Introduction to 3D Analysis. Jinwu Ma Jie Chang Khalid Duri

Transcription

1 Introduction to 3D Analysis Jinwu Ma Jie Chang Khalid Duri

2 Area & Volume 3D Analyst Features Detect Change Determine Cut/Fill Calculate Surface Area & Volume Data Management Data Creation Data Conversion Lidar QA/QC Lidar Classification Lidar Management Surface Interpolation Overlay 3D Statistics 3D Proximity 3D Intersections Visualization Profile Graphs Interpolate Features Extrude Between Surfaces Surface Derivatives Contours Slope Aspect Statistics Identify Outliers Interpolate Geometry Perform Math Operations Building Footprint Regularization Visibility Sight Line Analysis Viewshed Determination Skyline Analysis Shadow Modeling Hillshade

3 What s New for 3D Analysis Enhancements for ArcGIS Pro 1.3 Automated lidar building classification Interactive lidar point classification Create tiled LAS & ZLAS files Convert LAS file versions & point record formats Split a multipatch feature into its constituent parts Export the footprint of groups of multipatch features

4 How is XYZ Information Represented? 3D Features Points Lines Polygons Multipatch LAS Dataset Thematic Layers CityEngine RPKs KML Surface Raster Mosaic TIN Terrain LAS Dataset NetCDF

5 Understanding the Surface Z = ff xx, yy A continuous measurement that represents one Z value for a given XY location Temperature Gravity Soil studies Epidemiology Chemical concentrations Many diverse applications

6 Surface Types Raster Surface - Made by interpolation, generalize source measurements to cell size - Fast to process, support robust math operations TIN Based Surfaces - Created by triangulation, maintain source measurements - Support robust surface definitions & data

7 Triangulated Irregular Network (TIN) Based Surfaces TIN Well-suited for engineering applications and analysis of study areas that are not exceedingly large, provides interactive editing options. Terrain Multi-resolution, scalable, offers robust support for handling large amounts of data. LAS Dataset Rapidly visualize, filter, perform QA/QC and analyze lidar data. Well suited for aerial collections, supports compressed lidar in ZLAS format. Delaunay Triangulation

8 Surface Features TIN Based Surface Concepts Mass points: Measurements used for triangulation Erase polygon: Interior areas of no data Replace polygon: Assigns a constant z value Clip polygon: Defines the interpolation zone Also supports: Break lines Tag values Note: Tag values are only supported by the TIN dataset.

9 Breaklines & Hard/Soft Designation TIN Based Surface Concepts

10 Editing a TIN Surface in ArcMap TIN Editors: Add, modify, or remove nodes, edges, triangles & tag values Grading Tool: Modify surface using line with slope properties.

11 Exploratory Analysis Interactive Tools in ArcMap Steepest Path: Determines steepest path from select point. Interpolate Geometry: Creates 3D features based on surface Z. Target Surface Layer: Surface layer in document that will be processed by interactive tools. Contour: Creates a single isoline at the selected point. Profile: Creates profile graph of surface or point cloud. Line of Sight: Determines visibility of sight line & identifies possible obstructing point

12 Geoprocessing Tools ArcGIS Framework for Data Creation, Management, & Analysis 3D Features: Overlay, proximity, and geometric analysis of 3D features. Data Management: Lidar classification & analysis, TIN & terrain management. Data Conversion: Robust interoperability. Functional Surface: Surface analysis. Raster toolsets: Interpolation, mathematic operations, reclassification & surface derivatives. Triangulated Surface: TIN based analysis. Visibility: Sightline, viewshed, & skyline analysis.

13 Doing More with Lidar Classification, Data Management & Analysis Automated classification: Ground Buildings Height above ground (vegetation, noise) Interactive classification Clip, tile, and project lidar Perform QA/QC Statistical analysis DEM/DSM production Download 3D Sample Tools for more lidar solutions:

14 Interacting with Lidar in ArcMap Filters: Shortcuts to commonly used LAS classification filters. 3D View: Provides 3D view of LAS points within ArcMap. Target Layer: LAS dataset layer in document that will be processed by interactive tools. Symbology: Shortcuts to commonly used symbology options. Profile View: Provides profile view of LAS points, enables interactive classification editing.

15 Interacting with Lidar in ArcGIS Pro

16 Raster Interpolation Distance Based Weight Interpolators Inverse Distance Weighted (IDW) Consider using when source data measurements are dense enough to capture the local surface variation required for analysis, and interpolation barrier enforcement is needed. Natural Neighbor A better version of IDW, but takes longer to process due to its smarter method of applying weights. Consider using if you do not want your surface to exceed the min/max values in the sample measurements.

17 Raster Interpolation Trend Interpolators Spline Consider when needing to capture sinks and peaks that are not part of sparsely sampled measurements. Trend Use when looking for trends in source measurements that represents data with gradual variation (e.g. wind speed, temperature)

18 Raster Interpolation Kriging Widely used when working with sparse measurements if trends in data are well understood. Consider Kriging with Geostatistical Analyst. Topo To Raster Semivariance Empirical Semivariogram Distance Generates hyrdologically correct surface that connects drainage structures, eliminates localized sinks, and captures ridges & streams.

19 Choosing the Most Appropriate Surface Model What is the nature of data being modeled? How is the data distributed? How will the data be used? Linear Interpolation from TIN Topo To Raster Spline

20 3D Feature Analysis

21 Proximity Analysis Create 3D buffers Determine distance to closest features Model the minimum bounding volume Find intersection of 3D lines, planes and volumes

22 Spatial & Statistical Analysis Calculate slope Determine area & volume Find 3D length Regularize building footprints Create sealed enclosures

23 Overlay Analysis Find the intersection of 3D lines, planes, and volumes Determine the difference between 3D features Find features that are contained within an enclosed region Merge intersecting features

24 Viewshed Analysis Surface Visibility Determine how many observers can see a given location Determine which observers see a specific location Find the height a non-visible location must be raised to become visible fadf

25 Sight Line Analysis Determine visibility along a line in true 3D space Identify points of obstruction

26 Skyline Analysis Studying the Horizon Delineate the horizon for each observer Segment the horizon by each contributing feature Graph the percent of sky that is obstructed

27 Skyline Barrier Visualize the visible frustum Identify visible facades of 3D features Model shadows cast by localized light sources

28 Hillshade Visualization & Analysis Localized illumination from a fixed trajectory of light Provides 3D experience on a 2D map Offers planimetric view that s helpful for identifying features Can model shadows Hillshade at 45 Hillshade at 90

29 Sun Shadow Volume Determine the shadows cast by 3D features Creates closed volumes that can be used in overlay analysis Find what features intersect or are entirely contained by one or more shadows Urban heat island evaluation Right-to-light studies

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