2004
the different layers, and select, modify and display profiles. Interactive Segmentation. The magic wand provides a tool
for Separate horizontal and vertical scaling is provided to view for interactive segmentation by region growing based on data
bject slight variations in the vertical direction over large areas and characteristics like elevation, intensity, and/or, surface color.
(see long profiles. The user may select specific data ranges to be Starting with the seed point marked by the user all connected
cture displayed, having full control over the assigned color-coding, poinés within given min and max values are selected. Instead of
scaling, image, and gamma settings. Several color tables are absolute limits it is also possible to define a bandwidth of
available to color-code elevation, height differences, intensities, relative change to for example select all connected points
use point and surface classes, etc. appropriately, and user-defined where the height difference from one point to the next does not
plex color tables may be created within LasTools. change more than +20 cm or less than —50 cm. A combination
nany of several data characteristics may be defined (e.g. min/max
sing Data can be displayed in plan, profile, and perspective views, as absolute elevation AND max. elevation change AND min/max
reas point clouds, wire meshes, contour lines, surface renderings, intensity). This tool can be very efficient to locate extended
3D-vectors, and 3D-slices. 3D display using appropriate connected areas like road surfaces or fields with a certain type
hardware (LCD goggles) is in preparation. The data viewer also of vegetation.
d to provides access to data statistics (histograms) and the object
>S as database, making the retrieval and output of information about Interactive Re-classification. The paintbrush tool is especially
tural any specific object a matter of point-and-click. Furthermore, useful for the second type of manipulation approach, as it
> the information about multiple objects, either individually selected provides on-the-fly data manipulation and display update. With
> the or by one of the selection functions can be extracted on this tool, it is for instance possible to define a surface class, and
selectable levels and output, for example to a text file or a to apply (or “paint” this class to all points touched by the
and vector graphics file. paintbrush. If the display shows a shaded-relief view, the re-
thin classification immediately causes a local re-calculation and
The interaction of the viewer is designed to be highly intuitive display of the modified surface model, so that the effect of the
vide and efficient: only a minimum number of mouse actions and manipulation is seen as it is performed. The function of this tool
key-strokes are required to switch between different display is not only limited to changing the class of all points directly. It
aps, manipulation functions (e.g. zoom in/zoom out/pan) and display is also able to apply a local filter that effects a re-classification
rom modes, as it is also known from popular image-manipulation according to filter criteria (e.g. set class “ground” only to lowest
the software. The display engine and the internal data organization points in a 5-m-radius). Similarly, the surface may be
fine are geared for flexibility and display performance using data smoothed, lifted up or lowered, etc.
etry pyramids and a multi-threading approach to provide a high
responsiveness of the viewer at all times. The inefficiency and Elevation Model Manipulation. The data editor allows the
like leaning requirements of typical CAD-based applications are user to edit elevation models (DSM, DTM) before output, to
nce avoided without compromising on accuracy and speed. > remove residual surface features that could not be removed by
the classification, or to blacken out areas of industrial or military
ally Data Editor installations that are classified and should not be present in the
DSM product. It assists to approximate or smoothen areas that
The graphical data editor expands the capabilities of the data only have a very coarse representation due to, for example, low
viewer and provides features for manipulating certain aspects of ground point density in dense forest. An “extrusion” tool,
the data. Its main function is to provide a way to interactively finally provides the possibility to shape the terrain by applying
the optimize point classification and to edit elevation models. The a profile along a user-defined path. This can help to
and interaction concept puts emphasis on intuitive interaction and approximate terrain along a heavily-vegetated ridge or cliff
cal immediate feedback to make interactive data editing as efficient which initially appears heavily distorted locally due to missing
as possible. ground points, but where it can be assumed that the terrain
profile shape does not change substantially for some distance. A
Two approaches are implemented: path along the (suspected) ridge edge is defined by the user, and
=» the user selects one or more regions of interest (which can one or multiple profiles that are taken from open parts of the
ant also be objects), and applies certain filtering or ridge are placed along the path to define intermediate model
manipulation functions to the selected ROI(s). He can points. This tool can also be used in classification, if instead of
ta, select the filtering/classification/ manipulation functions changing the model it is only used to select all ground points
ted and vary the parameters interactively to find the best near the extrude profile that may not have been detected by the
ind setting for the selected area, or automatic classification due to the complexity of the terrain.
= the user defines a filtering/classification/manipulation
tes function (or sequence thereof) along with the parameters
pot and then selects the area(s) or objects to which the effect is 4. SUMMARY
to be applied.
led LasTools provides a next-generation integrated lidar processing
ital Data Selection. Several types of selection tools are available: environment including multi-user, networked production
individual selection of points and objects by directly clicking process, workflow management, and quality control for
ta, them, selection of areas with rectangle, ellipsis, or polygon operational and efficient lidar data production. While it
selection tools, selection of areas with similar characteristics currently does not provide all the application-specific features
ple using the “magic wand” locally or a property selection dialog implemented in other products yet, its object-oriented modular
Ma globally, and a paintbrush tool for directly marking one or approach with integrated point, vector, raster, volume, and
9r multiple areas of interest. The selection tools may be used in — model-handling capabilities facillitates its expansion with
combination to define complex areas using include and exclude ~~ additional features to address customer requirements and
n, functionality. upcoming technologies.
nx
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
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