LiDAR Remote Sensing

Methods

The first step is to enter all of the .las files into Erdas Imagine. While doing this, make sure to uncheck "Always Ask" and then select No on computing statistics. This is important, because all of the statistics will be calculated later on once the user knows the tile size and metadata. The next step is to open ArcCatalog and open the lab folder created to store the data. Create a new LAS Dataset and bring in the data for the lab. At this point, the statistics are calculated by opening the frame properties. While in the properties, the next step is to change the horizontal and vertical coordinate systems to NAD 1983 HARN Wisconsin CRS Eau Claire (Feet) and NAVD 1988 US feet respectively. A shapefile is brought in to verify that the projection has done the job correctly. In ArcMap, the dataset is brought in and the symbology is changed to have 8 breaks. With the LAS dataset toolbar open, the different ways of displaying the data is identified. Contours are also set up. Points are set to elevation and the First Return is what is being visualized. The next portion is to create new products, so the environments are set to the Lab 5 output folder. The LAS Dataset to Raster is utilized to create a raster with the maximum cell assignment and nearest neighbor void fill. The resulting raster is then hillshaded. The filter is then set to ground on the initial dataset and the LAS Dataset to raster tool is used again to generate a bare earth image by switching the cell assignment to minimum. It is then also hillshaded. The last image to create is an intensity image. It is done by changing the elevation setting to intensity. It is best viewed in Erdas Imagine.

Results


Figure 1: Digital Surface Model Created. This displays the surface model gathered from LiDAR data.



Figure 2: Bare Earth Image Created. Displays the ground level return points.


Figure 3: Intensity Image created. This displays the intensity values each pixel represents.

Sources

Lidar point cloud and Tile Index are from Eau Claire County, 2013. 

Eau Claire County Shapefile is from Mastering ArcGIS 6th Edition data by Margaret Price, 2014.

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