lidar and gis applications and examples clayton crawford, esri
TRANSCRIPT
![Page 1: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/1.jpg)
Lidar and GISApplications and Examples
Clayton Crawford, Esri
![Page 2: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/2.jpg)
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
![Page 3: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/3.jpg)
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
![Page 4: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/4.jpg)
Supporting Data structures and Tools
• Vector features- points
- multipoints
- lines
- polygons
• Raster
• TIN
• Terrain Dataset
FunctionInput Input OutputOutput
Workflow
• Point File Information
• LAS To Multipoint
• ASCII 3D To Feature Class
• Point To Raster
• Terrain To Raster
• Terrain To TIN
![Page 5: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/5.jpg)
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
FunctionInput Input OutputOutput
Workflow
![Page 6: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/6.jpg)
Lidar point coverage and sample density
• Basic QA/QC before loading data into geodatabase
• Verify xy and z extent
• Examine point spacing
![Page 7: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/7.jpg)
LAS Dataset Layer (10.1)
![Page 8: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/8.jpg)
LAS Dataset Properties (10.1)
![Page 9: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/9.jpg)
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
![Page 10: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/10.jpg)
Point File Information Tool
![Page 11: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/11.jpg)
LAS Point Statistics As Raster Tool (10.1)
Pulse/sample density
![Page 12: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/12.jpg)
Point To Raster Tool
Pulse/sample density
![Page 13: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/13.jpg)
• LAS = industry standard file format for lidar
• Multipoints used for efficiency
• Filter options- By class
- By return
Loading Data: LAS To Multipoint Tool
![Page 14: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/14.jpg)
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.
![Page 15: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/15.jpg)
Demo
![Page 16: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/16.jpg)
Creating Raster DEMs and DSMs
Bare earth surface made using only ground hits.
Includes ground, trees, and buildings made using first returns.
Digital Elevation Model Digital Surface Model
![Page 17: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/17.jpg)
LAS Dataset To Raster (10.1)
• Binning- Fast
- Reasonable for DSMs
- Void filling options
- Honors replace andclip constraint types
• Triangulation- True interpolation
- Always fills voids
- Appropriate for DEMs
- Honors all constraint types
![Page 18: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/18.jpg)
Point to Raster Tool
• Fast
• Rasterize based on multipoint vertex z
• Not true interpolation
• Doesn’t support breaklines
• Data gaps
• Arguably works best with 1st return data because there are fewer and smaller data voids to deal with.
![Page 19: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/19.jpg)
Point to Raster Post-process: Void Filling
Point To RasterRaster
Calculator
Con(IsNull("pt2ras"), FocalStatistics(“pt2ras", NbrRectangle(3, 3, "CELL"), "MEAN", "DATA"), "pt2ras")
Con(IsNull([pt2ras]), FocalMean([pt2ras], Rectangle, 3, 3, DATA), [pt2ras]) 9.3
10.0
![Page 20: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/20.jpg)
Don’t Abuse Con
• Introduces anomalies if used repeatedly
Hilltop
Valley bottom
Nodata cells
Steeper slope
![Page 21: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/21.jpg)
Terrain to Raster
• Quality
• Supports ancillary data (breaklines, water bodies, etc.)
• True interpolation
• Can handle large datasets
![Page 22: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/22.jpg)
Comparison
Interpolation Binning
![Page 23: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/23.jpg)
Data Area Delineation
Dense collection of source measurement points (green)
Triangulation of those points without a boundary constraint
Constraint applied
![Page 24: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/24.jpg)
Workflow to Calculate a Data Area Polygon (10.1)
LAS Point Statistics As Raster
Input LAS datasetInput LAS dataset
Con Expand Shrink
Raster to Polygon
Eliminate Polygon
Part
Output polygonOutput polygonfeature classfeature class
![Page 25: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/25.jpg)
Workflow to Calculate a Data Area Polygon
Point to Raster
Input multipointInput multipointfeature classfeature class
Con Expand Shrink
Raster to Polygon
Eliminate Polygon
Part
Output polygonOutput polygonfeature classfeature class
![Page 26: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/26.jpg)
Demo
![Page 27: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/27.jpg)
Estimating Forest Canopy Density and Height
![Page 28: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/28.jpg)
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.
- 10.1 or later can use LAS Point Statistics As 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.
![Page 29: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/29.jpg)
Creating Intensity Images
![Page 30: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/30.jpg)
Input LAS datasetInput LAS dataset
Intensity Image Workflow (10.1)
LAS DatasetTo RasterGP Tool
Intensity ImageIntensity Image
![Page 31: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/31.jpg)
Intensity Image Workflow
LAS To MultipointGP Tool
Output Output multipoint multipoint
feature classfeature class
Intensity ImageIntensity Image
Input LAS filesInput LAS files
Point To Raster GP
Tool
![Page 32: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/32.jpg)
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.
![Page 33: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/33.jpg)
Reducing Noise for Contouring and Slope Analysis
![Page 34: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/34.jpg)
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
![Page 35: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/35.jpg)
• 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
![Page 36: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/36.jpg)
Point Thinning, Interpolation, and Rasterization
Input lidarInput lidarCreate Terrain GP Tool
Terrain To Raster GP Tool
ContourGP Tool
SlopeGP Tool
Workflow
![Page 37: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/37.jpg)
Floodplain Delineation
![Page 38: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/38.jpg)
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)
![Page 39: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/39.jpg)
Demo
![Page 41: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/41.jpg)
Thank you…
• Please fill out the session survey in your mobile app
• Select ‘Lidar and GIS: Applications and Examples’in the Mobile App- Use the Search Feature to quickly find this title
• Click “Technical Workshop Survey”
• Answer a few short questions and enter any comments
![Page 42: Lidar and GIS Applications and Examples Clayton Crawford, Esri](https://reader035.vdocument.in/reader035/viewer/2022062308/56649e7e5503460f94b80f53/html5/thumbnails/42.jpg)