pen ~n~ ink: Tools, Techniques, Illustration Jes Davis AHS

Ball Point Pen Quill Pen + Ink Design with Felt Tip

Intro to Pen -n- Ink I. Tools II. Techniques III. Basics IV. Fine Art vs. 2D V. Mixed Media

Shoulder Partner: List the benefits a medium such as pen+ink has over other media such as paint, pastel and colored pencils. Create a list with your shoulder partner.

Why Pen -n- Ink? O Most convenient in terms of storage, transportation, and adaptability. O Cost effective- cheap! O Ideal for mixed media such as: watercolor, colored pencils, printmaking, etc. O Ideal for outlines, tones and textures. O Very versatile as far as subject: Realistic vs 2D Design. O Blend nicely with text and font in design.

History of Pens The pen has a long history! People began writing on stone tablets by carving into them. This lead to cuneiform, an ancient writing system, on clay tablets. We finally moved on to the inventions of papyrus, parchment, and paper centuries later. The following chart briefly illustrates the development of pens over the last several thousand years BC100 BC79 AD953 AD Reed PenQuill PenDip PenFountain Pen Ballpoint Pen Felt-tip Pen Rollerball Pen

History of Pens Despite advances in technology, most of these pens are still in use today because of the different qualities each type brings to writing and drawing. The dip pen is still used by artists, although its use as a writing instrument has mostly died out. Fountain pens are still carried by many people. The use of ballpoint, felt-tip, and rollerball pens is fairly even, and the choice of one over the other is primarily a matter of personal preference, since pricing is comparable and all types are sold in bulk packs of disposable pens as well as in refillable designs BC100 BC79 AD953 AD Reed PenQuill PenDip PenFountain Pen Ballpoint Pen Felt-tip Pen Rollerball Pen

Tools I. Felt Tip Pens II. Quill Pens + Nibs III. Ink IV. paper

Felt Tip Pens Felt tips pens are by far the easiest to control. They create a smooth line with varying widths… 0.1- smallest point and creates fine lines 0.4- medium width 0.8- largest width creates the darkest, thickest lines

Quill Pens Quill pens used to be made of a feather but a more modern version, called a “dip” pen, is made of a handle and an interchangeable NIB. A “nib” refers to the part of a quill or dip pen which comes into contact with the writing surface in order to deposit ink. Different types of nibs vary in their purpose, shape and size, as well as the material from which they are made.

Indian Ink India ink is a simple black, or colored, ink once widely used for writing and printing and now more commonly used for drawing and outlining, specially when inking comic books and comic strips. India ink is also used in medical applications. Basic India ink is composed of a variety of fine soot, known as “lampblack”, combined with water to form a liquid. No binder material is necessary: the carbon molecules are in a colloidal suspension and form a waterproof layer after drying. A binding agent such as gelatin or, more commonly, shellac may be added to make the ink more durable once dried.

Felt Tip Dip Pen Benefits: 1. Smooth delivery of ink because of the fiber (felt) tip Interchangeable with most roller ball refills 2. Ink dries quickly, which is very helpful for left-handed writers Drawbacks: 1. A rich flow, but not as expressive as a fountain pen 2. Spring-load action gives a smooth write but takes some getting used to because of its give Benefits: 1. Pleasure of expressing liquid ink 2. Flexible nib accentuates personal expression Drawbacks: 1. Requires a little skill and care 2. Ink can splatter or leak if not careful

Assignment: Compare and Contrast Create a comparison chart…Label and try each size in both types of pens. What do you like more? Felt Tip Pen Quill Pen and Nib 0.1C6 0.4C3 0.8C0

Techniques I. Hatching II. Cross Hatching III. Parallel IV. Contour V. Stippling VI. Scribbling

Hatching: Hatching and Cross Hatching

Parallel:

Contour:

Stippling:

Scribbling:

Basics I. Holding and using the pen II. Using Weighted line to create depth III. Creating Textures

Basics of Pen -n- Ink… O Weighted Lines: Thick lines come forward and thin lines recede. A thin stroke can give a washed-out appearance A thick stroke can detract from the details (bad) A thick stroke can detract from mistakes (good) O Strokes must look natural; the thickness of a line should vary along its length and taper off at the end O Vary the pen position, pressure, and pace. This will allow more control over the medium. O Wavy lines are awesome…but if the line is supposed to be straight- use a ruler if needed.

Artist Leonardo Da Vinci During the Renaissance era ( ), stylus, metal-point and pen with ink were considered as fine line media as opposed to the broad line of charcoal and chalks. The precise effect of pen and ink is exemplified by the skillful draughtsman Leonardo Da Vinci in his work Five Grotesque Heads…

STOP for Now!

Fine Art vs. 2D

Mixed Media

Basics: Tones and texture O Weighted Lines: Thick lines come forward and thin lines recede. A thin stroke can give a washed-out appearance A thick stroke can detract from the details O Strokes must look natural; the thickness of a line should vary along its length and taper off at the end O Vary the pen position, pressure, and pace. This will allow more control over the medium. O Wavy lines are awesome…but if the line is supposed to be straight- use a ruler if needed.

Basics-Tones and texture O The tone is achieved by a combination of strokes. O Strokes can convey both tone and texture O Use equal weight and spacing of lines to create tones O Correct arrangement of tones among adjacent regions is important O Use of indication

Basics-Tones and texture Force tone by enhancing contrast or shadows to disambiguate objects O The character of strokes is important: O Crisp, straight lines are good for glass O Horizontal surfaces should be hatched with mostly horizontal lines O Absence of detail indicates glare O Sketchy lines are good for old materials; careful stippling is good for new material

Basics-Outlines O Use outlines to convey texture (crisp lines for hard objects) O Use outlines to bring one object forward in the scene O Using indication for drawing outlines is important

Computer-generated pen-and- ink illustration O Two fundamental differences from traditional graphics rendering pipeline: O Dual nature of strokes O Need to combine 2D and 3D information O Stroke density O 2D adjacent regions O Level of contrast

Non-photorealistic Rendering Pipeline O Standard pipeline (unchanged) O Model O Assignment of texture (strokes) O Lighting model (phong model) O Visible surface algorithm (BSP) O Shadow algorithm O Differences from the standard pipeline: O Maintaining 2D spatial subdivision O Rendering of texture and tone (strokes) O Clipping (stroke base) O Outlining (boundary & interior)

Rendering process O Compute visible surfaces and shadow polygon O Project polygon to build 2D BSP tree and planar map O Visible surface is rendered O Procedural texture for each surface O Clip strokes O Draw outlines

Strokes O Nib moving along a basic straight path O Use waviness and pressure function to add character to the strokes

Stroke textures O Stroke texture – a collection of strokes used to produce texture and tone O Prioritized stroke texture: O Strokes of highest priority are drawn first O Continue until the proper tone is achieved

Resolution Dependence O Existing drawing program do not scale well when printed at different sizes or resolution O Pixel replication yields aliasing artifacts O Drawing same stroke at higher resolution yields overall lighter illustration O Reduction yields large black mass of overlapping strokes O Prioritized stroke textures do not suffer from these problems!!

Indication O Indication lends economy to an illustration O Suggest texture without drawing every stroke O Hard to do, paper suggests semi-automated method O W(x, y) = (a + b*distance((x, y), l))^(-c)

Indication

Expression texture with outline O Associate each stroke texture with boundary or interior outline texture

Minimizing outline O Outline is omitted in the presence of sharp changes in tone, and added in the absence of tone changes

Accented outlines for shadowing and relief O Thickened lines can provide cues about the 3D aspects of a scene O Edges that cast shadows are rendered with thickened lines

Dependence of viewing direction O Viewing direction should be taken into account O Each stroke texture is associated with BRDF O describes outline features in terms of light and viewing directions.

Conclusion O Traditional pen-and-ink illustration can be used to communicate visual information effectively O Showed a large number of these techniques can be incorporated as part of the rendering pipeline O Introduced prioritized stroke texture to allow resolution-dependent rendering

Robie House

Questions?

Computer-Generated Pen-and- Ink Illustration of Trees Oliver Deussen, Thomas Strothotte Presented by Johnny Chang

Traditional Illustration of Trees O Tree skeleton is drawn up to the second branching level with silhouette lines and crosshatching on the stem surface. O Use abstract lines or collection of small objects to draw foliage.

Traditional Illustration of Trees O Three areas of foliage: O Top of the tree- visualized by few details and its outline. O Half shadow area – more details are drawn to achieve gray level. O Shaded area

Synthetic Illustration of Trees O Stem skeleton is represented by silhouette lines and crosshatching O Different types of leaves and illustration styles for abstract leaf representation O Drawing of leaf is modulated by three areas: top, half and deep shadow.

Automated Illustration O Create 3D tree model, using xfrog O Store geometry of the tree skeleton O Store leaves as particles each with a position and a normal vector O Draw the trunk and branches (silhouette lines+cross-hatching) O Draw foliage using depth difference algorithm

Drawing the tree skeleton O Apply analytical silhouette algorithms (Markosian, Rakarand Cohen) O Skeleton is shaded to find dark regions. Dark regions are crosshatched in the illustration. O Use gray scale to determine stroke size. O Direction of the strokes affected by normal vector of the geometry.

Drawing the foliage O Each leaf is represented by the outline of an abstract drawing primitives O Position is determined by 3D leaf position. O Size of primitive is controlled by the user

Depth Differences O Use depth-buffer to determine the outline of objects. O Use zero order derivatives for determining lines O The outline of a primitive is drawn if depth difference is above a threshold

Depth Differences O Depth z in the camera coordinates is determined from a depth value d z1 z0(d1 - d0)/(z1 - z0) d -(z 1+z0)(d1 - d0)/2(z1 - z0) -(d 1+d0)/2 Z=

Abstract Drawing Primitives O 9 polygons was generated to represent leaves from different views O Normals were used to interpolate the shapes of the leaves

Level of Abstraction O Visual level of abstraction can be supported by scaling the primitive size O Scale factor: r=w(d/s)+(1-w), w [0..1]

Conclusion O A Framework for pen-and-ink illustration of trees O Tree skeleton is represented by silhouette lines and crosshatching in dark areas. O Foliage is drawn using abstract drawing primitives. O An interpolation scheme to adapt the form of the primitives to the normal vector of the leaves O Depth differences are used to determine what part of the primitives is drawn.