The Triangulation method produces a regular gridded surface through a set of data points by using an optimized Delaunay triangulation algorithm. This method is very useful for situations where the data must be honored very closely (e.g. elevation data in a digital terrain model).
Fundamentals of creating TIN surfaces
You can create a TIN
surface from features, such as points, line, and polygons that contain
elevation information. Use points as spot locations of elevation data.
Use lines with height information to enforce natural
features, such as lakes, streams, ridges, and valleys.
Creating a TIN surface from raster
data
A TIN surface can also be created from other
functional surfaces, such as raster or terrain datasets. You may want to convert your raster surface to a TIN to simplify
the surface model for visualization & add additional features, such as
streams and roads, to the surface model.
The z-tolerance is the maximum number of units
by which the TIN surface may differ from the cell center heights of the input
raster. A low number results in a TIN that preserves more of the detail of the
raster surface. A higher number results in a more generalized representation of
the surface. No. from 1 – 10.
The Z factor is used to convert z-units (for
example, feet to meters).
Editing TIN Surfaces
You can add features to the TIN with the option
to save it as a new TIN. For example, line feature classes that represent
roadways that have been constructed or new elevation data, such as point
feature classes that show mining excavation in the study area.
There are two ways to edit a TIN
in ArcGIS:
Fundamentals of TIN surface analysis
Interactive 3D Analyst tools in ArcMap
TIN Conversion toolset
These conversions allow different types of
analysis, show different interpretations, or extract features from TINs that
you can use to enhance your analysis results or visualization in 3D.
Converting between raster and TIN formats
allows you to employ the benefits of each while modeling the same surface. For
example, use a TIN to model a surface if you have features, such as lines or
polygons, which you want to use to enforce natural features, such as ridges or
valleys, or clip a TIN to a study area. Convert this TIN to a raster using the
natural neighbors interpolation option to preserve the linear features in the
output raster. You'll now be able to use spatial operators on the raster that
may not have been available for the TIN. In addition, the TIN-to-raster
conversion is a smoothing process, so contours you generate on the raster are
smoother than they would be as a TIN.
Displaying TIN surfaces
The internal structure of a TIN contains nodes,
edges, and faces, which can independently display different surface
characteristics in either ArcMap or ArcScene. These surface characteristics
include slope, aspect, elevation, and contours.
0 التعليقات:
Post a Comment