Dealing with Gaps in Surveillance Coverage

By John Honovich, Published on Feb 14, 2011

Gaps, or holes, in one's surveillance coverage is a fact of life for most organizations. Unfortunately, it can become a painful fact when incidents occur in areas where surveillance coverage is inadequate or missing. Often, users, management and outside observers cannot understand why this 'mistake' happened. In this note, we examine the key tradeoffs and options involved in dealing and minimizing gaps in surveillance coverage. We conclude with a video screencast to show these principles in action.

A February 2010 article criticizing surveillance in Mumbai rail stations is a good example of the frustration and concern gaps create:

  • "Close-circuit cameras at most stations are fitted at improper angles and do not cover the entire area though the police often bank on CCTV images to solve crimes."
  • "The CCTVs do not move 360 degrees and we get blurry images of offenders. The cameras should move at least 180 degrees. We have complained to the railways many times"

While each site is different and we do not know the details of this case, we can easily examine some general principles that impact surveillance usability:

  • Very Narrow Areas For Clear Face Shots: If you want to capture a clear image of someone's face that can be used to identify a person, even with a 1080p HD camera, the maximum width of your cameras' FoV can be no more than about 30 feet or 10 meters. Unless you are in a very small confined environment everywhere (e.g., a bank branch), delivering such clarity/detail is extremely difficult / expensive. Inevitability, there are going to be areas captured by the camera but too blurry to be capable of identifying an unknown suspect.
  • Restrictions on Camera Placements: Often, you know a certain area needs surveillance but have major logistical barriers placing a camera. This frequently happens when ceilings are very high or there are no walls or poles close by to mount the camera. In those cases, cameras are frequently mounted in areas where it is cheaper / less complex. Additionally, sometimes there are ideal places for mounting cameras but other stakeholders block camera placement for aesthetic reasons.
  • Use of Choke Points: Because it is difficult to capture high quality video everywhere, most organizations focus their coverage on choke points (typically doorways/entranceways) that are relatively narrow and funnel people. Choke points are always a good tool. However, there are 2 common issues:
  • Open Area Challenges: Some facilities, by design, are open areas. Common examples include parks, city centers and smaller rail stations. In these scenarios, there are vey few 'natural' choke points and a high probability that people will enter from many directions. 
  • Tracking Suspect Back to Choke Point: Even if you have a choke point, incidents often occur outside of those choke points. An example is a person entering a stadium and then causing a fight near their seats. While the camera may capture a detailed image of the suspect entering, the video of the fight may be blurry. Tracking that person with a blurry image back to their entrance can be quite difficult.

For all of those reasons, depending on fixed surveillance cameras to saturate your grounds is a difficult proposition. Indeed, this explains the motivation and the frequent use of PTZ (controllable) cameras.

On the one hand, someone could argue that a PTZ has no gaps because when controlled it can capture in any direction over great distances (see our note on how far a PTZ can see). On the other hand, the PTZ is essentially blind in whatever direction it is not currently pointed. This can lead to a false sense of surveillance/security.  See our Should You Use PTZ Cameras? review for an in-depth analysis of PTZ tradeoffs.

In Action

In the video below, we examine a public park camera layout demonstrating the tradeoffs and gaps a surveillance designer faces:

In the video, we referred to our pixels reference chart and used the Pelco camera design tool [link no longer available].

Recommendations on Reducing and Dealing with Gaps

  • Increased resolution is the most powerful new tool to reduce gaps. However, as we demonstrated in the above video, even multi-megapixel video will struggle to eliminate blurry or unclear video over larger areas.
  • Since gaps in coverage are essentially inevitable, this must be communicated up front to key stakeholders so they have appropriate expectations
  • Making clear the risks of potential gaps up front may also help the user to justify spending more money or getting approvals to place cameras in more advantageous locations
Comments : Members only. Login. or Join.

Related Reports

Covert Elevator Face Recognition on Oct 24, 2019
Covert elevator facial recognition has the potential to solve the cost and...
"Severely Impacted" Mercury Security 2020 Leap Year Firmware Issue on Jan 17, 2020
One of the largest access controller manufacturers has a big problem:...
Terrible Convergint Coronavirus Thermal Camera Recommendation on Apr 01, 2020
A week after Convergint disclosed falling revenue, pay and job cuts,...
Worst Over But Integrators Still Dealing With Coronavirus Problems (June Statistics) on Jun 30, 2020
While numbers of integrators very impacted by Coronavirus continue to drop,...
Facial Recognition: Weak Sales, Anti Regulation, No Favorite, Says Security Integrators on Jul 07, 2020
While facial recognition has gained greater prominence, a new IPVM study of...
The US Fight Over Facial Recognition Explained on Jul 08, 2020
The controversy around facial recognition has grown significantly in 2020,...
Converged vs Dedicated Networks For Surveillance Tutorial on Feb 12, 2020
Use the existing network or deploy a new one? This is a critical choice in...
Verkada: "IPVM Should Never Be Your Source of News" on Jul 02, 2020
Verkada was unhappy with IPVM's recent coverage declaring that reading IPVM...
Clearview AI Alarm - NY Times Report Says "Might End Privacy" on Jan 20, 2020
Over the weekend, the NY Times released a report titled "The Secretive...
Face Masks Increase Face Recognition Errors Says NIST on Aug 04, 2020
COVID-19 has led to widespread facemask use, which as IPVM testing has shown...
Wide Dynamic Range (WDR) Guide on Oct 01, 2019
Understanding wide dynamic range (WDR) is critical to capturing high quality...
The Problem With Fever Detecting Thermal Sunglasses on Apr 15, 2020
While the media has promoted using thermal sunglasses to detect fevers, this...
Critiquing Carnegie's AI Surveillance Paper on Sep 25, 2019
The Carnegie Endowment has issued an ambitious paper on the Global Expansion...
Forced Door Alarms For Access Control Tutorial on Aug 17, 2020
One of the most important access control alarms is also often ignored....
ADT Slides Back, Disappointing Results, Poor Commercial Performance on Aug 06, 2020
While ADT had an incredible start to the week, driven by the Google...

Recent Reports

Panasonic Presents i-PRO Cameras and Video Analytics on Oct 19, 2020
Panasonic presented its i-PRO X-Series cameras and AI video analytics at the...
Augmented Reality (AR) Cameras From Hikvision and Dahua Examined on Oct 19, 2020
Hikvision, Dahua, and other China companies are marketing augmented reality...
18 TB Video Surveillance Drives (WD and Seagate) on Oct 19, 2020
Both Seagate and Western Digital recently announced 18TB hard drives...
Watrix Gait Recognition Profile on Oct 16, 2020
Watrix is the world's only gait recognition surveillance provider IPVM has...
Intel Presents Edge-to-Cloud Ecosystem for Video Analytics on Oct 16, 2020
Intel presented its processors and software toolkit for computer vision at...
Best Manufacturer Technical Support 2020 on Oct 16, 2020
5 manufacturers stood out as providing the best technical support to ~200...
Microsoft Azure Presents Live Video Analytics on Oct 15, 2020
Microsoft Azure presented its Live Video Analytics offering at the September...
Worst Manufacturer Technical Support 2020 on Oct 15, 2020
4 manufacturers stood out as providing the worst technical support to ~200...
Clorox Announces, Then Pulls, Fever Camera on Oct 15, 2020
For almost one week, Clorox was marketing fever cameras. The booming...
Faulty Hikvision Fever Cam Setup at Mexico City Basilica and Cathedral on Oct 14, 2020
Donated Hikvision fever cameras (claiming screening of 1,800 people/min. with...
Directory of 209 "Fever" Camera Suppliers on Oct 14, 2020
This directory provides a list of "Fever" scanning thermal camera providers...
Avigilon UMD / UAD Tested on Oct 14, 2020
Avigilon's Unusual Activity Detection and Unusual Motion Detection claim to...
Longse Promoting Hikvision Partner Fullhan Chip Based Cameras on Oct 14, 2020
With Huawei HiSilicon production being shut down at TSMC, camera...
Meridian & Goodview (BEMS Relabeller) Temperature Screening Tested on Oct 13, 2020
A lot of temperature tablets look exactly alike and that is because they use...
Monitoring Alarm Systems From Home - Innovation or Danger? on Oct 13, 2020
Remote monitoring by alarm companies since COVID-19 is bringing cost savings...