Digital
Surface Model, Digital Terrain Model, Intensity Image, and Anaglyph
Geography 338: Remote Sensing of the Environment
Spring
2016
The population of Lake County recorded by the 2015 census was 703,910 people (Quick Facts Lake County, Illinois). In 2012, it was recorded that 99% of the county is urban and 1% is rural. The population density in 2012 was 1,578 people per square mile. As of March 2013, the cost living index in Lake County was 101.5, very close to the United States average of 100.0 (Lake County, Illinois (IL)). The 2014 census data recorded that about 12.2% of the population is 65 years or older and 25.4% of the population is under eighteen years of age. Women represented 50.1% of the population in 2014. In 2014, the population of Lake County was 82.3% White and 7.5% African American (Quick Facts Lake County, Illinois). Lake County is in the Central Standard Time Zone. The city of Waukegan is the most populated city in Lake County with a population of 98,503 people as of July 2015. Lake County has one college, the Lake Forest College and as of July 2015 89% of the population was high school grads and 42% of the population held a bachelor’s degree (Lake County, IL, USA) Lake County, Illinois can be seen in Figure 1 and 2.
The types of remote sensing analysis I performed on the LiDAR data for this study area include, a digital surface model (DSM) with a hillshade, a digital terrain model (DTM) with a hillshade, an intensity image, and an anaglyph image. All of the raster derived products I created are at 2 meters spatial resolution.
To create the digital surface model (DSM) with first returns I started by activating the LAS Dataset toolbar in ArcMap and going into the Customize dropdown heading and selecting Extensions. In the Extensions popup window I checked the boxes next to 3D Analyst and Spatial Analyst and closed the window. I also made sure my LAS dataset was set to First Returns in the LAS Dataset toolbar. I next opened Arc Toolbox and expanded the Conversion Tools and the To Raster tools to access the LAS Dataset to Raster tool. I opened the tool and inputted my LAS dataset and set a name and location for my output file to save to. I made sure the Value Field read Elevation and I set the Binning Cell Assignment Type to Maximum and the Void Fill Method to Natural Neighbor. I made sure Sampling Type was set to Cellsize and in the Sampling Value field I entered 6.56168 feet so that the spatial resolution would be 2 meters. To make the tool process faster I selected the Environments… button at the bottom of the window and expanded the Parallel Processing heading where I set the Parallel Processing Factor to 100%. I ran the tool and when the tool was complete my DSM was displayed the ArcMap viewer. The only difficulties I had with creating the DSM was that it took about two hours to create the image. My DSM image can be found in the Results section, Figure 2.
Introduction
Lake County is located in the state of
Illinois. Lake County was established in
the United States as a county on March 1, 1839. Lake County was given its name because it was
named after Lake Michigan. This county
lies on the border between the states of Illinois and Wisconsin. Lake County is bordered by Kenosha County, WI
to the north, Lake Michigan to the east, Cook County to the south, and McHenry
County to the west (Lake
County, Illinois Genealogy, History & Facts). The land area of Lake County is 448 square
miles, and Cook County has a water area of 910.4 square miles (Lake County, Illinois (IL)).
The population of Lake County recorded by the 2015 census was 703,910 people (Quick Facts Lake County, Illinois). In 2012, it was recorded that 99% of the county is urban and 1% is rural. The population density in 2012 was 1,578 people per square mile. As of March 2013, the cost living index in Lake County was 101.5, very close to the United States average of 100.0 (Lake County, Illinois (IL)). The 2014 census data recorded that about 12.2% of the population is 65 years or older and 25.4% of the population is under eighteen years of age. Women represented 50.1% of the population in 2014. In 2014, the population of Lake County was 82.3% White and 7.5% African American (Quick Facts Lake County, Illinois). Lake County is in the Central Standard Time Zone. The city of Waukegan is the most populated city in Lake County with a population of 98,503 people as of July 2015. Lake County has one college, the Lake Forest College and as of July 2015 89% of the population was high school grads and 42% of the population held a bachelor’s degree (Lake County, IL, USA) Lake County, Illinois can be seen in Figure 1 and 2.
The types of remote sensing analysis I performed on the LiDAR data for this study area include, a digital surface model (DSM) with a hillshade, a digital terrain model (DTM) with a hillshade, an intensity image, and an anaglyph image. All of the raster derived products I created are at 2 meters spatial resolution.
Figure 1. Map of Lake County Illinois.
Data
LiDAR point
cloud and Tile Index are from Lake County,
2007.
National Agriculture Imagery Program (NAIP) image is from United States Department of Agriculture, Lake County 2007.
United States Counties Shapefile Esri 2013 Dataset.
Remote Sensing Analysis
National Agriculture Imagery Program (NAIP) image is from United States Department of Agriculture, Lake County 2007.
United States Counties Shapefile Esri 2013 Dataset.
Remote Sensing Analysis
After
downloading the LiDAR point cloud and Tile Index for Lake County, I started by
creating a LAS dataset from the Lake County LiDAR point cloud tiles. I opened ArcMap and went into ArcCatalog
where I created a folder for my project. I right clicked that folder and
selected New and choose LAS Dataset from the options. I named the new dataset and opened the
properties of the dataset. I opened the
properties and when to the LAS Files tab where I imported all of the LAS files
for Lake County by selecting the Add Files… button and importing all of the LAS
files. I assigned a proper XY coordinate
system by first consulting the metadata file for the imported files and I set
the XY coordinate system under the XY Coordinate System tab in the LAS Dataset
Properties window to NAD 1983 HARN State Plane Illinois East FIPS 1201
Feet. I consulted the metadata for the
vertical coordinate system and I set the vertical coordinate system under the Z
Coordinate System tab to North American Vertical Datum of 1988. I displayed the LAS dataset in ArcMap.
To create the digital surface model (DSM) with first returns I started by activating the LAS Dataset toolbar in ArcMap and going into the Customize dropdown heading and selecting Extensions. In the Extensions popup window I checked the boxes next to 3D Analyst and Spatial Analyst and closed the window. I also made sure my LAS dataset was set to First Returns in the LAS Dataset toolbar. I next opened Arc Toolbox and expanded the Conversion Tools and the To Raster tools to access the LAS Dataset to Raster tool. I opened the tool and inputted my LAS dataset and set a name and location for my output file to save to. I made sure the Value Field read Elevation and I set the Binning Cell Assignment Type to Maximum and the Void Fill Method to Natural Neighbor. I made sure Sampling Type was set to Cellsize and in the Sampling Value field I entered 6.56168 feet so that the spatial resolution would be 2 meters. To make the tool process faster I selected the Environments… button at the bottom of the window and expanded the Parallel Processing heading where I set the Parallel Processing Factor to 100%. I ran the tool and when the tool was complete my DSM was displayed the ArcMap viewer. The only difficulties I had with creating the DSM was that it took about two hours to create the image. My DSM image can be found in the Results section, Figure 2.
To
create the digital surface model hillshade with first returns I started in
ArcMap where I made sure the 3D Analyst and Spatial Analyst tools were still
active. I then opened Arc Toolbox and
expanded the 3D Analyst Tools and the Raster Surface tools to access the Hillshade
tool. I opened the tool, inputted my DSM
image and set a name and location for my output file to save to. I ran the tool and when the tool was complete
my DSM hillshade was displayed in the ArcMap viewer. My DSM hillshade can be found in the Results
section, Figure 3.
To
create the digital terrain model (DTM) with ground returns I started in ArcMap
where I made sure the 3D Analyst and Spatial Analyst tools were still
active. I also made sure my LAS dataset
was set to the Ground filter in the LAS Dataset toolbar. I next opened Arc Toolbox and expanded the
Conversion Tools and the To Raster tools to access the LAS Dataset to Raster
tool. I opened the tool and inputted my
LAS dataset and set a name and location for my output file to save to. I made sure the Value Field read Elevation
and I set the Binning Cell Assignment Type to Minimum and the Void Fill Method
to Natural Neighbor. I made sure
Sampling Type was set to Cellsize and in the Sampling Value field I entered
6.56168 feet so that the spatial resolution would be 2 meters. To make the tool process faster I selected
the Environments… button at the bottom of the window and expanded the Parallel
Processing heading where I set the Parallel Processing Factor to 100%. I ran the tool and when the tool was complete
my DTM was displayed the ArcMap viewer.
The only difficulties I had with creating the DTM was that it took about
two hours to create the image. My DTM
image can be found in the Results section, Figure 4.
To
create the digital terrain model hillshade with ground returns I started in
ArcMap where I made sure the 3D Analyst and Spatial Analyst tools were still
active. I then opened Arc Toolbox and
expanded the 3D Analyst Tools and the Raster Surface tools to access the
Hillshade tool. I opened the tool,
inputted my DTM image and set a name and location for my output file to save
to. I ran the tool and when the tool was
complete my DTM hillshade was displayed in the ArcMap viewer. My DTM hillshade can be found in the Results
section, Figure 5.
To
create the intensity image I started in an ArcMap viewer displaying my LAS
dataset for Lake County. I set the
dataset to Points and First Return in the LAS Dataset toolbar. I next opened Arc Toolbox and expanded the
Conversion Tools and the To Raster tools to access the LAS Dataset to Raster
tool. I opened the tool and inputted my
LAS dataset and set a name and location for my output file to save to. I made sure the Value Field read Intensity
and I set the Binning Cell Assignment Type to Average and the Void Fill Method
to Natural Neighbor. I made sure
Sampling Type was set to Cellsize and in the Sampling Value field I entered
6.56168 feet so that the spatial resolution would be 2 meters. To make the tool process faster I selected
the Environments… button at the bottom of the window and expanded the Parallel
Processing heading where I set the Parallel Processing Factor to 100%. I ran the tool and when the tool was complete
my intensity image was displayed the ArcMap viewer. My intensity image can be found in the Results
section, Figure 6.
To
create the anaglyph image of Lake County I started in ArcMap with the newly
created digital surface model (DSM) with the hillshade of Lake County. I couldn’t open the image in Erdas Imagine
because it was not saved in the right format.
To fix this, I right-clicked the DSM in the Table of Contents and
selected Data and then I selected the Export option. In the Export Raster Data window, I set my
format to IMAGINE Image (.img) and set a location for my output image. I clicked save to create the Imagine image. Next, I needed to prepare my NAIP downloaded
imagery. In ArcMap I brought in the
MrSID (.sid) version of the downloaded data.
I right clicked the data in the Table of Contents and selected Data and
then I selected the Export option. In
the Export Raster Data window, I set my format to IMAGINE Image (.img) and set
a location for my output image. I
clicked save to create the Imagine image.
After the export was complete, I brought the new NAIP image into an
ArcMap viewer and when the prompt to calculate pyramid layers popped up, I
selected to calculate pyramid layers.
When the pyramid layers were finished being calculated, I added the DSM
image to the viewer as well. The two
images were not the same size, and covered different amounts of Illinois land
area, so I had to create a shapefile to clip the images with. I used an Esri 2013 shapefile of the counties
of the United States. I opened this
shapefile in a new ArcMap document and used the Identify tool to locate Lake
County. I used the Select Features tool
to select Lake County. I created a layer
from the selected features and exported the layer. I next brought the exported layer into the
ArcMap viewer. I projected the clip to
the same coordinate system as the NAIP image, NAD 1983 UTM Zone 16N with the
use of the Projection tool. When the
projection finished running I opened a new black ArcMap document and added the
newly projected shapefile of Lake County and the NAIP image. I changed the shapefile to a hollow symbol
with a red boarder so I could see how the shapefile and the NAIP image lined up. There were major errors, to fix this I needed
to edit the shapefile. I activated the
Editor Toolbar and selected Start Editing.
I selected the Lake County shapefile as the feature to start
editing. I used the Edit tool on the
toolbar to select the shapefile for editing. I selected the Reshape Feature Tool on the
Editor Toolbar and drew in a new line along the Lake Michigan and Lake County
boarder following the shape of the DSM to shape the county shapefile. When I was finished I selected to Save Edits
and Stop Editing. Next, I clipped the
NAIP image with the shapefile. I opened
Arc Toolbox and accessed the Data Management Tools and expanded the Raster
tools to select the Clip tool. I set my
NAIP image as the Input Raster and set the Output Extent to the shapefile of
Lake County. I checked the box for the
use of input features for clipping geometry and I ran the tool. When the clip tool finished running the
output image was brought into the ArcMap viewer. I made sure it clipped correctly by bringing
it into the viewer with the Lake County shapefile, the two matched up. Next, I needed to prepare my DSM image. I brought it into the ArcMap viewer and used
the Project Raster tool to set it to the NAD 1983 UTM Zone 16N. When the tool finished running I brought the
image into the viewer. I overlaid the
Lake County shapefile on the newly projected DSM and noted that the DSM did not
match the shapefile and the DSM needed to be clipped. I opened Arc Toolbox and accessed the Data Management
Tools and expanded the Raster tools to select the Clip tool. I set my DSM image as the Input Raster and
set the Output Extent to the shapefile of Lake County. I checked the box for the use of input
features for clipping geometry and I ran the tool. When the clip tool finished running the
output image was brought into the ArcMap viewer. I made sure it clipped correctly by bringing
it into the viewer with the Lake County shapefile, the two matched up. I exported the clipped DSM image and the
clipped NAIP image as IMAGINE Image images, so that they could be accessed in
Erdas Imagine.
With
all of my data prepared I was ready to create the anaglyph image of Lake County. I opened an Erdas Imagine viewer where I
brought in the DSM and NAIP image. From
the Erdas Imagine main interface I clicked on the Terrain tab and selected the
Anaglyph tool. The Anaglyph Generation
window opened I inputted my DSM as the Input DEM and I inputted the NAIP image
as the Input Image. I set a name and
location for my output file to save to.
I confirmed the Exaggeration was set to 1 and I left all of the other
parameters at their default. I clicked
OK to run the model. When it finished
running I dismissed the notice and brought the image into the Erdas Imagine
viewer. All of the difficulties in
creating the anaglyph image occurred when preparing the data. Projecting, clipping, and exporting the data
in different formats were unexpected steps I had to take to create the anaglyph
image. My anaglyph image can be found in
the Results section, Figure 7. To view
the image properly polaroid glasses should be worn.
Results
The digital surface model with first
returns with a hillshade gives a three-dimension representation of the surface
of Lake County. This image shows what feature
the laser pulse hit first, usually a taller object. This model is useful in identifying surface
features like buildings, vegetation and other features. The digital terrain model of ground returns
with a hillshade gives a bare-earth model of the topographic surface of Lake
County. This image shows what the laser
pulses hit last, the ground. This model
is useful in interpreting the different elevations in the county area. This model shows what the land looks like
with no surface features, all trees, houses, and other features that usually
cover the county are absent in this image.
This model helps with examining what the earth looks like under the
features that are normally there. The
intensity image will help with giving a very clear, detailed image of Lake
County. LiDAR intensity measures the
strongest return from each laser pulse.
This image will help with seeing the finer detailed parts of the
county. In this image smaller details
will be able to be seen. The intensity
image can be used in feature detection and extraction. The anaglyph gives a three-dimensional view
of Lake County. The anaglyph image
combines a digital surface model and a NAIP image to create a three-dimensional
view. Elevation changes can be visually
seen and the features visually pop off the screen when viewing the image while
using polaroid glasses.
Digital Surface Model
Figure 2. Created Digital Surface Model of Lake County, IL.
DSM Hillshade
Figure 3. Created Digital Surface Model Hillshade of Lake County, IL.
DTM Hillshade
Figure 5. Created Digital Terrain Model Hillshade of Lake County, IL.
Anaglyph Image
Figure 7. Created Anaglyph Image of Lake County, IL.
Conclusions
The
major conclusions I can draw from this project are that Lake County is a very
flat land area. Lake County is mostly
covered with neighborhoods and subdivisions.
There are no major city components like Lake County’s neighboring
county, Cook County, which contains the city of Chicago. The land is very flat as the digital terrain
model shows. The only area with a change
in elevation is on the coast of Lake Michigan there is a slight drop in
elevation leaving this area prone to flooding from the lake. There are no major hills or mountains. The tallest structures in Lake County are
roofs on homes and treetops. There are
many trees in Lake County as the digital surface model shows. The highest density of trees is located along
the county’s boarder with Lake Michigan.
Overall Lake County is residential living with many homes, probably for
commuters that work in Chicago. There is
also a great amount of farm land in Lake County. The anaglyph highlights the rectangular plots
of land being used for farming. Farming
locations fall farther away from Lake Michigan and are located on the west side
of Lake County. The anaglyph image also
allowed for the interpretation that there are numerous lakes located in Lake
County all located on the west side of the county. Using the anaglyph image I could identify an
airport in the city of Waukegan. Overall
Lake County looks like a flat county located on Lake Michigan with thriving
farm and residential life.
References
Lake County, IL, USA. (2015, July 17). Retrieved May 09, 2016, from http://www.worldatlas.com/na/us/il/c-lake-county-illinois.html.
Lake County, Illinois (IL). (n.d.). Retrieved May 09, 2016, from http://www.city-data.com/county/Lake_County-IL.html.
Lake County, Illinois Genealogy, History & Facts. (n.d.). Retrieved
May 09, 2016, from http://www.genealogyinc.com/illinois/lake-county/.
LiDAR point
cloud and Tile Index are from Lake County,
2007.
National Agriculture Imagery Program (NAIP) image is from United
States Department of Agriculture, Lake County 2007.
Quick Facts Lake County, Illinois. (n.d.). Retrieved May 09, 2016, from http://www.census.gov/quickfacts/table/PST045215/17097.
United States
shapefiles cities, states, lakes, and counties from Esri 2013 Dataset.
