1. Biomorphic Form II (from observation) by Brian Curtis
© 2002, The McGraw-Hill Companies

2. A PowerPoint lecture series to accompany DRAWING FROM OBSERVATION

3. Drawing biomorphic forms from observation is similar to drawing them from imagination, but with the one difference we alluded to earlier. When you draw from observation, the simplified geometric framework that is used to establish structural integrity must correspond visually to the pre-existing object you are attempting to draw.
The effectiveness of applying a geometric schema depends on the appropriateness of its correspondence to what is observed. For your schema to work, you must come up with a schema that reflects the object’s dominant visual character. This analysis consists mainly of a series of mental comparisons between the observed form and any possible geometric forms that share structural similarities. The analysis concludes when you have found the most appropriate match(es). Your choices are much more restricted than they were when you were drawing from imagination and were free to begin with any structural armature, but the goal is very much the same. You must keep the conceptual geometric core simple while making sure that it corresponds specifically enough to maintain an easily understandable relationship with the essential structural character of the observed form.

4. Fruits and vegetables are sensuous subjects with considerable surface variation and recognizable geometric structure. As you will quickly realize, there are often multiple geometric solutions for any particular form. While one may turn out to be slightly more helpful than the others, each attempt to find a match provides new and useful insights into the biomorphic form’s structural integrity.

5. Applying geometric schema to an observed biomorphic form intensifies your perceptual engagement with that object. As you analyze its structure, you begin to categorize and differentiate the complex visual patterns that make up the object. As noted earlier in this chapter, it is only after you have focused your conceptual expectations through the use of simplified schema that you become appropriately sensitized to the object’s eccentric irregularities.

6. Trees make particularly good subjects for biomorphic form drawings
Trees make particularly good subjects for biomorphic form drawings. They combine the structural characteristics of cylinders, ovoids, rectangular solids, hemispheres, and cones with a surface that swells, undulates, puckers, bulges, stretches, ripples, and droops as it wraps itself elastically around the core. Every cross-contour must be spatially consistent with every section of the form, not just the localized irregularity it is defining. In order to achieve this, the relative curvature of cylindrical or spherical cross-sections, or the relative steepness of the angles of rectilinear convergence, must increase as the segment it is defining gets further away from eye level.
Because geometric schema are abstract approximations of the observed object, you will find that there are times when two or more geometric armatures function with comparable degrees of clarity and appropriate structural correspondence. When multiple schemas can be applied, you are encouraged to apply all of them to the same drawing. Applying multiple schema provides considerably greater insight into the structural character and integrity of the observed object because each schema allows for slightly different ways of thinking about the form.

7. While you are encouraged to be accurate in the details of the objects you are drawing, structural integrity and clarity of form are far more important.

8. Exaggeration plays as important a role in the application of geometric schema as it does with any of the previous illusionistic drawing techniques you have covered. There are times when you will have to rely more heavily on your geometric schema than on what you are observing because sometimes it will be necessary to "correct" (clarify, reformulate or even delete) certain irregular forms or surface variations whose appearance conflicts with a clear and readable depiction of that object.

9. You will want to maintain as much of the unique and idiosyncratic detail from the object as possible, but structural and surface changes have to be made if and when the irregularity compromises the structural integrity and clarity of the drawing.

10. One of the most familiar phrases that is heard in a perceptual drawing class is “draw through the form.” This exhortation is specifically directed toward increasing your ability to embrace the fullness of the three-dimensional form with your analytical mind. Direct perception is the cornerstone of drawing from observation, but the rational mind, properly applied, can sharpen your perceptions.
Branches of older trees are excellent subjects with which to practice contour line variation, cross-contour, the proportion of foreshortened cross-sections, and their axial relationship to the central axis of the branch as it meanders and snakes its way irregularly through space.

11. The cross-contour lines in this drawing are used very effectively to define the simplified masses of the form, the transitions between the larger masses, and the localized variations of surface. The cross-contours are effectively integrated in a manner that clearly establishes a unity between the constituent elements.

12. This carefully rendered cross-contour drawing was done with a clear sense of the underlying geometric structure of a gold-plated reproduction of the portrait on Tutankhamen’s ( BC) sarcophagus lid.

13. Biomorphic Form II (from nature)
This concludes the lecture
Biomorphic Form II (from nature)