radioviz.services.spatial_calibration

Spatial calibration utilities for axis labels and scale bars.

This module provides helper functions to select readable distance units and format axis labels for display based on the image physical extent.

Functions

axis_decimal_places(pixel_size_m, ...)	Determine decimal places for axis labels based on current view scale.
nice_value(value)	Round a value to a 1-2-5 * 10^n sequence.
select_distance_unit(max_extent_m)	Select a unit so the max extent is readable (1 <= value < 1000).

Classes

DistanceUnit(name, meters_per_unit)

Distance unit definition.

class radioviz.services.spatial_calibration.DistanceUnit(name: str, meters_per_unit: float)

Bases: object

Distance unit definition.

Parameters:

• name (str) – Display name for the unit (ASCII).

• meters_per_unit (float) – Scale factor to convert unit values to meters.

radioviz.services.spatial_calibration._floor_log10(value: float) → float

Compute floor(log10(value)).

radioviz.services.spatial_calibration._log10(value: float) → float

Compute base-10 log without importing math for minimal dependencies.

radioviz.services.spatial_calibration.axis_decimal_places(pixel_size_m: float, meters_per_unit: float, lims: tuple[float, float]) → int

Determine decimal places for axis labels based on current view scale.

Parameters:

• pixel_size_m (float) – Pixel size in meters.

• meters_per_unit (float) – Unit scale in meters.

• lims (tuple[float, float]) – Axis limits in pixel units.

Returns:

Number of decimal places.

Return type:

int

radioviz.services.spatial_calibration.nice_value(value: float) → float

Round a value to a 1-2-5 * 10^n sequence.

Parameters:

value (float) – Input value.

Returns:

Rounded value.

Return type:

float

radioviz.services.spatial_calibration.select_distance_unit(max_extent_m: float) → DistanceUnit

Select a unit so the max extent is readable (1 <= value < 1000).

Parameters:

max_extent_m (float) – Maximum extent in meters.

Returns:

Selected distance unit.

Return type:

DistanceUnit