Remote Sensing Lab 5: LIDAR

   Goals and Background: This lab familiarized me with basic LIDAR processing, and had me make DTMs and DSMs, and an intensity image.
 
   Methods: 

Part 1: I copied the 40 individual LAS files from my department server into a personal folder for LIDAR processing. I then opened them all in a new 2 dimensional viewer ERDAS Imagine. I denied the software's request to make LOD. I then took a look at metadata in this software in order to familiarize myself with this dataset.

Part 2: I opened ArcMap and ArcCatalog. In ArcMap I right clicked on the top interface in order to turn on the LAS Dataset toolbar. I also clicked on customize, then extensions, and turned on 3D analyst, and spatial analyst. I also clicked on geoprocessing, then environments, to set my scratch and current workspace, afterward saving the ArcMap map file in my folder for future ease of work on this lab. Next, I right clicked on my folder in ArcCatalog, and created a new LAS dataset. I then named it and went into its properties in order to add all of my LAS tiles files, and to click on statistics, and then calculate. I then examined the statistics and compared them to other research for quality assurance purposes. Examining the metadata supplied with the data in an external .xml file, I found the horizontal and vertical coordinate systems and their respective units. With this information I set the coordinate systems of the dataset in ArcMap by right clicking on the dataset in the catalog and selecting properties.

I now dragged this correctly configured dataset from the catalog into the map. Loading a shapefile containing the boarders of the county as reference, I checked that the LIDAR tiles were located in the appropriate place. I now played with the LAS Dataset toolbar in, displaying the dataset in a variety of ways, also changing the classification settings in symbology layer properties and the selection to slope, elevation, and contour.

In order to create a profile of a bridge in Eau Claire, I clicked on the appropriate button on the toolbar, and positioned the resulting box over the bridge. I did the save with the 3D interactive profile function, and also used the two functions to explore other areas of the city.

Part 3: In this section I created a DTM and a DSM, hillshades of both, and an intensity image. Setting data to dots of elevation and first return, I began my DSM. I opened the LAS Dataset to Raster tool and set value field to elevation, cell type to maximum, void fill to nearest neighbor, sampling type to cell size and its value to 6.56168, and saved it in the right place with a descriptive title. After displaying this new file I used the hillshade tool inputting the DSM file, and looked at this file.

Now I created a DTM by using the LAS Dataset to Raster tool again but changing settings to binning, natural neighbor, minimum, and cellsize with the same size as the DSM. Before this I made sure to set the data to ground, and to points of elevation. I again ran the hillshade tool to make another hillshade image..

Next I created the intensity image. In order to do this I changed my dataset to points of elevation, and first return, then running the LAS Dataset to Raster tool again. I set the parameters to intensity, average, and natural neighbor, and cell size with the same size. I now opened this image in ERDAS Imagine because it automatically enhances the display.

Results: 

DSM

DTM

DTM Hillshade

DSM Hillshade

Intensity Displayed in ERDAS Imagine

Sources:

Data was provided by my instructor. 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.