If you only see gaze data on a black background in the Spatial Overlay view, it's usually due to one of the following common issues.
To quickly figure out which issue you're facing, switch to the Animation Playback View and play the trial.
To quickly figure out which issue you're facing, switch to the Animation Playback View and play the trial.
- If you see your stimuli: The problem is you need to set an Interest Period.
The Spatial Overlay view defaults to showing the last screen displayed within the currently selected interest period as the background. If your trial ends with a blank screen, that is what you will see when your interest period is set to the Full Trial Period.
You can easily resolve this by Defining an Interest Period (IP) to tell Data Viewer which part of the trial (and which background image) you want to analyze.
- Click the "Full Trial Period" dropdown menu at the top of the window and select Edit....
- In the Interest Period Manager, click the "New Interest Period" icon.
- Give the IP a name (e.g., Stimulus_Display).
- Enter the message text that marks the start of your stimulus presentation (e.g., Display_Sentence).
- Enter the message text that marks the end of the stimulus presentation (e.g., Display_Blank), or set a fixed duration.
- Close the manager and apply your new IP from the dropdown menu.
- Click the "Full Trial Period" dropdown menu at the top of the window and select Edit....
- If you still see a black background: The problem is your file paths may be broken, and you need to move or package your data correctly.
The EDF (data) and EVS (session) files do not contain your images or videos. They only contain pointers to these files. If you move the EDF or EVS file by itself to a new location, these links will break. To preserve the links, you must move all the necessary files together.
You can verify this by going to the File menu -> Verify Dependency Files and let Data Viewer check linkages to the dependencies within your viewing session. Should the tool identify any missing file you will need to restore them to their original state.
Keep in mind when moving data from location to location that you have two options:- Option A (Recommended): Copy the entire deployed project folder to the new location. This keeps all relative file paths intact.
- Option B (Packaging): In Data Viewer, load your data and then go to File > Package.... This creates a single .dvz file that contains all the necessary data and dependency files. You can then safely move and unpack this .dvz file on another computer.
- Option A (Recommended): Copy the entire deployed project folder to the new location. This keeps all relative file paths intact.