By Assaf KostinerDiscover different methods to create oil paintings, directly from expert artists. Descriptions of the tools required to do oil painting and their importance. In recent years many people like to have their own oil paintings. There are few companies in the market who offers 'a painting from photo' services. The whole process is done online when the customer sends his digital image directly to a studio who paints it. Once the artist finishes the painting, he will send it to the customer. A painting from photo is highly complicated it is one of the most difficult style of painting. An artist who paints according to a given photo should be highly skillful and must have a long experience in paintings. There is no other style that requires such high level of technique. Any mistake in the painting may cause the customer to reject the painting. If a customer sends a photo of his daughter, hoping to have an oil portrait of her, he expects that all his daughter's details will be capture carefully in the painting. If the artist makes a slight change in the facial details, it may change the whole appearance of the child. Therefore, the artist must have tools to help him to make the right proportions of the subject. When we talk about paintings from photos, we must remember that proportions are the basics to a successful painting. The artist has various tools that he can use in order to start a painting according to a given photo. If the artist doesn't use any tool and paints only according to his intuition, the painting will have a more artistic feeling but on the other hand it will be less accurate and may show the subject in the wrong proportions. Listed below are some of the most popular tools an artist can use while making a portrait from a photo: Roller: a roller is a special tool designed for artists to enable them to draw the outer lines of the subject to the canvas according to the proportions in the original photo. This special roller is placed on the photo and on the canvas at the same time, when the artist moves the roller on the subject in the photo, it moves in bigger proportion on the canvas. The side of the roller that moves on the canvas has a pencil attached to it so when it moves, it draws lines on the canvas. This is an accurate tool, it is cheap and it is easy to use. Copy paper: some artists will print the photo on a paper which is in the same size as the canvas. They put a copy paper between the canvas and the printed image so when they move a pencil on the printed image, it is transferred lines of ink to the canvas. This is an accurate tool, it is relatively expensive but once you have the printed image it is fast to paint the proportions. Printed canvases: in the last few years a new technique has developed to help the artists to capture the fine details and colours in the painting. This new method is very simple, The artist prints the image directly on the canvas. After the photo the artist will paint over the print. The quality of the painting is related to the number of layer that the artist uses to cover the print. The print is a tool that shows the artist the correct proportions and colors of the original photo. however, if the artist use only one ore two layers to cover the print, the painting may lack the artistic feeling because it will be very similar to the photo. Another disadvantage of the print is that if there are not enough layers to cover it, the oil paints might fade or break after few years. The reason is that the ink layer doesn't have good reaction with the oil paint. The longevity of an oil painting is determined by the quality of the canvas, the oil paints, the print thickness and the numbers of layers. (which should be 3-4 layers for an oil painting). To solve the problem cause by the ink, there are new printers which produce prints based on watercolours. Projector: this tool is preferred by many artists. The artist puts inside a special projector which projects the photo directly on the canvas. The image is shown on the canvas in full colours and the artist uses a pencil to mark important details on the canvas. This method allows the artist to see and draw the correct proportions of the photo directly on the canvas. Discover the perfect gift for a wedding, anniversary or any other occasion.
By JoAnne WestcottPublished: 9/6/2007
Follow A Child For Free Face Painting Ideas
Children are the best guides to help you find free face painting ideas. Here are some ways they'll lead you to the most popular ones.
Just follow a child around for a while and they'll lead you to dozens of Free Face Painting Ideas.
Favorite animated television programs, popular movies, even children's books, coloring books and arts and crafts books can be inspiration for face painting designs. One of the best places to find free face painting ideas is in preschool coloring books. The bold and simple line art make these designs easy to duplicate in a cheek art design. Popular designs that almost anyone can paint with little research include hearts, smiley faces, sunshines and rainbows. By using only FDA compliant, water-based face paints, painting simple face painting designs will be easier for you, the painter, and safer for the child. Avoid using craft paints, acrylic paints, homemade paints or any other type of paint not specifically for use on skin. Once you discover the designs you want to learn, practice them on paper by placing a piece of acetate over the design. Simply "paint by numbers." The acetate will allow you to wipe the design clean with a damp paper towel and allow you to reuse the acetate over and over again until you are comfortable with the design. Limit the number of colors used and then begin practicing on skin. Even your own arm, hand or cheek will do. Begin with the lighter colors first, then let dry for a few seconds before painting additional colors. Let your child take the lead. By watching them, they will help you find free face painting ideas that are sure to be popular with other kids. You can find more Free Face Painting Ideas at EasyFacePainting.
There was once a very famous Aikido player in Japan who spent
his whole life studying Usheba's legendary art. Although he had
dedicated his whole existence to this beautiful art he had never
actually had occasion to test it in a real life situation against a
determined attacker, someone intent on hurting him. Being a
moralistic kind of person he realised that it would be very bad
karma to actually go out and pick a fight just to test his art so he
was forced to wait until a suitable occasion presented itself.
Naively, he longed for the day when he was attacked so that he
could prove to himself that Aikido was powerful outside of the
controlled walls of the dojo.
The more he trained, the more his obsession for validation grew
until one day, travelling home from work on a local commuter
train, a potential situation did present itself -an overtly drunk and
aggressive man boarded his train and almost immediately started
verbally abusing the other passengers.
'This is it,' the Aikido man thought to himself, 'this is my chance
to test my art.'
He sat waiting for the abusive passenger to reach him. It was
inevitable that he would: he was making his way down the
carriage abusing everyone in his path. The drunk got closer and
closer to the Aikido man, and the closer he got the louder and
more aggressive he became. Most of the other passengers
recoiled in fear of being attacked by the drunk. However, the
Aikido man couldn't wait for his turn, so that he could prove to
himself and everyone else, the effectiveness of his art. The drunk
got closer and louder. The Aikido man made ready for the
seemingly inevitable assault -he readied himself for a bloody
encounter.
As the drunk was almost upon him he prepared to demonstrate
his art in the ultimate arena, but before he could rise from his
seat the passenger in front of him stood up and engaged the
drunk jovially. 'Hey man, what's up with you? I bet you've
been drinking in the bar all day, haven't you? You look like a
man with problems. Here, come and sit down with me, there's
no need to be abusive. No one on this train wants to fight with
you.'
The Aikido man watched in awe as the passenger skillfully
talked the drunken man down from his rage. Within minutes
the drunk was pouring his heart out to the passenger about how
his life had taken a downward turn and how he had fallen on
hard times. It wasn't long before the drunk had tears streaming
down his face. The Aikido man, somewhat ashamed thought to
himself 'That's Aikido!'. He realised in that instant that the
passenger with a comforting arm around the sobbing drunk was
demonstrating Aikido, and all martial art, in it highest form.
This paper has presented a number of anatomy-based muscle modelsappropriate for simulating the behavior of skeletal muscles inhumans. Each muscle model allows the extremities of muscles tobe specified relative to different underlying bones, whether adjacentor not, and automatically adjusts the dimensions of the musclewhen the extremities are moved closer together or further apart.The models are implemented in classes with consistent interfaces,thereby creating reusable components which may be used in contexts other than in human figure modeling, such as in 3D characteranimation and the animation of other animals with endoskeletons.The muscle models manage the deformation of muscles due toisotonic contraction. These deformations are inherent in the models,completely automatic, and functionally dependent on the configuration(or pose) of the underlying articulated skeleton. To allowfor isometric muscle contraction, we introduced a tension parameterto control the ratio of a muscle’s height to its width, independentof the current pose. The muscle models take the muscle’s tension asan instance parameter and deform the muscle accordingly. By bindingthe tension of individual muscles to articulation variables, usershave complete control over the deformations of individual muscles.We used a procedural modeling language to describe all ouranatomy-based models. A language-based definition of complexhierarchical models is elegant and intuitive, and affords the creationof functional dependencies between different components. Interactivecontrol is supported through the use of articulation variables,which may be used either directly, or in expressions, to modifycomponents of the hierarchical model. Cooperating tools can bemade available to give nontechnical users interactive control overthe complex models.We adopted an approach to modeling which parallels the onetaken in the discipline of artistic anatomy. By analyzing the relationshipbetween exterior form and the structures responsible forcreating it, surface form and shape change may be understood best.We identified three general anatomical structures responsible forcreating surface form and described one of these, the musculature,in some detail. Application of knowledge of the human anatomy tothe development of human figure models is necessary if we hope toachieve a high degree of realism.We are currently investigating anatomy-based models for generatingskin surfaces based on the influence of underlying deformablestructures. The capability of implicit functions to blend individualprimitives together is exploited in the generation of surfaces torepresent the skin. Initial results look promising.Implicit versions of the simple geometric modeling primitives areused to adjust the control points of bicubic patch meshes representingthe skin. This technique also allows us to model fatty tissuebetween the muscles and the skin—adjusting the radius of influenceof the implicit functions allows different thicknesses of fattytissue deposits to be modeled.Future research could analyze the structure and function of musclesfurther to enable a more automated approach to their creationthan the one used here. If the origin, insertion, volume, and generalshape of a muscle could be determined heuristically, perhapsbased on the type of joint(s) being acted upon, or the desired actionof the muscle, the creation of human figure models may be greatlysimplified. Used in conjunction with a method for generating articulatedskeletons automatically, this approach has great potential increating new or fictional articulated figures for 3D animation applications.
To illustrate the application of the muscle models, we consider threetypical muscles of the arm and torso:
1. The biceps brachii, the familiar muscle on the upper arm thatflexes and supinates the forearm;
2. The pectoralis major, a large, fan-shaped muscle on the upperfront part of the chest; and
3. The brachioradialis, a muscle that twists around the elbowjoint and assists in flexing the forearm.
Two instances of the fusiform muscle model are used to representthe biceps brachii. We define two functions forspecifying the muscle’s attachments and one for instantiating themuscle. Notice that the biceps brachii is a multi-joint muscle. Itoriginates from the scapula, spans over the shoulder, elbow, and radioulnarjoints, and inserts into the radius bone. Therefore, whenspecifying the attachments of the muscle in the hierarchy, the originfunction must be called just after creating the scapula, and theinsertion function must be called just after creating the radius. Thisensures that the origin and insertion points will be transformed togetherwith their underlying parts; the scapula in case of the origin,and the radius in case of the insertion. Another action performedby the biceps brachii is supination of the forearm, an action thatis most powerful when the elbow joint is flexed to 90. In this position,if the forearm is pronated and supinated in alternation, thebiceps brachii can be seen to elongate and shorten correspondingly.Even though this motion is less dramatic in its effect on the bicepsbrachii, it nevertheless is important to simulate. The pectoralis major originates from the clavicle and the sternum and inserts into the humerus. Because of this naturaldivision into two sections, we use two instances of the multi-bellyclass to represent the muscle. The figure shows the behavior of thepectoralis major when the arm is abducted at the shoulder joint. Themodel represents the general shape of the muscle quite well, and iteven creates the armpit where the muscle bellies overlap near theinsertion into the humerus.We use the general muscle model and a simple tendonmodel to represent the fleshy and tendinous portions of thebrachioradialis, respectively. This behavior is made possible by allowingthe two points defining the mid-section of the muscle to approach each other. Recall that these points are thesecond and third control points of the cubic curve defining the muscle’saxis. As the angle between the origin and insertion section ofthe axis becomes more acute, the second and third control pointsmove closer together and the bend in the muscle’s mid-section becomesmore pronounced. Of course, if the fold is not desired, thepositions of the second and third control points can be adjusted asneeded.
Wide muscles with complex shapes can not be modeled with thesame ease as straight fusiform muscles. Although one could usemultiple instances of fusiform muscles to approximate the shape ofa complex muscle, a better alternative would be to use a generativeapproach in which any number of muscle bellies may be positionedautomatically. The multi-belly muscle model accomplishesthis task. In order to locate and orient a number of muscle bellies automatically,we need to define the origin and insertion of the muscle tobe represented. Spline curves provide a convenient alternativeto merely enumerating the individual origin and insertion points.Relatively few control points are needed to define these curves, andby using a parametric formulation of the spline curve, points alongthe curve can be sampled simply and efficiently. Thus, instead oforigin and insertion points, the multi-belly muscle model requiresthat origin and insertion curves be specified. Locating each muscle involves finding two points of attachment on each curve for everymuscle belly, a task easily accomplished by sampling the curvesand pairing-off corresponding sample points. Orientation of individualmuscle bellies requires finding a reference vector to indicatethe ‘up-direction’ of a muscle belly. As illustrated in Figure 8, thereference vector for each pair of points (oj ; ij ) is the normal vectorof the plane through three sample points,The origin of each multi-belly muscle model resemblesthat of the fusiform muscle model. The origin of each multi-bellymuscle is represented by a list of control points defining the origincurve. Another list defines the insertion curve in a similar way. Asbefore, the origin and insertion curves may be defined in whicheverlocal coordinate system necessary; the class transforms the controlpoints (and hence, the curves) into world coordinates prior to storingthem. By default, ten muscle bellies are created between theorigin and insertion curves. This default behavior can be changed by specifying a different belly count before instantiating the muscle.
In this section we present three anatomy-based muscle models forsimulating the behavior of skeletal muscles. Before doing so, however,we discuss the representation of muscle bellies.
Muscle bellies
We use ellipsoids to represent muscle bellies. As Wilhelms argues, the ellipsoid is a natural and convenient primitive forrepresenting muscle bellies because it can be scaled along its threemajor axes to simulate bulging. We automatically adjust the dimensionsof the muscle belly when its extremities are moved furtherapart or when they are brought closer together. These adjustmentsnot only preserve the ratio of the belly’s height to its width, but alsothe volume of the muscle belly—an approach justified by consideringthe anatomical structure.
Fusiform muscles
Many skeletal muscles are fusiform and act in straight lines betweentheir points of attachment. For these muscles we use a simplemodel with relatively few parameters, called the fusiform musclemodel. This model provides a convenient mechanism for locatingmuscle bellies relative to underlying skeletal bones. Specifically,since muscles attach to different bones, the origin may be given inthe local coordinate system of the bone where the muscle originates.Similarly, the insertion may be given in the local coordinate systemof the bone where the muscle inserts. Muscles with tendons may bedefined by giving two additional points, as illustrated in Figure 6.The model takes care of transforming all the points to a commoncoordinate system.Like the joint types, the fusiform muscle model isimplemented in a class. We use two class parameters to define thevolume v and ratio r of the muscle in its natural state, and a numberof instance parameters to specify the location and orientation of themuscle.Two fusiform muscles of the same volume are modeled, but only one has tendons.Notice the effect of the tendons on the perceived bulging ofthe muscle belly on the right. Notice also that the tendons retaintheir lengths, an important attribute of tendons which is not incorporatedin Wilhelms’ modeling of animal muscles.
In this section we give a brief overview of a procedural model forskeletal support. The model is implemented in AL, a proceduralmodeling and animation language with facilities for definingand manipulating articulated models. We introduce articulationvariables (or avars) to the model and use them to provide animationand interaction controls. The model is applied to the armskeleton to illustrate its operation. This example will be extendedin the next section when the modeling of muscles is considered.
Bones and joints
Since bones are hard relative to other anatomical structures in thehuman body, a rigid model for individual bones is appropriate. Wemodel bones with functions that select one representation out ofa number of alternatives based on a complexity parameter. Two ofthese alternatives, constructed in piecewise fashion from predefinedgeometric primitives. If necessary,arbitrarily complex boundary representations could be included asalternatives, but for our purposes the g-prims representations suffice.
The different types of movable joints in the human skeleton canalso be modeled with functions. Conceptually, each function appliesthe required transformations to locate and orient the joint.Joint motions may be restricted to predetermined excursion ranges,one for each of the degrees of freedom of the joint. We use anobject-oriented style of programming in AL to encapsulate the implementationdetails into a joints class. This abstraction allows theinstantiation of joint types to be stated succinctly, which, in turn,simplifies the arrangement of bones and joints into hierarchies.
The arm skeleton
The upper limb of the human body is supported by a complex andintricate skeleton which provides an excellent testbed for developingarticulated models. To simplify interaction, we introduce‘anatomically appropriate’ simplifications to the arm skeleton. Forexample, since the acromioclavicular joint is capable of very littlemotion in itself , we separate the scapula from the arm skeletonand define its motion functionally in terms of avars. Weplace the rooted reference skeleton first, and use nested blockingconstructs to specify the kinematic chain from the sternoclavicularjoint and the clavicle bone down to the wrist joint and the hand skeleton. Low-level motion control is provided by binding avars
to joint angles. High-level motion control is also possible. For
example, by relating a normalized avar clench to the flexion angles
of interphalangeal joints, the fingers of the hand can be clenched
into a fist simply by setting clench equal to one.
Skeletal muscles attach to other structures directly or by means oftendons. A tendon is a dense band of white connective tissue thatconnects the belly of a muscle to its attachment on the skeleton.Tendons are nonelastic, flexible, and extremely strong. They concentratethe force produced by the contractile muscle belly, transmittingit to the structure to be moved. Tendons decrease the bulkof tissue around certain joints, obviating the need for long fibers inthe belly portion of the muscle. For example, in the forearm andlower leg, long tendons shift the weight away from the hand andfoot, making the ends of the arm and leg lighter.Influence on surface formSkeletal muscles can be thought of as independent convex forms placed in layers on top of the underlying skeleton. Although theforms of adjacent muscles tend to blend with each other, furrowsor grooves are present between some muscles and muscle groups,especially between those that have different or opposing actions.This arrangement of muscles is visible on the surface as a seriesof convexities, especially when the muscles are put into action.In their relaxed state, however, muscles are soft and appear lessdefined, even hanging loosely because of the pull of gravity .Upon contraction, the belly of muscles become shorter and thicker.In superficial muscles, this change in shape can be observed on thesurface where the muscle’s relief becomes increasingly defined.When muscles with narrow tendons contract, the tendons oftenstand out prominently on the surface of the skin. For example, someof the tendons of the forearm muscles can be seen on the wrist whenthe fingers are clenched into a fist. In superficial muscles, the areaof attachment of a tendon and its muscle belly is often apparent onthe surface.
Skeletal muscles are voluntary muscles which contract in order tomove the bones they connect. Located throughout the body, thesemuscles form a layer between the bones of the skeleton and subcutaneousfatty tissue.Structurally, skeletal muscles consist of a contractile belly andtwo extremities, often tendinous, called the origin and the insertion.The origin is usually the more stationary end of a contractingmuscle, and the insertion the more movable. Skeletal muscles consistof elongated muscle fibers and fibrous connective tissue whichanchors the muscles to the underlying skeleton. The composition ofmuscle fibers in a muscle determines the potential strength of musclecontraction and the possible range of motion due to contraction.The shapes of muscles often reveal their function.Anatomists distinguish between two types of muscle contraction.In isotonic contraction, the length of a muscle changes and the muscleproduces movement, while in isometric contraction, themusclecontracts or tenses without producing movement or undergoing achange in length.Skeletal muscles act across one or more movable joints, workingtogether in groups to produce movement or to modify the actionsof other muscles. Depending on the types of joints involved andthe points of attachment of the muscle , a standard name can begiven to any movement so produced, for example flexion/extensionor protraction/retraction .
The remainder of this paper is organized as follows. In Section 2 weidentify the anatomical structures that influence surface form anddiscuss the musculature and its influence in some detail. In Section3 we briefly describe a procedural model for skeletons. Section4 presents anatomy-based muscle models for simulating thedeformable nature of skeletal muscles. We illustrate the operationof each muscle model and show how the muscle models may beused in conjunction with the skeleton model presented in Section 3.Concluding remarks are given in Section 5 where we discuss possibilitiesfor future research. ARTISTIC ANATOMYAnatomy is a biological science concerned with the form, position,function, and relationship of structures in the human body. Artisticanatomy is a specialized discipline concerned only withthose structures that create and influence surface form. Whereasmedical anatomies consider the human body in an erect and motionlessstance, artistic anatomy is also concerned with changes thatoccur when the body moves into different stances.Three general anatomical structures create surface form:1. The skeleton, consisting of bones and joints organized into anarticulated structure;2. The musculature, consisting of contractile muscles andnonelastic tendons; and3. The panniculus adiposus (or fat layer), consisting of fatty tissuelocated beneath the skin.Before discussing the musculature and its effect on surface form,we briefly mention the influence of the skeleton. Interested readersshould consult reference for more detail.2.1 The skeletonThe skeleton is the basis of all surface form. It determines thegeneral shape of the body and each of its constituent parts. Theskeleton also affects surface form more directly: bones create surfaceform where skin abuts to bones, such as at the elbows andknees. Bones are attached at joints which allow the bones to moverelative to one another. Parts of bones that appear not to create surfaceform in some postures do so in others. For example, the headsof the metacarpal bones cannot be seen unless the hand is clenchedinto a fist.2.2 The musculatureOf the anatomical systems that determine surface form, the musculatureis the most complex. Muscles are arranged side by sideand in layers on top of bones and other muscles . They oftenspan multiple joints. Muscles typically consist of different kinds oftissue, allowing some portions to be contractile and others not. Dependingon their state of contraction, muscles have different shapesand they influence surface form in different ways.
Ignoring the effects that gravity and other external forces may haveon tissue, some researchers have concentrated on the deformationsthat occur in the vicinity of joints. One simplifying assumption considersthe human body as consisting of rigid body parts connectedwith flexible surfaces at joints. Chadwick et al. use free-formdeformations to deform skin surfaces that surroundthe underlying skeleton. By using abstract muscle operators, a relationshipbetween skeletal parameters (such as joint angles) andthe control points of the FFDs is established. For example, tendonmuscle operators are used to control deformations near joints.The Thalmanns use joint-dependent local deformation operatorsto control the changes that surfaces undergo near flexing joints.Singh models the skin surfaces near joints with polyhedral objectsembedded in implicit functions. As the joints move, the implicitfunctions deform the polyhedral definition, and therefore theskin surface in the vicinity of the joint.Surfaces may also be deformed in areas other than near joints.Chadwick et al. use flexor muscle operators based on FFDsto simulate the visible result of muscle contraction, while Nahaset al. manipulate the control points of a B-spline model tomimic deformations. Henne [10] and Singh both use implicitfunction primitives to model muscles and pseudo-physical modelsto cause these muscles to bulge. None of these methods model individualmuscles in an anatomically appropriate way, nor do any ofthem attempt to account for all muscles that create or influence thevisible surfaces surrounding the underlying skeleton.Early physically-based techniques for modeling facial expressionsconsider the face to be sufficiently representable by its skin,applying abstract muscle actions to the skin to produce facial expressions. The work of Waters in this regard is particularlynoteworthy. More recent physically-based techniques areanatomically more appropriate . Pieper [16] developed a modelof soft tissue which accounts for the 3D structure and mechanicalproperties of human facial tissue, allowing accurate simulation ofthe interaction between soft tissue, muscles, and bony structures inthe face. Waters extended his earlier work by using a physicalmodel of the epidermis, subcutaneous fatty tissues, and bone tomodel facial expressions more realistically.Chen and Zeltzer developed a finite element model of muscleto simulate muscle forces and to visualize the deformations thatmuscles undergo during contraction. They used polygonal data derivedfrom MRI scans or data digitized from anatomically accurateplastic models to represent muscles. Their model accounts forshape changes due to external forces, such as gravity, or due to internalmuscle forces which produce movement.In her approach to modeling and animating animals, Wilhelmsuses ellipsoids tomodel bones, muscles, and fatty tissue.She uses an iso-surface extraction program to generate polygonalskin surfaces around the ellipsoids in some rest posture of the body,and anchors the skin to the underlying body components, allowingthe skin to be adjusted automatically when the body moves. Herresearch concentrates on the generation of models that may be developedat least semi-automatically.
Because of demands for rapid feedback and the limitations ofpresent-day technology, human figures are often represented withstick figures, curves, or simple geometric primitives. This approachsacrifices realism of representation for display efficiency. Recently,a layered approach to the representation of human figures has beenadopted in which skeletons support one or morelayers, typically muscle, fatty tissue, skin, and clothing layers. Theadditional layers serve to flesh-out the skeleton and to enhance therealism of the representation.
Most human figure models use a simplified articulated skeletonconsisting of relatively few jointed segments. Magnenat-Thalmannand Thalmann challenged researchers to develop more accuratearticulated models for the skeletal support of human figures.They observe that complex motion control algorithms which havebeen developed for primitive articulated models better suit robotlikecharacters than they do human figures. To address this issue,researchers have revisited the skeletal layer of human figure modelsto solve some specific problems. In Jack, the shoulder ismodeled accurately as a clavicle and shoulder pair. The spatial relationshipbetween the clavicle and shoulder is adjusted based onthe position and orientation of the upper arm. In another treatmentof the shoulder-arm complex, the Thalmanns use a movingjoint based on lengthening the clavicle which produces good results.Monheit and Badler developed a kinematic model of thehuman spine that improves on the realism with which the torso canbe bent or twisted. Scheepers et al. developed a skeleton modelwhich supports anatomically accurate pronation and supination ofthe two forearm bones. Gourret et al. use realistic bones in theirhand skeleton to assist in producing appropriate deformations of thefingers in a grasping task.
Artists study anatomy to understand the relationship between exterior
form and the structures responsible for creating it. In this
paper we follow a similar approach in developing anatomy-based
models of muscles. We consider the influence of the musculature
on surface form and develop muscle models which react automatically
to changes in the posture of an underlying articulated skeleton.
The models are implemented in a procedural language that provides
convenient facilities for defining and manipulating articulated models.
To illustrate their operation, the models are applied to the torso
and arm of a human figure. However, they are sufficiently general
to be applied in other contexts where articulated skeletons provide
the basis of modeling.
Human figure modeling and animation has been one of the primaryareas of research in computer graphics since the early 1970’s. Thecomplexity of simulating the human body and its behavior is directlyproportional to the complexity of the human body itself, andis compounded by the vast number of movements it is capable of.Although articulated structures containing rigid segments is a reasonableapproximation of the human skeleton, most researchers usearticulated structures that are too simple to be deemed anatomicallyappropriate. The shoulder, spine, forearm, and hand are typicalexamples where accuracy is sacrificed for simplicity. The more difficultproblem of fleshing-out a skeleton is currently an active areaof research. In several of these cases, oversimplification causes undesirable or distracting results. Using flexiblesurfaces at or near joints is a poor approximation because many deformations(like bulging muscles) occur far away from joints. Also,producing intricate joint-dependent changes in the shape of the skinwithout considering the motivators for those shape changes seemsimplausible.In this paper we present an approach to human figure modelingsimilar to the one taken in artistic anatomy—by analyzing the relationshipbetween exterior form and the underlying structures responsiblefor creating it, surface form and shape change may beunderstood and represented best. We focus on the musculature bydeveloping anatomy-based models of skeletal muscles, but many ofthe principles apply equally well to the modeling of other anatomicalstructures that create surface form, such as bones and fatty tissue.
This article is about the philosophical concept of Art. For the group of many expressive disciplines
Art refers to a diverse range of human activities and artifacts, and may be used to cover all or any of the arts, including music, literature and other forms. It is most often used to refer specifically to the visual arts, including mediums such as painting, sculpture, and printmaking. Aesthetics is the branch of philosophy which considers art.
|
MARVEL and SPIDER-MAN: TM & 2007 Marvel Characters, Inc. Motion Picture © 2007 Columbia Pictures Industries, Inc. All Rights Reserved. 2007 Sony Pictures Digital Inc. All rights reserved. blogger template by blog forum |
