Coastal LiDAR

From Bellman
Jump to navigation Jump to search

This is called the "Coastal" LiDAR page because I generally go to NOAA's coastal data viewer to find my LiDAR. Since I live near the coast it's generally the best place for me to go.

Currently I use the data for (1) my own education (2) TrailPeople projects. For TrailPeople mostly I have been downloaded DEM's as a short cut for getting accurate elevation data. I am trying to develop a good workflow for processing the LAS point data directly.

Lincoln county, Oregon

Feb 2017- I am looking for a house in Lincoln county and have decided to commit to a full GIS approach, so I am collecting all the data I can find to build up an analysis. Then I can look at properties from afar and be better informed.

Workflow: My intent is to go full open source on this project.

This will include LiDAR so that I can check on slope and aspect to help evaluate solar access. I want PV so I need sun.

Santa Clara county

2016- TrailPeople

For this project I want to closely examine a reach of road that goes into the hills to see if it can accommodate addition of a footpath.

Workflow: On this project I did use LAZ point files but I used ESRI tools.

I downloaded data that was collected by the Santa Clara Water District in 2006. The area of interest is small, covered by 4 tiles. See https://coast.noaa.gov/htdata/lidar1_z/geoid12a/data/4870/ The data is in LAZ format.

What coordinate system is this data in? It's in WGS84 and the vertical unit is 1 meter.

First thing I want to do is generate simple first return and last return surfaces.

The files are already classified, see the metadata:

"This data set is an LAZ (compressed LAS) format file containing LIDAR point cloud data. LAS format files, raw LiDAR data in its native format, classified bare-earth LiDAR DEM and photogrammetrically derived breaklines generated from LiDAR Intensity stereo-pairs. Breakline, Top of Bank, and contour files in ESRI personal geodatabase format, Microstation V8 .dgn format, and AutoCAD 2004 formats for the San Jose Phase 3 project of Santa Clara County, Ca. This project arrived with only unclassified data. NOAAs Office for Coastal Management performed an automated classification using lasground. Although class 1 and class 2 are available, there was no QA/QC on the points after lasground was performed."

Generating surfaces from raw data For ArcGIS this means "terrains". For QGIS it means DEM rasters. I am starting with terrains, which means first I need to get the data out of the LAZ files and into ArcGIS.

http://www.spatialguru.com/lidar-data-to-raster-file-with-open-source-gdal-tool/

http://www.laszip.org/

Problem encountered: One of the tiles was misclassified; vegetation (tall trees) and buildings ended up in the "bare earth" category resulting in some crazy contour lines.

Gold Beach

This project goes back a ways now, and I recall the big problem was holes in the data that probably no longer exist. The holes became the interesting problem but if I were to try again, I'd probably be able to get 2009 or later data with 100% coverage of the area of interest.

20-Apr-2011 Going to Gold Beach for Easter weekend, so naturally I am looking at Curry county data once again.

I have a nice NAIP 2009 photo of the area now. 1/2 meter 2009 county level files are available as zipped files via FTP from Oregon Explorer

Working with LiDAR obtained from the Oregon Coastal Atlas

Holes in LiDAR data

I have created a contour and a hillshade, which is great, but the LiDAR is full of holes! I think since it's a coastal dataset (NOAA) they don't care about the areas up a bit from the beach.

I am thinking I can fill the holes with 10m DEM data, so I found an example on how to do this and will look at it this evening.

http://blogs.esri.com/Support/blogs/mappingcenter/archive/2009/06/16/Filling-and-clipping-a-raster.aspx