Regulatory Visual Requirements for HMD€¦ · – LP test for RG&WColors (HMD’s use subpixel...

Regulatory Visual Requirements for HMD

David Emig

FlightSafety Visual Systems

[email protected]

PROPRIETARY NOTICE: This document is the property of FlightSafety

International Inc. It is not to be copied in any manner or disclosed to others,

except as expressly authorized. 1

Persistent Growth in HMD Tech & Application

• Mass Market – More than 5yrs of Mass-Market VR Hype

– Nearing “Slope of Enlightenment”

– Giant markets (social media, smartphone, industry)

– Expect persistent, tangible gain

• Aviation Simulation– Many HMD-enabled Devices Already

• BISim

• Rockwell Collins

• CAE

• Boeing

• FlightSafety

• etc.




• Fast and Responsive Regulation Needed for Safety & Efficacy in a new ‘Wild West’

Hype Cycle in Progress

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Elephants in the Room

Training Challenges

1. Corporeal Compromise1. Comfort / Duration

2. Social & Physical Isolation

2. VR Sickness, Sim Sickness1. Vergence Accommodation Conflict

2. Occulomotor Conflict w/ Sim Motion

3. Limited Fidelity1. Visual: FOV, Res, Artifacts

2. Sensor: 6DOF Tracking, MR & AR EnvSensing

Long Term Solutions

1. Real & Virtual United by AR

2. Multi-Focal & VariFocal– Dynamic Lensing

3. HMD System Continuous Improvement – Imager, Optics

– Foveated, Computational Displays




HMD’s Promise for Aviation Tng

• More Training– Accessible/Portable/Remote

– Highly affordable Lower Level Device

– Future FFS-HMD, massive cost reduction

• Potential for Better Training

– Less time constraint / greater access

– On-screen & interactive instruction

– Limitless shared experience (Crew Tng, etc.)

– Advanced task-loading / Stress

– More efficient use of FTD, FFS




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Non-Visual General Req’s - TBD

• sensor/eye-tracking tests

• Possible multiplicative discomfort

(VR & Sim Sickness resonance)

• Undefined Period of Usage

• Head Tracker Accuracy

• Non-Piloting tasks, MX Tng




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Regulatory Visual Requirements for HMD




Cover all Device Types

• HMD impacts all Devices

– 2018 – Lower Level

– 2030 – Full Flight Sim

• Greatest pilot learning opportunity

in Low & Mid Level Devices --------->

• Visual requirement framework must

cover all Devices




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Cover all HMD Designs

• Many HMD Optic Designs– Magnifiers

– Relay-Based

– Monocentric

– Pancake / Polarized

– Pupil Splitting

– Tiled

– Foveated

– Fiber Scanning

– Retinal Scanning

– …

• Visual requirement framework must ensure efficacious training for all HMD designs




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Overview: Visual Requirements for HMD

• Visual Requirementsfor HMD-based Regulatory Tng– Low, Mid & High Device

– Aero/Helo

– HMD Fidelity will grow into the list

• A Prototype Framework– Details & Limits are estimates and require

review

– Leverages Today’s Requirements where possible

– < 20 HMD Specific Items & Tests, Three Sections

• Under review by ICAO 9625 TDWS VTEG

Optical System

Viewing Volume

FOV

Distortion

V.A.C.

System Artifacts

Chromatic Aberration

Lens Flare / Crepuscular

Aliasing / S.D.E.

VR Boundary Transition

Display Panel

Transport Delay

Resolution & Focus

Motion Blur & Dyn Res

Contrast

Chromatic Luminance




Measurement / Compliance Testing

• Lab equipment is costly…

– > $100k Optical Measurement Equipment

for HMD (plus annual calibration)

• Recommended Alternative…

– Visual Objective Test where possible

– Simple Re-Imager & Close-Focus Light Meter

• 60 Diopter Lens

• 4mm Aperture

• Konica Short-Focus Lens & 40.5mm lens hoods




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Specific HMD Visual Requirements

Section 1: Optical System




Viewing Volume (“Eye Box”)

• FOV, Res & Lum requirements

shall be met at DEP and at all

Eye Points within 5mm distance

from DEP.

• Method Of Compliance

– SOC that Res & Lum requirements

are met at Eye Position Extremum

– Testing, via Re-Imager, that FOV is

met at Extremum




• Training Need

– Ensure performance within margin

of head position and fitment error

– Reduce other tests to a single

Design EyePoint, DEP

• Discussion

– Human Factors

evaluation

needed to set

limits

Multiple Field Of View Requirements




• 3 FOV Types1. Field Of Regard

2. Instantaneous Monocular FOV

3. Instantaneous Binocular FOV

• Method of Compliance– Testing, via Re-Imager.

– Re-Image checkerboard onto screen template. Confirm FOV extent.

– Confirm at DEP & Extremum EPs

• Training Need – Situational awareness cues

– Adequate FOV allows gaze change, avoiding unnatural head movement

360° FoR

FOV 1 : Field Of Regard

• With head movement, the Field

Of Regard shall include all visual

area not otherwise occluded

within the aircraft.

• Method Of Compliance

– Visual Test: observe reproduction of

real-world content within 360° x

360° domain




• Training Need

– Full F.O.R for Situational Awareness

• Discussion

– Many HMD’s

provide full

visual FOR

FOV 2 : Instantaneous FOV

• Lower Device Types

– Single requirement for mono/binoc

– Covers comfortable eye rotation

range (MIL-STD-1472F 5.2.1.5.6.1)

• Mid/High Device Types

– HiFi FTD/FFS must meet visual

performance of non-HMD systems

– Cover's Full HVS range, except HFOV

reduced to match established

regulation (ICAO 9625)




HFOV VFOV HFOV VFOV

Total 45 50 180 135

Pos 27.5 25 90 60

Neg -17.5 -25 -90 -75

HFOV VFOV HFOV VFOV

Total 45 50 114 135

Pos 27.5 25 57 60

Neg -17.5 -25 -57 -75

* Binasal occlusion regions exempt >20 degrees from center

Low Device Mid / High Device


Instantatneous Combined Monocular FOV

Instantatneous Combined Binocular FOV

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Geometric Distortion




• Visual Acuity Regions

– Similar to ICAO 9625 Zones

1. Near-peripheral (< 30°)

2. Mid-peripheral (30° ~ 60°)

3. Far-peripheral (>60°)

– Absolute & Rate Of Change (ROC)

– HMD distortion also grows radially

• Training Need

– Distortion -> false cueing -> neg tng

• Method of Compliance

– Testing, via Re-Imager.

• Re-Image checkerboard onto screen

template. Confirm deviation of lines

• Rotate Re-Imager for large angles

• Confirm at DEP Only

Geometric Distortion




• Visual Acuity Regions

– Similar to ICAO 9625 Zones

1. Near-peripheral (< 30°)

2. Mid-peripheral (30° ~ 60°)

3. Far-peripheral (>60°)

– Absolute & Rate Of Change (ROC)

– HMD distortion also grows radially

• Training Need

– Distortion -> false cueing -> neg tng

Near-peripheral (< 30°)

Mid-peripheral (30° ~ 60°)

Far-peripheral (>60°)

Near-peripheral (< 30°)

Mid-peripheral (30° ~ 60°)

Far-peripheral (>60°)

NA 3

none

none

NA

0.075

0.15

0.2

Absolute Geometric Distortion (deg)


Distortion Rate Of Change (deg/deg)


0.25 0.25

0.5 0.5

Vergence – Accommodation Disparity




• VAC Requirements– Criterion: Percival's Zone of Comfort

– Lower Device – clear vision zone

– Mid/High Device – comfort zone

• Method of Compliance– SOC from Manufacturer

– Micro Vergence Tester or Analysis

– Accommodation via Analysis

• Training Need– VAC creates discomfort/sickness &

limits training duration

HMD

Piloting


Section 2: System Artifacts




HMD Visual System Artifacts

• No distracting artifacts, within a given device type’s required FOV– Flare degrades Night training

– Others primarily limit Day training

– All SpatioTemporal Aliasing included

– VR Boundary Transition applies only in AR, MR

• Method of Compliance– CAA to determine ‘distracting’

– Fully objective test possible, but disqualifies many task-effective HMDs

• Training Need– Application dependent. For a given task, artifacts can

be negligible, or can dramatically reduce visual quality and create dangerous mis-cues

Chromatic Aberration Flare / Crepuscular Rays

Aliasing

(Screen Door, Pixel Fill)

VR Boundary Transition

(VR-MR, VR-AR)




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Section 3: Display Panel




Transport Delay / Latency

• All Devices Baseline - ICAO 9625 System Requirement– No device < 200ms

– Motion must precede Visual

• AND, Higher Devices Head Rotation Requirement– Head Rotation Visual Latency

– < 32ms (20ms Vis Limit + 12ms Frame)

– Applies separately to MR & VR regions

– Tests Worst-case Grey-to-Grey Transition

• Method of Compliance– Latency tested by CAA, using manufacturer-integrated

Latency Test Mechanism

– SOC from manufacturer confirms Test Mechanism

• Training Need– Powerful determinant of Sickness/Comfort

– Latency limits training efficacy, duration and safety




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ICAO 9625

Static Resolution• Highly Modified ICAO 9625 Light Point Size Requirement

– Supersedes Surface Resolution test as design limiter (hyperacuity)

– Alternative Test Pattern, ranged to Just Noticeable Modulation

– LP test for RG&W Colors (HMD’s use subpixel rendering)

– 5 measurement locations average (Center & Eye Rot Limit Corners, ±25°)

– Multi-Location also ensures adequate optic focus

– Applies to VR and MR regions

– For Virtual Cockpit, requirement changes to minimum cockpit

information element (within reason… 5 ≥ Res ≥ 2 arcmin / OLP)


– Visual test, Modified ICAO LightPoint Size

– For Virtual Cockpit, Manufacturer analysis IDs min cockpit element

• Training Need

– Resolution necessary for detection of LightPoint, OTW Objects & Cockpit

– HMD res and focus vary across visual field, so multiple meas locations




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Motion Blur & Dynamic Resolution

• Modified ICAO 9625 Motion Blur Req.– Ensure no HMD movement during test

– Applies to VR and MR regions

– Slew Rate = established 10°/sec + nominal Head Rotation Rate.• Human Factors Analysis needed to determine Rate

• Separate rates for OTW & Virtual Cockpit

– Confirms Frame Rate via two pattern differential• Further Analysis needed to determine pattern differential approach

• Confirming frame rate mitigates sim sickness

– Additional (pattern not shown) confirms Grey-to-Grey response time via visual blur

• Method of Compliance– Visual Test per modified ICAO Motion Blur

• Training Need– Visual smooth pursuit is ubiquitous, generally unnoticed due to Vestibulo-

Ocular Reflex, but exacerbates HMD blur

– Limiting motion blur maintains safe & efficacious training




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Blur Pattern Dyn Res Pattern

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Contrast

• ICAO 9625 Surface Contrast

• ICAO 9625 Sequential Contrast

• ICAO 9625 Black Level


– Measurement via Re-Imager & Light Meter

• Training Need

– Long established regulatory minimums




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Chromatic Luminance / HK Effect

• Modified ICAO 9625 Surface Brightness, All Devices– Reduces brightness requirement per color gamut increase

• HMD color gamuts exceed today’s devices

• Helmholtz-Kohlrausch Effect

– AR regions must abide, where real-world illumination allows• Ensures adequate AR transmittance

– AR regions color neutral, within FAA runway lighting tolerances

• Method of Compliance– Measurement via Re-Imager & Light Meter

– White & color primary measurement

– Real-World target measured, before AR view

• Training Need– Long established regulatory minimums, modified for HMD display tech




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H-K Effect – Saturated colors increase perceived luminance

Further Considerations

• TBD’s

– Missing foveated Rendering tests

– Missing sensor/eye-tracking tests

– Possible multiplicative discomfort

(VR & Sim Sickness resonance)

– Undefined Period of Usage

– Head Tracker Accuracy

– Non-Piloting tasks, MX Tng

• Next Steps

– ICAO TDWS, under review by VTEG

– Many Human Factors evaluations

needed for limit-setting

– Industry feedback on proposed

framework

– Watch for HMD’s Kobayashi Maru




THANK YOU !




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Regulatory Visual Requirements for HMD€¦ · – LP test for RG&WColors (HMD’s use subpixel...

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