don’t know what the x-axis angle of the camera wants to be. Also, the projector’s built-in lens shift means that it’s, essentially, optically keystoned, and I doubt that can be replicated in Unreal’s cameras.

Still, I’ve been able to get the projectors sufficiently aligned, and while the trial-and-error for those two parameters does take some time, at this point can get it done in less than an hour. I’m certain that doing this at scale will be easier, since it means that my projector adjustments in real life will have much higher precision, but I’m not sure what other issues might come up.