Raster Data Explained - Open Source Geospatial Tools: Applications in Earth Observation - page 51

gdalinfo --formats
Supported Formats:
GRASS (ro): GRASS Database Rasters (5.7+)
VRT (rw+v): Virtual Raster
GTiff (rw+v): GeoTIFF
NITF (rw+v): National Imagery Transmission Format
RPFTOC (rov): Raster Product Format TOC format
ECRGTOC (rov): ECRG TOC format
HFA (rw+v): Erdas Imagine Images (.img)
SAR_CEOS (rov): CEOS SAR Image
CEOS (rov): CEOS Image
JAXAPALSAR (rov): JAXA PALSAR Product Reader (Level 1.1/1.5)
...
The abbreviated raster format is followed by identifiers in brackets that indicate
whether the format supports read only (ro), read and write (rw), write update (w+)
and virtualization (v) or a combination of these. Section 5.4 provides some more
information on write update. Virtualization is covered in Chap. 11 . Some formats
support subdatasets and are indicated with an appended 's'.
A widely used format for georeferenced raster data that allows embedded geo-
referencing information is GeoTIFF. This is also the default format for most GDAL
utilities and many of the examples on raster data in this topic will use it. However,
the snippets provided can be easily adapted to other formats using the option -of ,
followed by the name of the format. Instead of embedding the georeferencing infor-
mation within the raster file, some formats use a header or separate World File (.tfw,
.tifw, .tiffw or .wld). In addition, in Europe, the Infrastructure for Spatial Information
in the European Community (INSPIRE) has defined metadata elements for spatial
dataset interoperability. In order to be INSPIRE compliant, the coordinate reference
system used in a data set must be described in the metadata 2 (in XML format).
3.1 Coordinate Reference Systems
Pixels in a raster image can be identified by image coordinates, expressed by a
column (i) and row (j). A schematic overview is given in Fig. 3.1 . The origin is
commonly chosen as the upper left (UL) pixel of the image. As a convention, we
will reference these coordinates as (0,0). Image coordinates i and j increase from left
to right (columns) and downwards (rows).
The situation is different for images defined in a spatial reference system (SRS).
The position of the pixels are then uniquely referenced in space as a set of coor-
dinates (e.g. X, Y, Z). In geodetic coordinates the position is expressed as latitude,
longitude and height with respect to a reference ellipsoid, approximating the Earth's
2 INSPIRE Metadata Implementing Rules: Technical Guidelines based on EN ISO 19115 and EN
ISO 19119.