Calibration Data

From IGSTK

IGSTK needs a common file format for storing tool calibration transformations. Since the tools must be calibrated ahead of the time of surgery, it is necessary to verify that the correct calibration file is applied to the correct tool.

The tool calibration file must contain the following information:

• The data and time when the calibration was performed (in DICOM date/time format: YYYYMMDD HHMMSS.SSSS)
• information about the method and equipment used to calibrate the tool
• Identification information for the tool, including the manufacturer, part number, and serial number for the tool
• The transform type (which will be limited to rigid quaternion transforms for now)
• The transform parameters
• A description of the error associated with the calibrated transform

XML Specification (Updated)

<?xml version="1.0"?>

<IGSTKFile type="ToolCalibration" version="0.1">
 <Creation date="20050824" time="070907.0705" method="PivotCalibration" />
 <Tool type="Pointer" manufacturer="Traxtal" partNumber="023-X" serialNumber="200501268" />
 <Transform type="Rigid3D">
   <Parameters>
     <Parameter name="translation_x" value="5.0"/>
     <Parameter name="translation_y" value="2.0"/>
     <Parameter name="translation_z" value="3.0"/>
     <Parameter name="quaternion_x" value="9.7467943448089631"/>
     <Parameter name="quaternion_y" value="0.9233805168766388"/>
     <Parameter name="quaternion_z" value="-0.20519567041703082"/>
     <Parameter name="quaternion_w" value="0.30779350562554625"/>  
   </Parameters>
   <Errors>
     <Error name="rms" value="0.187876234"/>
   </Errors>
 </Transform>
 <CRC32>
   3096710971
 </CRC32>

</IGSTKFile>

XML Specification (old)

<?xml version="1.0"?>
<IGSTKFile type="ToolCalibration" version="0.1">
  <Creation date="20050824" time="070907.0705" method="PivotCalibration" />
  <Tool type="Pointer" manufacturer="Traxtal" partNumber="023-X" serialNumber="200501268" />
  <Transform type="Rigid3D">
    <ParameterNames>
      translation_x translation_y translation_z
      quaternion_x quaternion_y quaternion_z quaternion_w
    </ParameterNames>
    <ParameterValues>
      5.0 2.0 3.0
      9.7467943448089631 -0.20519567041703082 0.9233805168766388 0.30779350562554625
    </ParameterValues>
    <ErrorParameterNames>
      rms
    </ErrorParameterNames>
    <ErrorParameterValues>
      0.187876234
    </ErrorParameterValues>
  </Transform>
<IGSTKFileCRC32>
  4f6a3b2d
</IGSTKFileCRC32>
</IGSTKFile>

• The crc32 is a 32-bit CRC that can be checked to validate the integrity of the data.
• The crc is calculated from the start of the <IGSTKFile> tag to the end of the </IGSTKFile> tag, not for the whole file.
• A proper DTD should be specified for the above XML file.

The naming of the error parameters is still undecided, as our igstk::Transform only has one error parameter so far. The following error parameters could be defined:

• rms: the root-mean-square error for the translation (FRE or Fiducical Registration Error for landmark registration)
• centroid_x,_y,_z: the landmark centroid (or the center of rotation that was used for image registration)
• additional parameters to express rotational error

Original Specification (never used)

# TR: IGSTK transform file.

CreationDate: 20050824
CreationTime: 070907.0705
CreationMethod: PivotCalibration
CreationEquipment: None
ToolType: Pointer
ToolManufacturer: Traxtal
ToolPartNumber: 023-X
ToolSerialNumber: 200501268
TransformType: Rigid3D
TransformParameterNames: translation_x translation_y translation_z quaternion_x quaternion_y quaternion_z quaternion_w 
TransformParameterValues: 5.0 2.0 3.0 9.7467943448089631 -0.20519567041703082 0.9233805168766388 0.30779350562554625
TransformErrorParameterNames: rms centroid_x centroid_y centroid_z ...
TransformErrorParameterValues: 0.187876234 ...