Down Sample Filter

The foglamp-filter-downsample filter is a mechanism to reduce the amount of data ingested, it allows the effective data rate to be reduced by a given factor, for example to have the data rate you select a down sample factor of 2, to get a third the rate you select a down sample factor of 3. There are a number of algorithms available to select the value to be sent.

  • Sample - the first value in the sample is used as the value for the sample set.

  • Mean - the average value in the down sampled set is sent as the down sampled value.

  • Median - the mathematical median value is sent as the down sampled value. This is the number found by sorting the sample and choosing the mid point of the sample.

  • Mode - the mathematical mode value is sent as the down sampled value. This is the number that appears most often in the sample.

  • Minimum - the minimum value in the sample is sent forward.

  • Maximum - the maximum value in the sample is sued as the sample value.

Downsample filters are added in the same way as any other filters.

  • Click on the Applications add icon for your service or task.

  • Select the downsample plugin from the list of available plugins.

  • Name your downsample filter.

  • Click Next and you will be presented with the following configuration page

downsample_1

  • Configure your downsample filter

    • Down Sample Factor: The number of incoming values in each sample set.

    • Down Sample Algorithm: The algorithm used to determine the value for the sample.

      downsample_2

    • Excluded Assets: A list of assets that are excluded from the down sampling process.

  • Enable your filter and click Done

See Also

foglamp-filter-asset - A FogLAMP processing filter that is used to block or allow certain assets to pass onwards in the data stream

foglamp-filter-change - A FogLAMP processing filter plugin that only forwards data that changes by more than a configurable amount

foglamp-filter-delta - A FogLAMP processing filter plugin that removes duplicates from the stream of data and only forwards new values that differ from previous values by more than a given tolerance

foglamp-filter-rate - A FogLAMP processing filter plugin that sends reduced rate data until an expression triggers sending full rate data