Add multi-temporal map layer

Modified on Fri, 02 Feb 2024 at 12:29 PM


The Add multi-temporal map layer block allows you to see changes over time in a static map layer. You can display three different dates on the map using each of the Red, Green and Blue (RGB) channels. Colour indicates areas where there has been a change, and shades of grey (with no hue) indicate areas where there has been no change.


This block must be placed after an Aggregate images in time block. The options for each of the Red, Green and Blue channels is determined by the way you have chosen to aggregate the images (eg. by month or year).


Visualisation options

Click on the cog icon to adjust the visualisation options and add a description.


Contrast options

The contrast options are for defining the minimum and maximum value to scale your images.


  • Default Dataset Visualisation:  The minimum and maximum scaling is pre-defined by the dataset provider.
  • Dataset Min and Max: The minimum and maximum scaling is set to the lowest and highest values within the dataset.
  • Mean +/- 1 Standard Deviation:  The minimum and maximum are defined by the mean of the data plus and minus the standard deviation of the data. If the data are normally distributed this includes approximately 68% of all data.
  • Mean +/- 2 Standard Deviations: The minimum and maximum are defined by the mean of the data plus and minus two standard deviations of the data. If the data are normally distributed, this includes approximately 95% of all data.
  • p90: Excludes values below the 5th percentile and above the 95th percentile. This ensures that infrequent but very high or low values don't bias the scaling. 
  • p98: Excludes values below the 1st percentile and above the 99th percentile. This ensures that very infrequent but extremely high or low values don't bias the scaling. 
  • Custom: Specify your own minimum and maximum value for each of the Red, Green and Blue channels.


When analysing a time series, the contrast statistics are calculated for the middle image (by time) and then applied to all other images in the time series. 


Description

Add a description to your map layer that will display under the map layer name in the map panel.


How do I change the opacity of map layers?

When your workflow has run, and the map layer is shown on the map, click the extras menu next to the map layer legend, and select the ‘Opacity’ option.


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