Blog Archives

LiDAR Training

Source: U.S. Forest Service Remote Sensing Applications Center

Lidar Training

Lidar Supporting Documentation

New article on sinkhole detection published in Geomorphology

My new peer-reviewed article titled “Automated delineation of karst sinkholes from LiDAR-derived digital elevation models” has been published in the latest issue of Geomorphology. You can download a free online copy using this link: http://authors.elsevier.com/a/1T3d9_,Oh6mAl8 (expires on July 8, 2016). In this paper, we present a localized contour tree method for automated extraction of sinkholes in karst landscapes. The study area was Fillmore County in southeastern Minnesota, USA. See some figures below:

Fig1_study_area

Fig. 1. Distribution of sinkhole inventory points in Fillmore County, Minnesota, USA.

Fig2_contour_tree

Fig. 3. Contour representation of a compound surface depression. (a) Contours overlain on DEM shaded relief. (b) Elevation profile of the transect A–B shown in (a).

Fig7_sinkhole_distriutions

Fig. 8. LiDAR DEM shaded relief (a) and examples of extracted sinkhole boundaries overlain on LiDAR DEM shaded relief (b) and color infrared aerial imagery (c).

Fig9_sinkhole_comparison

Fig 9. Sinkhole boundaries delineated using different methods. (a) The sink-filling method. (b) The localized contour tree method.

ArcGIS 3D LiDAR Toolset

ESRI has released a new version of 3D LiDAR toolset, which was designed to extend the LiDAR capabilities of ArcGIS Desktop. It can be downloaded from : http://www.arcgis.com/home/item.html?id=fe221371b77940749ff96e90f2de3d10

cwduyyhweaau4fdFunctionalities of the LiDAR toolset:
  • Classify ground*, building, vegetation, and noise points
  • Extract building footprint approximations
  • Clip LAS files*
  • Improve QA/QC processes with lidar data:
    • Evaluate LAS files for errors through the CheckLAS utility
    • Export LAS file header information
    • Define the spatial reference of LAS files with missing/incorrect information*
    • Project LAS files to desired coordinate systems*
    • Evaluate coverage of overlaps in lidar scans
    • Rearrange LAS files to optimize data access I/O*
  • Optimize lidar data for operational use and rapid access through the compressed ZLAS format
  • Evaluate Z statistics with advanced height metrics*
  • Analyze the proximity of LAS points to 3D features**
  • Convert lidar data between various data formats
  • Create tiled raster derivatives
Analysis & Data Management of 3D Features & Surfaces
  • Correct the Z value of a multipatch model so that it “sits” on the ground
  • Create a point skymap of sun positions for visualization and solar analysis workflows
  • Simplify dense, 3D breaklines to support scalability in TIN-based surface modeling*
  • Integrate a design surface, such as one created using the Grading tool, into a base TIN
  • Export a TIN to LandXML for use in 3rd party applications
  • Cross sections of a multipatch can be used with the Intersect 3D tool to:
    • Generate contours in 3D space that capture cliff overhangs
    • Determine a 3D model’s footprint at different heights
    • Generate sightlines for visibility analysis

ArcGIS Terrain Toolbox

Terrain Tools Sample v1.0 beta:  A suite of Geoprocessing tools to produce cartographic effects for terrain representation

Download it here.

Source: http://blogs.esri.com/esri/arcgis/2015/05/21/take-your-terrain-mapping-to-new-heights/

Take your terrain mapping to new heights

by Kenneth Field, Senior Cartographic Product Engineer

Standard techniques for representing terrain, like a hillshade, are adequate for many applications, but you may want to represent terrain under different lighting conditions, or perhaps use more artistic techniques. In these cases you might need to go a little further than creating a simple hillshade. For this reason (and because we like making tools that extend what we can do!) we’ve built a new toolbox, called Terrain Tools, that helps you take your terrain mapping to new heights.

Cartographic research often develops techniques, models and tools that supplement or extend what you find in software out-of-the-box. They are often difficult to find, hidden in journal articles or cumbersome to implement. We’ve brought together some of these ideas and workflows in the Terrain Tools toolbox that provides capabilities for creating alternative terrain representations in ArcGIS (ArcMap and ArcGIS Pro). Terrain Tools are designed to extend your out-of-the-box toolkit for representing terrain in GIS by encouraging you to be more creative; how to think more critically about design choices; and how to go beyond the defaults.

You can download a zip file from ArcGIS Online that contains the toolbox, sample data, documentation and also an ArcMap Map Document and ArcGIS Pro Project. The Map Document and Pro Project also include results layers so you can see how the tools work before you use them on your own data. It’s important to note that the sample results show the results of running the tools using the default output. They are a starting point and many of the tools give you the flexibility to modify parameters and customize your own output. The documentation is in workshop format that includes discussion of each tool and instructions for use. Because the tools are written in Python they can be viewed, modified and used as a starting point for further development.

Here’s a brief look at some of the output you’ll get from running Terrain Tools.

Terrain Tools incorporates a few previously available tools which were available as models (built originally using ModelBuilder). They have been rewritten and optimized as Python scripts which improves stability and speed of processing. Additionally, a range of new tools have been either written (from the original published algorithms) or optimized as Python scripts from code samples.

One of the highlights of Terrain Tools is the new Cluster Hillshade which provides you with the ability to make spectacularly detailed and artistic hillshades with your own data. This is just about as close as you can get with an automated process to classic hand-drawn hillshading – and all from just a Digital Elevation Model input and a click of a mouse.

The Tanaka method for creating Illuminated Contours and Filled Contours are also included, here depicted one on top of the other:

Thematic maps haven’t been ignored. It’s perfectly possible to run the tools for any input raster (e.g. a statistical surface rather than a DEM) but there’s also a specific 3D Choropleth tool, useful for adding depth to a choropleth, encoding a second piece of information or as a way to see variation within a single class interval:

There’s plenty more tools to explore and, of course, the scripts are entirely open to being customised further. Here’s the full list of what’s included in the Terrain Tools sample:
Read the rest of this entry

The 3D Elevation Program (3DEP) for collecting 1-m nationwide LiDAR data

The 3D Elevation Program (3DEP) initiative is being developed to respond to growing needs for high-quality topographic data and for a wide range of other three-dimensional representations of the Nation’s natural and constructed features. The primary goal of 3DEP is to systematically collect enhanced elevation data in the form of high-quality light detection and ranging (lidar) data over the conterminous United States, Hawaii, and the U.S. territories, with data acquired over an 8-year period. Interferometric synthetic aperture radar (ifsar) data will be collected over Alaska, where cloud cover and remote locations preclude the use of lidar over much of the State. The 3DEP initiative is based on the results of the National Enhanced Elevation Assessment.

http://nationalmap.gov/3DEP/

https://www.youtube.com/watch?v=tTaZxcm9QGg

3DEP-1

3DEP-2

 

LAS2DEM: Creating raster DEMs and DSMs from *.LAS (Lidar) files in ArcGIS 10.2

Esri Australia Technical Blog

Imagery and remote sensing has always been one of my areas of interest in GIS. As a support analyst at Esri Australia I get a large number of imagery-related questions and I often help clients learn how to process their geospatial imagery and LiDAR data in ArcGIS.

Lidar (or Light Detection and Ranging) technology has become very popular and accessible in recent years. Because it provides high resolution elevation data, it’s now extensively used in the GIS world for mapping, spatial analysis and 3D visualization.

Although Lidar data can be used in many of the ArcGIS Desktop software,  it turns out that many users are not aware of some basic workflows that can be utilized to extract raster Digital Elevation Models from their LAS point clouds in ArcGIS.

The question “how do I create a DEM from my Lidar data” is one of the most frequently asked questions when it…

View original post 1,312 more words

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