Concerning Rendering of the Geometric Shape

My last post introduced the reader to Andrew Loomis’ concept of imagining any object primarily as a geometric shape, prior to attempting to draw it.  After one is able to conceptualize subject matter as a series of three-dimensional geometric shapes, Loomis reminds the reader that:

Every plane must have its relative values correctly rendered, or the entire image will fail to convince.

It is appropriate at this time to therfore indicate how one correctly renders the five essential, three-dimensional geometric shapes.  To do this we will perforce need to leave Andrew Loomis for a short while.

The essential shapes, if the reader recalls, are

  1. the Cylinder
  2. the Cone
  3. the Sphere
  4. the Torus
  5. the Rectangular Prism

All other geometric shapes are derivatives of these primaries.

Rendering the Shapes

Each of the above 5 shapes show their dimensionality and mass in predictable and easily memorized  patterns of rendering. To help the student, the patterns of value can be remembered as “value shapes”, in that the lights and darks will take on a recognizable geometric form when laying upon the larger three-dimensional shape being represented.  These rules should be memorized in order for the artist to properly represent the shapes. (each of the rendering examples are from this site by Bill Martin)

  • The Cylinder:  rendering the cylinder is done in bands of value, laying lengthwise along the body of the shape; i.e.  if the cylinder is sitting upright, as does a soup can in your cupboard, the bands of value will be vertical.  Should the cylinder be laying down, as does a felled tree or a log, the bands of value will run horizontally (or at whichever angle the log lays at). Below is a representation of a cylinder, as well as an example of how the bands of value will fall.  The “value shape” is essentially rectangular.
  •  The Cone:  when rendering the cone, the values take on a basically triangular shape, with the vertex of each  triangular “value shape” corresponding to the vertex of the cone.  The bases of the “value shapes” are slightly curved to follow the curvature of the cone’s base.


  • The Sphere: to render light and dark on the sphere, the artist must look to create two sections of “value shapes”.  Primarily, an oval shape, which will form on the section of the sphere where the highlight is, and the corresponding darker values in crescent shapes, nearer to the edges of the sphere
  • The Torus:  the torus is somewhat complicated in that it’s “value shape” bears the qualities of both the cylinder and the sphere.  To render the torus, some sections of the “value shape” need to be treated as one does the cylinder; i.e. it will be basically rectangular, whereas other sections of the shape is more like the sphere’s crescent.  The rectangular, band-like aspect of the torus’ “value shape” are found within the length , whereas the crescent aspects  are found at the extreme right and left of the shape, relative to the viewer.
  • The Rectangular Prism:  this shape, though likely being the most familiar to the artist, is actually the most complex to render.  This is because of the necessary lack of curvature on the Rectangular Prism’s 6 planes.  The flatness of the planes necessitates a gradation effect to be represented on their faces. The Rectangular Prism therefore has no “value shape” to look for when rendering its planes; each of the shape’s sides will feature a gradation. The key factor to remember when rendering the Rectangular Prism is that the gradation on the planes are in opposition to one another, i.e. that the darkest value of any plane will meet on an edge  with the lightest value of the adjacent plane. Correspondingly, the values of each other section of plane will meet on an edge with their opposite value on adjacent planes.


Next time, we will return to Andrew Loomis and his final considerations of geometric shapes, their use in figure drawing, and his closing thoughts to this section of the book, Successful Drawing.

Of interest to my readers, I would like to inform you that I will be now posting new entries for Understanding Loomis every Sunday, in order to complete my synthesis of Andrew Loomis’ writing in a more timely manner.

See you in 7 days.

2 thoughts on “Concerning Rendering of the Geometric Shape

  1. Great explanation of geometric shapes and their importance in grasping the underlying structure of the object to be rendered. It seems so obvious but often is the very thing that is not given enough consideration.

    Liked by 1 person

  2. Thanks! I agree that the fundamental points are pretty obvious, but I am not sure that I would have remembered them in a specific way while working without concretizing them. I think that having these observations concretized as rules is valuable, since there are so many things to think about when making art; a few “laws” to rely on can act as a conceptual shorthand for us, which frees up our cognitive processes for the other challenges being faced.


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