This submenu allows interactive specification of the parameters controlling two dimensional particle tracking. The parameters specified here are automatically saved to a binary file Track2D.DIG in the current working directory. On entering the 2D particle tracking facility, the parameters are automatically restored from this file. The tracking process itself utilises these parameters to operate in a psuedo batch mode.
Note the permanent reference points and the pixel-world transformation must also be set up. This is achieved from [;P Coordinate system mapping] This coordinate system information is stored in the CalPnt2D.DIG, CalWorld.DIG and CalWldPt.DIG files in the current directory.
When tracking is started, a copy of Track2D.DIG is made in BaseName.PAR, where BaseName is the basic file name specified by [F File name] (see below). Similarly a copy of CalWorld.DIG is made in BaseName.WLD for use in the subsequent analysis phase. Both these files are in binary form.
This option allows entry to a submenu which specifies the method to be used to remove background variations in the image. A number of techniques are supported, including simple subtraction of the background intensity (which may be derived in a number of ways), and masking off a fixed region of an image. Note that the background used by this option is static in that it has no temporal temporal variation. In contrast, [R: Record background region] is able to perform masking and aritmetic operations with a time-varying background.
This option allows selection and inhibition of the display of particle paths and the cost matrix while the tracking process is proceeding. Display of the particle paths is a useful indication of how the tracking process is proceeding. Particles may be plotted either as they are located (<L>), or matched (<M> or <B>), using either single points or connecting lines. For diagnostic purposes, the transportation algorithm cost matrix may be displayed some of the time in buffer 0 (<C> or <B>). To increase tracking speed, all these plots may be suppressed (<N>).
This field specifies the title of the experiment being tracked. The contents are used for record only as they have no influence on the tracking process.
This option allows specification of the base file name to which the tracking parameters (base_name.PAR), coordinate system (base_name.WLD), sample index (base_name.IND), and particle locations and associations (#.PRT) are saved during the tracking process. Except for the frame index file (base_name.IND), all these files are binary.
This submenu enables and specifies the use of various filters for improving the quality or consistancy of digitized image prior to locating the particles. These filters are in addition to the interlace filters defined in [TI: Interlace filters] and are applied after them.
Enters the Particle Location submenu from which parameters governing the range of acceptable particle characteristics may be specified. See the [f1 Help] option within this submenu for more details.
Particles which do not have a velocity history may be matched with particles a relatively large distance away. As the velocity history is normally used when determining the cost, and for new particles we have no idea what the velocity is, it is necessary to both predict the mean velocity of new particles (see [N New particle behaviour]), and increase the maximum allowable separation between the "predicted" position and the actual position. This option allows the user to specify a maximum error between the predicted velocity and the actual velocity at which new particles may be allowed to enter the system. The maximum error may be specified either as a velocity (world units/second), or a separation distance (in pixels).
The menu access by this option allows specification of the characteristics which a new particle (ie. one which has not been tracked for long enough to have a velocity history).
Enters the Pricing Policy submenu from which parameters governing the cost of the various possible particle-particle and particle-boundary associations may be specified. See the [f1 Help] option within this submenu for more details.
This option allows entry into the menu controlling the various methods of recording the background intensity in the region of a particle. These methods include dynamic contour masking to divide the image into two regions which may be used to either select part of the image or record which region the particle falls in, and the ability to record the actual background illumination near the particles.
This option accesses a menu containing the timing details required for the tracking process. In particular, the sample spacing, tracking start time and total tracking time. See [f1 Help] in the submenu for more details.
Under normal circumstances, the tracking process is undertaken within a normal DigImage rectangular window, though this window may be modified by the masking options of [B Background removal] or [R Record background region]. Note that this window is utilised in the reference pixel coordinate system so that it remains fixed in the experimental coordinate system. This option allows the window to be specified interactively, using whatever buffer is desired, with the normal DigImage window selection submenu.
This field places a limit on the allowable rms error associated with the mapping from the current pixel coordinate system to the reference pixel coordinate system. The value of this rms error is an indication of the quality of an image. A high value of the rms error indicates a poor quality frame. If the rms error is greater than the limit specified by this field, then up to five attempts to recapture the image will be made.