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Esri UC 2014 | Technical Workshop | ArcGIS 3D Analyst - Lidar Applications Clayton Crawford.

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Presentation on theme: "Esri UC 2014 | Technical Workshop | ArcGIS 3D Analyst - Lidar Applications Clayton Crawford."— Presentation transcript:

1 Esri UC 2014 | Technical Workshop | ArcGIS 3D Analyst - Lidar Applications Clayton Crawford

2 Esri UC 2014 | Technical Workshop | Outline Data structures, tools, and workflows Assessing lidar point coverage and sample density Creating raster DEMs and DSMs Data area delineation Estimating forest canopy density and height Creating intensity images Reducing noise for contouring and slope analysis Floodplain delineation Lidar Applications

3 Esri UC 2014 | Technical Workshop | Big Picture Solutions for GIS end users - Not about lidar data production Operate on clean/classified lidar points Produce useful derivatives Perform analysis Handle large datasets Both file and database oriented solutions Lidar Applications

4 Esri UC 2014 | Technical Workshop | Supporting Data structures and Tools Vector features - points - multipoints - lines - polygons Raster TIN Terrain Dataset Function Input Output Workflow Point File Information LAS To Multipoint ASCII 3D To Feature Class Point To Raster Terrain To Raster Terrain To TIN Lidar Applications

5 Esri UC 2014 | Technical Workshop | Supporting Data structures and Tools (10.1) LAS dataset - LAS Dataset Statistics - LAS Dataset To Raster - LAS Point Statistics As Raster - LAS Dataset To TIN Mosaic dataset - Extensive collection of raster tools Function Input Output Workflow Lidar Applications

6 Esri UC 2014 | Technical Workshop | Relative Storage Costs One LAS* file - LAS file (with attributes)44MB - Shapefile (geom only)52MB - PersonalGDB (geom only)40MB - FileGDB (geom only) 7MB Project of many LAS files LAS files12.5GB - Bare earth terrain1.3GB - 1 st return terrain 2.2GB * LAS is industry standard format for lidar data Lidar Applications

7 Esri UC 2014 | Technical Workshop | Lidar point coverage and sample density Basic QA/QC before loading data into geodatabase Verify xy and z extent Examine point spacing Lidar Applications

8 Esri UC 2014 | Technical Workshop | LAS Dataset Layer (10.1) Lidar Applications

9 Esri UC 2014 | Technical Workshop | LAS Dataset Properties (10.1) Lidar Applications

10 Esri UC 2014 | Technical Workshop | Point File Information Tool Inputs files (LAS and ASCII) and folders of files and outputs a polygon feature class. Each output record includes - Polygon of file’s data extent - Source filename - Point count - Point spacing estimate - Z min - Z max Lidar Applications

11 Esri UC 2014 | Technical Workshop | Point File Information Tool Lidar Applications

12 Esri UC 2014 | Technical Workshop | LAS Point Statistics As Raster Tool (10.1) Pulse/sample density Lidar Applications

13 Esri UC 2014 | Technical Workshop | Point To Raster Tool Pulse/sample density Lidar Applications

14 Esri UC 2014 | Technical Workshop | LAS = industry standard file format for lidar Multipoints used for efficiency Filter options - By class - By return Loading Data: LAS To Multipoint Tool Lidar Applications

15 Esri UC 2014 | Technical Workshop | Loading Data: ASCII 3D To Feature Class Tool Points, lines, polygons Recommendations: - Use ASCII as ‘open’ format for breakline data (otherwise shapefile) - Use LAS for lidar points Lidar Applications

16 Esri UC 2014 | Technical Workshop | Point to Raster Tool Used after points are loaded into geodatabase More detailed assessment than Point File Information Based on actual points loaded (i.e., filtered by class code or return) rather summary of entire file. Lidar Applications

17 Esri UC 2014 | Technical Workshop | Demo Lidar Applications

18 Esri UC 2014 | Technical Workshop | Creating Raster DEMs and DSMs Bare earth surface made using only ground hits. Includes ground, trees, and buildings made using first returns. Digital Elevation ModelDigital Surface Model Lidar Applications

19 Esri UC 2014 | Technical Workshop | LAS Dataset To Raster (10.1) Binning - Fast - Reasonable for DSMs - Void filling options - Honors replace and clip constraint types Triangulation - True interpolation - Always fills voids - Appropriate for DEMs - Honors all constraint types Lidar Applications

20 Esri UC 2014 | Technical Workshop | Point to Raster Tool Fast Rasterize based on multipoint vertex z Not true interpolation Doesn’t support breaklines Data gaps Arguably works best with 1 st return data because there are fewer and smaller data voids to deal with. Lidar Applications

21 Esri UC 2014 | Technical Workshop | Point to Raster Post-process: Void Filling Point To Raster Raster Calculator Con(IsNull("pt2ras"), FocalStatistics(“pt2ras", NbrRectangle(3, 3, "CELL"), "MEAN", "DATA"), "pt2ras") Con(IsNull([pt2ras]), FocalMean([pt2ras], Rectangle, 3, 3, DATA), [pt2ras]) Lidar Applications

22 Esri UC 2014 | Technical Workshop | Don’t Abuse Con Introduces anomalies if used repeatedly Hilltop Valley bottom Nodata cells Steeper slope Lidar Applications

23 Esri UC 2014 | Technical Workshop | Terrain to Raster Quality Supports ancillary data (breaklines, water bodies, etc.) True interpolation Can handle large datasets Lidar Applications

24 Esri UC 2014 | Technical Workshop | Comparison InterpolationBinning Lidar Applications

25 Esri UC 2014 | Technical Workshop | Data Area Delineation Dense collection of source measurement points (green) Triangulation of those points without a boundary constraint Constraint applied Lidar Applications

26 Esri UC 2014 | Technical Workshop | Workflow to Calculate a Data Area Polygon (10.1) Lidar Applications LAS Point Statistics As Raster Input LAS dataset ConExpandShrink Raster to Polygon Eliminate Polygon Part Output polygon feature class

27 Esri UC 2014 | Technical Workshop | Workflow to Calculate a Data Area Polygon Point to Raster Input multipoint feature class ConExpandShrink Raster to Polygon Eliminate Polygon Part Output polygon feature class Lidar Applications

28 Esri UC 2014 | Technical Workshop | Demo Lidar Applications

29 Esri UC 2014 | Technical Workshop | Estimating Forest Canopy Density and Height Lidar Applications

30 Esri UC 2014 | Technical Workshop | Canopy Density and Height Density is the ratio of vegetation hits to total hits within a unit area (i.e., raster cell). - LAS to Multipoint to make two feature classes: ground and non-ground. - Point to Raster to make ‘count’ grids. - Add ground and non-ground to make a ‘total’ grid. - Use Divide to get the ratio between non-ground and total. Height is the difference between DSM and DEM - Use Point to Raster or Terrain to Raster followed by Minus. Lidar Applications

31 Esri UC 2014 | Technical Workshop | Creating Intensity Images Lidar Applications

32 Esri UC 2014 | Technical Workshop | Input LAS dataset Intensity Image Workflow (10.1) LAS Dataset To Raster GP Tool Intensity Image Lidar Applications

33 Esri UC 2014 | Technical Workshop | Intensity Image Workflow LAS To Multipoint GP Tool Output multipoint feature class Intensity Image Input LAS files Point To Raster GP Tool Lidar Applications

34 Esri UC 2014 | Technical Workshop | BLOB Based Storage of Intensity BLOBs are used, in the context of lidar, to store multiple numeric values together in one thing. Each BLOB contains as many values as there are vertices in the corresponding multipoint. Lidar Applications

35 Esri UC 2014 | Technical Workshop | Reducing Noise for Contouring and Slope Analysis Lidar Applications

36 Esri UC 2014 | Technical Workshop | Lidar Is Noisy Lidar has measurement error Typically 12-15cm vertical accuracy Horizontal sample density is often 1m or less This results in high frequency noise - Extremely messy contours - Average slope skewed to be very high Goal is to reduce noise without degrading the accuracy Lidar Applications

37 Esri UC 2014 | Technical Workshop | Use only those points necessary Some applications refer to points selected for use in making contours as ‘model key’ points Terrain pyramids - Original points filtered into different levels of detail - Can specify which pyramid level to use when interpolating to raster or extracting TIN Natural neighbors - Conservatively smooth Point Thinning, Interpolation, and Rasterization Lidar Applications

38 Esri UC 2014 | Technical Workshop | Point Thinning, Interpolation, and Rasterization Lidar Applications Input lidar Create Terrain GP Tool Terrain To Raster GP Tool Contour GP Tool Slope GP Tool Workflow

39 Esri UC 2014 | Technical Workshop | Floodplain Delineation Lidar Applications

40 Esri UC 2014 | Technical Workshop | Surface Difference Tool Subtract lidar based ground surface from modeled (e.g., HEC-RAS) water surface Output polygons used to delineate floodplain Optional output of depth surface(s) Lidar Applications

41 Esri UC 2014 | Technical Workshop | Demo Lidar Applications

42 Esri UC 2014 | Technical Workshop | For those wanting models: Lidar Applications

43 Esri UC 2014 | Technical Workshop | Thank you… Please fill out the session survey: Offering ID: 1105 Online – Paper – pick up and put in drop box Lidar Applications

44 Esri UC 2014 | Technical Workshop | Thank you… Please fill out the session survey: Offering ID: 1240 Online – Paper – pick up and put in drop box Lidar Applications

45 Esri UC 2014 | Technical Workshop | Lidar Applications

46 Esri UC 2014 | Technical Workshop | Please include the following slide at the end of your presentation encouraging the audience to fill out the session surveys and how to do so. These slides should be included for: - 75 minute Technical Workshops - 30 minute Technical Workshops - Demo theaters (paper only) Notes to presenters: Lidar Applications

47 Esri UC 2014 | Technical Workshop | Lidar Applications Put presentation name on the footer: Go to Insert tab > Header & Footer > Apply to All


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