Description
Check supplied DICOM row/column direction cosines for unit lengths and orthogonality using an explicit tolerance.
An image grid has array indices as well as physical spacing, timing, and signal conventions. A calculation on supplied metadata describes one part of that grid or signal; it does not inspect an image, validate a complete file, or interpret anatomy.
Check supplied DICOM row/column direction cosines for unit lengths and orthogonality using an explicit tolerance.
When to use this tool
Use it for dicom image orientation dot orthogonality gap when the required inputs and conventions are already available.
How to use the tool and how it works
- Enter rowDirection, columnDirection, tolerance. Keep parallel arrays aligned and use the stated units and conventions.
- Run the calculation. Correct any input error before interpreting a result.
- Read dot, rowNorm, columnNorm, withinTolerance. Inspect any known, defined, inclusion, or boundary flags before interpreting numeric values.
Require row and column vectors of three components and nonnegative tolerance. Calculate their dot product and norms; withinTolerance requires the absolute dot product and both norm deviations from one to be no greater than tolerance.1
DICOM Image Orientation describes row and column direction cosines, which form orthonormal directions.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| rowDirection | Row Direction | Required. Array of Finite number.; maximum items 256. |
| columnDirection | Column Direction | Required. Array of Finite number.; maximum items 256. |
| tolerance | Nonnegative absolute tolerance in the quantity tested, unless the mechanics state a different convention. | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| dot | Dot | Required. Finite number. |
| rowNorm | Row Norm | Required. Finite number. |
| columnNorm | Column Norm | Required. Finite number. |
| withinTolerance | Within Tolerance | Required. Boolean. |
{
"input": {
"rowDirection": [
1,
0,
0
],
"columnDirection": [
0,
1,
0
],
"tolerance": 0.001
},
"output": {
"dot": 0,
"rowNorm": 1,
"columnNorm": 1,
"withinTolerance": true
}
}Limitations and assumptions
- Tolerance is an absolute numeric tolerance. Passing these checks does not determine handedness, validate all DICOM geometry, or supply an image-to-patient transform.
- The field tables describe structural bounds; the mechanics also state cross-field requirements. Malformed input shapes, disallowed keys, and invalid domains cause input errors. Results must remain finite and within the declared output contract. A successful false flag or zero placeholder is distinct from an error.
- Numeric arithmetic uses binary floating point. Exact comparisons have no hidden tolerance or decimal rounding; negative zero is exported as zero. Decimal-text integer operations retain the exactness specifically stated above.
Alternative or Complementary methods
For dicom image orientation dot orthogonality gap, check the source records and the supplied rule before comparing the result with another method. Use a full image reader and geometry or signal analysis when the task requires interpreting image data.
References
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