Measuring and Sighting
Introduced| English | Meaning |
|---|---|
| sighting/ˈsaɪtɪŋ/ | Estimating and checking observed angles, alignments or proportions before transferring them to a drawing. |
| comparative measurement/kəmˈpærətɪv ˈmeʒəmənt/ | Judging one observed dimension against another chosen reference dimension. |
| plumb line/plʌm laɪn/ | A cord with a hanging weight that indicates the vertical direction under gravity. |
| envelope/ˈenvələʊp/ | A simplified enclosing shape used to establish a subject's overall extent and proportions. |
The pencil as instrument
- Sighting 目测 means measuring the subject with your pencil at arm's length.
- Full arm's length, locked elbow, one eye closed — now the pencil is a ruler and protractor.
- It is the survival skill of observational drawing.
When sighting, your arm must be ____.
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A locked, extended arm keeps the measuring unit constant.
One unit measures everything
- Pick one unit — often the head, or a cup's height — and measure everything in it: comparative measurement 比较测量.
- "The body is seven and a half heads" is a comparative measurement.
- Check angles by rotating the pencil to match an edge, then carrying it to the paper.
Which measuring tool?
Sort each studio action by the measuring idea it uses.
The envelope is the big simple shape drawn before dividing into parts.
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Envelope first, parts after.
Select all things you can check by sighting.
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Sizes, angles, alignments — not chemistry.
Plumb lines and the envelope
- A plumb line 铅垂线 (imagined vertical) shows which landmarks line up above and below.
- Draw the envelope 外包形 first: the big simple shape containing the whole subject, then divide.
- Measured accuracy is visual evidence of the space and proportion skills.
An imagined vertical used to check what lines up is a ____ line.
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Plumb lines check vertical alignment.
Match the tool to its question.
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Three questions, three tools.
Sighting fails silently if your arm bends or you lean forward — the unit changes between measurements. Same arm, same lean, same eye, every single time.
Drawing a chair: the seat is one "cup" wide, the back two cups tall; the back leg lines up plumb under the top rail's left end. Three checks, and the chair cannot drift far wrong.
Sighting turns the pencil into an instrument: one comparative unit, angle checks, plumb lines for alignment, and an envelope first — observation beats memory every time.
Write from a bottle of 2 pencil-lengths
- Held at arm's length, the bottle measures 2 pencil-lengths.
- The glass beside it measures 1.
At arm's length the bottle measures 2 pencil-lengths and the glass measures 1. The drawing makes the glass taller than the bottle. What measurement was ignored?
One is half of two, so the glass is the shorter object.
How tall should the glass be relative to the bottle?
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The sight size is 2 to 1, so the bottle is the taller form.