Envelope/block-in
Use straight-edged shapes to establish a subject’s proportion, tilt, and placement before adding curves and detail.
What it is
An envelope or block-in places the subject inside a simple angular boundary made from straight lines. Identify the outermost edges and the major angle changes before adding detail or curves.
Subdivide the envelope into smaller blocks to place major features, masses, light and dark divisions, folds, and silhouette breaks. Keep these approximations short and straight at this stage.
A figure or object may begin as a 6–12-line polygon. Check its angles, distances, placement, and fit on the page before developing specific shapes and interior structure.
Why it matters
The envelope gives you a simple structure for checking proportion, tilt, placement, and page fit. Weak control can cause features to become misspaced, tilts to drift, or the drawing to expand beyond its initial shape.
You can check it when
- ✓Begin a drawing with 6–12 straight lines that record the subject’s outer shape and tilt before curves or details appear.
- ✓Compare finished drawings with their initial envelopes and check whether the main shape, placement, and proportions remain consistent.
- ✓Block in a moving or complex subject with straight lines while preserving its pose and overall proportion.
- ✓Record more accurate proportions when a drawing begins with straight-line blocks than when it begins with outlines or details.
Related skills
- Measurement (comparative, angles, plumb lines)
- Accurate proportion — including correcting errors mid-drawing
- Shape simplification
- Primitive forms in any rotation (boxes, cylinders, spheres and modified spheres, cones, pyramids)
- Basic mannequin
- Boxes in perspective (above/below eye level, rotated)
- Thumbnailing (multiple variations, simplification, reading at thumbnail scale)