9.6 DATA PRODUCTS OUTPUT MEDIUM
9.6.1 PHOTOPRODUCT
To generate a photographic product, the electrical information is converted
to light energy, which is written on a photosensitive film or paper. The
simplest way of doing this is to modulate the output intensity of a light
emitting diode (LED) according to the DN value. The LED carrier moves
across producing optical data corresponding to the scan lines. At the end,
the film carrier is stepped to produce successive lines. The basic first
derivative product is called ‘master’. Masters of most IRS photographic
products will be 240 mm films. For some of the special products, the master
will be a 960 mm film.
The output data is supplied either as a paper print or as positive film
transparency. Both black and white (B/W) and FCC products are available.
Positive transparency has the advantage that by using suitable optical
magnifiers, the image can be enlarged to match suitable scale reference
maps for generating interpreted maps. However, paper prints are very
convenient to carry during field checks, ground truth collection etc. The
photoproduct also carries a number of other information useful to the
interpreter. This is called product annotation. Figure 9.14 gives the layout of
an IRS photographic product.
, Fig. 9.14 IRS-1C photographic product layout.
The annotation format has three lines on the top of the image data and
one annotation line at the bottom of the data (NRSA, 1995). The first
annotation line 1 on the top gives details regarding the satellite, and the type
of product including the type of projection and resampling technique used.
The second annotation line 2 on the top gives details regarding the date
of acquisition with time, path/row details, sensor sub-scene details,
quadrant number, look angle information, the corrected scene centre and
information on the sun elevation and azimuth in degrees.
9.6.1 PHOTOPRODUCT
To generate a photographic product, the electrical information is converted
to light energy, which is written on a photosensitive film or paper. The
simplest way of doing this is to modulate the output intensity of a light
emitting diode (LED) according to the DN value. The LED carrier moves
across producing optical data corresponding to the scan lines. At the end,
the film carrier is stepped to produce successive lines. The basic first
derivative product is called ‘master’. Masters of most IRS photographic
products will be 240 mm films. For some of the special products, the master
will be a 960 mm film.
The output data is supplied either as a paper print or as positive film
transparency. Both black and white (B/W) and FCC products are available.
Positive transparency has the advantage that by using suitable optical
magnifiers, the image can be enlarged to match suitable scale reference
maps for generating interpreted maps. However, paper prints are very
convenient to carry during field checks, ground truth collection etc. The
photoproduct also carries a number of other information useful to the
interpreter. This is called product annotation. Figure 9.14 gives the layout of
an IRS photographic product.
, Fig. 9.14 IRS-1C photographic product layout.
The annotation format has three lines on the top of the image data and
one annotation line at the bottom of the data (NRSA, 1995). The first
annotation line 1 on the top gives details regarding the satellite, and the type
of product including the type of projection and resampling technique used.
The second annotation line 2 on the top gives details regarding the date
of acquisition with time, path/row details, sensor sub-scene details,
quadrant number, look angle information, the corrected scene centre and
information on the sun elevation and azimuth in degrees.
