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AS.420.603.81 – Environmental Applications of GIScience
Activity 4: Site Selection
In this activity you will explore site selection in more depth, perform a simple spatial analysis, and continue to tailor the geospatial data you are gathering for use in your final project. In this activity, you will be required to respond to questions, answer short essay questions, and upload images of your maps. All questions in the activity that are required for submission are highlighted in bold red in these instructions. When you have completed your work, write up the answers to your activity and submit your assignment to Blackboard. You will also post images of your mapped data to the discussion board and answer the question prompts. If you have a technical problem, contact the instructor.
These activities are intended to build knowledge and skills week to week. Reference previous activities or ESRI Training to refresh any skills that you may have learned previously.
Part I: ESRI Tutorial
Go to: https://desktop.arcgis.com/en/analytics/case-studies/understanding-the-suitability-modeling-workflow.htm Take the “Understanding the suitability modeling workflow” tutorial.
Read through the information included in this tutorial with the step-by-steps on how to determine site suitability. After reading this information, got to the “Lessons for ArcGIS Pro” at the bottom of the page. Complete lessons 1-4.
Q1. Create a basic map of your choice of design of best bobcat patches and include this in your activity write-up. (3 points)
Part II: ESRI Web Course
Go to the ESRI Training website (https://www.esri.com/training/) > Catalog > Find Training. Take the “Locating suitable regions” web course.
Q2. Take a screen capture of the output regions raster over a basemap of your choice and include this in your activity write-up. (2 points)
Part III: ESRI Tutorial (OPTIONAL BUT RECOMMENDED for 5 points Extra Credit)
Go to the ESRI Training website (https://www.esri.com/training/) > Catalog > Find Training. If you would like to explore this concept more, take the “Build a model to connect mountain lion habitat” tutorial.
Q3. Create a basic map of your choice of design of potential wildlife corridors for mountain lions and include this in your activity write-up.
Part IV: Your Turn!!!: Tailoring your data further
At this point, you should have located and downloaded several geospatial datasets related to your topic of interest (e.g. DEMs). Two main initial steps are needed to start organizing your data for processing and analysis: 1) Clipping your data and 2) Reprojecting your data
A) Selecting your area of interest
Often your datasets are too large and you only need to look at a small or specific area of interest.
There are many ways to clip your data down to a smaller area, but the easiest is to use an already provided shapefile layer. If you already have a ready shapefile to clip your data (e.g. a park boundary, county boundary), you won’t need to do either of the next steps.
If you want to create your own shapefile boundary layer, go to the instructions on page 6.
I will use data from Activity 2 to work through how to select an area of interest from a larger layer and clip datasets.
For the Rana sierra species I chose in Activity 2, I am using the Eldorado National Forest boundary from the U.S. Forest Service Administrative boundary shapefile layer for future analysis. Since the Eldorado National Forest boundary is part of the U.S. Forest Service Administrative boundaries layer, I need to extract this boundary.
1) Note: Data you have obtained from the ArcGIS Catalog Portal
If the shapefile layer or raster is from the portal, you may have to make a copy first and then work with your data if it is a read-only file. You will get an error message if you try to modify the data as is from the Portal if it is in read-only format. When you modify data, you overwrite the original file and in essence, the files from the Portal are read only and many are not editable in their present state.
Prior to working with Portal data, first make a copy of the data you want to reproject. In the Geoprocessing pane search for the Copy Features (Data Management Tools).
In this tool, for the input feature, put in the layer you would like to make a copy of and for your output (I am assuming you have a folder you are working out of on your computer), save the file with whatever file name you would like in this folder. Click run.
Once you have made a copy, you should now be able to reproject your data.
2) There a couple of ways to select this boundary:
1) You can use the Select Attribute Tool in the Map ribbon and click on Eldorado National Forest or
2) You can open the Attribute Table and manually click on the Eldorado National Forest field.
You will see the selected boundary highlighted in neon blue (see screen capture on the next page).
2) Right click on the U.S. Forest Service Administrative boundaries layer > Data > Export Features
3) The Feature Class to Feature Class window will pop up. Choose your working folder for you Output Location. Make sure you name the layer you want to create with a good identifier so you can find it easily in the future in the Output Feature Class option. Click “Run”
4) Your data should now be added to your map and should be the only field in your attribute table.
5) If you would like to create your own shapefile boundary layer:
1) In the Geoprocessing pane search for the Create Feature Class (Data Management tool). This will create a new blank shapefile. (In the editing basics web course on the ESRI Training website)
2) For the Feature Class Location, I suggest you choose a general folder you are working out of to save this in rather than a geodatabase.
3) Choose any Feature Class Name you like (e.g. study_area)
4) For Geometry, you want this to be a polygon.
5) Choose the Coordinate System (GCS WGS 1984)
6) Leave the rest of the options as default.
7) You will have now created a new empty polygon shapefile you can edit and it should automatically have been added to your table of contents.
8) Next go to the Edit ribbon and select the Create option in the Features section.
9) In the Create Features window that pops up, select your new study area polygon.
10) In the options with shapes that pop up, I suggest you choose the Polygon or Rectangle option for now to keep it simple.
11) Move your mouse over your map and you will see a new cross symbol. You can now click on your map to create the vertices (corners) and draw your polygon of your study area region of choice.
12) Once you have drawn your polygon to your satisfaction, click Save in the Manage Edits section.
B) Clipping your data
Now we will clip down the digital elevation model (DEM) data from the last activity. Add either the 10 m or 30 m DEM to your map from the Catalog pane. Reminder: The DEM data should be within your study area of interest (e.g. the DEM in the example overlaps with Eldorado National Forest boundary and the species of interest).
1) In the Geoprocessing pane, type clip. In this case, we are using a polygon shapefile to clip a DEM raster file. Note: You can only clip with a polygon file and not a line file.
Choose Clip Raster (Data Management Tools)
2) In the Clip window that pops up, select your elevation data you want to clip in the Input Raster field, choose Eldorado National Forest as the Output Extent, Select “Use Input Features for Clipping Geometry” (this will clip the raster to the shape of the input polygon rather than a rectangle), and save your Output Raster with a name of your choosing.
You can save this clipped image as the default ESRI raster grid in a geodatabase (no file extension), but I recommend you save ALL clipped images with extensions (e.g. .tif, .img, etc.) in a folder. This makes for fewer files created and easier recognition for some of the processes you will perform in a later activity (i.e. NDVI). (This might take a bit depending on the size of your raster and your computer processing speed so be patient).
3) The elevation raster data is now clipped to the shape of the Eldorado National Forest boundary.
4) If you need to, you can also Clip shapefiles using a shapefile. In the Geoprocessing pane, type clip > choose Clip (Analysis Tools) > Run
5) Clip your Slope raster from the previous activity. As you will see, you will lose the default symbology from the original slope raster and instead get a stretched grey scale image.
You can fix this two ways:
i. You can choose the Slope Symbology color ramp (put the check mark next to Show Names to see color ramp names) though the symbology won’t completely match up.
ii. Use the Apply Symbology From Layer (Data Management Tools) to reset the color scheme to match precisely what existed before. The Input Layer is the new clipped file, the Symbology Layer is the original file which has the color scheme you would like.
The color schemes will now match though the values will be slightly different as the clipped data is smaller and therefore will not have the same slope degree range (see screen capture on the next page).
6) Clip your Aspect and Hillshade rasters.
Use the Apply Symbology From Layer (Data Management Tools) to reset the color scheme for the Aspect raster. From the Update Symbology Ranges by Data drop down, change this from Default to Maintain Ranges.
You can NOT clip certain files including the default Basemaps that come with the program.
C) Masking your data
The NLCD 2011 data represents land cover for the entire United States. We would like to clip this data down to just the land cover in your study area (e.g. Eldorado National Forest). This data is a bit different to work with though. If you look at the legend, you will see colors assigned to land cover types.
However, if you open the attribute table (see screen capture on the next page), you won’t see these land cover type names listed in any of the columns. If you open the Symbology pane, you will see these listed under ClassName. A Colormap was created for this particular dataset so the pixels in this raster data represent specified land cover types.
If you use the clip function you previously used to clip the DEM data, you would lose the land cover type names and color scheme and end with random numbers representing pixel values and a grey scale stretched color scheme.
Instead you will want to use the Extract by Mask tool.
1) In the Geoprocessing pane, choose the Extract by Mask (Spatial Analyst Tools) option.
2) In the window that pops up, put the NLCD 2011 raster layer in the Input Raster field, your study area boundary file into the Input raster or feature mask data field, and name your output raster. Click Run.
Your output NLCD 2011 raster should now be within the study area boundary. The land cover class names will now be retained and you will see these now in the attribute table. The color scheme will also be retained. In addition, the only land cover classes to remain will be ones existing within your study area boundary. All others included in the original data will be excluded.
D) Reprojecting your data
In order to run any analyses, all of your data must be in the same projection. While ArcGIS Pro can re-project data on-the-fly, this is for display purposes only and temporary. In reality, none of the data line up. All data must be in the same coordinate system for analysis.
3) From previous activities, you should be aware of each layer’s coordinate system, but if not, locate this information in the layer’s properties under Source > Spatial Reference.
4) For simplicity purposes, we will reproject everything to a common coordinate system which is the Geographic Coordinate System WGS84 (Geographic World Geodetic System 1984) since this data has the least distortion as it is based on the globe rather than a 2D projected map plane.
5) You will use the Project tool to reproject your data. (When you are projecting your data, you will use the Project tool for shapefile data and the Project Raster tool for raster data.) You can find this in the Geoprocessing search pane > Project or Project Raster (Data Management Tools).
6) Let’s begin with the DEM data you clipped in part B. Choose the Project Raster tool. When you open the Project Raster tool window, you will (see screen captures on the next page):
a. add the DEM raster layer you would like to reproject in the Input Raster
b. choose a location and name your reprojected dataset (click on the folder icon) in the Output Raster Dataset location (To stay organized, I recommend you name all of your output data with gcs84 to differentiate them from the originals (e.g. studyarea_dem_gcs1984.shp)
c. choose an output coordinate system (select the globe icon to the right). In the Spatial References Properties window that pops up, you can:
i. either navigate to the GCS WGS 1984 projection under “Geographic coordinate system” > World > WGS 1984 or
ii. more simply, if you already have a layer with that projection as you do with the species data you previously downloaded from a previous activity, select “Layers” > GCS WGS 1984 > OK
iii. if this layer is not loaded in this project, you can select the globe with the plus icon > select “Import Coordinate System” > navigate to and choose your species file
iv. Click “Run” to reproject your data
7) Make sure all of your final project data are in the Geographic Coordinate System (GCS) WGS 1984. Reproject your Aspect, Slope, Hillshade, and NLCD layers. Use the Apply Symbology From Layer (Data Management Tools) to reset the color scheme.
8) Remove all of your original data from your current ArcGIS project and keep all of your reprojected layers. Save this ArcGIS project under a new name. I suggest Save As “Final_Project.aprx” to stay organized.
You should have clipped/masked and reprojected:
e. NLCD 2011
f. Also, find one additional layer you locate of your choosing
Q4. Include in your write-up a screen capture of your ArcGIS display with your study area boundary shapefile. (1 points)
Q5. Include in your write-up screen captures of your clipped reprojected data (see list above and should be at least 6 images though feel free to include more). (12 points)
Part V Create a map
Create a map of your choosing representing an aspect of your tailored topic of interest using your clipped data. Use map layouts of your choosing, but map elements you MUST include are:
1) Map title
2) Scale bar
3) North arrow
5) Map inset of the overview area
If you need a refresher on map layouts, refer to the “Make a Layout” tutorial from Activity 2 from the ArcGIS Pro Get Started website (https://pro.arcgis.com/en/pro-app/get-started/pro-quickstart-tutorials.htm). Feel free to be creative with your map design and include additional elements beyond the seven listed above if you so choose.
Q6. Export your completed map as a jpg image to include in your activity write-up. (2 points)
Advanced Academic Programs Krieger School of Arts and Sciences
Johns Hopkins University