Surveying
and Land Information Science
Vol. 62,
no. 2
(September
2002)
The Priority of the Original Survey
Andrew C. Kellie
Every rule of evidence laid down for guidance in boundary
questions is for the purpose of ascertaining the true location of the line in
dispute, by which is meant the place at which the original surveyor ran the
line…it is…not only permissible, but required, that we resort to any evidence
tending to establish the place of the original footsteps, which meets the
requirement that it is the best evidence of which the case is susceptible
(Taylor v Higgins Oil & Fuel Co (2 S.W.2d 288) in Clark (1992) § 14.01).
The proper conduct of a boundary retracement frequently
involves locating the original survey lines on the ground, as they had been
located by the first surveyor. When used as the basis for conveyance and
correctly retraced on the ground, such lines will control boundary location
even when distances and directions are at variance with the writings. This
paper examines the general legal concepts pertaining to original surveys. It
then discusses application of these concepts to specific boundary cases in both
metes and bounds and public land states.
Comparison of Aerial Videography and Digital Camera Imagery
for Improving Land Cover Classification
Scot E. Smith, Leonard Pearlstine, and John Stenberg
This paper describes how aerial videography and digital
camera imagery were used in the process of classifying land cover satellite
imagery and subsequent accuracy assessment. The primary data used for the
classification was Landsat Thematic Mapper (TM) satellite imagery. The imagery
was used in conjunction with ancillary data such as soil maps, the national
wetlands inventory map series and elevation data, as well as other sources of
information. This paper describes the difference between videography and
digital camera systems; the means of geocoding and georeferencing the two types
of systems; and the means of integrating video and digital camera data into the
process of land cover classification. The relative advantages and disadvantages
of each system were assessed. The following conclusions were drawn: 1.
Videography is relatively inexpensive to initiate and operate in the short run
due to the low cost of cameras, viewing devices, and operator training.
Drawbacks include the fact that videotape (and, consequently, image quality)
degrades with time and use, videotape has lower resolution than a digital
camera, the images cannot be spectrally manipulated and storage requirement are
higher. 2. A digital camera and necessary viewing equipment are initially more
expensive to purchase than a video system, but its operating costs are lower
over time due to the fact that less operator time is required. A digital camera
has higher spatial resolution, and the imagery does not degrade with time and
use. Access to images is rapid and precise, making geocoding easier. Finally,
digital cameras provide the imagery in a multi-spectral rather than a broad,
one-channel panchromatic format, which means that it can be used in any image
processing system.
Multitemporal Remote Sensing and Geographic Information
Systems: A Useful Tool for Detecting and Mapping Forest Changes
K. Benhanifia, A. Bekradda, and S. Smith
This paper describes a methodology for processing Landsat
satellite imagery for the detection and mapping of forest changes during the
period 1984 to 1993. The study area was M’Sila located in western Algeria. In
addition to the satellite imagery, topographic and land-use maps were used in
the analysis. Due to the high degree of topographic relief in the study area, a
digital terrain model (DTM) was used to mitigate the effect of the topography
on the radiance measured by the sensor. Both of the images were radiometrically
corrected for atmospheric attenuation and geometrically rectified with respect
to projection and datum to fit base maps. Vegetation change between the two
images was measured using a band ratio technique. The result of this analysis
and other complementary information were then integrated into a GIS. The
results show that approximately 20 percent of the forest land in this region
was converted to another type of land cover between 1984 and 1993. It was not possible, however, to distinguish
between fire, disease, clear cutting or some other cause of the forest cover
loss.
Grid, Ground, and Globe: Distances in the GPS Era
Thomas H. Meyer
This paper reviews various types of distances as they are
measured and derived in all the various coordinate systems used by surveyors.
Unlike measurements made with transits and levels that are oriented according
to gravity and are traditionally considered to be horizontal and vertical,
respectively, GPS measurements are inherently three-dimensional and not
oriented to the geoid in an obvious way. GPS measurements are placed into a
geographic context by the use of mathematical reference ellipsoids and geodesy
computations. Opto-mechanical measurements must be reduced to become geodetic
quantities. The GPS and opto-mechanical instruments operate in intrinsically
different worlds and only can be reconciled by rigorous application of the
principles of geodesy. This paper reviews the issues, the fundamental
principles, the reductions and geodetic computations, and presents a real-world
measurement campaign showing how to reconcile total station and GPS
measurements.