Introduction
What makes data geospatial? That is, what makes the data you worked with today geospatial in nature (think coordinates)?
Data becomes geospatial when it is put into a frame of reference that has coordinates on a map with scale and a north heading. This style of data without these reference points cannot be understood because without them the data would not make sense.
What makes data in a GIS different than a digital map?
A digital map is just that, a map that the user can move around and look at but cannot interact with or learn information from. By adding GIS information it creates a map with data that the user can learn from, such as flight day and time, wind speed, and the data gathered from the UAS itself.
Why is having an understanding of geospatial concepts and geospatial data so fundamental to working with UAS data?
UAS is a powerful tool that can be used in many ways. One of the most effective methods is using geospatial data with a UAS so when a flight is conducted to collect data there is an effective way to represent, share, and understand the data.
What are some of the key geospatial concepts and fundamentals that this lab addresses
This lab demonstrates the basic functions of ArcMap and ArcCatalog as we learn to understand the basics of data types such as point, polygon, line, and raster.
Lab Instructions
Working with the Data
We will start by getting to know and understand the software, especially some of the more important tools.
Start by copying the UAS data folder for this lab, and shown in the demonstration, designated by Prof. Hupy, into your own folder for the UAS class.
Examine the contents of the folder and note how many different file types are associated with just one type of geospatial data file.
Open the Tornadoes folder and find the Tornado_tracks files. List out each file with its extension.
TORNADO_tracks.dbf
TORNADO_tracks.prj
TORNADO_tracks.sbn
TORNADO_tracks.sbx
TORNADO_tracks.shp
TORNADO_tracks.shp
TORNADO_tracks.shx
Take a screen shot of the files and save it for later use to post to your e-portfolio.
Figure 1
Why is file management so key in working with UAS data?
There are a series of files and images that when put together create a working map full of data for the user to interact with and learn from. Because of these large complex data sets, it is important to keep all files well organized in order to understand how the program functions.
ArcCatalog
Open ArcCatalog. You should know how to do this from the demonstrations. Establish a folder connection to your student folder on the server.
What is the purpose of establishing a folder connection?
The data we will be using in lab comes from the folders provided by the professor and will be saved into our student folders. By establishing a connection it allows for easy and quick importing and exporting of said data to and from the program.
Open the data folder you pasted into your student folder. Open the folders within that folder. Examine how many files appear and contrast that with the number and appearance of files when you viewed them in Windows Explorer.
Take a screen shot of the file structure here to compare.
What is the difference between viewing the files in Arc
Catalog vs. Windows explorer?
When viewing the files in Arc Catalog they have different images that show what kind of data is within the file. Also, the series of files that are composed of that specific data set are all contained within the single file that is shown in Arc Catalog. For example, in figure 1 the series of files represent the tornado tracks file which is shown as a single file in Arc catalog rather than a series of files.
Why is it so important, beyond maintaining proper file management/naming, to use Arc Catalog for managing your GIS data?
Arc Catalog is able to open and process the data and represent it in a way that is visible and understandable to the user. Without Arc Catalog the user would be unable to open and understand the data. This program provides the user with a platform that will allow for easy sorting of files along with opening and layering different models.
Take a close look at the files and note the icon to the left of the file.
What do those icons mean? Hint: Use the preview tab to view the file
These icons represent the different types of geospatial data so that the user can understand which type of data is being used within the file.
List out each of the geospatial data types, and then provide an example file for that data type.
Point: The data showing all the dams in the US
Polygon: The frequency of an event occurring with an area
Line: The data representing all tornado tracks in the US
Raster: Cell-based data such as a map representing data within certain countries
Click on the description tab.
What topic/term relates to this description tab?
Why is having this information so important in the UAS realm?
Keeping on the Metadata theme lets now explore the details behind some of the UAS raster data. If it is not already expanded, expand the Wolfpaving_X5 folder. Right click on the 20170613_wolfpaving_dsm.tif raster, and then select ‘properties’.
After you select properties, you will see a table with all sorts of information to come up. Before we get into it too much, scroll down to the statistics section.
What does it say?
Band_1
Build parameters: skipped columns:1, rows:1, ignored values:
If you saw ‘No statistics calculated’, that is O.K. But we need those statistics to get an idea of the dataset. Right click on the layer again, and this time hover over ‘caculate statistics’.
What types of tasks rely on statistics?
Representing data by showing values such as maximum and minimum and averages can be important when comparing information. Tasks such as a change in values over time and represent that change can benefit from statistics.
Now go ahead and calculate statistics. Leave all the default values in place. Then open up the properties table again and scroll down to the statistics section.
List the Min, Max, and Mean elevation of the DSM.
Why would this information be important for data processing, analysis, and communication with the client? (Think of what was discussed in lecture/demo)
Min 281.05
Max 323.09
Mean 296.97
Std Dev 4.18
Classes 0
There is more useful information in this table. Provide the following information:
Cell Size: (X,Y) .02, .02
Format: TIFF
XY Coordinate System: WGS_1984_UTM_Zone_16N
Linear Unit: WGS_1984_UTM_Zone_16N
Datum: WGS_1984_UTM_Zone_16N
Use the Linear unit and write the pixel size in square cm:
.04cm^2
Keep ArcCatalog Open and open up ArcMap
ArcMap
(As you work through this section, take screen shots where you feel needed to back up with graphics the questions asked. A picture is worth a thousand words – especially in an e-portfolio post)
Once you open ArcMap, you will want to add data.
Referring to your notes from the demo/lecture, list out some different ways to add data.
There are multiple ways to add data into the program. One way is to go to file and select add data. Another would be to drag in the desired file from the catalog folder. Finally, one could right cluck on the base layer and select add data.
Before we add UAS data, lets add a basemap, and a few other types of data. Examine the basemap options, and add a basemap of your choice.
What basemap did you use? Why? Topographic Map because it is a map that clearly and accurately represents the United States without distracting background features such as roads.
Go into the Tornadoes folder, and add the states.shp shapefile. The basemap can bog things down, so let’s go ahead and uncheck reference and basemap.
What type of GIS data is this? Justify your answer.
Polygon, figure 4 shows the data is Polygon.
Figure 4
Now add the TORNADO_tracks.shp file.
What type of GIS data is this? Justify your answer.
This is polyline data because the data that is represented on the map is a series of lines to show the track of tornados.
Let’s add one other kind of file. Go into the hydro features folder, and add the dams00x020.shp file.
What type of GIS data is this? Justify your answer.
Poly point data because the map shows a series of points each representing a dam in the United States.
· Now that we’ve added several different types of GIS data, let’s explore that data a bit. The first item we want to explore is coordinate systems. Right click on the Tornado_tracks file, and go to properties, then click on the source tab.
o Write down the Coordinate System:
o Projected Coordinate System:NAD_1983_UTM_Zone_16N
o Geographic Coordinate System:GCS_North_American_1983
o Now write the coordinate system for the other two data layers.
o States:
o Projected Coordinate System:USA_Contiguous_Equidistant_Conic
o Geographic Coordinate System:GCS_North_American_1983
o Dams:
o Geographic Coordinate System:GCS_North_American_1983
o Are all of these coordinate systems the same? Why might that be an issue?
All these coordinate systems are not the same and this can become an issue when trying to overlay various datasets onto one base map to compare the data. If the coordinate systems are not the same the data might be misplaced on the map and lead to inaccurate results.
It used to be back in the day that you would have to have all coordinate systems the same in ESRI, but then they came up with project on the fly. This is great, but also causes many problems when it comes to doing analysis, or working with data in other software. Later on we will see how unmatching coordinate systems can wreak havoc in data processing.
o How might the need for metadata relate to coordinate systems.
Metadata provides the user with information in regards to the scene where the data was collected. By using metadata in coordination with a coordinate system the user can get a greater sense for what was happing when the data was collected and thus conduct more thorough research.
o Attributing in flight characteristics to coordinates
Coordinates provide a very specific location for where a flight was conducted. Sometimes flights can encounter strong crosswinds or turbulence that can cause error in data. By attributing coordinates with data collection during a flight the user can gain a stronger sense for what was happening during the flight and also confirm that the flight was flown properly.
Before we move to UAS data, let’s look at the attribute data, which is what truly makes up a GIS. Right click on the TORNADO_tracks file, and then select attribute data. Maximize the table. What you are looking at is the information attached to each tornado track line on the map. This data is what makes the data smart, and why you can do all sorts of analysis with properly collected UAS data.
o Think of some different types of attribute data that could be used in conjunction with UAS data and list it here with a use example.
o Length, scale, width, miles, etc. These attributes combined with data collected from UAS can be used in programs such as ArcMap to create GIS data that a user can user to represent data. An example of this is using a drone to create an orthomosaic and overlaying it on a base map on ArcMap to create an image with scale that a user can observe.
Uncheck all the data layers to ensure they are not visible.
O.K., finally let’s add some UAS data. Go into the Wolfpaving_X5 folder and using the Add data icon, or Arc Catalog, bring the orthomosaic and the DSM into ArcMap. Uncheck the DSM for now, and make sure the Orthomosaic is the top layer.
o What type of data is this?
§ File System Raster
o What is the format?
§ TIFF
o What is the projection?
§ X, Y Coordinate System
You may note black around the image. Remembering the demo, go ahead into properties and symbology, and turn that off by setting the background to clear.
Figure 7
If I use ground control markers, I always like to see if they line up with my data properly. If they don’t, we can have lots of angry people.
Add the XYWOLF_PAVING_UTM16_massaged.shp file. Make sure you bring it in on top of the orthomosaic. Go into its properties and check the projection information.
o What is the projection?
o Projected Coordinate System: WGS_1984_UTM_Zone_16N
o Projection: Transverse_Mercator
o Does this projection match the Ortho? Why is this so important?
o Yes it does match which is important because in order to properly overlay the image and corresponding data the coordinate system must match in order for the correct locations to be displayed and the two can properly coincide.
Zoom in over a few of the GCP points.
o Do the points line up with the markers on the ground?
Yes, this can also be noted in figure 8.
You are almost done, but before we end, we want to use a few tools that will come in use as you within ArcMap, and later, ArcPro. We are only scratching the surface regarding tools, but I wanted to just show you a few.
o Measure: Measure several features on the map. How might this type of tool be useful in working with UAS data?
This tool, which can be observed in figure 9, can be useful in measuring between two points such as measuring between ground points to ensure they are the proper distance between each other and that the data was correctly collected.
Identify: Use the identify tool on several of the GCP points. Also, turn on the DSM and identify pixels on that layer. How might this tool come in handy when working with UAS data?
This tool, which can be seen in figure 10, might be useful in identifying the specific color of a crop with UAS data to ensure the crop is growing correctly and is healthy by ensuring it is the correct shade of green.
Swipe: Use the swipe tool to move between the Orthomosaic and the DSM. How might this tool be useful when working with UAS data?
This tool is helpful because two different forms of data can be overlaid on the same base map and then the swipe tool can allow the user to instantly compare the various layers.
Part 3 (Conclusions):
- Summarize what makes UAS data useful as a tool to the GIS user
UAS has the ability to capture a multitude of data that can then be used in a program like ArcMap to create stunning visuals that represent data in an easy to understand and use way. This can revolutionize how data is collected and represented as various maps can be quickly created and displayed.
- What limitations does the data have? What should the user know about the data when working with it.
The data can be skewed depending on the flying conditions at the time and the quality of the gps data. Things such as clouds and wind and quickly disrupt the data being collected and the accuracy of the gps data is always limited. Things such as ground control points and flying on clear days can help solve these issues. The user should receive metadata that informs on the conditions of the day. The user should also always know the scale of the GIS data being worked on.
- Speculate what other forms of data this data could be combined with to make it even more useful.
GIS data can be combined with data such is LiDAR or hyperspectral to create detailed maps of things such as a corn field. By combining these one can create various maps that would inform the user on crop height, health, and other useful features that could help farmers grow healthier crops.
Figure 1Why is file management so key in working with UAS data?There are a series of files and images that when put together create a working map full of data for the user to interact with and learn from. Because of these large complex data sets, it is important to keep all files well organized in order to understand how the program functions.ArcCatalogOpen ArcCatalog. You should know how to do this from the demonstrations. Establish a folder connection to your student folder on the server.What is the purpose of establishing a folder connection?The data we will be using in lab comes from the folders provided by the professor and will be saved into our student folders. By establishing a connection it allows for easy and quick importing and exporting of said data to and from the program.Open the data folder you pasted into your student folder. Open the folders within that folder. Examine how many files appear and contrast that with the number and appearance of files when you viewed them in Windows Explorer.Take a screen shot of the file structure here to compare.Figure 2
What is the difference between viewing the files in ArcCatalog vs. Windows explorer?When viewing the files in Arc Catalog they have different images that show what kind of data is within the file. Also, the series of files that are composed of that specific data set are all contained within the single file that is shown in Arc Catalog. For example, in figure 1 the series of files represent the tornado tracks file which is shown as a single file in Arc catalog rather than a series of files.Why is it so important, beyond maintaining proper file management/naming, to use Arc Catalog for managing your GIS data?Arc Catalog is able to open and process the data and represent it in a way that is visible and understandable to the user. Without Arc Catalog the user would be unable to open and understand the data. This program provides the user with a platform that will allow for easy sorting of files along with opening and layering different models.
Go into the Tornadoes folder, and add the states.shp shapefile. The basemap can bog things down, so let’s go ahead and uncheck reference and basemap.What type of GIS data is this? Justify your answer.Polygon, figure 4 shows the data is Polygon.
Now add the TORNADO_tracks.shp file.What type of GIS data is this? Justify your answer.This is polyline data because the data that is represented on the map is a series of lines to show the track of tornados.Let’s add one other kind of file. Go into the hydro features folder, and add the dams00x020.shp file.What type of GIS data is this? Justify your answer.Poly point data because the map shows a series of points each representing a dam in the United States.Figure 5
· Now that we’ve added several different types of GIS data, let’s explore that data a bit. The first item we want to explore is coordinate systems. Right click on the Tornado_tracks file, and go to properties, then click on the source tab.o Write down the Coordinate System:o Projected Coordinate System:NAD_1983_UTM_Zone_16No Geographic Coordinate System:GCS_North_American_1983o Now write the coordinate system for the other two data layers.o States:o Projected Coordinate System:USA_Contiguous_Equidistant_Conico Geographic Coordinate System:GCS_North_American_1983o Dams:o Geographic Coordinate System:GCS_North_American_1983o Are all of these coordinate systems the same? Why might that be an issue?All these coordinate systems are not the same and this can become an issue when trying to overlay various datasets onto one base map to compare the data. If the coordinate systems are not the same the data might be misplaced on the map and lead to inaccurate results.It used to be back in the day that you would have to have all coordinate systems the same in ESRI, but then they came up with project on the fly. This is great, but also causes many problems when it comes to doing analysis, or working with data in other software. Later on we will see how unmatching coordinate systems can wreak havoc in data processing.o How might the need for metadata relate to coordinate systems.Metadata provides the user with information in regards to the scene where the data was collected. By using metadata in coordination with a coordinate system the user can get a greater sense for what was happing when the data was collected and thus conduct more thorough research.o Attributing in flight characteristics to coordinatesCoordinates provide a very specific location for where a flight was conducted. Sometimes flights can encounter strong crosswinds or turbulence that can cause error in data. By attributing coordinates with data collection during a flight the user can gain a stronger sense for what was happening during the flight and also confirm that the flight was flown properly.Before we move to UAS data, let’s look at the attribute data, which is what truly makes up a GIS. Right click on the TORNADO_tracks file, and then select attribute data. Maximize the table. What you are looking at is the information attached to each tornado track line on the map. This data is what makes the data smart, and why you can do all sorts of analysis with properly collected UAS data.o Think of some different types of attribute data that could be used in conjunction with UAS data and list it here with a use example.o Length, scale, width, miles, etc. These attributes combined with data collected from UAS can be used in programs such as ArcMap to create GIS data that a user can user to represent data. An example of this is using a drone to create an orthomosaic and overlaying it on a base map on ArcMap to create an image with scale that a user can observe.Figure 6
Uncheck all the data layers to ensure they are not visible.O.K., finally let’s add some UAS data. Go into the Wolfpaving_X5 folder and using the Add data icon, or Arc Catalog, bring the orthomosaic and the DSM into ArcMap. Uncheck the DSM for now, and make sure the Orthomosaic is the top layer.o What type of data is this?§ File System Rastero What is the format?§ TIFFo What is the projection?§ X, Y Coordinate SystemYou may note black around the image. Remembering the demo, go ahead into properties and symbology, and turn that off by setting the background to clear.
You are almost done, but before we end, we want to use a few tools that will come in use as you within ArcMap, and later, ArcPro. We are only scratching the surface regarding tools, but I wanted to just show you a few.o Measure: Measure several features on the map. How might this type of tool be useful in working with UAS data?This tool, which can be observed in figure 9, can be useful in measuring between two points such as measuring between ground points to ensure they are the proper distance between each other and that the data was correctly collected.Figure 9
Identify: Use the identify tool on several of the GCP points. Also, turn on the DSM and identify pixels on that layer. How might this tool come in handy when working with UAS data?This tool, which can be seen in figure 10, might be useful in identifying the specific color of a crop with UAS data to ensure the crop is growing correctly and is healthy by ensuring it is the correct shade of green.Figure 10
Swipe: Use the swipe tool to move between the Orthomosaic and the DSM. How might this tool be useful when working with UAS data?This tool is helpful because two different forms of data can be overlaid on the same base map and then the swipe tool can allow the user to instantly compare the various layers.Part 3 (Conclusions):
Comments
Post a Comment