NeuroMotive™ User’s Manual
LB-0336 Rev. 1.00
Page 23
Color Threshold
- For each marker defined the range in hue from the indicated color over which
NeuroMotive™ will detect (see Figure 16). This can also be used for non-color images; the range is just on
a grey scale.
Luminance Threshold
- For all markers defined the minimum brightness pixels must have in order to be
detected.
Radius
- Markers will be detected as semi-circular blobs of pixels that can change size and shape as the
tracked object is moved. This sets a minimum and maximum radius of pixels that NeuroMotive™ should
detect as a marker and track. The radius is only used for eliminating potential markers after other filtering
has occurred and there are more markers than are currently defined.
Low Pass Filter
- This is explained in more detail in section Low Pass Filter on page 27, but it essentially
averages the values of pixel blocks so that the image has less noise and smaller elements that might be
detected as markers may be removed. This can be set to average 5x5 pixel blocks, 3x3 pixel blocks or none.
Morph Open
- Stands for Morphological Opening Filter, this is also explained in more detail in section
Morphological Opening Filter (Morph Open) on page 27. It essentially removes smaller blobs of a 3 or 5
pixel radius.
Morph Dilate
- Stands for Morphological Dilation Filter, this is explained in more detail in section
Morphological Dilation Filter (Morph Dilate) on page 27. It essentially blows up the blobs NeuroMotive™
sees so they are bigger and possible merged with other nearby blobs; which helps in instances where a
marker is detected as multiple blobs. This affects blobs of a 3 or 5 pixel radius.
Marker Preparation
In order for NeuroMotive™ to successfully track objects, it is important to pick effective markers and ensure
appropriate lighting. For markers using the Color camera ensure colors are as distinctive from each other and the
object being tracked as possible. Biocompatible neon glow paint is a good option. LEDs are another good option as
they impart unique color and luminance allowing less ideal lighting conditions. For the IR camera, special reflective
material is provided that works specifically with the IR camera to ease tracking configuration. Concerning lighting,
the more light and the more diffuse and ambient that light is the better that lighting will be in helping to eliminate
reflective spots that can disrupt the camera’s ability to see the markers. LEDs used in low light is very effective.
The IR markers included with IR camera systems are useful at demonstrating the capabilities of IR tracking.
Marker Definition
To begin marker definition, freeze the camera image or stop playback, by clicking Freeze or any define button. This
begins definition mode. In definition mode the Freeze button text changes to Unfreeze and markers can be defined
by clicking on a define button; then clicking on the corresponding marker on the video display. Definition mode
ends when Unfreeze is clicked. Zoom is allowed when the image is frozen to assist in selecting the marker.
Marker Color
To the right of the Define buttons are the Marker Color Boxes. If Luminance is selected as the threshold function, a
greyscale luminance of the marker is shown in the Marker Color Box. If Color or LED is selected, the marker color
is shown in the Marker Color Box. When a marker is defined, the Marker Color Box is automatically filled with the
color or greyscale value of the marker. Because of variations in lighting and camera function, the marker color may
not appear correct. This can be fixed by clicking on the Marker Color Box and displaying a Marker Color dialog,
allowing the marker color to be changed. The process for color selection averages the pixel color at the clicked
location and nearby pixel colors to determine the color of the marker. Defining a marker more than once increases
accuracy by providing a larger sample size for the average, helping to filter noise.