© 2019 GeoSLAM Ltd
12
ZEB‐HORIZON User Manual v1.2
Transition around tight bends slowly and ensure that there is a period when the scanner can view features on
both sides of the bend.
Take care when transitioning from an enclosed feature rich environment to an open feature poor environment,
for example exiting a building. It may be necessary to turn and face the exit and the exterior of the building if no
other features are within range.
Avoid scanning any other moving objects (e.g. walking pedestrians) as you pass through a transition.
It is recommended that data is captured at walking speed to ensure good coverage and high‐resolution data. If
the forward movement is too fast there may not be enough repeat scans of features for the SLAM algorithm to be
able to process the raw laser data into a point cloud.
Data within a small range value is not processed (by default) to eliminate data from the scanner operator being
included in the final point cloud. Avoid close proximity to walls and ceilings.
The maximum range of the scanner is 100m. This range will only be achieved in optimal conditions (indoors with
good target reflectivity). The typical maximum range will be 60‐80m in most conditions. It is recommended that
the range is kept to less than 50m where possible to ensure good point density and to assist the SLAM algorithm.
For very large surveys the project should be broken down into more than one scan mission. This is to avoid very
large file sizes as well as reduce any drift that might be created in the data. It is recommended that each survey is
limited to 30 minutes. At slow walking pace, it is possible to cover 1000‐3000m of survey distance.
The scanning head can remain stationary for short periods of time whilst the operator negotiates difficult access
points (e.g. tight squeezes in cave systems). The scanning head can also be held in the hand and moved up and
down to mimic the normal oscillating motion for short periods of time to assist transition through survey areas
with restricted or difficult access.
In most case the SLAM algorithm is able to handle moving objects in the environment. In order to estimate the
sensor trajectory the algorithm assumes a large proportion of the environment is static. However, in some feature
poor environments where 3D structure is lacking in some dimensions, moving objects can have a greater impact
on the solution. In particular, moving objects should be avoided in long tunnel‐like environments (e.g. corridors),
relatively open spaces and when transitioning through doorways.
It is best practice not to have other people closely accompany the operator during the scan acquisition as they will
be scanned throughout the map leaving streaks of data and potentially corrupting the solution in feature poor
environments. If people are required to follow the operator they should ideally maintain a distance of 20m or
more from the operator.
4.8
MOVING OBJECTS IN THE ENVIRONMENT
4.4
WALKING SPEED
4.5
MINIMUM AND MAXIMUM RANGE
4.6
DURATION OF SCANNING
4.7
SURVEY AREAS WITH RESTRICTED OR DIFFICULT ACCESS
