Marker Tracking Configuration

The Marker Tracking Configuration Tool can be used for creating and managing configuration files appropriate for marker based tracking. For a general overview of supported tracking systems please go here.
A configuration file for marker tracking is created in two steps:

Step 1: create or load a markerset

First a list containing all the markers to be used in your project is created in the "Markerset" block of the tool. To that list you can add single markers (by clicking on the button) or multiple markers of the same size (by clicking on the button). As Marker-IDs values between 1 and 512 are valid. Every Marker-ID can only be used once within a markerset. Please choose the marker size according to the needs of your project. As default marker size we've chosen 140 mm because this allows printing on DinA4 paper (similar to "letter size"). You can always change the size of markers already added to the markerset by using the context menu, by clicking on the button or by clicking on the according value in the list but please be aware that you have to reprint the marker afterwards to get valid tracking results. By clicking on the button or by using the context menu you can remove markers from the markerset. The list of markers contained in the markerset can be sorted by marker-ID or by size by clicking on the respective column header.

You can save the markerset by clicking on the button and open markersets by clicking on the button. The dropdownbox just above the list containing the markerset allows easy and fast access to the five markersets you've used last. Be aware that you can not only load markerset files but also configuration files (TrackingData). In case of the latter, the markerset corresponding to that configuration is extracted.

As soon as you've saved your markerset you can create a PDF-file containing those markers by clicking on the button. This will open the metaio Marker Generator and the data of the created markers will automatically be passed along. You just have to choose the size of the markers you want to create and then click OK. If the markerset contains markers of only one size, this size is already selected so you just have to click OK. If the markerset contains markers of different sizes, one PDF-file has to be created for each size contained in markerset.

Now the "PDF" file with your markers will be created and opened afterwards. Print out the PDF file. In the print dialog make sure to NOT apply any kind of scaling (e.g. "fit to print area") is applied as this will change size and potentially the aspect ratio of the markers (which has to be square).

If you want to clear the list of markers to create a new markerset, please click on the button.

Step 2: create or load a configuration

In the "Configuration" block of the tool you can create coordinate systems and define by which markers those coordinate systems are to be represented. Configurations are displayed in a tree structure with coordinate systems, markers and offsets being the nodes. There are several varying approaches for creating a configuration:

If you want to create coordinate systems that are represented by a single marker each you can do that by clicking on the button. In the dialog opening on the click you just have to select all the markers for which a coordinate system is to be created and then confirm your selection by clicking OK. Coordinate systems according to your selection will then be added to the configuration and named "COS x" with x being replaced by the appropriate Marker-ID.

If you want to create a marker composite, which means that several markers represent the same coordinate system, please click on the button. In the dialog opening on the click you can add markers to the marker composite and choose one marker as "master marker" which means that the coordinate system will be placed over this marker later on. In addition you have the possibility to give the coordinate system a name of your choice.

Before the marker composite can be used for tracking, you'll have to let the configuration know how the markers are positioned relative to the master marker. The values of those relative positions have to be set as coordinate system offsets (COS Offsets) for all non master markers.

By clicking on the button you can add an empty coordinate system to the configuration and add single markers afterwards by clicking on the button. Naturally such single markers can also be added to coordinate systems created as described above.

The created configuration can be saved to an xml-file by clicking on the button. Existing configurations can be loaded by clicking on the button. When loading a configuration, a corresponding markerset is automatically generated and does not have to be created in advance.

By using the context menu or by clicking on the button, markers can be removed from coordinate systems and coordinate systems including the markers connected to them can be removed from the configuration. By clicking on the button, by using the context menu and partly also by clicking on the respective node its attributes can be edited.

The context menu also provides some more functionality where applicable:

• copy: copies transformation values of selected node to clipboard
• paste: pastes transformation values from clipboard to selected node
• reset: sets transformation values of selected node to "no transformation"
• expand all: opens all child nodes of selected node
• collapse all: closes all child nodes of selected node

If you want to clear the tree structure to create a new configuration please click on the button.

Remarks:

Configurations that have not been changed since last saving can be applied to Unifeye by clicking on the "Apply" button at the bottom of the tool. The indicator next to that button shows you whether the configuration currently loaded in this tool is acitve in Unifeye or not.

For your configuration you can choose from the tracking qualities "robust" and "fast". The robust option is set as default and should not be changed if possible. There are some cases though where the fast mode is needed (e.g. if markers are very large in the images). In such a case you might have to set the binarization threshold manually. This can be done by clicking on the "Threshold" button. Please note that this button is only activated if the image source set in Unifeye is a non-still-image. To be able to open the threshold window, Unifeye needs access to the configuration. Therefore the configuration has to be saved and activated for tracking in Unifeye. This is the reason why the "Save TrackingData" dialog is automatically opened if the "Threshold" button is pressed while the configuration is not yet active in Unifeye.

-- SupportMetaio - 2011-01-21