CellScale BioTester User Manual page 32

6. Modify search parameters:
Source
Template
Search Region
Use Source
Template From
Set Search
Region Centre
Use Strain
Based
Deformable
Templates
7. Perform tracking with either Track All Points or Track Selected Points.
The optimal source template is difficult to predict, but in general it is
advantageous for the template to be large enough that it contains at
least one feature, but not so large that it contains multiple features.
Typical values for this parameter are between 15 and 55, with 35
being a good starting point for most users.
The search region needs to be large enough that the optimal
location for the template is found. In general, no part of the
specimen moves more than the rake tines, so the motion of the
rake tines is a good guideline for how large the template needs to
be. For example, if the rake tines move 50 pixels over the 10
frames you are interested in, it is unlikely that any part of the
specimen is moving more than 5 pixels/frame and so a good value
for the search region parameter would be 11 (5 pixels each way,
plus the center pixel).
First Image tracks all images against the first in the series (1→2,
1→3, 1→4...).
Previous Image tracks each subsequent image against the image
before it (1→2, 2→3, 3→4...).
First Image Tracking tends to have poorer correlation than Previous
Image Tracking because the current image is usually closer in
content to the previous image than it is to the first image in the
sequence. Previous Image Tracking tends to have good correlation
for each individual step, but is prone to error accumulation since
each step is independent. The best method for a given data set will
depend on the number of images and the content of the images.
Sometimes it is best to use Previous Image Tracking but to only
use every other image or every n
available. Sometimes it is best to use First Image Tracking and use
every image but set the source image in the middle of the image
series rather than at the beginning.
New Point Locations The location of the center of the search
region is set to the same location of that point in the previous image
(even when the source template is from the first image).
When this option is checked, the source template will be scaled
(resized) according to strains calculated from the test Size X and
Size Y parameters. Best tracking results are often obtained when
using this option. This option may not be the best for uniaxial tests
or tests where the specimen deformation is non-uniform.
BioTester User Manual
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image rather than all the images
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