2.2 Software
Computer software is required at each
stage of the laser scanning process. This
includes the operation of the scanner, the
processing of the collected data and the
visualisation and utilisation of the
delivered digital product. Operation of the
scanner is likely to be handled by a
contractor. In this discussion we will
restrict ourselves to describing software
for processing the collected data (also
likely to be done by the contractor, but
given here to provide an overview), and
software that a user may need for using
the final results.
The choice of software will be based on a
number of f
actors, including data quantity,
the type of ‘deliverable’ required and user
expertise and skill. The process of turning
a point cloud into useful infor
mation is
covered in Section 5 below. However, it is
useful here to highlight the significant
components of software specially designed
to be used with point cloud data.
Such software will offer a three-
dimensional viewer that can be used to
preview the dataset. It will allow the view
to be rotated,
zoomed and panned,
colours to be changed and data to be
clipped from view. The software will have
been designed specifically to handle large
volumes of three-dimensional
measurements. Mainstream software for
CAD
,
GIS or 3D modelling may not be
designed to handling the large datasets
generated by laser scanning, although in
some cases specialist tools can be obtained
to improve the performance of these
mainstream tools, allowing the use of a
familiar software environment.
A user who is commissioning a laser
scanning survey is unlikely to need to
consider exactly what software to use to
process the collected data; rather, he/she
will need to ensure that the methodology is
appropriate for their needs. The user will,
however, need to ensure that the final
product, generated from the point cloud,
can be used for the task intended. He/she
may want to manipulate this with a
standard desktop GIS package, or may
require specialist software to enable easier
visualisation and analysis. Free viewers
designed for standard and proprietary
formats are available, and low cost tools,
designed to give a little more flexibility
(such as the ability to make simple
measurements) can be purchased. For more
information on particular products, see
below, section 7 Where to find out more.
2.3 Computer hardware
A standard desktop PC designed for
standard office use may be insufficient to
take full advantage of the generated
product, or for the analysis you wish to
carry out. However, desktop PCs with
computing power and specifications
suitable for the day-to-day use of large
geometric models (assuming appropriate
software is available) are more accessible
and less expensive now. At the time of
writing, if you are planning to buy a new
machine or upgrade an existing one in
preparation for the use of three-
dimensional data, consider the following:
l 3D graphics acceleration: Having a
dedica
ted 3D graphics card is one of the
most important features. Choose one
with at least 256 MB of dedicated video
RAM.
Note, some off-the-shelf
machines provide 3D acceleration
through integrated cards that share the
computer’s standard memor
y
. Although
less expensive this type of card should
be avoided.
l RAM: Plan to ha
v
e at least 1 GB of
RAM, although the more the better.
Memory is normally installed in pairs of
modules, so if y
ou are buying a new
machine, consider what will be the most
cost-effective way to add more memory
in the future.
l Hard disk: At least 100 GB will be
required for day-to-day storage.
Consider using an exter
nal USB hard
disk to provide a local backup. At the
time of writing, external USB disks with
a 300 GB capacity cost as little as £100.
l Display: Do not underestimate the value
of choosing a good quality monitor. If
y
ou have desk space, consider using a
CRT version rather than the more
popular flat-screen LCDs, as CRT
screens often give a much better image,
and are less expensive than their
equivalent TFT versions.
l Processor speed and type: While having
a fast processor may improve general
performance, it is less important than
are graphics card and RAM. Users
should aim for a processor speed of at
least 2 GHz.
While it may seem expensive to buy a
whole new system, an existing desktop PC
might be upgradeable by the simple
addition of some extra RAM, a new
graphics card and an additional hard drive
(changes that might cost less than £300 at
the time of writing).
Do not forget that whatever software you
choose to manipulate the derived models,
you may also benefit from some training.
Dedicated training helps to get you
started on the right foot and stops you
from adopting bad practices early on.
Software developers, service providers or
suitable educational establishments may
all be able to provide appropriate training;
for organisations that may be able to
suggest suitable training partners, see
below, section 7 Where to find out more.
3 Commissioning survey
3.1 Knowing what you want
It is unlikely that an individual requiring
laser scanning will ha
ve the means or
expertise to undertake the work him- or
herself. It is more likely that survey work
will need to be commissioned and
undertaken by a specialist contractor. The
following tips will help you when
preparing to commission a sur
v
ey:
l Consider the level of detail required and
the extent of the object/area. These are
often the overriding parameters used to
determine appropriate survey technique
and/or deliverable product.
l Start by working out what you need in
order to answer the questions you have
set. T
ry to come up with a requirement
for accuracy and product. Realise that
you might not need to specify the actual
technique,
just the product y
ou require.
l Consider how you will use the product
before it is procured/commissioned;
additional costs might be hidden in
buying new software/hardware.
l Discuss the requirements with
possible contractor
s. A good contractor
9
F
ig 19
A
irborne laser scanning.