MarkWrite Series detection

MarkWrite makes use of a status variable that marks where a sample is the "FIRST_ENTER" as the pen returns from being out of range (i.e. starts or re-starts recording). These mark the start of series - sequences of consecutive samples where the pen is in range and either hovering above or pressed on the tablet surface. This status information is already present in GetWrite generated data because GetWrite extracts this information directly from the tablet as the data are being collected. In generic tyxp files, series boundaries are inferred. They cannot be inferred from current HandSpy and eptxyp files.

MarkWrite assumes that txyp files include hover samples - samples recorded when the pen is in range but pressure > 0. It then detects times when inter-sample intervals are greater then would be expected on the basis of the modal sampling interval rate and identifies these a series boundaries (i.e. periods when the pen was out of range). This information is then used to set the status (HOVER, FIRST_ENTER and so forth) of each sample, which in turn is used for filtering (if this setting is turned on) and for selection actions, and for calculating output variables. How successful MarkWrite will be at determining series boundaries in this way will be dependent on quality of the timing data in the raw txyp file.

Currently neither Eye & Pen nor HandSpy give data when the pen is hovering. Pressed period ("run") boundaries are identified in Eye & Pen data by single rows where pressure = 0. These are removed when the data are read into MarkWrite, and a status field created. HandSpy xml data define "strokes", which correspond to what MarkWrite calls runs.