Geospatial Basics

Introduction

What makes data geospatial? That is, what makes the data you worked with today geospatial in nature (think coordinates)?

The data we used today was geospatial because it utilized geographic coordinate systems in order to position them on a map. The type of data that we used today could be used for a variety of geospatial reasons including looking at soil erosion or analyzing roads and tracks.

What makes data in a GIS different than a digital map?

Data in a GIS has much more detail than a regular digital map. The attribute data has much more information like coordinates, date, or other pertinent information for any given data set.

Why is having an understanding of geospatial concepts and geospatial data so fundamental to working with UAS data?

It is fundamental because the geospatial data and concepts are why the UAS data is useful. A high resolution orthomosaic is nice and all but the the geospatial data and the actual stats and attributes are what you’re typically going to be gathering and processing.

What are some of the key geospatial concepts and fundamentals that this lab addresses

• File management and Arc catalog 
• File types and GIS data types in arc catalog and arc map
• Finding, calculating, and using statistics
• Viewing properties and discerning what they mean
• Different coordinate systems, how they interact with each other, and project on the fly
• Meta data and attribute data
• Ground control points
• Some arc map tools

In an effort to improve our lab report abilities we have been asked to write our reports using a template format for the time being. The questions/ prompts will be in bold and my answers will be immediately after (not in bold.)

Lab Assignment

Working with the data

In this first part we opened up the data folders for the first time and examined what kinds of files were in them. 

Open the Tornadoes folder and find the Tornado_tracks files. List out each file with its extension.

As seen in figure 1 there are several .shx, .shp, .sbx, .sbn, .prj, and .dbf files.

Figure 1: Tornadoes folder

Why is file management so key in working with UAS data?

File management is important because of how many similarly named files there are. It would be pretty easy to mix files up or lose track of what files do what.

ArcCatalog

In this section we used ArcCatalog to view the files that we had just viewed in windows explorer.

What is the purpose of establishing a folder connection?

The purpose of establishing a folder connection is that it makes it easier for the user to access the folder from the ARCMap program. It should also be easier for the program to access (faster).

Figure 2: ArcCatalog Folder layout

What is the difference between viewing the files in Arc Catalog vs. Windows explorer?

There are much fewer files when viewing in Arc Catalog than in Windows Explorer. Figure 2, when compared to Figure 1, is much more readable and has fewer files to deal with.

Why is it so important, beyond maintaining proper file management/naming, to use Arc Catalog for managing your GIS data?

Everything is much more organized in the ArcCatalog and editing something in the ArcCatalog will edit the right files in the actual (windows explorer) folder.

What do those icons (figure 3) mean?

The icons correspond to what type of content is in the file. From left to right they are point, line, polygon, and raster data types.

Figure 3: ArcCatalog Icons

List out each of the geospatial data types, and then provide an example file for that data type.

Point: Dams map (dams00x020.shp)

Line: Tornadoes map (TORNADO_tracks.shp)

Polygon: States map (states.shp)

Raster: wolfpaving orthomosiac (20170613_wolfpaving_transparent_mosiac_group1.tif)

Figure 4: Description tab

Why is having this information so important in the UAS realm?

In case the data gets passed on in the future, whoever gets it can use the metadata to get a better idea of the data that they are looking at.

Figure 5: Statistics have not been calculated In the "20170613_wolfpaving_dsm.tif" raster we clicked on properties and scrolled down to the statistics section.

What does it say?

Statistics have not been calculated.

We then calculated statistics by right clicking on the file and clicking on "calculate statistics" in the same drop down menu that contained "properties"

What types of tasks rely on statistics?

Anything that would require that elevation be known or if you’re measuring something.

List the Min, Max, and Mean elevation of the DSM.

Mean - 296.966 Max - 323.08 Min - 281.04

This information was generated by the calculate statistics function.

Why would this information be important for data processing, analysis, and communication with the client? (Think of what was discussed in lecture/demo)

Statistics are nice to have to backup things that you say because it shows how the work was done and is provable.

There is more useful information in this table. Provide the following information:

Cell Size: 0.02077, 0.02077
Format: TIFF
XY Coordinate System: WGS_1984_UTM_Zone_16N
Linear Unit: Meter
Datum: D_WGS_1984

Use the Linear unit and write the pixel size in square cm: ~4cm^2

This information was found in the properties window.

ArcMap

Referring to your notes from the demo/lecture, list out some different ways to add data.

Adding data by dragging directly from the catalog, clicking on the plus with the square at the top and selecting add data, adding data when you're prompted when opening the program.

What basemap did you use? Why?

I used the imagery basemap because it is easier to see where maps line up with the satellite images than if I used street map or topographic

What type of GIS data is [states.shp]? Justify your answer.

This is a vector polygon GIS data type. It is comprised solely of lines and polygons in 2D.

What type of GIS data is [TORNADO_tracks.shp]? Justify your answer.

The file is a vector lines data type. It is only comprised of lines with no polygons.

What type of GIS data is [dams00x020.shp]? Justify your answer.

The file is a vector point data type. It only has points with neither lines nor polygons.

Coordinate Systems

Figure 6: Coordinate Systems - Tornado

Write down the Coordinate System:

Tornado map: NAD_1983_UTM_Zone_16N

Now write the coordinate system for the other two data layers.

States map: USA_Contiguous_Equidistant_Conic

Dams map: GCS_North_American_1983

Are all of these coordinate systems the same? Why might that be an issue?

They use different coordinate systems. That might be an issue because they won’t be as easy to compare to each other if you’re trying to use them together.

How might the need for metadata relate to coordinate systems.

The coordinate type will affect the coordinate data in the metadata. The metadata will have to specify what coordinate type the data uses.

Attribute Data

Figure 7: Atrribute data from tornadoes

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.
The date could be used with uas data to see how the area has changed over time or the amount of injuries/ deaths can be used with population data to see what areas have more of fatality rate in tornado prone areas.

Bringing in the raster data

What type of data is [the orthomosiac and DSM]?

This is a raster data type.

What is the format?

The file type is .tif

What is the projection?

WGS_1984_UTM_Zone_16N

What is the projection [for XYWOLF_PAVING_UTM16_massaged.shp]?

WGS_1984_UTM_Zone_16N

Does this projection match the Ortho? Why is this so important?It does match the orthomosaic. This is important because it’s important that we know the right positions of the ground control markers and they could be off position if we used differing coordinate projection systems.

Ground Control Points

Figure 8: Ground Control Points

Do the points line up with the markers on the ground [figure 8]?

Yes.

ArcMap Tools

Figure 9: Toolbar in ArcMap

Measure: Measure several features on the map. How might this type of tool be useful in working with UAS data?

As seen in figure 10, the measure tool can be useful to measure distance between objects or measuring the area of a defined space.

Figure 10: Mesaure Tool

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 might come in handy when working with UAS data because you can see where a point or pixel is relative  to the data that you’re working with and you can see that same point thorough all the layers for comparison.

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 makes it easier to compare two pictures like seeing change over time with two pictures.

Conclusions

Summarize what makes UAS data useful as a tool to the GIS user UAS as a tool could prove very useful to a GIS user. The ability to quickly gather high quality data about the surface of an area is invaluable especially when working with a limited time frame.  Having a highly detailed orthomosiac is much better than a lower quality satellite image at least for the time being. 

What limitations does the data have? What should the user know about the data when working with it. The data is not infinite so there is, naturally, a limit on the resolution of any digital image. It cannot see below the surface and is also limited by the sensors that the UAS utilized during the mission. A user should be aware of what kind of data they are working with beforehand as well as knowing general information like the projection used, the date the data was gathered, the altitude it was gathered from, the UAS that flew the mission, and what types of sensors were used.

Speculate what other forms of data this data could be combined with to make it even more useful.

I think that this type of UAS data could easily be combined with soil and water data when surveying and area and looking at the effects of erosion on an area or when estimating the future effects of erosion. It could also be used with things like census data to make some sort of heat map of places that people go or streets they go down.