For Timelapse Basemaps, imagery selection is constrained to within the specific time of interest for the Timelapse period (for example, a March 2018 basemap will only have data collected from Mar 1- March 31 of 2018 within the capture time zone). Timelapse Basemaps source imagery inputs are restricted to a specific time period, as defined by the contracted Time of Interest (TOI).
For Seasonal Basemaps, such as a Spring 2018 basemap, imagery selection is strongly weighted to lie within the calendar season but may extend beyond the calendar dates to find optimal visual imagery.
Planet Automated Basemaps are generated automatically using a proprietary “best scene on top” algorithm that selects the highest quality PlanetScope or RapidEye imagery from Planet’s catalog. By selecting the best images from frequent imaging intervals, Planet is able to create spatially accurate, high-resolution basemaps that minimize the effects of seasonality, cloud, haze, and image misalignments.
Find our Basemap Product spec sheet here: https://assets.planet.com/marketing/PDF/Planet_Basemaps_Product_Specifications.pdf