OE-6.2 Digital Imaging & Sensor Resolutions

Work through these

• Types of remote sensing

  The families of instrument, split by whether they supply their own energy. It is the organising distinction for this topic and the next.

• Sensor resolutions: spatial, spectral, radiometric, temporal

  The four numbers that describe what an instrument can see: how small, how many colours, how finely graded, how often. No satellite maximises all four, which is the trade to internalise.

• The digital image and sensor components

  What an image actually is as data, and the parts of the instrument that produce it. It grounds the resolutions above in hardware.

• Principle of along-track scanning

  Sweeping a line of detectors in the direction the platform is moving. No moving mirror, so it dwells longer on each spot and gets a better signal.

• Principle of across-track scanning

  Sweeping a mirror at right angles to the direction of travel instead. Older, mechanically harder, and it covers a wider swath, which is the trade against the item above.

• Hyperspectral imaging

  Many narrow bands instead of a few wide ones, which lets you identify a material rather than merely distinguish it. The data volume is the price.

• Thermal remote sensing

  Sensing emitted heat rather than reflected sunlight, which is why it works at night. It measures a different physical quantity, so the interpretation rules from earlier do not carry over unchanged.