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• [A] Absorbing some features into Tetent

  kelvinA • 04/09/2023 at 16:17 • 0 comments

  If your're not aware, I've recently added in a 1440x1440px screen into the Tetent deliverable, to try an absorb 80% of the utility from this project.

  This is a quite similar event to #SecSavr Sublime [gd0036] --> #SecSavr Suspense [gd0105] or #Tetent Turntable [gd0038] --> #Tetent [gd0090].

  It seems like a handheld is more attainable than the wearable solution, #Tetent TimerSpy [gd0136], and it's possible that TyMist falls into this category too. Tetent is much more portable, I'm not expecting the BOM of the added feature to cost over £50 and the optional optical gear (magnifying glasses with led) is as low as £4 which makes the display slightly larger and easier to focus on without significant abberations. 

  Without the magnifying glasses, it's a 120PPD 120Hz monitor with the potential to code up multiple virtual monitors by moving or tilting Tetent.

• [T][M] Pivot to non-optical passthough solution?

  kelvinA • 03/28/2023 at 16:56 • 0 comments

  Here is an OEM VR headset, only called the "MGLASS 1" in product images:

  I saw this months ago when I was asking about the 2560px screen for the first time. This headset uses them glued onto a pancake optical module, and has 2G of RAM and 16G of storage along with HDMI input. 

  Platform			RK3566
  	CPU		Quad-Core Cortex-A55
  	GPU		Mali G52-2EE
  	Memory		2GB LPDDR4  16GB eMMC5.1
  	OS		Android 11
  Display	Display		Si-OLED
  	Size		1.03 inch*2
  	Ratio		1:1
  	Resolution		2560*2560px per eye (5120*2560 Binocular)
  	Interface		MIPI
  	Luminance		1800nits
  	Frame Rate		60HZ Max 90HZ
  	Optics Solution		pancake
  Optical	FOV		90°
  	Diopter		0~-8D
  	IPD		56~72mm
  	Dustproof		IP6X
  Speaker	Integrated
  Button	5 buttons
  Sensor and I/O	Compass + Gyroscope + Accelerometer Distance Sensor Type C  3.5mm headphone jack Micro SD HDMI
  Wireless	Bluetooth 4.2 WIFI 6 Miracast DLNA & Airplay
  Battery	3950mAh working temp. 5-35℃
  Weight	310g
  Size	W*H*Thickness 155*55*17.5mm
  Color	White or Black
  OEM/ODM	Support

  The reason why I've spent like 20 minutes copying in that table is a) to learn something new about copying and pasting tables, b) because this headset keeps popping up and dissapearing on AliExpress and c) clean up the formatting. The specs make this product sound like a PCVR headset + thin-client for portable situations.

  Now, the reason why I've mentioned this headset is because I got an idea: non-optical passthrough near-eye display that doesn't take up any more of the users vision than required. Unlike VR headsets, where you try and block out side-light from entering, this idea tries to keep as much of the view unobstructed as possible. If anything, it's somewhat more ideal if the virtual monitor isn't see-through, from a visual perspective. 

  The idea is to have 2560px displays in those vertical rounded rectangles which are also motorised so that I have the option to move them out of my vision by sending a command through #Tetent [gd0090].

  A potential strategy could be to get an MGLASS 1, dissassemble it and DIY a custom solution. In the world of VR, 38 degrees diagonal FOV should be very straightforward to do, though it's not like any on the market are targetting 90PPD so I might still run into issues.

  Unfortunately, this expensive 2560px display seems to be an inescapable choice. Again, it's a very ideal display with its cost being the largest drawback.

• [P] F45, 37mm "Google VR" Lens

  kelvinA • 03/16/2023 at 12:16 • 0 comments

  (Annoyingly, this log broke when I tried to save a draft so I have to write it all over again.)

  I got this lens a while ago (March 2) and I finally got around to taking some images. I also decided to take more images of the 60mm lens but I didn't keep track of when I stopped taking pics of the 37mm lens and when I started taking pictures of the 60mm one. Also, here's the fresnel lens images to compare, and the fresnels sure look lower quality in comparison

  Most of these images have been taken with 2 lenses stacked to emphasise any optical imperfections.

  I think these ones are the 60mm lens

• [T] FoV Solution Failure

  kelvinA • 03/12/2023 at 18:39 • 0 comments

  [18:30] So I was looking into seeing if I could obtain a valid simulation for the large 2160px displays. For 4:3 displays, I'd need 66mm of visible area.

  On AliExpress, there seems to be quite a lot of options for achromatic lenses. It's kind of suspicious though because I'm not usually able to easily find so many diverse options using AliExpress search. Maybe they finally fixed / tweaked something in their systems? Well anyway there's a decent amount in the sub £10 range, but the focal distances are all quite large so it means will need to use multiple.

  Well I was happily using 24 degree FoV in the simulator and I just realised that optics don't work with horizontal / vertical FoV's but the largest diagonal FoV. For the 2160px, this would be 30.5 degrees and for the 2560 this would be 36 degrees, so even if the 2560px was cheaper, I couldn't use it with a flat combiner. The quad 1440px = 2880px idea I had a few months back would've had no chance.

  [19:15] A solution... fails, due to the proposed optical combiner.

• [T] Returning to the 2160px

  kelvinA • 03/10/2023 at 17:12 • 0 comments

  (This log looks like a wall of text so I'm going to see if I can underline-highlight the important parts.)

  Why 2160px again?

  I have to remember that the main requirement is that I need enough pixels to work with. While I wouldn't be able to multitask all that well on a single FHD monitor, a 2160x2160px display can fit dual 1080p or 2:1 aspect ratio displays without even having to turn my head.

  I'm still going to aim for 90PPD at 90Hz, as those two metrics are the most important for comfortable work over multiple hours/days. I'd also like to add "that doesn't cost £900" onto that list, because that's near the expected BOM cost if I were to use the 2560px screens, assuming that they cost around £650 after import taxes.

  This does mean that the FOV shrinks down to 24 degrees, or 25.4 degrees at 85PPD. This is the same as an iPad Pro 12.9" that is 62cm away from the user's eyes, so it's not small in respect to other portable display devices. 

  Screen brightness concerns using the 2160px display can be addressed after solving chromatic aberrations. Spherical aberration seems fine(the screen would either look more like a CRT or a spherically curved monitor).  
  

  Curved or flat optical combiner?

  I've been considering using the curved optical combiner, but that likely would only work for the 1" displays if I want to keep the FOV at around 30. It also seems like I'd still need lenses anyway, which is what I was trying to avoid with the curved combiner idea. 

  The flat, circular combiner seems like the best solution still, since it is the most likely to achieve 90PPD, which is unlikely to be true for other technologies currently known. They are made for different requirements, whether that be augmentation of visual objects, giving instructions or showing small snippets of useful information, not for use with 3D CAD and programming toolchains like with SimulaVR.

  Custom PCB and MST

  Like I said in the previous log, I also have the opportunity to create a custom PCB that is hopefully cheaper than the £80 (excl vat) ones on AliExpress. 

  I'd still have to use the MST hub I found a whilie ago, because it doesn't seem like I can access any DisplayPort 1.4 chips (or the datasheets to them so that I know how to connect and program them). The TC358860XBG is available (since 2017) and has a maximum throughput of 600 million pixels per second. 

  (2160^2 * 90) / (600 * 10^6) = 0.69984
                              = 70% utilisation
  

  For systems that don't support MST, each eye should see the same image and should still be perfectly usable. For those that do, it would be possible to have a DP_OUT port (or USBC ideally) so that a user could connect a portable monitor to the headset to show other people their display, for work that requires accurate colour reproduction or to have one main monitor and infinite ghost / virtual monitors around it.

• [T] SecSavr Suspense required?

  kelvinA • 03/03/2023 at 22:33 • 0 comments

  For almost all metrics, the 2560px microdisplay is better than the 2160px IPS, but the thing is that burn-in is a possibility and those SiOLEDs are expensive. Not even just a tad, but an order of magnitue more than the 2160px's. The gap reduces slightly considering I'd likely have to upgrade the backlight. Project Northstar seems to be fine with the brightness of the 1440px edition of these screens though, so it potentially could still be usable without the upgrade. I'll have to see if anyone in that project has used the headset outside though.

  Additionally, I can't get full resolution @ 90Hz, but I can get 1920px upscaled @ 90Hz. 75Hz is probably fine enough, but it just adds to the difficulty of justifying the price. 

  The 2160px also is a low enough resolution that I could create a PCB using 2 Toshiba eDP chips to process the data. I might also look into the chip used for DP MST, but using an AliExpress hub for £30 is a bit more likely.

  Anyway, it seems that off-the-shelf optics aren't going to be good enough for what I'm trying to do, and would have to spec #SecSavr Suspense [gd0105] to be able to manufacture finished optical elements, and continue this project after success. Additionally, those custom PCBs could get expensive since I'd very likely need more than 2 layers for the board. That's also something else the Suspense needs to do.

  Lastly, that acrylic visor is still kind of expensive. I'm not sure if 3D printing in some future #SecSavr Syrum [gd0141] could be cheaper, but at least I'd have more geometric options for it.

  Essentially, I've come back to the same conclusion I started the project with: A TyMist solution likey doesn't exist if the Suspense doesn't exist.

• [P] Double and Half

  kelvinA • 02/17/2023 at 19:58 • 0 comments

  The lenses shipped in 11 days (bundled with other orders) and I didn't expect to get 10pcs. That's double what I thought I was ordering and I guess the listing was 2pcs x 5. I also expected the lenses to be 10-11mm but it was just over half that at 5.7mm.

  Unfortunately, there's a defocused / distorted ring that is concentric with the lens centerpoint / circumference. All lenses have it and none of the product photos showed it.

  Additionally, a long focal length does not seem to equate that chromatic abberation is reduced (compared to a shorter length), so white text / icons are still reddish on one side and bluish on the other.

• [S] First look into Win32

  kelvinA • 02/14/2023 at 21:57 • 0 comments

  [S] = Software (for projects without the software tag)

  I'm trying to think of the audio pipeline for dynamic spatial audio and soon worried about how I was actually going to show the virtual monitors from Windows 10 in the first place.

  In search of the documentation, I stumbled on a 2012 showcase of a transparent monitor with hand and head tracking. It looks really advanced for something out of 2012.

  I think I've found the place I want to be at, since I need to be able to control how the desktops are animated and moved.

  Now I'm watching the below video, and have already found out something eye-opening; everything in Windows is actually made of windows, such as buttons and status bars. 

• [T] 360 Camera SLaM

  kelvinA • 02/14/2023 at 17:30 • 0 comments

  Since I have 2 eyes, I need 2 cameras. To get over the £136 import TAX, and because the store just so conviniently had a bulk listing for them, I'm also planning to get 20 VGA cameras that are £2 each.

  Most of these cameras are going into the #SecSavr Suspense [gd0105] (as a kind of doll-house CCTV since the machine is fully sealed) but 6 of them are going to be used for 360 degree Simultaneous Localization and Mapping (SLaM) and a 180+ degree "rear view mirror" if I ever get this project to a point where it can run without being connected to a PC. 

  For what I need to accomplish for this project, I think SLaM is entirely optional but it could be useful for the dynamic spatial audio feature or being able to have virtual monitor points in space. I will admit that there's a tinge of FOMO because basically any AR HMD has some level of SLaM. 

  Hopefully, 30FPS is good enough to get something. I couldn't find a video of the GC0307 but I did find one of the very similar GC0308:

  I also couldn't find any M5 lenses to use with these, so it sounds like I'd have to manually remove the IR filters in the stock lenses or keep the SLaM to visible light only and revisit the feature if it shows potential.

• [R] Long Speaker and Narrow Lens

  kelvinA • 02/11/2023 at 22:20 • 0 comments

  Speaker system

  I was able to find the speaker module I remembered seeing >1 year ago:

  There's at least 2 similar speakers that are 85mm and 90mm long, but it seems that this one should fit in the space provided. This 80mm speaker doesn't say, but the other speakers all have a thickness of 12mm so I'm going to assume the same for this speaker. The reviews I was able to scan across listings say that this speaker is "as good as the original", and since these are for Samsung TV's, I'd assume that they're actually pretty good.

  If I recall correctly, reproduction of bass frequencies require a good amount of air movement, which can be obtained by a higher cone surface area or higher excursion. It looks like this speaker has both, looking at these video:

  For reference, the below speaker looks like the 53mm speaker I found when I first did audio research, and the excursion is drastically less:
  

  It also looks nicer and higher quality. I know the aesthetic of the speaker is of little importance, but it's something I wanted to mention. It just feels like using higher quality ingredients.

  I also would like to believe a full-length speaker cone would emulate spacial sounds more accurately than a smaller one.

  This is the speaker (or one of its similar derivatives) in their enclosures and it sounds like it rip 'n' chews (it sounds good). The test songs are nice because I can hear the response across the enitre range, from bass beats to vocals to violin strums:

  Yeah... ok... I know how I said I don't care that much about audio quality in the previous audio log but that was just me trying (and failing) to reduce my expectations. I do need some quality, just perhaps not enthusiast grade. 

  Eye tracking system

  On the eyetracking side of this project, I think I've found a very good lens for this applicaiton:

  As long as the lens MP rating exceeds that of the sensor, I shouldn't run into problems. I believe something like a 16mm lens is ideal for this application because I can just have 2 mirrors inside a tube (see below) and there's less of a chance of the camera picking up the tube walls or the two images having unusably different focus levels (because the light path is longer on one).

  I've also found an IR led that looks a lot like the EyeTrackVR recommended one.

  This one is rated for 20mA whereas the recommended one is 30mA, so I should be in safe radiation levels.

  Exciting stuff!

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