Beyond Spectral and Spatial data: Exploring other domains of

information: 4

GEOG3010 Remote Sensing

and Image Processing

Lewis

RSU

Domains of Information

• spectral

• angular

• multi-temporal

• distance-resolved

• spatial

Distance-resolved

• Can determine distance from satellites:– based on time-delay of signal

Distance-resolved

• Can determine distance from satellites:– based on time-delay of signal

Distance-resolved

• eg GPS

Distance-resolved

• EO example:– radar interferometry

Distance-resolved• EO example:

– radar interferometry: • assume know satellite position

1 cycle (5.6 cm for C band)

¾ way through half cycle

(¾+1)x180 = 315 degrees

(360 degrees, 2 radians)

¾ way through

270 degrees

2 x d1 = (N1+¾)x5.6

Distance-resolved• EO example:

– radar interferometry:

0 way through2 x d2 = (N2) x 5.6

2 x (d2 - d1) = (N2- N1) x 5.6 + (¾-0) x 5.6

Distance-resolved• EO example:• position 1:

– 2 x (d2 - d1) = (N2- N1) x 5.6 + (¾-0) x 5.6

• position 2:– point on ground next to current point will have different

phase change– if its within the same cycle (height change less than

5.6cm)• can tell relative height change between these points• very precise (mm)

Shuttle Radar Topography Mission

Shuttle Radar Topography Mission

11 Feb 2000 (Endeavour) - 11 days

30m DEM of +/- 60 degrees latitude

Distance-resolved

Measure small change -

subsidence

Distance-resolved

Measure small change -

earthquake

Distance-resolved

LIght Detection And Ranging

RAdio Detection And Ranging

LIDAR

RADAR

Distance-resolved LIDAR

• Send laser pulse from sensor

• measure round trip time

• = 2x distance

• use NIR mostly– atmospheric effects minimised

Distance-resolved LIDAR

• Examples - EA

• fly aiborne LIDAR regularly for high resolution DEM

• use first/last return

• ground height / tree height

Distance-resolved - LIDAR

Distance-resolved LIDAR

• Examples - VCL

• Vegetation Canopy LIDAR

• NASA mission to fly ????

• waveform LIDAR

Distance-resolved VCL

• waveform LIDAR

Distance-resolved • waveform LIDAR

LIDAR

• ‘Simple’ form of measurement

• easy to use (? Simply)

• doesn’t work (well) on high slopes

• requires highly-sensitive instrumentation

• potentials for new forms of information – waveform LIDAR

Interferometry

• Used for number of years– operational (SRTM)

• different ‘scales’ for different SAR frequencies

• doesn’t work well (for height) if change between images– wind in forests

• doesn’t work on high slopes