On the OR Wiki page, I stumbled upon this information regarding the DK1:
"The 7-inch screen also makes the stereoscopic 3D no longer 100% overlapping, the left eye seeing extra area to the left and the right eye seeing extra area to the right. The field of view (FOV) is more than 90 degrees horizontal (110 degrees diagonal), which is more than double the FOV of previous VR devices from other companies, and is the primary strength of the device."
Can anyone help me with a reliable source for these claims?
All Oculus hmds have less than 100% stereo overlap. You can see this by looking at the actual numbers returned by the sdk, or by just putting one of them on and noticing the transparent sides where one eye can see the screen and the other eye can't. This is how human vision works too, each eye naturally has greater temporal fov (towards the temples, sides of the head) than nasal fov (towards the nose), because the bridge of the nose blocks vision. It's a lot more extreme on CV1 though. Most people didn't even notice it on DK2 (it was only about 5-10 degrees).
Doubling the fov is easy to verify, just look at hmds that were available before the rift. Most consumer level vr devices (from companies like Vuzix) were 30-40 degrees horizontal, compared to 90 on the DK1. The Sony HMZ-T1 was 45 degrees. The Vuzix 1200VR was 35 degrees. The only hmds back then that did 90 degrees or more were in the tens of thousands of dollars range from companies like Sensics. Here's a wikipedia quote: "Consumer-level HMDs typically offer a FOV of about 30-40° whereas professional HMDs offer a field of view of 60° to 150°." (hehe, I wrote 30-40 before looking for that wikipedia quote. I said it because I own a 35 degree 1200VR, so knew most sat around that number).
The reason the DK1 was able to double the FOV while also being less than half the price was because most hmds used tiny expensive screens and complicated optics to avoid distortion. Oculus realised that using a cheap large screen, cheap optics and then using the power of modern graphics cards to compensate for lens distortion was easier and cheaper.
Here's a comparison page. It has 20 vr hmds with specs. The only one that came close to the rift was a Visette 2 VRi at 60 degrees. But it also had 244x756 resolution, which is horrible. http://www.mellottsvrpage.com/index.php/fov-comparison/
(The SA Photonics SA-55 is also 60 degrees on that page, but it's a military hmd that probably costs as much as a small country)
When I first started with the DK2 there was a lot of chromatic aberration stil (each color is defracted by different angles in a lens)l. I don't notice it anymore. I wonder what they did in software to fix it. I am interested in doing this myself. Correcting for the barrel distortion and chromatic aberration myself. E.g. with the HDK2. I wonder how hard this is to do in software.
When I first had the DK2 you sill had to correct for these things yourself (I think they provided code in the SDK to do this). But then later run-times automatically corrected for this. Maybe the chromatic aberration is worse with the DK2 due to the lack of Fresnel lenses?
Oculus did two different styles of lens compensation. First they did a full screen pixel shader distortion. Then later they moved to a vertex shader mesh distortion. The latter was a lot faster and gave similar results.
Chromatic aberration correction is done by doing different distortion to the red, green and blue channels of a texture. The lenses bend the light differently depending on it's colour, so each channel needs to distort differently. The down side is that moving your eyes around changes the required distortion, so it didn't work perfectly for everybody, it was made for the best general case.
If you look in the old sdks (like 0.4 or 0.5) you should be able to see the shaders used for early distortion and the algorithms. Once they moved to the mesh distortion method, they stopped telling us the formulas.
The Vive uses lenses just like Oculus I assume to get a wide FOV. They suffer from the same distortions. I wonder if their algorithms are better or worse. Do you see more chromatic aberration with the Vive. What about the HDK2. Actually, that's what I am most interested in. I assume with the HDK2 you have to do these corrections yourself.
They are probably doing the same basic thing on the Vive, just with different values due to different lenses.
The old sdks did distortion using a 4 coefficient polynomial function (4 numbers defined the effect of the lens). From 0.4 sdk onwards they changed to a 10 coefficient catmull rom spline to define the lens.
If you get the 0.4 sdk (it's still available) and look in OVR_Stereo.cpp, the algorithm used is in the LensConfig::DistortionFnInverseApprox method. After sdk 0.4, that code was moved into the binary only portion of the runtime, so we don't know if it's changed since then.
I haven't noticed any chromatic aberration with the CV1 or Vive (I don't use a Vive as often, but I do have one at work and use it occasionally). I haven't tried a HDK2.
Apparently OSVR only added distortion correction to their SteamVR driver 4 months ago. Before that you'd get a fisheye view of any SteamVR game on an OSVR HDK hmd. Here's a video: https://www.youtube.com/watch?v=SI2vMIr4VvQ I don't know about their native distortion correction (in OSVR software). But their sdk was a lot less polished than the Oculus one.
Just to make sure there isn't a simple point of confusion here:
To the OP, the DK1 was the original developer kit that released several years ago. It was the device that started the boom, resulting in this current flood of VR devices to market. It was pretty advanced compared - for the price - with every other HMD available at the time.
The CV1 is the commercial release of the Oculus Rift. It is several generations beyond the DK1 being referenced in your quote, and it does NOT have a larger FOV than other competing HMD's.
I'm posting this because I feel you might be confusing these two separate devices. The DK1 was not competing with the Vive, PSVR, or any of the current-gen HMD's. That's where the claim "which is more than double the FOV of previous VR devices from other companies" is coming from. They're not saying the current Oculus Rift (CV1) has twice the FOV of other companies VR devices.
Any sufficiently advanced technology is indistinguishable from magic.
- Arthur C Clarke
@kojack, Wow, you've been really paying attention to the code. Couldn't have said it better myself. We still use the same general method of distortion correction but we don't publish the coefficients any longer since developers are no longer responsible for implementing the prewarp shaders.
@zboson, chromatic abberation on the DK2 is highly dependent on eye position - both in relief and in lateral offset. There were some tools in the old Configuration Utility that attempted to help dial-in the chroma correction but they were often more confusing than helpful and did nothing for users with IPD's they were far from 63.5mm Things are generally better now with the new lens designs and the IPD adjustment. If you still experience chroma you should experiment with a closer eye-relief - particularly with the Vive where chroma is calibrated for a very close relief.
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