# Glossary

### Anisotropic

:   Directionally dependent

### `crs`

:   Coordinate Reference System. A coordinate system, as defined by a relevant authority
    such as [EPSG](http://epsg.io/) or
    [SR-ORG](http://spatialreference.org/), specified as a string with the
    authority and the code separated by a colon, for example `'EPSG:4326'`.

### `crs_transform`

:   A post transform for a `crs`, defined as a
    list of affine transformation parameters in row-major order \[xScale, xShearing,
    xTranslation, yShearing, yScale, yTranslation\]. See
    [this
    reference](https://docs.oracle.com/javase/8/docs/api/java/awt/geom/AffineTransform.html) for more information.

### DEM

:   Digital Elevation Model

### DN

:   Digital Number

### DOY

:   Day Of Year

### FIRMS

:   [Fire
    Information for Resource Management System](https://earthdata.nasa.gov/earth-observation-data/near-real-time/firms)

### google:registration_count

:   An image metadata property for the number of points found to be positionally consistent
    with a reference image known to be accurately registered. Numbers greater than 1000
    indicate a good match.

### google:registration_offset_\*

:   The measured offset, in meters, between the image and a reference image known to be
    accurately registered.

### Isotropic

:   Independent of direction

### MODIS

:   [MODerate resolution Imaging Spectro-radiometer](http://modis.gsfc.nasa.gov/)

### NIR

:   Near Infra-Red

### NDVI

:   Normalized Difference Vegetation Index. (NIR - red) / (NIR + red)

### NDWI

:   Normalized Difference Water Index. (green - NIR) / (green + NIR)

### SAD

:   [Sistema
    de Alerta de Desmatamento](http://imazon.org.br/imprensa/sistema-de-alerta-de-desmatamento-sad-operacional-na-plataforma-google-earth-engine/)

### SD

:   Standard Deviation

### `system:time_start`

:   The Earth Engine time stamp in milliseconds since the UNIX epoch. See
    [this link](https://en.wikipedia.org/wiki/Unix_time) for more information.
    The time stamp is set to the nominal image acquisition time for single scenes. It is set
    to the nominal composite start period for temporal composites.

### `system:time_end`

:   See system:time_start. The ending time stamp is set to the nominal image acquisition
    time for single scenes. It is set to midnight on the day after the nominal composite
    end period for MODIS temporal composites.

### USGS

:   [United States Geological Survey](http://www.usgs.gov/)

### WRI

:   [World Resources Institute](http://www.wri.org/)