The Wyko Vision ASCII File Format
The Wyko Vision has three different measurement output data formats: the WYKO dataset (.opd), ASCII dataset(.asc), and SDF dataset (.sdf). The .opd and .sdf are binary and so far closed standards. Therefore, currently the ASCII format is the only available format as the input to our algorithms.
A .asc file consists of three major parts: the header, the z-profile array, and the intensity array (optional). A typical floating point, XYZ-triplet-pixel data file looks like:
The header: (partial)
Wyko ASCII Data File Format 1,0,1
Block Name,Type,Length,Value ......
The z-profile array: (partial)
The intensity array: (partial)
Various combinations of file saving options can affect the content of each part. The influences on data layout format are summarized in Various File Saving Options and the Data Format. See the following sections for detail.
The header is an array of lines of data blocks. Each block consists of fields of title, byte-length, and value separated by delimiters. See The Table of the Complete Header Information. See Various File Saving Options and the Data Format for detail on how different file saving options affect the header information.
- Data Arrays contains the z-profile and the intensity array (no intensity array in stitched data).
- They start right after the header and last until the end of file.
- A block of data is typically a line of an X-Y-Value triplet separated by delimiters.
- In Raw data format, bad data values appear as Bad in the file.
- A data array is also a single data block with the type code being 3.
- The title of the z-profile data array can be either RAW_DATA or OPD depending on whether the data is post-processed. If the data are saved as integers, there will be an additional block titled Mult between RAW_DATA or OPD row and the first line of the actual data.
- The intensity data array is titled as Intensity.
See Various File Saving Options and the Data Format for detail on how different file saving options affect the data.
Various File Saving Options and the Data Format
There are five independent option pairs that affect the output data format.
- Type of Data to Save:
- Processed: the output data will be post-processed according to the settings in the menu Analysis-Processed Options.
- Raw: the post-processing will be bypassed from the output data even if it is performed before saving.
- Data Format:
- Integer: the output value in the data arrays will be saved as integers. The header data are unaffected.
- Floating point: the output value in the data arrays will be saved as floating point. The header data are unaffected.
- Complete: most of the header terms in The Table of the Complete Header Information will be present. The data arrays are unaffected.
- Minimal: Only the header terms in The Table of the Complete Header Information that are Always Available will be present. The data arrays are unaffected.
- Tab: The delimiter of the entire data file will be set to Tab. This is not suggested by us because as it results in poor human readabililty of the data.
- Comma: The delimiter of the entire data file will be set to Tab. This is suggested by us because it leads to a better readability than Tab does.
- Array Format:
- Standard: All the data blocks will be serialized without line breaks; The X and Y coordinates of the data array will not be present while the data order will be the same.
- XYZ Triplet, Pixel: Default format, the data array element is presented as X-Y-Value triplet, with the X and Y coordinates being discrete values.
- XYZ Triplet, Real: The data array element is presented as X-Y-Value triplet, with the X and Y coordinates being real metric value, according to the header term _Pixelsize
There is another option of saving bad pixels as Null. However, this proves to cause Vision to incorrectly read the data. So the option is banned for now.
- Some of the orders of the header data blocks can be inconsistent among files.
- Sometimes some fields such as Title and Note will show up twice.
- There is a bad data chunk in the title field of the header data block RestoreRatioPercent.
- No specification is available for the ASCII format yet. Since our tests are performed without thorugh exploration of the other processing and analysis options, there could be other data blocks especially in the header part can be missing in our documentation. Therefore, This section is meant to be constantly updated as the project goes.
Veeco Metrology Group. 2003. WYKO NT8000 setup and operation guide. Tucson: Veeco Instruments, Inc.