3d visualization of dem by using arcscene
- 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.