ashtech Reliance FS/2, Operation Manual

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Using External Devices A-1
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Laser Range Finders
During a survey, it is not uncommon to come across survey points that the field operative
is physically unable or unwilling to stand next to. These features may include:
• features offset from a primary recording feature (e.g. row of telephone poles
running parallel to a road)
• features not amenable to satellite positioning (e.g. fire hydrant underneath heavy
tree canopy or next to a tall building)
• features not accessible to field operative (e.g. power pole on other side of fence
on private property or in a swamp)
• features distributed along a line of sight from a single location convenient for
data collection (e.g. group of road signs, telephone poles, and other features
within view of a single location).
The use of Laser Range Finders (LRF) or other external sensor devices make data
collection of these features much more time and cost effective as a field operative can map
several features from a single survey point with the same level of accuracy as if he
surveyed each point. In some cases, the satellite positioning of features next to tall
buildings or under heavy canopy is not possible without the use of LRF or other external
sensor devices.
FAMlog records and correctly processes data recorded while static or dynamic and in real-
time and post-processed mode.
LRFs can be used to map features that do not require a time tag with a satellite position,
and are ideal to use in situations where you want to map:
• multiple point features while remaining at a single position
• point features not embedded within a line or area feature
• point features embedded within a line or area feature
• line or area features recorded at an offset from the field operator's path of travel.
• area features mapped from the interior of the area.
Planning
As with conventional GPS surveying, planning is critical. When designing the survey and
data collection schedule, be sure to identify regions where features may be inaccessible to
GPS. These regions necessitate the use of offsets. LRF or other measuring devices can
greatly improve the productivity of field crews when GPS availability is partially or even
totally blocked.
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Using External Devices