The PPF / PPM Video Surveillance Guide

By: IPVM Team, Published on Dec 23, 2016

Pixels per foot / Pixels per meter is the most fundamental and valuable, though imperfect, metric for specifying video surveillance image quality.

In a single number, this metric (e.g., 10ppf, 40ppf, 100ppf) conveys important information about what the projected quality that a camera can provide.

The image below, taken from our Camera Calculator, demonstrates examples of common pixel per foot (ppf) levels:

PPF Established Metric

PPF has become a critical established metric for several reasons:

  • Broad camera manufacturer support: Most major manufacturers use this metric.
  • Common A&E specifications: Architects and engineers who plan large projects regularly use PPF / PPM as the basis for their designs and surveillance plans.
  • Need for Something: With so many resolution options today (from 1MP to 12MP and beyond), the old metrics which used percentage of screen covered make no sense. PPF has filled this void.

The Goal of PPF

PPF is a single metric (e.g., 10, 50, 90, etc.) that when specified should deliver a specific level of quality. For example, the parking lot camera must deliver 50 PPF. Instead of guessing or just specifying more resolution, using this metric should enable selection of the ‘right’ resolution for the scene. The final image, following the PPF metric, will then deliver a predictable level of quality.

PPF Problems

Alas, PPF suffers from many problems that must be factored in:

  • Assumes even lighting and ignores the impact of bright sunlight
  • Assumes day time lighting and ignores the impact of night time / low light viewing
  • Disregards differences in lenses and compression
  • Disregards that image quality needs are subjective and debatable
  • Fails to specify related and critical metrics to complement PPF

Despite this, PPF does have value for estimation and planning. It just cannot be used blindly or simplistically. Inside the PRO Member’s section, we explain:

  • How to calculate PPF
  • How to recognize PPF limitations and make adjustments
  • How to best use PPF productively

****** *** **** / Pixels *** ***** ** the **** *********** *** valuable, ****** *********, ****** for ********** ***** ************ image *******.

** * ****** ******, this ****** (*.*., *****, 40ppf, ******) ******* ********* information ***** **** *** projected ******* **** * camera *** *******.

*** ***** *****, ***** from ********* **********, ************ ******** ** common ***** *** **** (ppf) ******:

PPF *********** ******

*** *** ****** * critical *********** ****** *** several *******:

  • ***** ****** ************ *******: **** ***** ************* *** this ******.
  • ****** *&* **************: ********** *** ********* who **** ***** ******** regularly *** *** / PPM ** *** ***** for ***** ******* *** surveillance *****.
  • **** *** *********: **** ** **** resolution ******* ***** (**** 1MP ** **** *** beyond), *** *** ******* ***** used ********** ** ****** *********** ** *****. *** has ****** **** ****.

The **** ** ***

*** ** * ****** metric (*.*., **, **, 90, ***.) **** **** specified ****** ******* * specific ***** ** *******. For *******, *** ******* lot ****** **** ******* 50 ***. ******* ** guessing ** **** ********** more **********, ***** **** metric ****** ****** ********* of *** ‘*****’ ********** for *** *****. *** final *****, ********* *** PPF ******, **** **** deliver * *********** ***** of *******.

PPF ********

****, *** ******* **** many ******** **** **** be ******** **:

  • ******* **** ******** *** ignores *** ****** ** bright ********
  • ******* *** **** ******** and ******* *** ****** of ***** **** / low ***** *******
  • ********** *********** ** ****** and ***********
  • ********** **** ***** ******* needs *** ********** *** debatable
  • ***** ** ******* ******* and ******** ******* ** complement ***

******* ****, *** **** have ***** *** ********** and ********. ** **** cannot ** **** ******* or **************. ****** *** PRO ******’* *******, ** explain:

  • *** ** ********* ***
  • *** ** ********* *** limitations *** **** ***********
  • *** ** **** *** PPF ************

[***************]

Key ***************

**** ** ****:

  • *** ** *** **** art **** *******. *** are ******* ******** ** you ***** * ****** number *** *** ***** to ********** ********* ** complex ** ***** ******* across ********** *** ******.
  • ********** *** *** *********** of **** ** *** can ***** ********.
  • *** *** ** * baseline ** *** * sense ** ********* *********** then ****** *** ******** site ********.
  • *** *** ****** ***** guarantee ******* ****** **/*/*** in ***** ************.
  • *********** *********** *** *** proper ************.
  • ** *** ************ ** improve ********* *** ***** using **** ** **************. Instead, ******* ********** *** key ****** ********** (***, low ***** ***********, ***.)

PPF ** ***

****, ** *** *** throughout **** ******, *** sometimes the ****** **********, ****** Per ***** (***), ** used. *******, *** ** ******** used, **** ** **** regions ************ ** *** metric ******.

*** *********, *** ***** below ***** **** ******** *** values *** **********. **** that *** **** ****** ********** **** ******** ****** ************, in ******** ** ******** / ***.

How ** ********* ***** *******

*********** ***** ******* ******* ** two ******/*******:

  • *** ****** ** ********** pixels ** * ***** feed/camera
  • *** ***** ** *** FoV ** *** ****** at *** ***** ** interest

Horizontal ***** *****

** ******* ** ******** identify *** ********** ***** count *** ** *** confuse ** **** *** vertical *** *** ******* resolution. *** ********, * 720p ****** *** * total ********** ** *** (technically *.***) *** *** horizontal ***** ***** ** 1280 *** *** ******** pixel ***** ** ***, more ******** ********* ** 1280 * ***. ** is *** ***** ****** in **** ****, *** 1280, **** ****** *** measuring ***.

**** *** ********** ***** counts *** ****** ***********:

**** **** ** ******** them ** **** *** quite ***********.

Selecting *** *****

*** ****** **** ** the *********** ** *** wide * ***** ** View *** ***** ** cover. *** ***** ***** shows * ****** ******** for ********* *** ***, simply ******* ****** ** the ***** ** ********, like *** **** *****:

*********** *** ***** ** the *** *** ** trickier *** ******, **** areas, **** ** ******* lots ** ******. *** instance, *** ********* ***** shows *** ********* *** widths *** ******** * parking ***/*****.

**** ** ***** **** may ** '*****', *** it ******* ** ******** factors.

  • ** ***** ******* ***** the ****?** ******* ****** ** mounted ** *** ***** of **** ***, ****** to *** **** ** the ****** *****, ** may ** ****** ** use *** ******** ***' FOV *** ************. ** there ** ** ***** coverage, *** ***' *** need ** ** ****.
  • **** ********** *********** *** there?** ****** ********* ** limited ** ***********, ** must **** **** ** mind **** ********* ****. This *** ** *** if ***** *** ***** models *** ********, ***** are ********* ******* ** 1080p. *** ** ** or **** ******* *** be ****, ***** **** are ********.

** ***** ** *** uncertainty, ** ********* ***** wider ****, ** **** you ** *** ************* your ***.

PPF *******

**** *** **** ********** the ********** ****** ** the ****** ****** *** measured **** *** *****, *** is ****** ********.

**** *** * *** examples:

  • *** *** ***** * 720p ****** ** ***** a ** **** **** entrance: *** = *** because ********** ***** ***** is **** *** *** Width = ** (*.*., 1280 / **).
  • *** **** * *** camera ******** * *** foot **** ******* ***: PPF = ~** ******* horizontal ***** ***** ** 2592 *** *** ***** = *** (*.*., **** / ***).
  • * ***** ****** ** monitoring * ** **** wide ******* ********: *** = ** ******* ********** pixel ***** ** **** and *** ***** = 40 (*.*., **** / 40).

PPF ********* ** *** ***** *** ******** **** ****** *********

******* ** *** **** a '******' ***. **** the *** ** ******* on *** *** *** subject ** ******** ** from *** ******. *** instance, ***** *** **** ****** **********, ** *** ***** over * ******'* ***, which ***** *** ** that *****. ** *** see **** *** ********* as ** ******** *** target ** ** ***, but ******* *** ****** it ******* *********, ** 100, ***, ** *** PPF.

******* *********, *** *** level ********* ** ** widen *** ***, **** below. ******** *** ****** of *** *** *****, we *** *** *** decrease, *********** ** ***.

*** *** *** **** for ******** ** *** **** ****** **********. 

Fisheye ***** ** **** ******

*******, ****** ** ***** of **** ***** **** using ******* ********* ******, as *** ***** ************, much ****** **** ******** cameras. 

***** *** (*) *** ******* as ** *******, *** a fisheye ********* (*** ****) and *** ***** ***** a ~60° ****. ******* *** want ** *** ** intruder ** **** **** from **** ******:

  • **** * *** *********, at ** **** **** from *** ******, *** PPF ** ~**
  • **** * *** '************' 60° ****, ** ** feet **** **** *** camera, *** *** ** ~130

**** ** * ******* practical **********. ***** *** panoramic *** *** ** 'all' **********, ** *** direction, ** ** **** away, ****** **** **** like ***** (**** **** scenario). ** ********, *** 'conventional' **** **** ******* near ******** ******* ****** though ****** * **** narrower ****.

*** *** ***** *********** ********* ****** ******** *** **** *******.

Recognizing *** ***********

**** ***** *********** ***, there *** ******* ****** which ****** *** ********* quality ** ****** *********. Below, ** ******:

  • *** ****** ** ****** lighting / **** ******* scenes
  • *** ***** / ***** time *******
  • *********** / ***** ******* setting ******
  • **** ******* ***********
  • ********** ***** ******* ************
  • ************* ******* ** ***

Wide ******* ***** ***********

*** ******* *** ****** are *** **** *** the ********* ***** *** vary *************. *** ******* to ****** ****** ********* / ******** ** * *** example. ** *** ***** below, **** ******* **** the **** **********, ***** the **** *** *** are ***** ** *** same ****:

*******, *** ***** ** the ***** ***** **** it *** ***** *** PPF ***** ** *** other. ****** *** *** is *** ****, *** camera ** *** ***** has *** ******** *** more ********* ***. 

**** ** ** ***** even ** ****** **** even ******** ********** ** light ******. ** *** image *****, **** * has * ***** *** than **** * *** zone * ******* ******** more ***** ****** ******* **** B ** ** * shaded **** **** *** camera ********* ** ****** effectively.

*** *** *** ******** **** *** **** *********** ** wide ******* ***** *** these *******. 

Low ***** ***********

**** ** **** ********** low *****, ** **** as ****, ****** ********* **** ******* *********, **** ******* ***** reducing ***** *******. **** can ** **** ** the ****** ** ****** below, ******* *** ******* in *** **** **** over *** ****** ** several ***** **** *** to *****, **** ***** levels ******** ** ~*,***** on *** ****, *** under *** ** *** right.

******* *** ***** *** being '****' ** ******* standards, even *** **** ******* capture ***** ******* *** ******* more ***** **** ****** the ***. *******, ************ PPF ********** ****** ***** **** this ******** ********** *****.

** *** ****** **********, we ******* ******* ***** in **** ***** *** and ***** ****** ** show **** **********, **** PPF ********* ** **** time ** ***** ****** their *******' **********.

Differences ** ***********

******* *** ********* ******* with *** ** *********** level ********. **** ** the **** ********** *** the **** ***** *** ****, the ****** ** *********** can **** *******. ***** demonstrates ****:

** ***** **** ***** B's *** ** *** lower **** ***** *, but **** ** *** the ****. *** *** less *** **** ***** A *** **** ** not *** ****. **** images *** ***** **** *** same ******, **** *** only ********** ***** ********* compression ** ***** *. 

****** ** *** ********* confusion, ************* *** **** different ******* *********** ********, as **** ** ********* terminology *** ***** ******* quality ******. ******* ****** see *** ** ****** ************ *********** Comparison *** ******* ** ***** settings *** ************ *****.

***** ****** ** ******* to ***** *********** ****** and******* *********** ** ********* ** ***** these ******** ******. *** our***** ******* / *********** Tutorial *** **** ******* ** compression *** *** *******.

Lens ***********

**** ***** **** **** choices *** **** * huge ********** ** ***** quality, ********** ** *** pixels ********. *******, ** our *****, **** ******* is ****** * ***** concern, ******* **** ******* differences ***** *** *********** in **** ******. ***** factors, **** ***-****,******, *** ********** ************ are *** **** ****** to ****** ***** *******.

Subjective ***** *******

******* *** **** ********** ******* in *** ** *** subjective *** '*****' ******* level *** **. **** as '****** ** ** the *** ** *** beholder', *** ********** ****** may ***** * ***** quality ***** ** **** enough ** '********' * subject, *** ******* *** ******* significantly **** ****** ** target *** ********.

*** *******: * ******** wants ** ****** * human *******. ***** ** the ***** *** ****** below ** *****?

***** **** ** **** show ****** ******* *** all ** **** **** at ***** ** *******, some ***** ****** *** 18 ** ** *** images, ** **** **** more **** **** * moving '****', **** **** very ***** *******.

*** **** ********* ******** arises **** ******** ******* how **** ****** *** needed ** ******** * specific ******. ******* *** images *****:

**** ****** **** *** the ~** *** ** the **** ** *** fuzzy *** **** **** want * '*******' *****. Others **** **** ** good ******, ********** ** the ****** ** *****, such ** ** ******** or ********.

********** ** **** ** 'expert' ****** ** ******, one ***** ** ****** with *** ***** / decision ***** **** **** think ** **********.

Related / ******** *******

**** ********** *******, *** alone **** *** ******* enough *********** ** ******** select *******, ******* ** confusion ** *********. **** using ***, ******* ******* must ** ****:

  • ***** ** **** *****: ***** ************** **** to ****** *** *** the *** ***** ** be, ********* **** * PPF ******. **** *** create ********* ** **** will *** ******** ** wider **** **** ******. Instead, ************ ***** *** wide, *.*., ** *** at ** ****, ***.
  • ******** ** ******: ******* *** *** the ****** ***** ** deliver *** ***** *** impacts **** ********* ** well ** *** ***** of *** ***. ********, the ******* **** **** the ****** *** ****, the ***** *** ***.
  • ***** ** *********: *******, ********** ** the ****** ** ******, if *** ****** ****** too ******* ********** ** horizontally, *** **** **** key ******* **** ***** or ******* ***** **********. In ********* ****** ** ***** Quality ****, ** ********** **** 15° ** **** ** ideal *** ****** ****** images.

FOV **** **********

******* ** ********* ** resolution ***** ********* ******* were **********, *** ********* *** become ****** *** ******* areas. *** *******, ** areas **' **** ** less, * ***** ****** will ******* ~******, **** than ****** ****** *** a **** ******* *** time *****. ** ********, if *** **** ***** an ** ******, ** get *** **** ***, you ***** **** ** limit **** *** ***** to * **** **** - * **% ********. 

** *** ****** **** high, *** **** ********* issues *** *********** ********* such ** *** ******'* low ***** *** *** performance. ********, ***** ******* will ***** ******* **** bright ******** *** *** light *** *** **** number ** ****** ******** a '****** *** *****'. 

Larger **** **** *********

*******, ***** **-** **** wide ****, *** ********* becomes **** ********. ****** up **** ***** ** a *** ****** **** increases *** ********** ***** count ********, ~**%. ******* importantly, ********* *** ***** and *** *********** ** 5MP ******* *** ***** than ***** ****.

** ******* ***** ********** PPF *** ***** ***** as ** *** ****** problems ** *** ***. For ********, ***'* *** you **** ***** ****** a *** **** **** area. ** ** **, you **** **** **** horizontal ******. * ****** 14MP ****** *********** **** (as ** *** ~**** horizontal ******) ** ***** (2) *** *******. *** best ******** ***** ***** be (*) ***** *******. While *** ***** *** is ******** **** (****), the ******* ******* *** be ******** ** ***, low *****, ***** ****, broad ******* *******, ***.

PPF ********** ******* ** *************

**** *** **** ** mind, *** ****** ******* to ************ *** **********.********: ***** ******* ****** ******, even ******** *** ** not ****** ** *** impact ** ****** ******** or **** ****** ********, which ** ****** ************.

****** **********:

  • **** ******* / *********** people *** ******* ******:************* ******* ******* ** and *** ***. **** in ***** **********, ** is ******** ** ******* solid *********** *******, ********** of ******* ******. ** contrast, *** ** ****** overkill ****** ******** ** very **** ** **** fine ******* **** ** visible, **** ** *** serial ******* ** ********.
  • ******** ******* / ****** see **** ** ****** (person, ***) ** ***** but *** *** *********** *******:************* ********* ********* ******* 20 *** ** ***. This ** ****** ********* as long ** ******** ** ideal.
  • *** ******* / ********* only:************* ******* * - 10 ***. ** *******, because ** **** *****, it *** ** **** hard ** **** ******* out ****** *** ******* know **** **** *** there ** ** *** are ******* *********. ** course, **** **** ******** ideal ********. *** ** all, ** *** **** less **** ** ***, you *** ****** ****** to **** *******. *******, some ********* ******* **** a *** *** ** function, ** *** ***** be ****.

[****: **** ***** *** originally ******* ** **** but *** ******* ** ****/**** to ******** ******* ******* and ******* ****** ******** from *** **** ****** Calculator.]

Comments (11)

Undisclosed #1

12/23/16 04:01pm

However, in our tests, lens quality is rarely a major concern, despite fine quality differences which are perceptible in some lenses...

Has there been a specific test of lenses and their effect on apparent PPF?  Some tests have indicated that in certain cases there might be substantial differences, A Major Flaw in Long Lenses and PTZs Found.

Plus with imager pixel density increasing, lenses are needed to have higher MTF.  

Avatar

Ethan Ace

IPVM | In reply to Undisclosed #1 | 12/23/16 04:24pm

You raise a good point. We'll add more info about long lenses and clarify.

Gavin Botha

12/24/16 03:26am

Great article. 

James Drymiller

12/31/16 09:24pm

Note, we use PPF throughout this report, but sometimes the metric equivalent, Pixels Per Meter (PPM), is used. However, PPF is commonly used, even in many regions standardized on the metric system.

This bias for anything non-metric forever bemuses me.

Setting aside your 'regional' comment for just a moment, there are only 3 countries in the world not using the metric system.  And with no offense to Burma or Liberia, it's the USA that you are acquiescing to here.  So I ask you (IPVM) to reflect on PPF versus PPM.  As 'the world's leading video surveillance information source, IPVM provides the best reporting, testing and training for 10,000+ members globally' [my emphasis on the areas in bold], who are you serving?  What is the more exact measurement tool?

You say, 'PPF is commonly used, even in many regions standardized on the metric system.  I wonder what you base that comment on?  More importantly, if that is true, could the reason be because PPF is what we are force fed?

The US National Institute of Standards and Technology (NIST) has a very interesting paper on the subject of metric systems in the USA at https://www.nist.gov/sites/default/files/documents/pml/wmd/metric/1136a.pdf

Thanks for your consideration and Happy New Year.

John Honovich

IPVM | In reply to James Drymiller | 01/01/17 01:03am

James,

Our calculator has long supported metric and actually checks the country for each visitor defaulting to metric for those countries who use metric.

We will add in references to PPM values as well as PPF for all pictures / graphics after the New Year's and update the post.

John Honovich

IPVM | In reply to John Honovich | 01/06/17 03:18pm

James, all, we added PPM measurements to the images inside the report. Thanks.

Avatar

Eddie Moss

IPVMU Certified | 08/08/17 10:32pm

Can anyone explain why the Horizontal Pixel count of 2592, for 5MP resolution, is less than the figure of 2688, for 4MP resolution? 

This question is in reference to the table on page for of this tutorial.

John Honovich

IPVM | In reply to Eddie Moss | 08/08/17 10:37pm

Eddie, good eye.

The reason that 5MP has a lower horizontal pixel count than a 4MP camera is the difference in aspect ratios, i.e., 5MP cameras are 'taller' than 4MP ones:

5MP - 2592 x 1944

4MP - 2688 x 1520

Related - Aspect Ratio 16:9 vs 4:3 Shootout

Also, 3MP cameras have slightly greater vertical pixel count but much narrower horizontal one, i.e., 3MP - 2048 x 1536

Undisclosed End User #2

05/28/18 05:18pm

Give a better idea of ppm.

Avatar

Brian Rhodes

IPVMU Certified | In reply to Undisclosed End User #2 | 05/28/18 10:32pm

I want to help, but I don't understand the question.  Can you expand?

Undisclosed #3

11/20/18 11:29am

Clear explanation of changes in HFoV and change of PPF according to difference parameter.  Great information.

Login to read this IPVM report.
Why do I need to log in?
IPVM conducts unique testing and research funded by member's payments enabling us to offer the most independent, accurate and in-depth information.

Related Reports

Biggest Low Light Problems 2019 on Nov 08, 2019
Over 150 integrators responded to our survey question: "What are the biggest problems you face getting good low-light images?" Inside, we share...
Rhombus Cameras, VMS and Analytics Tested on Nov 06, 2019
Rhombus boasts they have created "the new standard in Enterprise, cloud-managed video security" and told IPVM in January 2019 they offer twice the...
IP Camera Mount Shootout - Axis, Bosch, Dahua, Hanwha, Hikvision, Vivotek on Nov 04, 2019
Which manufacturers offer the best or worst mounts? We bought and tested ~50 IP camera mounts and related components from Axis, Bosch, Dahua,...
Tailgating: Access Control Tutorial on Oct 31, 2019
Nearly all access control systems are vulnerable to an easy exploit called 'tailgating'. Indeed, a friendly gesture in holding doors for others...
Avigilon Appearance Search Tested on Oct 30, 2019
Avigilon Appearance Search claims that it "sorts through hours of video with ease, to quickly locate a specific person or vehicle of interest...
Lock Status Monitoring Tutorial on Oct 28, 2019
Just because access doors are closed does not mean they are locked. Unless access systems are using lock status monitoring, the doors and areas...
Covert Elevator Face Recognition on Oct 24, 2019
Covert elevator facial recognition has the potential to solve the cost and complexity of elevator surveillance while engendering immense privacy...
Illustra Pro Gen3 4K Camera Tested on Oct 23, 2019
Johnson Controls has released the latest generation in their Illustra Pro line, the Pro Mini-Dome Gen 3, a non-OEM model claiming to "optimize...
Access Control Door Controllers Guide on Oct 22, 2019
Door controllers are at the center of physical access control systems connecting software, readers, and locks. Despite being buried inside...
Integrated IR Camera Usage Statistics 2019 on Oct 21, 2019
Virtually every IP camera now comes with integrated IR but how many actually make use of IR or choose 'super' low light cameras without IR? In...

Most Recent Industry Reports

Hikvision Markets Uyghur Ethnicity Analytics, Now Covers Up on Nov 11, 2019
Hikvision has marketed an AI camera that automatically identifies Uyghurs, on its China website, only covering it up days ago after IPVM questioned...
Open vs End-to-End Systems: Integrator Statistics 2019 on Nov 11, 2019
Preference for open systems is on the decline, according to new IPVM statistics. We asked integrators: For video surveillance systems, do you...
Biggest Low Light Problems 2019 on Nov 08, 2019
Over 150 integrators responded to our survey question: "What are the biggest problems you face getting good low-light images?" Inside, we share...
US Issues Criminal Charges For Fraudulently Selling Hikvision And Other China Products on Nov 07, 2019
The US government has made an unprecedented move on the video surveillance supply chain, charging a US company, Aventura for "having conspired with...
The Access Control Codes Guide: IBC, NFPA 72, 80 & 101 on Nov 07, 2019
For access, there is one basic maxim: Life safety above all else. But how do you know if all applicable codes are being followed? While the...
Rhombus Cameras, VMS and Analytics Tested on Nov 06, 2019
Rhombus boasts they have created "the new standard in Enterprise, cloud-managed video security" and told IPVM in January 2019 they offer twice the...
"Stress in the Residential Market" - Major Lender Exits on Nov 06, 2019
The residential security / 'alarm' market is getting worse, at least for traditional players. Now, one of the biggest lenders in the industry has...
Aiphone Video Intercom Tested (IX Series 2) on Nov 05, 2019
Aiphone was one of integrator's favorite intercom manufacturers but how well do their products work? The company's newest offering, the IX Series 2...
90+ Companies Profile Directory on Nov 05, 2019
While IPVM covers the largest companies in the industry regularly (like Axis, Dahua, Hikvision, etc.), IPVM strives to do a profile post on each...
Hikvision USA Fights LTS on Nov 04, 2019
Hikvision's USA subsidiary is fighting with LTS, having recently quietly dropped LTS as an authorized distributor amidst ongoing face-offs between...

What IPVM Is

The world's leading authority on video surveillance, with 200,000+ visits monthly.

  • Articles on cameras, video analytics, VMS, and trends
  • Tests showing actual performance and problems
  • Courses in surveillance, access control, etc
  • Camera Calculator for designing systems

Dedicated To Independence

We're dedicated to staying independent and objective. We're the only industry source to refuse any and all advertisements, sponsorship, and consulting from manufacturers. Why?