Face Animation Parameter

{{Short description|Part of the MPEG-4 face animation standard developed by the Moving Picture Experts Group}}

A Face Animation Parameter (FAP) is a component of the MPEG-4 Face and Body Animation (FBA) International Standard (ISO/IEC [http://www.iso.org/iso/iso_catalogue/catalogue_ics/catalogue_detail_ics.htm?csnumber=24462 14496-1] & [http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=39259 -2]) developed by the Moving Pictures Experts Group.{{cite book |last=Ostermann|first=Jörn |editor1-first=Igor |editor1-last=Pandzic |editor2-first=Robert |editor2-last=Forchheimer |title=MPEG-4 Facial Animation: The Standard, Implementation and Applications |url=https://archive.org/details/mpegfacialanimat00pand_406|url-access=limited|publisher=Wiley|date=August 2002 |pages=[https://archive.org/details/mpegfacialanimat00pand_406/page/n301 17]–55 |chapter=Chapter 2: Face Animation in MPEG-4 |isbn=978-0-470-84465-6}} It describes a standard for virtually representing humans and humanoids in a way that adequately achieves visual speech intelligibility as well as the mood and gesture of the speaker, and allows for very low bitrate compression and transmission of animation parameters.{{cite journal |last=Tao |first=Hai |last2=Chen |first2=H.H. |last3=Wu |first3=Wei |last4=Huang |first4=T.S.|title=Compression of MPEG-4 facial animation parameters for transmission of talking heads |journal=IEEE Transactions on Circuits and Systems for Video Technology|publisher=IEEE Press |volume= 9|issue=3 |pages=264–276 |doi=10.1109/76.752094 |year=1999 }} FAPs control key [http://ivizlab.sfu.ca/research/iface/MPEG-4.gif feature points] on a face model mesh that are used to produce animated visemes and facial expressions, as well as head and eye movement. These feature points are part of the Face Definition Parameters (FDPs) also defined in the MPEG-4 standard.{{Cite journal |last=Kshirsagar |first=Sumedha |last2=Garchery |first2=Stephane |last3=Magnenat-Thalmann |first3=Nadia |date=2001 |title=Feature Point Based Mesh Deformation Applied to MPEG-4 Facial Animation |url=https://www.academia.edu/27181483/Feature_Point_Based_Mesh_Deformation_Applied_to_MPEG_4_Facial_Animation |journal=Deformable Avatars |pages=24–34}}

FAPs represent 66 displacements and rotations of the feature points from the neutral face position, which is defined as: mouth closed, eyelids tangent to the iris, gaze and head orientation straight ahead, teeth touching, and tongue touching teeth.{{cite book |last=Petajan|first=Eric|editor1-first=B. |editor1-last=Kisačanin |editor2-first=V.|editor2-last=Pavlović |editor3-first=T.S.|editor3-last=Wang |title=Real-time vision for human-computer interaction |url=https://archive.org/details/realtimevisionfo00kisa|url-access=limited|publisher=Springer|date=September 2005 |pages=[https://archive.org/details/realtimevisionfo00kisa/page/n256 249]–268|chapter=MPEG-4 Face and Body Animation Coding Applied to HCI |isbn=0387276971 }} These FAPs were designed to be closely related to human facial muscle movements.

In addition to animation, FAPs are used in automatic speech recognition,{{cite book |last=Petajan|first=Eric|editor-first=Alan |editor-last=Wee-Chung Liew|title=Visual Speech Recognition: Lip Segmentation and Mapping |publisher=IGI Global |date=January 1, 2009 |pages=128–148 |chapter=Chapter 4: Visual Speech and Gesture Coding Using the MPEG-4 Face and Body Animation Standard |isbn=9781605661872}} and biometrics.{{cite journal |last=Aleksic|first=P.S.|last2=Katsaggelos |first2=A.K. |date=November 2006 |title=Audio-Visual Biometrics |journal=Proceedings of the IEEE |publisher=IEEE Press |volume= 94|issue=11 |pages=2025–2044 |doi=10.1109/JPROC.2006.886017 }}