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Digital
Photogrammetry
Photogrammetry
is the art, science, and technology of obtaining reliable
information about physical objects and the environment
through the process of recording, measuring, and interpreting
photographic images and patterns of electromagnetic
radiant energy and other phenomena.
With the introduction of computer-based, softcopy
photogrammetric mapping and GIS systems that operate
in a desktop computing environment prove to be a more
economical solution for many mapping and GIS database
construction tasks. It also presents visual reference
of the earth's surface, providing a clear image base
for design engineering, asset management, planning,
and change detection, among others.
Utilizing photogrammetric processes, we can extract
vector data such as contours, street centerlines,
hydrography, utilities, vegetation, building footprints,
etc. This data can be populated with attribute information
pertaining to each feature, thus creating an intelligent
database related to a particular geographic area.
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Digital Elevation Models
A
DEM (Digital Elevation Model) is a collection of discrete
elevation points at regularly spaced intervals, while a DTM
(Digital Terrain Model) defines topographic shapes by elevation
points at significant topographic features which reflect abrupt
changes in relief such as incised streams, ridge lines, and
slope breaks.
In either case, these data points provide a regular (DEM)
or irregular (DTM) pattern of elevation information that can
be used for many purposes, such as the generation of a triangular
irregular network (TIN), where groupings of three elevation
points create adjoining triangular surfaces which mathematically
approximate the ground surface.
Orthorectification
An orthophoto map is produced by removing scale variations
from the original aerial photography. The original aerial
photograph is not a true map because as the elevation of the
ground changes, the scale of the image also changes. By using
an accurate representation of ground elevations, we are able
to fully rectify the ortho image so that all features are
correctly located.
We
do orthorectification of aerial photographs & spatial
imagery to produce map-quality ortho images. In preparation
for orthorectification of air photos or satellite imagery,
we obtain the source material to extract digital elevation
models. Masspoints, breaklines, and contour interpolation
features (CIP) are collected and processed in specialized
software to generate digital terrain models. Cross sections
of corridors are generated from 3D data for the design of
highways, pipelines, and powerline rights-of-way.
Products
- Topographical
& Thematic Maps
- Orthorectified
Photographs
-
Aerial Triangulation & Adjustment
- Stereo
Compilation
- Terrain
Modelling; DTM Generation
- DTM
Based Route Alignment
- Feature
Extraction & Validation
- Automated
Change Detection in Landuse & Land Cover
- Creation
of Digital Elevation Models
- Creating,
Balancing & Mosaicking of Orthophotos
- Editing
of Ground Features & Elevation Data
- Flythrough
Models
Our
Remote Sensing & Digital Photogrammetry Practice is powered
with full feature PCI, Intergraph, ERDAS & ER Mapper workstations
with dual monitors.
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