1 / 43

Accessing 2011-2012 LIDAR GIS day 2012

Accessing 2011-2012 LIDAR GIS day 2012. Larry Theller ABE Purdue University. Indiana's Statewide LiDAR data is produced at 1.5-meter average post spacing for all 92 Indiana Counties. Public Download has 50,000,000 point limit – about 4 square miles. Seven Miles.

addison
Télécharger la présentation

Accessing 2011-2012 LIDAR GIS day 2012

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Accessing 2011-2012 LIDARGIS day 2012 Larry Theller ABE Purdue University

  2. Indiana's Statewide LiDAR data is produced at 1.5-meter average post spacing for all 92 Indiana Counties

  3. Public Download has 50,000,000 point limit – about 4 square miles. Seven Miles

  4. As a registered user you have 150,000,000 point download. 7 Miles

  5. Points.las Dems.tar.gz

  6. Google Earth plug-in for viewing

  7. Conclusion • Out-of-the-box DEMs from OpenTopography do not support hydrologic modeling. • LAS cloud downloads from OpenTopography will require processing of point cloud downloads into larger data sets. • Dev blogs suggest LAStools as good software for this.

  8. http://gis.iu.edu/datasetInfo/index.php

  9. Examples • ArcGIS 10.1 enhanced for LiDAR • Check the ArcGIS 10.1 online help • Be prepared to manipulate VAST amounts of data. • You need a fast/high RAM computer • Terabytes of disk space….

  10. Floodplain Analysis with LIDAR Data • Flood extents are typically estimated by comparing models of water surfaces and ground surfaces. • Water surface profiles for a given flood event (for example, 50-year flood) are created • Each profile represents the height of water across the river at a given location. The length of each profile is long enough to capture the largest possible flood extent going out from either side of the river. • Profiles are generated at reasonable intervals along the river where the flooding is being modeled

  11. The primary output from the Surface Difference tool is a polygon feature class. Each polygon is classified as either ABOVE, BELOW, or EQUAL so you can tell where the modeled water surface is above the terrain dataset. These areas are potentially flooded.

  12. The Surface Difference tool provides an option to output a difference raster. Positive cell values in this dataset represent depth, which is another important piece of information in flood studies.

  13. Tree Canopy Analysis with LIDAR • Forest canopy density and height are used as variables in a number of environmental applications. • These applications include the estimation of biomass, forest extent and condition, and biodiversity. • Canopy density, or canopy cover, is the ratio of vegetation to ground as seen from the air. • Canopy height measures how far above the ground the top of the canopy is. • Lidar can be used to determine both of these variables.

  14. noise canopy ground

  15. Create a LAS dataset and layer ground noise canopy Create a LAS dataset and layer

  16. Calculating the density • The most effective way to determine the canopy density is to divide the study area into many small equal-sized units through rasterization. • compare the number of above ground points to the total number of points. • The important technique to remember here is to determine an appropriate cellsize for this analysis. It needs to be at least four times the average point spacing. • You can go larger but not smaller with the cell size.

  17. Observations • Modeling process requires a series of steps • May be done in Arcgis 10.1 • Cell-based analysis divides above ground hits by total hits to produce above ground density • Surface difference tool needs processed ground surface…

  18. Above ground density

  19. Canopy height above ground

  20. Conclusions • Download LAS from OpenTopography for small areas 2- 4 sq miles • Download (multi-tool) LAS from IU for larger areas • OT has no useable DEMs for hydrology • Download DEMs from IU or USGS seamless for hydrology models. • Learn to process LAS files outside of ArcGIS for point cloud LiDAR analysis

  21. Conservation ModelingGoogle this: conservation model lidarminnesota

More Related