CCTV Coverage Maps (Blind Spot Layouts)
A useful CCTV coverage map shows what each camera must monitor, where its view reaches, and where walls, glare, or other limits reduce that view. It is a planning and verification tool, not proof of complete coverage. Plan for specific monitoring tasks, respect privacy limits, and test the installed system under the lighting and conditions it will face.
A camera map can’t catch a person who is standing behind the map. That small joke points to a real issue: a floor-plan drawing may look complete while a doorway, face, or path is poorly captured on video. I use coverage maps to guide design and testing, not to promise a view without limits.
Planning: Define Coverage Tasks, Zones, and Privacy Limits
A coverage plan starts by listing what each area requires the system to do. One camera may need to detect movement across a boundary, while another must provide enough detail to recognize a person at an entrance. These tasks shape camera choice and placement. They also help keep views within authorized areas.
Start with a current floor plan or site drawing. Mark property limits, entrances, exits, walkways, lighting, and fixed obstructions such as columns, shelves, and signs. Then divide the site into zones and name the required task for each one. Avoid vague goals such as “cover the lobby.” State what needs to be visible, from where, and under which conditions.
IEC 62676-4 gives DORI image-detail guidance: Detection, Observation, Recognition, and Identification. These are planning targets, not universal legal minimums. Record the required task for each zone and consider whether operators need to spot activity, describe a person, or identify a person from recorded footage.
| DORI task | Guidance at the subject plane | Planning question |
|---|---|---|
| Detection | 25 pixels per metre (px/m) | Is a person or object present? |
| Observation | 62.5 px/m | What is happening, and how many people are there? |
| Recognition | 125 px/m | Can a familiar person be recognized? |
| Identification | 250 px/m | Is there enough detail to identify a person? |
“Subject plane” means the location where the person or object appears in the camera’s view. A camera’s megapixel rating alone cannot confirm pixel density at that location. Lens, sensor, distance, and viewing angle all affect the result.
Privacy limits belong on the plan from the start. Mark areas that should not be filmed, such as private rooms or neighboring property, and check applicable rules for field of view, audio, signs, storage time, and who may access recordings. Next step: assign a clear monitoring task and privacy boundary to every zone.
Model and Review: Plot Views and Find Authorized Gaps
A camera field of view is the area visible through a lens from its installed position. Mapping that view helps reveal blocked sightlines and areas that are not adequately monitored. A floor-plan overlay is only a model, though: it cannot prove image quality, show every lighting problem, or replace a field test.
Plot each proposed camera’s position, direction, and estimated view on the plan. Include the subject locations that matter, not just the outline of the camera’s broadest view. Check whether walls, open doors, furniture, plants, signs, or vehicles may block a person at those locations. Review the view from standing and seated subject positions where relevant.
Next, assess image detail at the target locations against the DORI task assigned to each zone. Lens and sensor data can help estimate performance, but the installed image should be measured or otherwise checked at the subject plane. Do not assume that two fields of view must overlap by a fixed percentage: there is no universal overlap rule for every site. Set placement from the task, geometry, lighting, and risk.
Flag uncovered areas only within the authorized monitoring plan. The aim is to correct operational gaps, not to publish a guide to avoiding cameras. Limit access to detailed plans, and avoid sharing unmasked views of private or neighboring spaces.
Plan review checklist – Are all entrances and key routes assigned a monitoring task? – Are likely obstructions shown? – Do the target locations meet the intended image-detail goal? – Are privacy boundaries and any required masks noted? – Are estimates marked as estimates until verified on site?
Next step: review the proposed views with the people responsible for operations, privacy, and system maintenance before installation.
Access and Clearances: Check Sightlines, Obstructions, and Cable Routes
Sightline review checks whether the camera can see the intended subject without a physical or visual barrier. A clear line on a drawing does not guarantee a clear image in use. Doors move, displays change, and lighting shifts, so the plan should note both fixed obstacles and conditions that may vary during normal operation.
Inspect the site at the camera’s proposed location and along its intended view. Look for columns, door swings, shelving, hanging signs, seasonal displays, and vehicle paths. Consider whether normal activity could block the view. Record the condition and decide whether to adjust the location, change the lens, or accept and document a limitation.
Check cable routes during the same review. Power and data cabling must suit the installation space and comply with locally adopted electrical, building, and fire codes. Requirements vary by cable type and location, including whether a cable passes through a plenum space. Confirm routing, support, protection, and firestopping needs with the applicable code and qualified professionals. Do not compromise fire or electrical safeguards to improve a camera view.
There is no single camera height or placement pattern that works for every site. Select mounting geometry based on the required task, lens, sensor, subject distance, lighting, and access needs. A higher position may widen a view but can reduce useful face detail; verify the trade-off in the actual image rather than relying on a rule of thumb.
Next step: mark proposed mounting points, sightline concerns, cable routes, and code checks together on the working plan.
Execution: Install, Aim, Configure, and Mask Cameras
Installation turns the reviewed plan into a working system. The camera must be mounted, aimed, connected, and configured for the task assigned to its zone. Recording settings and time accuracy matter too: an image may be clear, but a recording can be less useful if it is missing, poorly timed, or available to the wrong users.
Mount and aim each camera according to the approved plan, then compare its live view with the intended subject locations. Adjust only after checking image detail and privacy boundaries. Configure recording, date and time synchronization, user access, and any privacy masks. A privacy mask blocks selected portions of an image; confirm that it protects the intended area without obscuring required coverage.
Review exposure, focus, and motion handling in the conditions expected at the site. In particular, a bright doorway behind a person can turn a face into a silhouette. Low light can also reduce detail, while motion blur may make a moving subject hard to assess. If the image fails the task, consider lighting, exposure settings, camera position, or a different monitoring objective.
Keep a record of camera identifiers, intended zones, settings, mask locations, and known limits. Store detailed maps and access credentials securely. Follow applicable privacy rules for audio and recordings; do not assume that a camera’s technical ability to capture sound means recording audio is allowed.
Next step: compare the installed view with the approved map and document any change before closing out the work.
Verification: Test DORI Performance and Document Residual Gaps
Verification checks whether the installed system performs the assigned task at important subject locations. It should test actual images, not just camera specifications or drawn view cones. Test representative day and night conditions, movement paths, and expected lighting changes, then record what the system can and cannot show.
Use a repeatable test plan. Check each critical target location at the distance and angle expected in normal use. Assess image detail against the DORI goal, and check focus, exposure, glare, shadows, and motion blur. Where pixel density is measured, record the measurement point and method so later checks can be compared fairly.
Pay special attention to backlighting and low light. A doorway can appear covered on a map while faces are lost in glare or silhouette. Test when the bright background and interior lighting match operating conditions. If detail is insufficient, adjust lighting, exposure, position, or the task itself, then test again.
Record residual limitations in plain language: for example, “face detail is reduced when the exterior door is open at night.” Do not label a zone fully covered when a known condition prevents the assigned task. Keep the map current after changes to layout, lighting, camera settings, or the surrounding environment.
Next step: schedule a recheck after site changes and use the same target points where possible.
Worked Planning Examples and Coverage Table
The following examples are illustrative planning scenarios, not reports of specific installations. They show how a task-based map can guide decisions without claiming perfect coverage. In each case, the plan records the intended view, the condition to test, and any limit that remains after review.
| Site area | Assigned task | Issue found during review | Practical response |
|---|---|---|---|
| Building entrance | Identification at the approach | Daylight from behind the subject may cause silhouette | Test in daylight and at night; adjust lighting, exposure, or position |
| Shop aisle | Observation along a route | Shelving blocks part of the view | Reposition or add a camera if justified; retest the route |
| Shared property edge | Detection within authorized boundary | View may extend into a neighbor’s space | Re-aim or apply a privacy mask, then verify both coverage and masking |
| Parking access | Detection of movement near an entry | Headlights can cause glare | Test with vehicles present and adjust settings or placement |
For an entrance, the map should identify where a person needs to be seen and whether the goal is observation or identification. For a long aisle, it should show where shelving interrupts the view, rather than treating the whole aisle as covered. At a shared boundary, privacy limits may require a narrower view or a mask, even if that means accepting a documented coverage limit.
Next step: use the table format to log each zone’s task, test condition, corrective action, and remaining limitation.
Conclusion and FAQ
A useful camera coverage plan connects each area to a defined task, checks sightlines and privacy, and then tests real footage under real conditions. DORI guidance helps describe image detail, but it does not replace site review or legal and code checks. Keep the map secure and update it when the site changes.
What is a CCTV coverage map?
It is a plan showing camera positions, intended views, monitoring tasks, privacy limits, and known gaps. It guides installation and testing; it does not prove that every view will work in every condition.
What does DORI mean?
DORI means Detection, Observation, Recognition, and Identification. IEC 62676-4 provides image-detail guidance for these tasks, measured in pixels per metre at the subject plane.
What is the DORI target for identification?
The guidance target is 250 px/m at the subject plane. It is not a universal legal minimum, and actual performance should be checked in the installed image.
Can megapixels alone show whether a camera is suitable?
No. Megapixel count does not establish image detail at a subject’s location. Lens, sensor, distance, viewing angle, and lighting also affect the result.
How do I find a coverage gap?
Compare the assigned task with images from key subject locations. Check obstructions, image detail, glare, focus, lighting, and movement under expected operating conditions.
Is there a required camera height or overlap percentage?
There is no universal height or overlap rule for all sites. Choose placement based on the task, camera geometry, lighting, risk, and site conditions, then test it.
Why test both day and night?
Lighting can change what the camera records. Backlighting, glare, low light, and motion blur can reduce detail even when a floor-plan view appears clear.
How should a map show privacy limits?
Mark areas that should not be recorded and note any required camera adjustments or privacy masks. Check local rules for views, audio, signs, retention, and access.
How often should coverage be checked again?
Recheck after changes to the layout, lighting, camera settings, or nearby structures. A regular review schedule also helps identify changes that may affect image quality.
Should detailed camera maps be public?
Usually, detailed maps should be shared only with people who need them for authorized planning or maintenance. Keep them secure and avoid distributing information that could help someone evade monitoring.
(This article was written by one of our staff writers, Steven Langford. Visit our Meet the Team page.)
