How do I plan video surveillance properly?
Video surveillance.
Good images are created at the desk: with a clear goal, suitable technology and proper data protection.
In 60 seconds
- First define the goal, then choose camera, position and storage period.
- 72 hours is the guideline for the storage period.
- A sign, a balancing of interests and secured technology are part of it.
First the goal, then the camera.#
Goal first
Deterrence, evidence, operational monitoring or access verification: the goal determines camera type, position and storage period.
Technology
Resolution, lens, lighting, network with PoE and storage must fit together.
Legal and data protection
Balancing of interests, signs, storage periods and co-determination are part of it from the start.
5 camera types.#
Which design is meant for what.
Dome camera
Dome housing, unobtrusive and vandal-resistant. Good for interiors, entrances and corridors.
Bullet camera
Visible design with a deterrent effect. Typical for outdoor areas and car parks.
PTZ camera
Pans, tilts and zooms. Covers large areas, but needs an operator or automation.
Fisheye / 360°
One image for the whole room, corrected by software. Ideal for halls and reception areas.
Multi-sensor / panorama
Several sensors in one housing for very wide fields of view without gaps.
PoE power supply
Power and data over one network cable. Saves installation effort and simplifies planning.
Planning in 6 steps.#
From the idea to the running system.
Define the goal
What should be detected, and why? Put it in writing.
Define areas
Clarify viewing angle, mounting height, backlight and areas that must not be filmed.
Choose image quality
Pixel density to match the goal: recognise or identify?
Light and night vision
Check existing lighting, plan infrared or additional light if needed.
Network
Provide a PoE switch, bandwidth and a separate network for the cameras.
Storage and access
Size the recording, assign roles, automate deletion periods.
How sharp does the image need to be?#
The DORI levels: detect, observe, recognise, identify.
| Level | Pixel density | Intended for |
|---|---|---|
| Detect | 25 px/m | Detecting that someone or something is there |
| Observe | approx. 62 px/m | Observing characteristics such as clothing and movement |
| Recognise | 125 px/m | Recognising a known person |
| Identify | 250 px/m | Identifying a person unambiguously |
DORI levels as described in EN 62676-4. Guideline values: lens, lighting and compression affect the result.
Storage calculator.#
How much space do your cameras need?
Recommended capacity including 20% reserve
- Per day
- …
- Total without reserve
- …
- Total data rate
- …
RAID, mirroring or redundancy require additional space. Basis of calculation: 1 TB = 1000 GB.
Pixel density calculator.#
Which level does your camera reach at which distance?
| Level | Pixel density | Maximum distance |
|---|
Calculation for the centre of the image and a straight view. Real values depend on lens, angle and light. Guideline values according to EN 62676-4.
Data protection, explained simply.#
Guidance, not legal advice.
Legal basis and balancing
Legitimate interest usually applies (Art. 6(1)(f) GDPR). It must be documented and weighed against the interests of the people filmed. Check less intrusive means first.
Signs
People must be able to see that filming is taking place before they enter. A two-level approach is common: a sign with camera symbol, controller and contact, plus a complete information sheet.
Storage period
Supervisory authorities give 72 hours as a guideline. Longer periods need a clear justification, for example for rarely used rooms.
Employees and works council
If employees are captured, special requirements apply. A works council usually has a right of co-determination.
Image area and audio
Public paths, neighbouring properties and windows must be kept out of the picture (privacy masking). Audio recording is particularly critical and usually not permitted.
Documentation and DPIA
Record purpose, balancing and deletion concept in writing. For extensive monitoring of publicly accessible areas, a data protection impact assessment may be required.
Cameras are computers.#
They must be secured too.
- Change the default password. Many attacks exploit factory settings.
- Keep firmware up to date. Manufacturers close gaps, but only if updates are installed.
- Use a separate network. Cameras belong in a separate VLAN or network.
- No port forwarding to the internet. Access from outside only via VPN or a secured service.
- Connect with encryption. HTTPS and encrypted video streams instead of plain text.
- Roles and logs. Who may view live, who may export? Keep access traceable.
Check: planning and security.#
6 questions before you start.
Rough guidance, not legal advice. Your selection stays in your browser.
Frequently asked questions.#
May I film my entrance?
On your own property often yes, if purpose and scope are appropriate and public space and neighbours are not captured. A documented case-by-case assessment is decisive.
How long may I store recordings?
72 hours is the guideline. Longer is possible if there is a clear reason, for example weekends or rarely used rooms.
Are dummy cameras allowed?
Dummies can also create surveillance pressure and are sometimes treated similarly by authorities and courts. Better to clarify beforehand.
Do I need audio?
Probably not. Audio recording is legally particularly critical and usually not permitted. If in doubt, turn it off.
Questions? Get in touch.
Write to me if a topic is missing or you want to know more.