⚡ Optical & Thermal Surveillance Sizing Engine
Optical DORI & Thermal DRI Range Calculator
Calculate optical lens focal lengths, Johnson Criteria thermal DRI distances (Detection, Recognition, Identification), sensor target pixel densities, and field of view coverage for long-range PTZ cameras and dual-spectrum thermal payloads.
⚙️ 1. Optical Camera Sizing
Camera Sensor Resolution
Select visible camera resolution
Sensor Optical Format
Physical sensor dimensions
Lens Focal Length (Max Telephoto Zoom)
Optical zoom range
mm
Target Object Type & Physical Dimension
Standard dimension reference
Atmospheric Visibility & Weather Factor
Real-world extinction derating
📐 Sensor Physics & Resolution Spec
1/1.8" CMOS · 4.0 MP
Active Area (W × H)
7.18mm × 5.32mm
Pixel Pitch / Size
2.80 µm (4.0 MP)
Vertical Pixel Count
1440 Pixels (2K)
Standard Framework
EN 62676-4 DORI
💡 Engineering Note: 1/1.8" format delivers 42% larger light gathering area than 1/2.8", maintaining crisp 250 PPM facial identification in dusk conditions.
EN 62676-4 DORI Sizing Results
Calculated for 4.0 MP (2K QHD) @ 330mm Telephoto Zoom
🔍 1. Identification Distance
250 PPM · 450 Pixels
357 m
Facial detail, clothing pattern, and vehicle license plate positive identification.
👤 2. Recognition Distance
125 PPM · 225 Pixels
715 m
Verify target class (individual person vs vehicle, clothing color, weapon carrying).
👁️ 3. Observation Distance
62.5 PPM · 112 Pixels
1,429 m
Monitor scene context, crowd direction, and general perimeter activity.
🎯 4. Detection Distance
25 PPM · 45 Pixels
3.57 km
Trigger AI perimeter boundary tripwire and automated PTZ tracking alerts.
Horizontal FOV (HFOV)
1.25°
Ground Coverage Width
15.6 m
Engineering Formulation & Verification Principles
Mathematical derivation strictly compliant with EN 62676-4 international standards and thermal LWIR Johnson's Criteria.
💡 Direct Answer: Why Factory Engineers Use EN 62676-4 DORI PPM Standards
Generic online range calculators often inflate distances by using 24-pixel military detection thresholds. In commercial and industrial video surveillance, 24 pixels cannot prove target identity for legal evidence or security compliance. International standard EN 62676-4 specifies exact pixel densities: 250 Pixels Per Meter (PPM) for Identification, 125 PPM for Recognition, 62.5 PPM for Observation, and 25 PPM for Detection. This ensures system integrators pass site acceptance testing with zero disputes.
1. Optical DORI Distance (EN 62676-4)
Distance (m) = (f × vPix) / (Sensor_H × PPM)
Where f is focal length in mm, vPix is vertical sensor pixel count (1080 for 2MP, 1440 for 4MP, 2160 for 4K), Sensor_H is physical sensor height (5.32mm for 1/1.8"), and PPM is required standard pixel density.
2. Thermal DRI Distance (Johnson's Criteria)
Range (m) = (f × Dimension) / (N_cycles × Pitch_mm)
Where f is thermal focal length in mm, Dimension is target critical dimension (0.75m human, 2.3m vehicle), N_cycles is line pairs (1.5 Det, 6.0 Rec, 12.0 Id), and Pitch_mm is detector pitch (0.012mm).
3. Horizontal Field of View (HFOV)
HFOV (deg) = 2 × arctan(Sensor_W / (2 × f)) × (180/π)
Calculates exact angular coverage across the horizontal plane. Sizing telephoto focal lengths down to ~1.25° allows precise tracking of small perimeter breaches up to multiple kilometers.
4. Real-World Weather Transmission
Effective Range = Nominal Distance × Extinction_Factor
Derates nominal optical range by 15% to 60% based on atmospheric mist, sea spray, or fog density. Thermal LWIR (8-14µm) maintains 70-85% performance under light haze where visible light drops severely.
4-Step Optical & Thermal Sizing Methodology
How security consultants and EPC contractors specify multi-sensor PTZ camera systems for mission-critical sites.
Step 01
Define Surveillance Objective
Determine whether the operational requirement is positive identification (250 PPM for court evidence / facial recognition) or perimeter tripwire detection (25 PPM to dispatch patrol teams).
Step 02
Select Optimal Sensor Resolution
Choose 4MP (2K QHD) for balanced low-light sensitivity and 33% longer range than 2MP, or 8MP 4K for maximum pixel density in ultra-long-range coastal or border observation towers.
Step 03
Match Optical & Thermal Optics
Pair 30x–90x motorized zoom optical lenses with matching uncooled LWIR cores (25mm to 150mm lenses) to provide simultaneous wide situational awareness and 1-click zoomed investigation.
Step 04
Incorporate Environmental Safety Margins
Apply real-world weather derating factors (haze, precipitation, thermal atmospheric turbulence) and verify synchronized laser night vision (up to 1,000m) for complete zero-lux coverage.
Optical & Thermal Range Reference Matrix
Standard factory-verified DORI distances for popular Fengtaida industrial PTZ camera configurations.
| Camera Model / Configuration | Sensor & Resolution | Lens Focal Length | Identification (250 PPM) | Recognition (125 PPM) | Observation (62.5 PPM) | Detection (25 PPM) |
|---|---|---|---|---|---|---|
| IRW2S-55X Industrial PTZ | 1/1.8" 4.0 MP CMOS (2K) | 55x Optical (330mm) | 357 m | 715 m | 1,429 m | 3,573 m (3.57 km) |
| PTZH-86X Border Surveillance PTZ | 1/1.8" 4.0 MP CMOS (2K) | 86x Optical (860mm) | 930 m | 1,862 m | 3,723 m (3.72 km) | 9,308 m (9.31 km) |
| PTZH-4K 90X Ultra Long Range | 1/1.8" 8.0 MP 4K UHD | 90x Optical (1000mm) | 1,624 m (1.62 km) | 3,248 m (3.25 km) | 6,496 m (6.50 km) | 16,240 m (16.2 km) |
| IR6-50 Thermal PTZ (Human DRI) | 640×512 12µm Uncooled LWIR | 50mm F1.0 Lens | 260 m | 521 m | 1,042 m | 2,083 m (2.08 km) |
| IRW2D-75 Dual-Spectrum Thermal (Vehicle DRI) | 640×512 12µm Uncooled LWIR | 75mm F1.0 Lens | 1,198 m (1.20 km) | 2,396 m (2.40 km) | 4,792 m (4.79 km) | 9,583 m (9.58 km) |
| PTZD-150 Heavy-Duty Long Range Thermal | 640×512 12µm Uncooled LWIR | 150mm F1.0 Lens | 2,396 m (2.40 km) | 4,792 m (4.79 km) | 9,583 m (9.58 km) | 19,167 m (19.2 km) |
Frequently Asked Questions
Engineering principles, sensor physics, and deployment sizing guidance.
What is the difference between EN 62676-4 DORI standard and military Johnson's Criteria?
Military Johnson's Criteria relies on line pairs across critical dimensions (12 line pairs for identification, resulting in only 24 vertical pixels on a human). In commercial and industrial video surveillance, 24 pixels is insufficient for facial or license plate identification. International standard EN 62676-4 defines pixel density (Pixels Per Meter, PPM): 250 PPM for Identification (450 pixels on a 1.8m human), 125 PPM for Recognition, 62.5 PPM for Observation, and 25 PPM for Detection. This produces reliable, verifiable distances for project acceptance.
How does camera sensor resolution (2MP, 4MP, 8MP 4K) affect optical DORI distance?
Distance is directly proportional to sensor pixel count for a given sensor format. On a 1/1.8" sensor, switching from 2MP (1080P, 1080 vertical pixels) to 4MP (1440 vertical pixels) increases identification distance by 33.3%, and 8MP 4K (2160 vertical pixels) doubles identification range compared to 2MP under the same focal length (e.g. 55x 330mm).
How is thermal imaging DRI distance calculated for uncooled LWIR cores?
Thermal distance uses target critical dimension (0.75m for human, 2.3m for vehicle), thermal core pixel pitch (12µm or 17µm), focal length, and cycle criteria (1.5 line pairs for Detection, 6.0 for Recognition, 12.0 for Identification). For a 640×512 12µm sensor with a 50mm F1.0 lens, human detection reaches ~2,080 meters, recognition ~520 meters, and identification ~260 meters under clear atmospheric conditions.
How do weather, haze, and atmospheric visibility reduce effective surveillance range?
Atmospheric attenuation (Beer-Lambert law) scatters visible light and absorbs infrared radiation. In light coastal haze (visibility ~5-8 km), optical identification distance degrades by 15-20%. In moderate fog or dust (visibility <3 km), visible optical range drops by 35-50%, while thermal imaging retains superior detection performance due to longer 8-14µm wavelengths.
Can Fengtaida engineer custom dual-spectrum optical and thermal PTZ payloads for specific range requirements?
Yes. Fengtaida customizes multi-sensor PTZ payloads combining long-range optical zoom blocks (30x, 37x, 55x, 86x, 90x) with high-sensitivity uncooled thermal imaging cores (25mm to 150mm lenses) and synchronized laser illuminators (up to 1,000m) in rugged IP67 SUS304 stainless steel or marine-grade aluminum enclosures.