International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
4.5 Value Adding and Customization
Value adding and customization are conducted to fit-for-
purpose, when customers need products that are different from
the core products in terms of product types, contents/extents,
projection/datum, resolution etc.
QC/QA
Data Processing
SAR J Interferometric
Processing | Processing
Product
Finishing
Interactive
Editing
Core Products in iStore
Value Adding and Customization |
QC/QA
Satisfied Customers
Figure 3. A high-level STAR Production Process
5. AIRBORNE IFSAR MAPPING PRODUCTS
5.1 Digital Elevation Models (DEMs)
The STAR technology directly produces a first surface model
or a digital surface model (DSM), not the underlying bare earth
digital terrain model (DTM). Unlike a DTM that only
represents the topographical surface without vegetation or
buildings, a DSM contains elevation measurements for every
surface visible to the radar sensor. While DSMs have many
applications, DTMs are mostly expected by the geospatial
market and required for many topographic mapping purposes.
With Intermap's proprietary bare-earth processing technologies,
a DTM can be automatically derived from the original DSM for
many terrain types. However, to obtain a satisfactory DTM
product, manual editing will be required in many cases which
can be a lengthy and costly process. Furthermore, the high
accuracy of the original DSM cannot always be maintained for
the resultant DTM. In areas such as the urban core, DTM
accuracy will be lower than the DSM accuracy. Figure 4 and 5
show an example of a DSM and the DTM after the bare-earth
processing, respectively.
5.2 Orthorectified Radar Images (ORIs)
An ORI is a grayscale image of the earth's surface that has been
orthorectified to remove geometrical distortions using the
simultaneously generated DEM. Currently, ORIs from
Intermap's STAR systems have a pixel size of 1.25 m (and up)
and a planimetric accuracy of 2.0 m RMSE. The ORIs provide
a means of viewing the earth's surface in a way that accentuates
features far more than is possible with aerial photography.
Therefore, they can be used for cultural features (such as road
networks and buildings) extraction, and land cover and
geological analysis. Figure 6 gives an example of an ORI.
Table 2 lists the major parameters for the three core products.
STAR post RMSE Panne
Product Spacing ACCHFACYV Coordinate Format
/Pixel Size : Systems
z Type I: 0.5m WGS84/ SRI
DSM (e Type ll: 1.0m | EGM96/ I
s Type III: 3.0m Geographic eager du
E i WGS84/ de
ne I: 2 9. ;
DTM 5m Ty pe I: 0.7m EGM96/ 32-bit ‚bil and
(nominal) Fype I: 1.0m ; ; header info
Geographic
1.25m or "Je
ORI 2.3 m** 2.0m any ; 8-bit GeoTiff
; Geographic
(nominal)
Table 2. Specifications of Intermap's Core Products
* Other datum, projections and coordinate systems are also supported
depending on the area and requirements.
** Archive ORI products before January 2002 have a 2.5-m pixel size.
5.3 Value-Added Products
Many value-added products can be generated from the core
products. For example, topographic line maps (TLMs) at scales
up to 1:10,000 are generated using STAR DEMs and ORIs.
They are used to create a stereo radargrammetric compilation
environment where TLM features are extracted (Tighe and
Baker, 2000). Automatically derived contour lines (Figure 7),
3-D fly-through (Figure 8), and colorized radar imagery —
STARplus (Figure 9) are also in the value-added product list.
Interne
Figur
(Cour
