Dahua - Fisheye Cameras - Mounting Heights

Resolution Tiers and Lens Lengths

Dahua panoramic fisheye cameras are available in three resolution tiers. Each tier uses a specific lens focal length, and it is this combination of resolution and focal length that determines how high a camera can be effectively mounted. The three tiers and their typical lens specifications are as follows.

5 MP — 1.4 mm lens 180° field of view (horizontal and vertical). The shorter focal length and lower pixel count mean detail degrades more quickly with height. Best suited to standard commercial ceilings of 3.0–3.5 m.
8 MP — 1.85 mm lens 185° × 180° field of view. The higher pixel count and slightly longer focal length extend the effective mounting height range compared to the 5 MP tier, making it suitable for medium ceiling environments up to approximately 4.5 m.
12 MP — 1.85 mm lens 185° × 180° field of view. Uses the same focal length as the 8 MP but with significantly more pixels across the same scene. The extra pixel density allows reliable subject identification at the greatest mounting heights of the three tiers, up to approximately 5.5 m.

8 MP vs 12 MP — Same Lens, Different Pixel Budget

Because the 8 MP and 12 MP cameras share the same 1.85 mm focal length, the field of view is identical. The only meaningful difference at a given ceiling height is pixel density — the 12 MP resolves more detail of the same scene. This is the primary reason to select 12 MP for any environment where ceilings exceed 4.5 m.

DORI Reference Distances

Dahua publishes DORI (Detect, Observe, Recognise, Identify) distances for all fisheye cameras. These figures are calculated to the EN 62676-4 standard and represent the maximum range at which a camera can achieve each level of image detail. For a ceiling-mounted fisheye looking directly downward, the Identify distance is the most operationally significant — it defines the maximum distance at which a person's face can reliably be identified from the recorded image.

Resolution	Lens	Detect	Observe	Recognise	Identify
5 MP	1.4 mm	28 m (92 ft)	11 m (36 ft)	6 m (20 ft)	3 m (10 ft)
8 MP	1.85 mm	40 m (131 ft)	16 m (52 ft)	8 m (26 ft)	4 m (13 ft)
12 MP	1.85 mm	40 m (131 ft)	16 m (52 ft)	8 m (26 ft)	4 m (13 ft)

Important — How DORI Applies to Ceiling-Mounted Fisheyes

DORI distances are measured outward from the lens, not directly beneath the camera. For a ceiling mount pointing straight down, the camera-to-subject distance equals the mounting height minus the subject's height (assumed 1.70 m). A 5 MP camera with a DORI Identify distance of 3 m therefore has an effective identification ceiling of around 4.7 m above floor level in theory — but in practice, peripheral distortion and pixel stretch in the fisheye image mean the practical limit is lower. Use the mounting height tables below rather than raw DORI figures when determining installation height.

Recommended Mounting Heights

All figures below are for nadir (straight-down) ceiling installations. A standard assumed human height of 1.70 m (66.9 in) is used, consistent with Dahua's published installer documentation. Heights are measured from finished floor to camera lens.

5 MP — 1.4 mm Lens

The following data is taken directly from Dahua's published installation recommendations for the 5 MP / 1.4 mm fisheye.

Camera Height	Camera Height (in)	Surveillance Radius	Rating	Notes
2.50 m	98.4 in	4.30 m (169 in)	Acceptable	Minimum practical height; very close-range coverage
3.00 m	118.1 in	4.20 m (165 in)	Optimal	Ideal for small retail, café, reception areas
3.50 m	137.8 in	4.00 m (157 in)	Optimal	Good general-purpose height for offices and corridors
4.00 m	157.5 in	3.70 m (146 in)	Acceptable	Upper practical limit; face detail becomes marginal
> 4.00 m	> 157.5 in	—	Not Recommended	Pixel density insufficient for reliable identification

8 MP — 1.85 mm Lens

The 8 MP camera's greater pixel count extends the effective height range. Mounting height figures are derived from the confirmed DORI Identify distance of 4 m and proportional scaling against the 5 MP official data.

Camera Height	Camera Height (in)	Estimated Surveillance Radius	Rating	Notes
2.50 m	98.4 in	~3.80 m	Acceptable	Functional but this resolution is over-specified at low heights
3.00 m	118.1 in	~4.20 m	Optimal	Excellent detail; suits retail aisles and reception areas
3.50 m	137.8 in	~4.60 m	Optimal	Ideal for open-plan offices and showrooms
4.00 m	157.5 in	~5.00 m	Optimal	Good for warehouses and medium retail floors
4.50 m	177.2 in	~5.30 m	Acceptable	Near the practical limit; identification usable with good lighting
> 5.00 m	> 196.9 in	—	Not Recommended	Subject detail insufficient for identification; use 12 MP instead

12 MP — 1.85 mm Lens

The 12 MP camera delivers the same field of view as the 8 MP via the same 1.85 mm lens but with considerably more pixels, extending effective mounting heights by approximately 1.0–1.5 m over the 8 MP equivalent.

Camera Height	Camera Height (in)	Estimated Surveillance Radius	Rating	Notes
3.00 m	118.1 in	~4.20 m	Acceptable	Functional but 12 MP is over-specified at this height
3.50 m	137.8 in	~4.60 m	Optimal	Excellent detail for medium rooms and corridors
4.00 m	157.5 in	~5.20 m	Optimal	Ideal for hotel lobbies, banking halls, large retail
4.50 m	177.2 in	~5.70 m	Optimal	Ideal for open warehouse and airport terminal areas
5.00 m	196.9 in	~6.10 m	Optimal	High-bay environments; identification remains reliable
5.50 m	216.5 in	~6.40 m	Acceptable	Near the practical limit; ensure good ambient lighting at night
> 6.00 m	> 236.2 in	—	Not Recommended	Beyond effective IR range at night; pixel density insufficient for ID

Quick-Reference — Height to Resolution

Ceiling Height	Recommended Resolution	Lens	Typical Environment
2.5 m – 4.0 m	5 MP	1.4 mm	Small retail, cafés, receptions, corridors, small offices
3.0 m – 4.5 m	8 MP	1.85 mm	Open-plan offices, mid-size retail floors, warehouses
3.5 m – 5.5 m	12 MP	1.85 mm	Airports, banking halls, hotels, large atriums, high-bay warehouses

IR Illumination at Height

All three resolution tiers are equipped with three IR LEDs with a published maximum illumination distance of 10 m (33 ft). However, a fisheye camera disperses its IR output across a full 360° circle rather than concentrating it into a directional cone. This distribution significantly reduces IR intensity at any given point in the scene compared to a conventional camera at the same rated distance.

Warning — Practical IR Range on Fisheye Cameras

In total darkness, reliable IR performance on a ceiling-mounted Dahua fisheye is effective to approximately 6–7 m, not the full 10 m figure stated in the datasheet. The 10 m specification is more achievable where some ambient lighting is present at night — such as emergency lighting, signage, or streetlight bleed in public areas. For any installation above 5 m in a completely dark environment, supplementary lighting should be considered during the design stage.

Post-Installation Checklist

After mounting, set the installation mode to Ceiling via Setting → Camera → Conditions → Fisheye in the camera web interface. Verify the dewarped live view covers the intended floor area. Test IR illumination in the actual darkness conditions of the site before sign-off — do not assume datasheet IR range without on-site verification at height.

Sources
Dahua Technology — 12MP Panoramic Network IR Fisheye Camera Datasheet, incl. DORI distances (dahuasecurity.com)
Dahua Technology — 12MP IR Fisheye WizMind Network Camera Datasheet, incl. DORI and lens specifications (dahuasecurity.com)
Dahua Technology — 8MP IR Fisheye WizMind Network Camera Datasheet, incl. DORI distances (dahuasecurity.com)
Dahua Technology — 5MP Panoramic Network IR Fisheye Camera Datasheet, incl. DORI distances and lens specification (dahuawiki.com)
Dahua Wiki — Fisheye Camera Overview, Dewarp Modes and Ceiling Mount Reference (dahuawiki.com)
Dahua Technology — 5MP Fisheye Installer Height Table (1.4 mm lens). Mounting height and surveillance radius data (3.0–4.0 m range) sourced from Dahua published installation documentation.