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A
Surveying Test in Canopy: Does GPS or LIDAR Work Best?
By Mark Wagaman, Veritas DGC The survey methods tested included GPS with Real Time Kinematic (RTK)
corrections, an inertial (INS) backpack system, conventional optical,
Light Detection and Ranging (LiDAR) and a specialized GPS called Under
Canopy GPS™ (also RTK corrected). We compared the elevations
obtained from these methods and found excellent agreement between
the conventional optical, inertial and LiDAR, with very close
agreement occurring for the Under Canopy GPS. The standard GPS elevations
proved inconsistent and unreliable when compared to these other
methods. The results accomplished the two main goals of the test,
the first being to confirm the accuracy of the
LiDAR Z values and determine the fitness for use on this project.
The second goal was to investigate alternative survey methods
to use in this environment and determine if an economic alternative
existed.
click here to download article as PDF file...
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Sensor Fusion: Remote Sensing Alchemy Provides Intelligent
Data Gold
From the time man became intellectually curious, he has attempted
to manipulate the elements in order to gain control of his environment. In historical times, Alchemy was the fusion of science, magic and superstition to combine various elements for the creation of something of value – namely, Gold! It never succeeded. But, many of our scientific disciplines were born out of Alchemy
and, therefore, it could be argued that some value has been derived
from the ancient science.
This spirit of experimentation has reached through the mists of time to materialize in the modern, high-tech world of geographic information
systems. The remote sensing industry, relying on science rather than
magic, has discovered that the fusion
of data from diverse sensors can provide information of greater
value than the sum of its parts.
click here to download article as PDF file ...
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CSI Remote Sensing – Hyperspectral Imaging Provides
“DNA” for Geospatial Information
The crime scene investigation (CSI) television programs have popularized
how fingerprints and DNA can be used to solve crimes. The remote sensing industry has its own technology to detect and discriminate
unique characteristics of materials and features. Airborne Hyperspectral imaging (HSI) provides the capability to detect and
discriminate unique characteristics of materials and features, much like DNA is used in crime scene investigations.
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All LIDAR data is NOT
Created Equal
Even though LIDAR has gained universal acceptance as the source for accurate
elevation and terrain data for a host of applications, there is enough LIDAR data circulating around the geospatial world
that distinctions are becoming apparent between LIDAR data sets. For the most part, how final deliverables such as contours,
Digital Terrain Models (DTM), Digital Elevation Models (DEM), topographic features, planimetrics, 3D buildings/city models
are derived has been a mystery to many LIDAR customers or data users. This lack of understanding creates the situation where the LIDAR customer does
not have enough information to specify how they want to have their data processed and, therefore, the opportunity exists for
some LIDAR vendors to cut corners in their production process. And, because many LIDAR customers do not verify the accuracy
and quality of their data, they may never discover the discrepancies.
click here to download article as PDF file...
Spatial Resources, LLC, PO Box 3623, Centennial, CO 80161; Phone: 720-934-2482; Fax: 303-721-9042
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