3D Analyst Lidar Solutions

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Esri European User Conference October 15-17, 2012 | Oslo, Norway Hosted by Esri Official Distributor

3D Analyst Lidar Solutions Peter Becker

Agenda



Introduction to Lidar



Lidar and LAS datasets



Lidar and terrain datasets



Lidar and Mosaic datasets



Sharing Lidar

Lidar – Light detection and ranging



Lidar (light detection and ranging) is an optical remotesensing technique that uses laser light to densely sample the surface of the earth, producing highly accurate x,y,z measurements.



Laser pulses emitted from a Lidar system reflect from objects both on and above the ground surface.

Types of Lidar





Airborne -

Captured from aircraft

-

Suitable for surface analysis

Terrestrial -

Captured from the ground

-

Suitable for feature location and data validation

Dense data can have elements of both

Multiple laser returns Lidar data

First Return SecondReturn ThirdReturn

Last Return

Digital surface model creation from Lidar Lidar data

First Return SecondReturn ThirdReturn

Last Return

DSM

Digital elevation model creation from Lidar Lidar data

First Return

DSM

SecondReturn ThirdReturn

DTM

Last Return

Surface using breaklines Lidar data

First Return

DSM

SecondReturn ThirdReturn

DTM Breakline Last Return

Breaklines may be required for less dense lidar or for terrain form enforcement

Lidar Preprocessing

Acquisition

Point Clouds

Pre-Processing

File01.las File02.las … File99.las



Sensor calibration



Georeferencing Multiple



Q/A & Q/C?

Files / Folders



Automated classification?



Tiling?

Lidar storage



Lidar data is commonly stored in LAS files



A LAS file is a binary file format for Lidar data storage developed by the ASPRS in conjunction with private and government stakeholders.



Each LAS file contains metadata of the Lidar survey in a header block followed by individual records for each laser pulse recorded.

Lidar classification



Lidar points can be grouped together into classes that represent similar features.



Defined by the ASPRS.

Challenges of working with Lidar data



Huge volumes



Multiple sources



Multiple projections



Varying accuracy



Multiple representations



How to manage?



How to analyze?



How to access?

Previous ArcGIS 10.0 support for Lidar



Geodatabase oriented -

Import ASCII or LAS

-

Multipoints

-

Terrain dataset



Point To Raster tool



Terrain and TIN-based surface tools



Help -

Terrain concepts book

-

3D Analyst tutorial terrain exercise

-

3D Analyst ‘Lidar solutions in ArcGIS’ guide book

LAS support in ArcGIS 10.1

Analyze / P Update Data R O J E C LAS LAS LAS Dataset Dataset Dataset T 1 2 3 S LAS/Terrain Datasets

File01.las File02.las … File99.las Multiple Files / Folders

Tiled / Overlapping Extents (Location / Time)

O R G A N I Z E

Manage Serve / Share

Mosaic Dataset

Using Lidar as a LAS dataset



New data type



File based



Stores references to LAS files on disk



Optionally reference breakline & constraint data



Treats a collection of LAS files as one logical dataset

LAS Dataset Strengths



Direct access to LAS



Catalog of LAS files for a project



View as points, TIN



Direct measurements



Statistics, Q/A & Q/C



Filter, query



Profile, 3D



Edit LAS



Add and edit constraints

LAS Dataset Creation



Interactively via Catalog -



File folder context menu pick

Inside scripts and models with GP tools

LAS dataset properties

LAS Dataset / LAS File Statistics

Viewing Lidar as a LAS dataset



In 2D (ArcMap) or 3D (ArcScene)



As points -



As a surface -



Symbolize using LAS attributes (Class Codes, RGB, Scan Angle, etc.) Symbolize & filter using surface options (Bare earth, First return, etc.)

Control the number of points shown -

Full resolution in a local area

Data courtesy Merrick & Co.

LAS Dataset – Editing Class Codes



Manual -





Fixing data anomalies and misclassifications via point profile window

Process (GP tools) -

Classify relative to feature data

-

Reclassify to standard LAS spec

Automated -

Done by Partners

Interactive Editing

Batch Oriented Editing

Reclassify old class to new class

Set class by proximity to feature data

LAS Dataset Analysis







Derive surfaces -

As raster

-

As TIN

Direct surface analysis -

Interpolate shape

-

Add surface information

-

Line of sight

-

Skyline

-

Locate outliers

Rasterize on point metrics -

LAS point statistics as a surface

Airborne vs. terrestrial Lidar





Most tools primarily for airborne Lidar -

Surface views and analysis

-

LAS attributes

Terrestrial Lidar supported primarily as point cloud in ArcScene -

Points used as backdrop for measuring and digitizing

-

Display integrated with other GIS layers

LAS dataset

Modeling Elevation Options

• LAS • Terrains • Raster

Terrain Dataset Multi-resolution surface created from measurements stored in feature classes •

Points & constraints



Stored in the geodatabase



Schema: Defines feature class participation



On-the-fly TIN



Multi-resolution (pyramid z tolerance)



Highly scalable & I/O efficient



Attributes



Editable, versioned



For high quality surfaces

Points and Breaklines

Terrain Pyramids

High Resolution

Medium Resolution

Low Resolution

Terrain Dataset used to Define Managed Surface Lidar data

First Return

DSM

SecondReturn ThirdReturn

DTM Breakline Last Return

Terrains efficiently store and mange the terrain form

Terrain dataset editing





Updates accomplished through edits to source measurements -

Append, remove, replace mass points by area

-

Standard/custom edit tools (e.g. Standard ArcGIS license) used to modify polylines, polygons, spot heights

-

Terrain rebuild based on dirty-areas

Support for versioning in SDE

Creating a terrain dataset

Viewing Lidar as a terrain dataset



Symbology same as TIN in ArcMap



Resolution changes depending on zoom level in ArcMap



Terrain datasets can be displayed as either elevation or draped layers in ArcGlobe



Terrain datasets are not directly supported in ArcScene

Analysis capabilities for terrain datasets



QA/QC Lidar data



DEM / DSM creation



Slope, Aspect, Contours



Surface differencing



Intensity image generation



Estimating forest canopy



Data area delineation



Thinning / reducing noise



Spot interpolation



Profiling

Raster (Regular Grid) Advantages



Very Compact



Very Fast Access



Simple Viewing



Simple Analysis



Multiple derivatives

But Courser approximation Can not define breaklines Generated from LAS or Terrains As a Derived Product or On-The-Fly

Using Mosaic Datasets to Manage and Serve Lidar

Image Management Workflow – Using Mosaic Datasets Highly Scalable, from Small to Massive Volumes of Imagery •



Desktop

Large Image Collections

Create Catalog of imagery •

Reference Source



Ingest & Define Metadata



Define Processing to be Applied

Define Imagery Products •

Dynamic Mosaicking



On-the-fly Processing

Mosaic Dataset



Access as Image or Catalog

Image Dissemination – ArcGIS Server Making Imagery Accessible to Desktop, Web and Mobile Apps





Dynamic Image Services •

Processing & Analysis



Catalog of Metadata

Static Cached Imagery •

Desktop



Geoprocessing Services •

Large Image Collections

Mosaic Dataset

Server On Premise or In Cloud Desktop, Web & Mobile Users

Simple Backdrop

Processing Tasks

Using Lidar in Mosaic Datasets



Lidar sources treated as raster type -



LAS file -

Individual

-

Folder

-

LAS Dataset

-

Terrain Dataset

Must set properties to control the surface generation -

Pixel size

-

Return types

-

Classification types

Provides dynamic rasterization, mosaicking, and on-the-fly processing

Dynamic mosaicking and rasterization



Display multi-resolution data together



Mosaicking rules -



Control the order of display -

By attribute

-

Closest to center

-

Ensure best data is always displayed

-

Can be controlled by user

Queries -

Refine selection of data

On-the-fly processing



Data is processed as it is accessed



Create multiple products from one source



Processing for elevation



-

Hillshade

-

Shaded Relief

-

Aspect

-

Slope

-

Convolution Filters

Define processing functions -

On each item

-

On entire collection

Benefits of managing Lidar with the mosaic dataset



Store multiple collections and projects



Store variety of elevation data -

Topographic or bathymetric

-

Point or raster



Unlimited size



Provide access to all data -

As raster

-

As source data

-

Share internally and online

Manage and share using a mosaic dataset



Optimum model for Lidar and image data management



Manage





-

Multiple projects as single dataset

-

Metadata

Visualize and process -

As 2D or 3D surface

-

DEM, hillshade, slope, etc.

Share -

As a single dataset

-

As image service

Using a mosaic dataset





As an image -

Seamless display

-

Perform pixel-based analysis

-

Use as an input to geoprocessing tool

-

Export a raster dataset

As a catalog -

Selection/query

-

Add selected images to map

-

View data and metadata

-

Time aware

Sharing Lidar data



Share as image services



Easy to -

Access

-

Discover

-

Download

How to serve Lidar data





Image service -

Lidar data (or imagery) added to a mosaic dataset and made available by a server to a client application

-

Requires the Image Extension

-

Access • Discover • Download

Map service -

Point data, terrain dataset, or mosaic dataset* added to a map document and made available by a server to a client application

* requires Image Extension

-

Views map layer as it was designed

Access, discover, and download

Rasterized surfaces Catalog/table VIEW/QUERY

LAS files Image service

DOWNLOAD LAS dataset

New

Multiple Elevation Data Sources Constraints

LAS files

LAS Dataset

Terrains

Raster grids

Multiple Elevation Data Sources Constraints

LAS files

LAS Dataset

Terrains

Mosaic Dataset

Raster grids



Catalog of data sources



Contains metadata



Defines processing



Directly accessed

Multiple Elevation Data Sources Constraints

LAS files

LAS Dataset

Mosaic Dataset

Desktop

Raster grids

Terrains

Web



Catalog of data sources



Contains metadata



Defines processing



Serve to many applications

Mobile

Questions?