To learn how to create a heatmap, and where to edit these styles, visit this page.
The advanced heatmap options are not displayed by default in any page. However, during the heatmap creation wizard and while editing heatmap settings you can show them by clicking the ‘Advanced settings’ button.
Gaze and Mouse tracks
By default, gaze and mouse tracks are not displayed in aggregate heatmaps. However, if you have selected a small number of views they may be useful.
The heatmap generates a Gaussian distribution around each measured gaze point. This is the kernel. As more samples accumulate – either from the same, viewing, or other viewings – these kernels are added together to produce a surface representing the density of likely gaze samples at each pixel in the image.
You can choose from 4 different kernels. They only vary in the spread of the shape produced by a single gaze sample. They range from wide (1) to narrow (4):
- Average: This kernel deliberately merges nearby measurements, to give you a broad picture of which areas are attracting attention.
- Visible: [Default]. This kernel represents the approximate foveated area of vision of the viewer. If there was no measurement error at all, this kernel represents the area someone can see in one glance without moving the eyes (we don’t see a point, we typically see an area about the size of a large coin).
- Focus: This is a narrower kernel. If you have a large number of samples, this can help to bring out more subtle differences between different features only detectable on average.
- Narrow: This is the most specific heatmap sample function.
There are two options for this setting: Dwell, and Order. The default is “Dwell” – meaning that the longer you look at something, the “hotter” it becomes. In “Order” mode, samples are weighted depending on how far they are from the start of the time-window. The earliest samples are “hottest”.
Aggregate mask Colour
This setting is used in conjunction with the “Mask” heatmap style. Use it to pick a background colour. Areas viewers did not look at will be blended into the selected mask colour, making them invisible.
Aggregate Low Threshold (%)
This parameter controls how much of the image is transparent (completely “cold”). The percentage is measured as a fraction of all gaze samples. For example, if set to 10%, then areas with less than the 10th percentile of the cumulative gaze-sample-weight will be completely transparent. This represents no-one looking at these areas. You can think of this parameter as a sensitivity setting, that determines how many “looks” an area needs to become coloured in the heatmap.
Aggregate High Threshold (%)
This parameter controls saturation of the gaze data. Say the threshold is set to 90%. This means that all areas with a cumulative gaze-sample-weight over the 90th percentile all have the same appearance (the hottest colour). This is useful when there are a few very hot spots, and you’d like to see some of the other slightly less popular features. Simply reduce this threshold until you get the range of data you’re looking for.