The PPF / PPM Video Surveillance Guide

Author: 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

****** *** **** / ****** *** ***** ** *** **** fundamental *** ********, ****** *********, ****** *** ********** ***** ************ image *******.

** * ****** ******, **** ****** (*.*., *****, *****, ******) conveys ********* *********** ***** **** *** ********* ******* **** * camera *** *******.

*** ***** *****, ***** **** ********* **********, ************ ******** ** ****** ***** *** **** (***) ******:

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

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

  • ***** ****** ************ *******: **** ***** ************* *** **** ******.
  • ****** *&* **************: ********** *** ********* *** **** ***** ******** ********* *** PPF / *** ** *** ***** *** ***** ******* *** surveillance *****.
  • **** *** *********: **** ** **** ********** ******* ***** (**** *** ** 12MP *** ******), *** *** ******* ***** **** ********** ** ****** *********** ** *****. *** *** ****** **** ****.

The **** ** ***

*** ** * ****** ****** (*.*., **, **, **, ***.) that **** ********* ****** ******* * ******** ***** ** *******. For *******, *** ******* *** ****** **** ******* ** ***. Instead ** ******** ** **** ********** **** **********, ***** **** metric ****** ****** ********* ** *** ‘*****’ ********** *** *** scene. *** ***** *****, ********* *** *** ******, **** **** deliver * *********** ***** ** *******.

PPF ********

****, *** ******* **** **** ******** **** **** ** ******** in:

  • ******* **** ******** *** ******* *** ****** ** ****** ********
  • ******* *** **** ******** *** ******* *** ****** ** ***** time / *** ***** *******
  • ********** *********** ** ****** *** ***********
  • ********** **** ***** ******* ***** *** ********** *** *********
  • ***** ** ******* ******* *** ******** ******* ** ********** ***

******* ****, *** **** **** ***** *** ********** *** ********. It **** ****** ** **** ******* ** **************. ****** *** PRO ******’* *******, ** *******:

  • *** ** ********* ***
  • *** ** ********* *** *********** *** **** ***********
  • *** ** **** *** *** ************

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

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

**** ** ****:

  • *** ** *** **** *** **** *******. *** *** ******* yourself ** *** ***** * ****** ****** *** *** ***** to ********** ********* ** ******* ** ***** ******* ****** ********** and ******.
  • ********** *** *** *********** ** **** ** *** *** ***** mistakes.
  • *** *** ** * ******** ** *** * ***** ** potential *********** **** ****** *** ******** **** ********.
  • *** *** ****** ***** ********* ******* ****** **/*/*** ** ***** surveillance.
  • *********** *********** *** *** ****** ************.
  • ** *** ************ ** ******* ********* *** ***** ***** **** in **************. *******, ******* ********** *** *** ****** ********** (***, low ***** ***********, ***.)

PPF ** ***

****, ** *** *** ********** **** ******, *** ********* *** ****** equivalent, ****** *** ***** (***), ** ****. *******, *** ** ******** used, **** ** **** ******* ************ ** *** ****** ******.

*** *********, *** ***** ***** ***** **** ******** *** ****** *** conversion. **** **** *** **** ****** ********** **** ******** ****** ************, ** ******** ** ******** / ***.

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

*********** ***** ******* ******* ** *** ******/*******:

  • *** ****** ** ********** ****** ** * ***** ****/******
  • *** ***** ** *** *** ** *** ****** ** *** point ** ********

 

Horizontal ***** *****

** ******* ** ******** ******** *** ********** ***** ***** *** do *** ******* ** **** *** ******** *** *** ******* resolution. *** ********, * **** ****** *** * ***** ********** of *** (*********** *.***) *** *** ********** ***** ***** ** 1280 *** *** ******** ***** ***** ** ***, **** ******** described ** **** * ***. ** ** *** ***** ****** in **** ****, *** ****, **** ****** *** ********* ***.

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

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

Selecting *** *****

*** ****** **** ** *** *********** ** *** **** * Field ** **** *** ***** ** *****. *** ***** ***** shows * ****** ******** *** ********* *** ***, ****** ******* across ** *** ***** ** ********, **** *** **** *****:

*********** *** ***** ** *** *** *** ** ******** *** larger, **** *****, **** ** ******* **** ** ******. *** instance, *** ********* ***** ***** *** ********* *** ****** *** covering * ******* ***/*****.

**** ** ***** **** *** ** '*****', *** ** ******* on ******** *******.

  • ** ***** ******* ***** *** ****?** ******* ****** ** ******* ** *** ***** ** **** one, ****** ** *** **** ** *** ****** *****, ** may ** ****** ** *** *** ******** ***' *** *** calculations. ** ***** ** ** ***** ********, *** ***' *** need ** ** ****.
  • **** ********** *********** *** *****?** ****** ********* ** ******* ** ***********, ** **** **** this ** **** **** ********* ****. **** *** ** *** if ***** *** ***** ****** *** ********, ***** *** ********* limited ** *****. *** ** ** ** **** ******* *** be ****, ***** **** *** ********.

** ***** ** *** ***********, ** ********* ***** ***** ****, so **** *** ** *** ************* **** ***.

PPF *******

**** *** **** ********** *** ********** ****** ** *** ****** chosen *** ******** **** *** *****, *** ** ****** ********.

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

  • *** *** ***** * **** ****** ** ***** * ** foot **** ********: *** = *** ******* ********** ***** ***** is **** *** *** ***** = ** (*.*., **** / 10).
  • *** **** * *** ****** ******** * *** **** **** parking ***: *** = ~** ******* ********** ***** ***** ** 2592 *** *** ***** = *** (*.*., **** / ***).
  • * ***** ****** ** ********** * ** **** **** ******* entrance: *** = ** ******* ********** ***** ***** ** **** and *** ***** = ** (*.*., **** / **).

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

******* ** *** **** * '******' ***. **** *** *** is ******* ** *** *** *** ******* ** ******** ** from *** ******. *** ********, ***** *** **** ****** **********, ** *** ***** **** * ******'* ***, ***** ***** PPF ** **** *****. ** *** *** **** *** ********* as ** ******** *** ****** ** ** ***, *** ******* the ****** ** ******* *********, ** ***, ***, ** *** PPF.

******* *********, *** *** ***** ********* ** ** ***** *** FOV, **** *****. ******** *** ****** ** *** *** *****, we *** *** *** ********, *********** ** ***.

*** *** *** **** *** ******** ** *** **** ****** **********

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

*******, ****** ** ***** ** **** ***** **** ***** ******* panoramic ******, ** *** ***** ************, **** ****** **** ******** cameras. 

***** *** (*) *** ******* ** ** *******, *** * ******* ********* (360 ****) *** *** ***** ***** * ~**° ****. ******* *** want ** *** ** ******** ** **** **** **** **** camera:

  • **** * *** *********, ** ** **** **** **** *** camera, *** *** ** ~**
  • **** * *** '************' **° ****, ** ** **** **** from *** ******, *** *** ** ~***

**** ** * ******* ********* **********. ***** *** ********* *** see ** '***' **********, ** *** *********, ** ** **** away, ****** **** **** **** ***** (**** **** ********). ** contrast, *** '************' **** **** ******* **** ******** ******* ****** though ****** * **** ******** ****.

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

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

**** ***** *********** ***, ***** *** ******* ****** ***** ****** the ********* ******* ** ****** *********. *****, ** ******:

  • *** ****** ** ****** ******** / **** ******* ******
  • *** ***** / ***** **** *******
  • *********** / ***** ******* ******* ******
  • **** ******* ***********
  • ********** ***** ******* ************
  • ************* ******* ** ***

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

*** ******* *** ****** *** *** **** *** *** ********* power *** **** *************. *** ******* ** ****** ****** ********* / ******** ** * *** *******. ** *** ***** *****, **** cameras **** *** **** **********, ***** *** **** *** *** are ***** ** *** **** ****:

*******, *** ***** ** *** ***** ***** **** ** *** twice *** *** ***** ** *** *****. ****** *** *** is *** ****, *** ****** ** *** ***** *** *** stronger *** **** ********* ***. 

**** ** ** ***** **** ** ****** **** **** ******** variations ** ***** ******. ** *** ***** *****, **** * has * ***** *** **** **** * *** **** * clearly ******** **** ***** ****** ******* **** * ** ** * shaded **** **** *** ****** ********* ** ****** ***********.

variances lighting

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

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

**** ** **** ********** *** *****, ** **** ** ****, ****** ********* **** ******* *********, **** ******* ***** ******** ***** *******. **** *** ** seen ** *** ****** ** ****** *****, ******* *** ******* in *** **** **** **** *** ****** ** ******* ***** from *** ** *****, **** ***** ****** ******** ** ~*,***** on *** ****, *** ***** *** ** *** *****.

******* *** ***** *** ***** '****' ** ******* *********, **** *** best ******* ******* ***** ******* *** ******* **** ***** **** ****** the ***. *******, ************ *** ********** ****** ***** **** **** ******** limitation *****.

** *** ****** **********, ** ******* ******* ***** ** **** world *** *** ***** ****** ** **** **** **********, **** PPF ********* ** **** **** ** ***** ****** ***** *******' parameters.

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

******* *** ********* ******* **** *** ** *********** ***** ********. Even ** *** **** ********** *** *** **** ***** *** ****, the ****** ** *********** *** **** *******. ***** ************ ****:

** ***** **** ***** *'* *** ** *** ***** **** image *, *** **** ** *** *** ****. *** *** less *** **** ***** * *** **** ** *** *** case. **** ****** *** ***** **** *** **** ******, **** *** only ********** ***** ********* *********** ** ***** *. 

****** ** *** ********* *********, ************* *** **** ********* ******* compression ********, ** **** ** ********* *********** *** ***** ******* quality ******. ******* ****** *** *** ** ****** ************ *********** ********** *** ******* ** ***** ******** *** ************ *****.

***** ****** ** ******* ** ***** *********** ****** ********** *********** ** ********* ** ***** ***** ******** ******. *** ******** ******* / *********** ******** *** **** ******* ** *********** *** *** *******.

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

**** ***** **** **** ******* *** **** * **** ********** in ***** *******, ********** ** *** ****** ********. *******, ** our *****, **** ******* ** ****** * ***** *******, ******* fine ******* *********** ***** *** *********** ** **** ******. ***** factors, **** ***-****,******, *** ********** ************ *** *** **** ****** ** ****** image *******.

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

******* *** **** ********** ******* ** *** ** *** ********** *** 'right' ******* ***** *** **. **** ** '****** ** ** the *** ** *** ********', *** ********** ****** *** ***** a ***** ******* ***** ** **** ****** ** '********' * subject, *** ******* *** ******* ************* **** ****** ** ****** *** required.

*** *******: * ******** ***** ** ****** * ***** *******. Which ** *** ***** *** ****** ***** ** *****?

***** **** ** **** **** ****** ******* *** *** ** them **** ** ***** ** *******, **** ***** ****** *** 18 ** ** *** ******, ** **** **** **** **** just * ****** '****', **** **** **** ***** *******.

*** **** ********* ******** ****** **** ******** ******* *** **** pixels *** ****** ** ******** * ******** ******. ******* *** images *****:

**** ****** **** *** *** ~** *** ** *** **** is *** ***** *** **** **** **** * '*******' *****. Others **** **** ** **** ******, ********** ** *** ****** is *****, **** ** ** ******** ** ********.

********** ** **** ** '******' ****** ** ******, *** ***** to ****** **** *** ***** / ******** ***** **** **** think ** **********.

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

**** ********** *******, *** ***** **** *** ******* ****** *********** to ******** ****** *******, ******* ** ********* ** *********. **** using ***, ******* ******* **** ** ****:

  • ***** ** **** *****: ***** ************** **** ** ****** *** *** *** *** needs ** **, ********* **** * *** ******. **** *** create ********* ** **** **** *** ******** ** ***** **** than ******. *******, ************ ***** *** ****, *.*., ** *** at ** ****, ***.
  • ******** ** ******: ******* *** *** *** ****** ***** ** ******* *** given *** ******* **** ********* ** **** ** *** ***** of *** ***. ********, *** ******* **** **** *** ****** one ****, *** ***** *** ***.
  • ***** ** *********: *******, ********** ** *** ****** ** ******, ** *** camera ****** *** ******* ********** ** ************, *** **** **** key ******* **** ***** ** ******* ***** **********. ** ********* ****** ** ***** ******* ****, ** ********** **** **° ** **** ** ***** *** proper ****** ******.

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

******* ** ********* ** ********** ***** ********* ******* **** **********, *** selection *** ****** ****** *** ******* *****. *** *******, ** areas **' **** ** ****, * ***** ****** **** ******* ~100ppf, **** **** ****** ****** *** * **** ******* *** time *****. ** ********, ** *** **** ***** ** ** camera, ** *** *** **** ***, *** ***** **** ** limit **** *** ***** ** * **** **** - * 70% ********. 

** *** ****** **** ****, *** **** ********* ****** *** performance ********* **** ** *** ******'* *** ***** *** *** performance. ********, ***** ******* **** ***** ******* **** ****** ******** and *** ***** *** *** **** ****** ** ****** ******** a '****** *** *****'. 

****** **** **** *********

*******, ***** **-** **** **** ****, *** ********* ******* **** trickier. ****** ** **** ***** ** * *** ****** **** increases *** ********** ***** ***** ********, ~**%. ******* ***********, ********* low ***** *** *** *********** ** *** ******* *** ***** than ***** ****.

** ******* ***** ********** *** *** ***** ***** ** ** can ****** ******** ** *** ***. *** ********, ***'* *** you **** ***** ****** * *** **** **** ****. ** do **, *** **** **** **** ********** ******. * ****** 14MP ****** *********** **** (** ** *** ~**** ********** ******) as ***** (*) *** *******. *** **** ******** ***** ***** be (*) ***** *******. ***** *** ***** *** ** ******** less (****), *** ******* ******* *** ** ******** ** ***, low *****, ***** ****, ***** ******* *******, ***.

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

**** *** **** ** ****, *** ****** ******* ** ************ PPF **********.********: ***** ******* ****** ******, **** ******** *** ** *** ****** in *** ****** ** ****** ******** ** **** ****** ********, which ** ****** ************.

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

  • **** ******* / *********** ****** *** ******* ******: ************* ******* between ** *** *** ***. **** ** ***** **********, ** is ******** ** ******* ***** *********** *******, ********** ** ******* plates. ** ********, *** ** ****** ******** ****** ******** ** very **** ** **** **** ******* **** ** *******, **** as *** ****** ******* ** ********.
  • ******** ******* / ****** *** **** ** ****** (******, ***) is ***** *** *** *** *********** *******: ************* ********* ********* ******* 20 *** ** ***. **** ** ****** ********* ** **** ** lighting ** *****.
  • *** ******* / ********* ****: ************* ******* * - ** PPF. ** *******, ******* ** **** *****, ** *** ** very **** ** **** ******* *** ****** *** ******* **** that **** *** ***** ** ** *** *** ******* *********. Of ******, **** **** ******** ***** ********. *** ** ***, if *** **** **** **** ** ***, *** *** ****** likely ** **** *******. *******, **** ********* ******* **** * few *** ** ********, ** *** ***** ** ****.

[****: **** ***** *** ********** ******* ** **** *** *** revised ** ******** **** ** ******** ******* ***** *** ******* better ******** **** *** **** ****** **********.]

Comments (6)

*******, ** *** *****, **** ******* ** ****** * ***** concern, ******* **** ******* *********** ***** *** *********** ** **** lenses...

*** ***** **** * ******** **** ** ****** *** ***** effect ** ******** ***? **** ***** **** ********* **** ** certain ***** ***** ***** ** *********** ***********,* ***** **** ** **** ****** *** **** *****.

**** **** ****** ***** ******* **********, ****** *** ****** ** have ****** ***.

*** ***** * **** *****. **'** *** **** **** ***** long ****** *** *******.

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

****, ** *** *** ********** **** ******, *** ********* *** metric **********, ****** *** ***** (***), ** ****. *******, *** is ******** ****, **** ** **** ******* ************ ** *** metric ******.

**** **** *** ******** ***-****** ******* ******* **.

******* ***** **** '********' ******* *** **** * ******, ***** are **** * ********* ** *** ***** *** ***** *** metric ******. *** **** ** ******* ** ***** ** *******, it's *** *** **** *** *** *********** ** ****. ** I *** *** (****) ** ******* ** *** ****** ***. As '********'******** ***** ************ *********** ******, **** ******** *** **** *********, testing *** ******** *** **,***+ ***************'[** ******** ** *** ***** ** ****], *** *** *** serving? **** ** *** **** ***** *********** ****?

*** ***, '*** ** ******** ****, **** ** **** ******* standardized ** *** ****** ******. * ****** **** *** **** that ******* **? **** ***********,****** ** ****, ***** *** ****** ** ******* *** ** what ** *** ***** ***?

*** ** ******** ********* ** ********* *** ********** (****) *** a **** *********** ***** ** *** ******* ** ****** ******* in *** *** ** *****://***.****.***/*****/*******/*****/*********/***/***/******/*****.***

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

*****,

*** ********** *** **** ********* ****** *** ******** ****** *** country *** **** ******* ********** ** ****** *** ***** ********* who *** ******.

** **** *** ** ********** ** *** ****** ** **** as *** *** *** ******** / ******** ***** *** *** Year's *** ****** *** ****.

*****, ***, ** ***** *** ************ ** *** ****** ****** the ******. ******.

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