b2KIT

Symmetry Group Visualizer

Explore rotational and reflective symmetry groups. Draw a motif and see it replicated under dihedral and cyclic group operations.

Tested tool guide Tested browser tools Checked August 16, 2026

What Symmetry Group Visualizer does, with a checked example

Every image this tool shows you is a copy of one thing: the motif you draw. Pick a symmetry group such as C_6 or D_4 and copies appear under the group's operations: rotations through multiples of 360/n degrees, plus, for dihedral groups, reflections across axes spaced 180/n degrees apart. The result is a rosette showing the orbit of your drawing under the group. The surprise: the visible count is not always the group order. A motif that is itself mirror-symmetric, or lies on a reflection axis, is fixed by some operations, so overlapping copies merge and the count drops to |G| divided by the stabilizer size.

Worked example

A concrete input and expected output from the current implementation.

Input

Choose the dihedral group D_4 and draw a single dot one unit to the right of the center, at (1, 0).

Expected output

Four copies, not eight: dots at (1, 0), (0, 1), (-1, 0), and (0, -1).

The dot lies on the 0 degree mirror axis of D_4 (the other axes are at 45, 90, 135 degrees), so the reflection in that axis fixes it and the other three reflections only send it to positions the rotations already produce. Eight group elements divided by a stabilizer of size 2 gives 4 distinct images. A dot at (1, 0.5), off every axis, gives 8.

How the result is produced

1

Choosing the group

The group selector fixes the operations applied to your motif. C_n applies the n rotations through multiples of 360/n degrees. D_n applies those same n rotations plus n reflections, one across each mirror axis at a multiple of 180/n degrees, giving 2n operations in total. Reflecting and then rotating by one step lands on the next mirror axis, which sits halfway between two rotation angles.

2

Why copies can overlap

The number of distinct images equals the group order divided by the stabilizer size: the subgroup of operations that leave your motif unchanged. A motif with mirror symmetry, or one placed on a reflection axis, has a stabilizer larger than the identity alone, so several operations draw identical copies on top of one another. The group still acts fully; only the visible count shrinks, to at most n copies under D_n.

Good uses

  • Planning a rosette or mandala and wanting to see exactly how a hand-drawn motif repeats before committing to the layout.
  • Checking whether a hand-drawn glyph is mirror-symmetric: compare the picture under D_n with the picture under C_n, and a match, copy for copy, indicates the motif carries its own mirror symmetry.
  • Demonstrating chirality, for example showing that an asymmetric motif such as a drawn 'R' gains reflected versions under D_n that rotations alone can never produce.

Limits and checks

  • The visible count equals the group order only when the motif has no symmetry of its own and lies off every reflection axis; any self-symmetry or axis placement lowers the count, sometimes by half or to a single copy.
  • For a mirror-symmetric motif, D_n and C_n give identical pictures, so you cannot infer from the output alone that reflections were applied; try an asymmetric motif to see them.
  • The count depends on exact placement: a dot slightly off an axis of D_4 gives the full 8 copies, while the same dot on the axis gives 4, so small drawing errors change the result and the axes are easy to misjudge by eye.

Common questions

Why does my D_4 drawing show four copies instead of eight?

Because the motif is fixed by some group element. The stabilizer is the set of operations that leave your drawing exactly where it is, and it always contains at least the identity. The distinct copies number |G| divided by the stabilizer size, so for a dot on a reflection axis of D_4 the stabilizer has two elements and eight divided by two gives four.

Will D_n ever produce mirror images that C_n cannot?

Yes, when the motif is not mirror-symmetric. Reflections change chirality, so an asymmetric drawing such as a small letter 'R' appears in left-handed and right-handed versions under D_n, while rotations alone under C_n can never reverse handedness. If your drawing has mirror symmetry of its own, the two groups produce identical pictures, so the chirality difference becomes invisible.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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