Description
Return the exact centered planar stimulus angular width from supplied compatible dimensions, without an acuity score.
Vision research uses stimulus angles, chart notations, image scales, viewing distances, coordinate origins, and observation windows. These quantities have different denominators and measurement conventions. A conversion or support share does not independently establish a visual measurement or its clinical interpretation.
Return the exact centered planar stimulus angular width from supplied compatible dimensions, without an acuity score.
When to use this tool
Use Visual Angle Stimulus Size when you need this image, stimulus, notation, coordinate, or observation component for supplied research data.
How to use the tool and how it works
- Enter stimulusWidth, viewingDistance. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read angleRadians, angleDegrees. Use the output convention below.
For nonnegative stimulusWidth and positive viewingDistance return angleRadians=2*atan(stimulusWidth/(2*viewingDistance)) and angleDegrees=angleRadians*180/pi.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| stimulusWidth | Stimulus Width | Required. Finite number; minimum 0. |
| viewingDistance | Viewing Distance | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| angleRadians | Angle Radians | Required. Finite number. |
| angleDegrees | Angle Degrees | Required. Finite number. |
{
"input": {
"stimulusWidth": 2,
"viewingDistance": 1
},
"output": {
"angleRadians": 1.5707963267948966,
"angleDegrees": 90
}
}Limitations and assumptions
- Width and distance need one length unit under a centered perpendicular target model. This full visual angle does not establish chart calibration, acuity, retinal size, or clinical visual function.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use calibrated acquisition and a documented visual or imaging protocol for complete interpretation. Confirm the reporting notation, viewing geometry, image scale, and support of the underlying observations.
References
Similar or alternative tools
- Near Target Angular Size
Compute exact geometric angular extent of a centered planar target from compatible supplied dimensions.
- Retinal Pixel Angle Factor
Apply a supplied retinal research image angular calibration, without inferring retinal anatomy or disease.