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Evaluating drawings is a difficult process. Generally there is no right answer, yet it is accepted that there are good drawings and bad drawings. Even the same drawing may be excellent for one purpose yet a failure for another. Drawings are graphic representations which follow different conventions depending on the function, the author's intent, the medium/media used, the expected audience, even the culture from which they are made. Sometimes it is appropriate for a drawing to be ambiguous and inexact, while in other instances clarity and precision are most important. The purpose of the writing which follows is to present some guidelines and issues to consider while evaluating freehand drawings and sketches. It may be used by the author for self-criticism, or by a grader. Evaluation of technical drawings is not included here. The established conventions for multiviews, dimensioning, toleranceing, and working drawings are well covered in the text book provided in the course.[1]

1. Understanding intent in a drawing is the basis upon which one can make a fair evaluation. The same drawing could be judged successful for one set of intentions and a failure for another. In this course intent should be understood from the parameters of the assignment. The author then will have a sense of what to produce and the reader will know what to expect in a good drawing by understanding the assignment. For example, if an assignment is given to deliver a dimensioned, three view, free hand drawing of a brick, the reader can expect to see a certain type of drawing. On the other hand, if the assignment is to draw a piece of fruit which conveys a sense of how it tastes, a different set of expectations would be appropriate in its evaluation. Whenever making or evaluating a drawing, it is essential that intent is understood.

   LINE QUALITY

   Line quality describes the character of a single line: its weight (i.e. thickness), its consistency, its shape (wavy, shaky, hard edged...). It also concerns the ensemble of lines which make up an entire drawing. Line quality can either augment a drawing or ruin it depending on how it is used. Manipulation of line can itself be a mode of communication. In most conventions, lines typically represent transitions: the outside contour of a physical object, a change in angle of a surface, an aperture, a detail in a surface, etc... The physical quality of each of these transitions is different, and may be more or less important to the drafter. Consequently, the quality of the lines representing these transitions will also be different. One generally accepted convention for line weight (line thickness) in drawing is the following:

   * The heaviest line is used for contours and outside edges.

   * A slightly lighter line is used in drawing convex corners.

   * A lighter line is used to draw inside corners.

   * The lightest line weight should be used to render details on a surface, or surface patterns.

   (See Illustrations)

   Line quality can also be effectively used in suggesting depth. Objects in the foreground are typically rendered with heavier weight lines than those appearing in the distance. Line character can also suggest relative distances. An object rendered with broken or slightly wavy lines can appear farther away than an object rendered with sharp straight lines.

   Line Quality Guidelines

   Attempt to draw a line with one stroke of the pen/pencil. Avoid drawing a single line in multiple segments, or drawing multiple lines one on top of the other.

   Use multiple line weights (line thicknesses) in the same drawing. A drawing made up of lines of the same weight appears flat, and can be more difficult to read.

   The weight of a single line need not be continuous in a sketch. It may be thicker at one point along its length than at other points. Some sketching techniques make lines heavier at their endpoints than in the middle. Such a technique places more emphasis on the lines' points of termination, and the transitions that occur there.

   If it is desired to emphasize one portion of a drawing over another, the drafter might choose to render that portion in a heavier line weight than other parts of the drawing.

2. CONSTRUCTION

   The actual construction of elements in a drawing has a dramatic effect on the overall quality of the finished piece. Generally for a given drawing, adopt a convention for drawing construction, and use that convention consistently within it. For example, if the drafter chooses a one point perspective convention, it is typically inadvisable to construct some of the elements using a different convention like two point perspective, or in an isometric convention. [2]

   Perspective Drawings

   Perspective drawing conventions all rely on the same basic principle. As we look at our environment through our eyes, it appears that space and the objects in it tend to compress as they recede away from us. If one is looking along a street, it appears to narrow in the distance, though physically it is the same width far away as it is near by. Perspective drawing conventions use this illusion of spatial compression to communicate depth.

   A major concern in construction for perspective drawings is the placement of the vanishing points and how well lines conform to that vanishing point placement. Vanishing point placement can communicate clues about relative scale and position between the observer and the object rendered. **** In this context, the observer should be considered both the creator and the viewer of the drawing. **** The location of the vanishing point(s) in a drawing is associated with the location of the observer's eyes. Anything rendered above a vanishing point is located above the observers eyes, and vice versa for things rendered below the vanishing point. If the vanishing point(s) are located in the upper portion of the page of a drawing, then most of the field of view (and often most of the subject) is below the eyes of the observer. This suggests that the observer is looking down on what he/she is viewing, which could leave a clue that the observer is larger than the objects she/he sees. The reverse can be extrapolated from placement of vanishing points low in the drawing. (See Illustrations)

   Horizontal placement of vanishing points is also important. They need not be placed in the center of the drawing for example. In fact it is not necessary that their placement be on the drawing itself. Compositions can be made more interesting sometimes by placing vanishing points off the page. Avoid horizontally centering objects in a drawing with a vanishing point, because often they will appear distorted or difficult to understand in this location.

   Perspective Drawing Suggestions

   The main issue to remember in a perspective sketch or drawing is that parallel lines which extend away from the direction of sight of the viewer should all converge at the vanishing point(s). This convergence creates an illusion of depth by reconstructing the illusion we experience in sight, where space and the objects in it appear to compress as they recede into the distance. If the lines do not converge, then that illusion is disrupted, which can create confusion if not handled carefully.

   Typically designers use perspective drawings for purposes of illustration. Because they provide illusions of depth and size, they can convey to the viewer a better sense of the visual quality of objects or a space. On the other hand, it is difficult, if not impossible to take measurements of an object drawn in a perspective convention. Other conventions such as three view, and axonometric drawings are more appropriate for such purposes.

   Axonometric Drawings

   Axonometric drawings (axons) are useful in describing the three dimensional shape of an object. Unlike a perspective drawing, axons can convey direct numerical information about size and proportion if they are constructed correctly. Unlike a perspective view, it is difficult to contextualize an axon view of an object because it is difficult to convey a sense of space in axons. When creating axons be sure to exploit line weight variation as described in the line quality guidelines of this tutorial.

3. DETAIL

   Determining the appropriate level of detail for a drawing depends on number of factors:

• As with other concerns in a drawing, the rendering of detail is not an exact science, but one might consider the following examples as guides to the extremes.

1. If one is drawing the facade of an entire building, it is likely inappropriate and difficult to render a crack in one of its windows.

2. If one is drawing a single bolt, neglecting to render its threads is likely to be leaving out one of its more important features.

3.If the level of detail desired is difficult to render because the drawing instrument seems too large, there may be one of two problems. Either a) the drawing itself is too small to support the desired detail, or b) the drawing instrument is too large compared to the size of the drawing. In most cases, (a) is the more likely problem than(b).

 

Mixing Detail

Mixing detail in a drawing can be an effective technique to emphasize an element of a drawing, while giving it a context.

Issues To Consider While Critiquing A Sketch

Howis the page set up?

Composition

• Arrangement of elements on the page?
• Does the sketch interact with the borders in some way, or does it ignorec them?
• Is there evidence that the author considered how the sketch was to be laid out in the drawing field available?