Terrestrial remote sensing toolkit

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# Temporal resolution

Pertains to time image data are collected (AM or PM) and the frequency at which images are collected over a site. Environmental considerations can influence when its best to collect an image:

- Angle of sun,
- day or night,
- seasonal variations in vegetation,
- water clarity and tidal heights in case of marine environments.

## Time of data collection

- Set time:
  Some satellite acquire always an image that covers the same extent of each area on earth at every overpass at roughly the same time of day(e.g. Landsat Enhanced Thematic Mapper, or MODIS Aqua).

- On request:
  Airborne sensors can capture an image during almost any time on a day determined by the image provider and limited to local weather conditions and/or local air traffic. Some satellite sensors can be programmed to capture an image of a certain area by adjusting the direction of the field of view of the sensor. The time during the day for the image acquisition is roughly the same for each overpass. The date when it is taken depends on when an overpass is of the satellite over the area of interest and if no other request had first preference. Examples of these satellites are mostly the high spatial resolution multi spectral sensors (e.g. Quickbird, Ikonos, WorldView 2).

## Frequency of data collection

1. Extremely high – multiple daily
2. High – daily
3. Medium – weekly
4. Low – < monthly, seasonally or yearly

See also temporal vs spatial resolution.