3d visualization of dem by using arc scene

1. TOPIC:
3D VISUALIZATION OF DEM USING
ARCSCENE

2. CONTENTS:
▪ INTRODUCTION
▪ DATA USED FOR 3D VISUALIZATION
▪ Z-VALUES
▪ RASTER DATA
▪ TRIANGULATED IRREGULAR NETWORKS(TIN’S)
▪ MULTIPATCH FEATURES
▪ 3D FEATURES
▪ 3D NAVIGATION BASICS
▪ IDENTIFY DATA TYPES

3. INTRODUCTION:
• 3D technology in GIS maps is explanatory illustrations that represent
the scale of real-world objects.
• 3D models assist appearance, survey in a large number of different
domains.
• For instance, 3D maps can show the height of a built-up area or a
mountain and not just its location.
• Over the years, GIS has made a significant impact in creating
mapping as an essential tool to solve problems.
• Conventionally, GIS information was based on a two-dimensional
recording, which apparently limited its usage in most applications.
• Incorporating 3D technology in GIS customizes the whole experience,
making it more personal and enabling detailed visualization.

4. • Arc Scene, the three dimensional viewing application that is part of
the ArcGIS 3D Analyst Extension.
• Arc Scene allows to overlay many layers of data in a 3D environment.
• Features are placed in 3D by providing height information from
feature geometry, feature attributes, layer properties, or a defined 3D
surface, and every layer in the 3D view can be handled differently.
• Data with different spatial references will be projected to a common
projection, or data can be displayed using relative coordinates only.
• ArcScene is also fully integrated with the geoprocessing environment,
providing access to many analysis tools and functions.

5. Some of the uses of 3D GIS:
▪ City Planning:
➢ Incorporating 3D technology in GIS can help government agencies, architects and engineers envision,
evaluate and analyze as to how certain changes in a city will look like, and how these changes can
meet the needs of the future generations.
➢ A typical 3D model would consist of building information, satellite imagery and traffic data that can be
used by urban planners to find alternative solutions effectively and address emergency situations
efficiently.
▪ Building Information Modelling(BIM):
➢ Building Information Modeling (BIM) is an important technology that depicts real-world settings of an
environment.
➢ The combination of BIM and GIS provides the necessary know-how to build a robust model.The
combination of 3D GIS and BIM can help produce error-free building management plans that would
eventually allow for a more detailed analysis of data.

6. ▪ Coastal Modelling Analysis:
➢ Coastal areas are important as they connect a country with the rest of the world for trade.
➢ Coastal areas globally face major threats and challenges for development.
➢ It is important for planners to recognize what all factors affect the construction and preservation of
ports, fisheries and mining operations.
➢ Efficient and effective planning of resources on 3D GIS can provide some level of understanding in the
economic, environmental movements along the coast.

7. Data used for 3D visualization:
➢A Digital Elevation Model (DEM) is a representation of the bare ground (bare earth)
topographic surface of the Earth excluding trees, buildings, and any other surface objects.
➢DEMs are created from a variety of sources. USGS DEMs used to be derived primarily from
topographic maps. Those are being systematically replaced with DEMs derived from high-
resolution lidar and IfSAR (Alaska only) data.
➢The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global
scale to generate the most complete high-resolution digital topographic database of Earth.
➢ SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle
Endeavour during an 11-day mission in February of 2000.
➢SRTM is an international project spearheaded by the National Geospatial-Intelligence
Agency (NGA) and the National Aeronautics and Space Administration (NASA).

8. • Elevation Z-values:
➢Elevation data is the foundation for the creation of three-dimensional displays.
➢Data in digital elevation model(DEM) format is commonly used for storing and displaying
topographic surfaces.
➢Also, points, lines, polygons, grids, and images can be positioned in three dimensional
space with information from underlying DEM data.
➢Alternatively, a feature can be displayed in three-dimensions with a constant z-value or a z-
value derived from an attribute of a feature.

9. Raster Data:
➢ Raster data is any pixelated(or gridded)
where each pixel is associated with
geographical location.
➢ The value of a pixel can be continuous (e.g.
elevation) or categorical (e.g. land use).
➢ Some examples of continuous raster's
include: Precipitation maps, Maps of tree
height derived from LiDAR data.
➢ Some rasters contain categorical data like for
examples LULC maps, Tree height maps
classified as short, medium and tall trees.

10. Triangulated Irregular Network(TIN):
➢ A TIN is a vector-based representation of the physical
land surface or sea bottom, made up of irregularly
distributed nodes and lines with three-dimensional
coordinates (x,y,z) that are arranged in a network of non-
overlapping triangles.
➢ A TIN comprises a triangular network of vertices, known
as mass points, with associated coordinates in three
dimensions connected by edges to form a triangular
tessellation(Tiling).
➢ A TIN used to represent terrain is often called a digital
elevation model (DEM), which can be further used to
produce digital surface models (DSM) or digital terrain
models (DTM).

11. Terrain Dataset:
➢A terrain dataset is a multiresolution, TIN-based surface built from measurements stored as
features in a geodatabase.They're typically made from lidar, sonar, and photogrammetric
sources.
➢Terrain data is usually expressed as a series or collection of points with x, y, and associated
z-values. It generally includes a series of points representing the high and low extremes in
the terrain that define topographic features such as streams, levees, ridges, and other
phenomena.
Multipatch Features:
➢A multipatch feature is a GIS object that stores a collection of patches to represent the
boundary of a 3D object as a single row in a database.
➢Patches store texture, color, transparency, and geometric information representing parts of
a feature.
➢The geometric information stored in a patch may be triangles, triangle fans, triangle strips,
or rings.