shadow
Let an agent explain shadows and their geometry, relay umbra, penumbra and related effects from optics references, describe uses in timekeeping, astronomy, art and graphics, and distinguish the physical sense from figurative ones.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent explain shadows and their geometry, relay umbra, penumbra and related effects from optics references, describe uses in timekeeping, astronomy, art and graphics, and distinguish the physical sense from figurative ones.
A dark area or region where light from a source is blocked by an opaque object, consisting of the umbra where the source is fully hidden and the penumbra where it is partly hidden, lengthening as the source approaches the horizon into long shadows, and showing effects such as the shadow blister effect when two shadows approach; shadows underlie sundials, eclipses, rendering in computer graphics and much visual art, and the word carries wide figurative meanings.
What it is for: Not applicable; a physical phenomenon.
It can be explain geometry and optics; relay umbra and penumbra; describe applications; distinguish figurative senses.
Distinguishing features
Absence of light
Umbra and penumbra
Geometry of source and object
Diffraction at edges
What it looks like
A dark shape on a surface behind an object lit from one side.
Physical character
parts: umbra, penumbra, antumbra list - for extended sources
How it is recognised
Region where light is blocked
Umbra, penumbra, antumbra, long shadows, shadow blister effect
A silhouette is the outline; a reflection is returned light; shade is a shadowed area
Related models
is a kind of - in registry terms
is a kind of - in registry terms, of light
is a kind of - in registry terms
causes - when cast by celestial bodies
In practice
Families and kinds
shadows from point and extended sources
umbra, penumbra and antumbra
long shadows at low sun
eclipse shadows
shadows in computer graphics such as shadow maps
shadow phenomena such as the shadow blister effect and crepuscular rays
Standards and regulation
No regulation; daylight and shadow rules in planning law for buildings
Failure modes and hazards
Confusing physical and figurative senses
Misreading shadow effects as optical illusions
Rendering artefacts in graphics
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.shadow-person
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Understand What a shadow is.
Science.
Definition
Definition and geometry.
Definition
Definition.
- What is a shadow, and how do source size and distance shape umbra and penumbra? definition
- Is the question about a physical shadow or a figurative use? boundary
Effects
Effects.
Effects
Effects.
- What are long shadows, the shadow blister effect, crepuscular rays and diffraction at shadow edges? definition
- Which entry fits the specific effect? action
Apply Applications.
Application.
Time
Sundials and astronomy.
Time
Time.
- How do sundials and eclipses use shadows, and how do shadows reveal the geometry of the solar system? provenance
- Which entry fits sundial? action
Graphics
Computer graphics.
Graphics
Graphics.
- How are shadows rendered with shadow maps, ray tracing and ambient occlusion? provenance
- Which references are standard? provenance
Art Art and design.
Context.
Art
Art.
Art
Art.
- How have artists used shadow in painting, photography and film, as art historians describe? provenance
- Which sources are cited? provenance
Design
Architecture and planning.
Design
Design.
- How do architects and planners consider shadows in building design and daylight rights? provenance
- Which entry fits daylighting? action
Context Culture and science history.
Context.
Culture
Culture.
Culture
Culture.
- What do shadows mean in mythology, psychology and idiom? provenance
- Which entry fits shadow in culture? action
History
History.
History
History.
- How did Eratosthenes and later scientists use shadows to measure the Earth and light? provenance
- Which entry fits the history of optics? action
What the second pass must settle
- Should umbra and penumbra be separate entries?
- How should optics references be linked?
- The registry entry has merged aliases naming effects; should they be split off?