ENVS708/808: Assignment 2 Data Capture, Raster Analysis and Advanced Mapping
Geographic information systems (GIS) are used to create, manage, analyse and store spatial information. In Assignment 1 you learned how to manage, analyse and store vector data. In this assignment, you will learn how to: (1) collect/create spatial data for GIS using a handheld GPS; (2) analyse raster data; (3) create vector data through digitizing, and (4) make advanced maps.
Assignment 2 has four parts. Part 1 teaches you how to use a Global Positioning System (GPS) unit and how to import GPS data into ArcGIS. In Part 2, you will learn how to analyse raster data. In Part 3, you will learn how to digitize vector layers from a geo-rectified image. In Part 4, you will learn about advanced mapping in GIS. As a guide, aim to finish Part 1 in Week 6, Part 2 in Week 7, Part 3 in Week 8 and Part 4 in Week 9. The Assignment is due on 1700 hrs Friday 10 May 2019.
Text in red are the Assignment 2 questions. The maximum number of points for each question is indicated next to the question. Round your answers to two decimal places where appropriate e.g. X.YZ
Assignment 2 is worth a total of 75 marks, and has a weighting of 20% of your final grade.
The Assignment 2 template is available in ENV708/808’s iLearn webpage under Week 6 Practical Assignment2_Template.doc. Record your responses to each question in the assignment template. Give the file an appropriate name (e.g. ENVS708/808_Assignment2_YOURNAME).
Assignment 2 is to be submitted in a MS Word or PDF file format via the link provided in iLearn by 5PM Friday 10 May 2019.
The data that you need to complete Assignment 2 is available in ENV708/808’s iLearn webpage under Week 6 Practical Assignment2Data.zip. Remember to decompress or unzip Assignment2Data.zip to your working directory (e.g. ENVS708/808 Assignment2).
Internal Students: Create a new folder (working directory) on your memory stick/external hard drive (e.g. ENV708/808 Assignment2). Save all your data outputs for this assignment to this folder.
External Students: Create a new folder (working directory) on your hard drive (e.g. ENV708/808 Assignment2). Save all your data outputs for this assignment to this folder.
Warning: Don’t use spaces or funny symbols (e.g. % * # and @) in your folder and file names as the GIS software does not like it. It is very important that you save all your map files (.mxd), tables, images and shapefiles to your working directory. The map file (.mxd) does not save the layers, images and tables that appear in the Table of Contents. It only saves the location of the layers and tables on your computer, and the way the layers appear (symbology) in the map file.
General comments on data capture, raster analysis and advanced mapping
ArcGIS provides you with a wide range of tools for deriving information from spatial data. Each tool will do a number of different analyses. Spatial questions can be answered using a range of different tools, but some tools will work better than others. This assignment will help you gain experience in choosing and using these tools to answer spatial questions. Tip: Before starting a new analysis, think about the question you are trying to answer and choose the most appropriate tool.
Macquarie University Academic Honesty Policy
You can view Macquarie University’s academic honesty policy by selecting this link:
It’s ok to talk to your neighbour during the practical class – we encourage it! However, you must work through the assignment on your own computer. Assignment 2 is NOT a group task. The responses to the Assignment 2 questions must be your own work. Do not copy the answers of your neighbour or friend and insert them in your Assignment 2 template – they could be incorrect (your lecturer/tutor has seen this happen many times before).
Part 1: The Global Positioning System
The Global Positioning System (GPS) is a network of 31 satellites (at least 24 operational at any one time) that provides location (i.e. latitude and longitude/eastings and northings) information where there is an unobstructed line of sight to three or more GPS satellites. It is maintained by the United States government and is freely accessible to anyone with a GPS receiver. Other Global Navigation Satellite Systems (GNSS) used around the world include:
• Russia’s GLONASS (Russian Global Navigation System)
• China’s BeiDou Navigation Satellite System
• European Union’s Galileo satellite network
It is important to note that there is only one GPS network (i.e. that run by the United States Government), but the other global networks (listed above) and regional networks (such as those developed by Japan and India’s government) use a similar technology but are called GNSS. Many devices (both consumer and professional grade) are becoming multi-GNSS compatible, which can result in an increased accuracy and capacity (i.e. more challenging environments such as within gorges, under dense tree canopies etc.).
By the end of Part 1 you will be able to:
1. Perform basic tasks using a handheld GPS unit.
2. Upload GPS data to a computer.
3. Import data from Excel spreadsheets into ArcGIS.
During this practical, you will capture location data of the sculptures of Macquarie University and locate nearby fire hydrants using a Garmin 72H handheld GPS unit. The techniques you will use to capture location data are identical to those that are used in industry and government to capture spatial information on, for example, the distribution of weeds, buildings, trees, water holes, etc.
External Students: You will not be learning how to use a GPS unit (Task 1 &2). Instead, you have been provided with two excel files with data on Hydrants (Hydrantsimport.xls) and Sculptures
(SculptureImport.xls). Skip Tasks 1 and 2 and start from Task 3 (read through the instructions, however to get a sense of the GPS activity in Tasks 1 and 2). You must answer the question denoted with External Students Only at the end of Part 1.
Task 1: Getting ready to collect spatial data (Internal Students Only)
In this task you will be getting familiar with the use of a handheld GPS.
Getting familiar with the use of a handheld GPS
Your tutor will provide you with a Garmin GPS 72H unit and hard copies of the quick start manual and log sheet. Before we leave the computer lab, we will show you how to:
1. Turn the GPS unit on.
2. Navigate through the various pages of the GPS unit.
3. Set the measurement units and location (datum and projection) information.
4. Delete existing waypoints.
Setting the units and location information
Access the ‘Main Menu’ by pressing the MENU button twice. Scroll down to ‘Setup’ using the rocker, and press ENTER. Scroll across to the ‘Units’ tab. Make sure the settings are:
Elevation = Metres
Depth = Metres
Distance and Speed = Metric
Temperature = Celsius
Direction Display = Numeric Degrees
Speed Filter = Auto
Scroll across to the ‘Locations’ tab. Make sure the settings are:
Location format = UTM UPS
Map Datum = GDA
Press QUIT twice to go back to the ‘GPS Information’ page.
Delete existing waypoints
Access the ‘Main Menu’ by pressing the MENU button twice. Scroll up or down to ‘Points’ and press the ENTER button.
If you get a warning beep and a message that no waypoints have been found, just press MENU twice to retreat from this page as there are no waypoints to be deleted.
If you see a list of ‘Waypoints’ or ‘Nearest Waypoints’, press MENU and then scroll down to ‘Delete All’ and press ENTER. And yes, you really want to delete all the waypoints.
You have been asked by Macquarie University to locate the sculptures that are housed within the Central parts of the University grounds (See map below), and give them the relevant attributes (including name, sculpture material, GPS accuracy). As part of this activity they have also asked you to collect information concerning the location of nearby fire hydrants that are suitable to protect these art installations. This spatial data will be collected using handheld GPS using the proforma provided (one for each).
Your tutor will now take you outside and introduce you to how to collect data using a Handheld GPS. Feel free to conduct this activity in small groups, however each person must collect their own data.
Walk up to a sculpture. Admire its beauty for approximately one minute so that the accuracy of your GPS unit has enough time to settle down to ~8 metres.
Press and hold the ENTER button to mark the position as a waypoint.
Press ENTER again to ok the location.
Using the provided proforma record the waypoint id number, eastings, northings, accuracy, and material of construction (i.e. sandstone,Aluminium, Steel, Bronze, Mixed)
Capturing waypoints for fire hydrants
Walk up to a hydrant. Admire its beauty for approximately one minute so that the accuracy of your GPS unit has enough time to settle down to ~8 metres.
Press and hold the ENTER button to mark the position as a waypoint.
Press ENTER again to ok the location.
Using the provided proforma record the waypoint id number, eastings, northings, accuracy, number of hydrant outlets, nearest path/road name
Task 2: Uploading GPS data
MapSource software was developed especially for Garmin GPS receivers and will be used to upload your waypoints to the laboratory computers. A USB data cable is required. Ask a tutor for a cable before proceeding. Note: There are limited cables available so you may have to wait until one becomes available.
Open the rubber cover on the back of the GPS receiver (i.e. the small cap near the bottom left corner of the unit - not the twist ring on the battery compartment). Correctly align the plug on the USB data cable and plug it into the GPS receiver and then into your computer. Make sure your GPS unit is ON.
Click on the start menu and search for MapSource to start the software. Ask your tutor if you cannot locate the software.
If you receive a message telling you to insert the World Map Disk, click Cancel to ignore the message.
In the MapSource window, select Edit ? Preferences.
Under the Position tab, use the drop-down arrow to select:
Grid = UTM
Datum = GDA or GDA94
Click OK to close the Preferences menu.
From main menu, choose Transfer ? Receive from Device
The software should find the device (GPS unit) automatically. If you do not see the GPS unit’s name in the ‘Receive from Device’ window, get assistance from your tutor. In the lower part of the ‘Receive from Device’ window, tick Waypoints (Don’t check the other options). Then select Receive.
Click OK in the ‘Transfer complete’ window. You should be able to see some numbered points on your screen/map. Use the Zoom tool to zoom to the area with the points.
To save the points in a file format that can be used in ArcGIS, select ‘File ? Save As’. In the ‘Save As’ window, navigate to your working directory. Select the ‘Save as type: Text (tab delimited) (*.txt)’, and type a suitable name for your file (e.g. HydrantsANDSCulptures_XY.txt where XY are your initials). Click ‘Save’.
Exit MapSource. Unplug the USB cable and return the GPS unit and cable to your tutor.
Task 3: Importing Excel spreadsheet data into ArcGIS
Most, but not all, GIS software provides functionality to enable the uploading of GPS data directly to the software. However, it is also useful to know how to handle spatial data using generic methods. These methods are always available no matter what hardware or software is being used. Microsoft Excel provides a user-friendly interface which is very useful for editing spatial data before importing into ArcGIS.
Use Windows Explorer to find the HydrantsANDSCulptures_XY.txt file saved in Task 2. Double click the file to open it via the default text editor on your computer. In the text file, you should see the projection and datum information; and for each waypoint, the waypoint number (or identifier/ID), date and time of capture, UTM zone, location within the zone, and some text.
For use in ArcGIS, data must be stored with each field (e.g. the coordinates) in a separate column and irrelevant text removed. We will use Excel to edit the text file to the appropriate format.
‘Close’ the text file. Start ‘Microsoft Excel’.
In Excel, select the ‘Open’ icon. Navigate to your working directory. Change the ‘file type’ at the bottom of the screen to ‘Text’ files and then double click your ‘Hydrants_XY.txt’ file.
Excel starts a ‘Text Import Wizard’ to import the data.
Step 1: Choose the file type that best describes your data as 'Delimited'.
Step 2: Tick both the ‘TAB’ and ‘Space’ delimiters. You should see how the values are separated and saved into different columns in the ‘Text Import Wizard’ preview.
Step 3: Simply click Finish to import the text file into an Excel spreadsheet.
Before importing the data into ArcGIS, you need to add column (field) names. Right click the row number ‘1’ and choose Insert to insert a new row at the top of the spreadsheet. In the blank row, type the column’s name, i.e. WpointID, X (for eastings) and Y (for northings). Type in the data for accuracy (column name: AccM), Number of Hydrant Outlets (HYD_OUT)- if the point represents a hydrant, sculpture material (leave blank if waypoint belongs to a Hydrant), sculpture material (Mat) (leave blank if waypoint belongs to a fire hydrant) and Factors affecting accuracy (FACT_ACC) that you recorded on your proforma.
Save your spreadsheet by selecting ‘File ? Save As’. Change ‘Save as type’ to Microsoft Excel Workbook 97-2003 (*.xls). Choose an appropriate name for your new file (e.g. Hydrant_Sculpt_Import_XY, where XY are your initials).
Open a new empty map in ArcMap 10.5.
Click the ‘Add Data’ icon on the main menu. Navigate to your working directory and double-click
‘Hydrant_Sculpt_Import_XY’. Your GPS data should be saved under “Sheet1” or
‘Hydrant_Sculpt_Import_XY. Double click or drag and drop “Sheet1” to the map as a table.
Right click the table in the TOC and Open it. Make sure that you can see all the field (column) names and the coordinates (if necessary, seek assistance from your tutor). Close the table.
Right click the table in the TOC again, and choose ‘Display XY Data…’
In the ‘Display XY Data’ window, ArcMap tries to identify which columns the x and y coordinates are in. By calling the columns ‘X’ and ‘Y’ you have made this process easy! Now you must specify the coordinate system. Click ‘Edit’.
Select ‘Projected Coordinate Systems ?, National Grids ? Australia’. Then select the correct datum and zone for Macquarie University (i.e. ‘GDA 1994 MGA Zone 56’). See screenshot below. Click ‘OK’.
In the ‘Display XY Data’ window, click OK. A warning is displayed that the layer lacks an Object-ID field. Click ‘OK’ (this will be fixed automatically). After a few seconds your data are displayed in the map and a new point dataset is added to the TOC as an ‘Event’. An ‘Event’ is a temporary file. The next step is to save your data as a permanent spatial layer.
Right click the new data layer in the TOC and select ‘Data ? Export Data’.
Save the point data as a shapefile in your working directory with an appropriate name (e.g.
‘Hydrants_Sculpt_XY.shp’, where XY are your initials). Click ‘OK’ and ‘Yes’ to add the new shapefile to your map.
Using ‘Select by Attribute’ tool and ‘Data ? Export Data’ to create two Shapefiles for hydrant and sculpture (Hydrants_xy.shp and Sculpt_XY.shp’) respectively. To do this, think about what query you can create to separate the Hydrants from the Sculptures.
With only the Hydrants_xy.shp and Sculpt_XY.shp in your TOC, add a basemap to your map by selecting the drop down arrow next to the ‘Add Data’ button and then ‘Add Basemap…’ Select the ‘Imagery’ or ‘Topographic’ basemap to add to your map.
Calculating the number of sculptures at increased fire risk: Internal students: For this section, use the standardized layers provided ‘MQ_Hydrants_2019’ and ‘MQ_Sculptures_2019’ layers for this question (Folder SculpFire_2019).
You have been instructed by the University that the fire department uses 40 and 60 metre hoses, with the 60 metre hoses being unwieldy and not carried on all vehicles). There are many ways (a series of buffers, a multiple ring buffer, select by location etc.) you could undertake this task, however we will use the following technique.
Use a series of buffers and the erase tool to determine how many sculptures are located within the 0-40 m and 40-60 m distance of the fire hydrants, OR, Try out the ‘Multiple Ring Buffer’ tool (search ‘Multiple Ring Buffer’ in the search pane. If you are using the ‘Multiple Ring Buffer’ tool the input feature will be your ‘MQ_Hydrants_2019.shp’ and the ‘Distances’ will be 40 and 60 m. You can ‘Dissolve all’.
For Q1.1a you will need to create an A4 map of your sculptures and fire hydrant locations (including the fire risk buffer layer, created for Q1.1b) in the Layout View. Give the sculptures a unique symbol for each material type and make sure that they are easily differentiated from the fire hydrants/buffer. Include your initials in the title of the map (e.g. WF). Use an appropriate basemap (i.e. imagery or topographic), title (remember this must be clear, concise and descriptive), scale bar (in kilometres), north arrow, and legend.
Q1.1a: Everyone: Export the map (instruction above) of your sculptures/hydrant locations in jpeg file format and insert it in your assignment template. Show each sculpture material as a different symbol (10 marks for internal students, 6 marks for external students)
Q1.1b: Everyone: Using the table provided in the answer template how many sculptures (using MQ_Sculptures_2019) are found within each zone? (2 marks).
Q1.1b: External students only: What are the three segments of GPS and what are their functions? Show how they interact with each other using a diagram (4 marks)
Q1.2: Everyone: Using the table provided identify and give a brief description of the different sources of error in GPS (max. 300 words). Try and cover at least 4 sources. (4 marks)
Part 1 Total: 16 marks
Part 2: Raster Analysis
Raster data consists of a matrix of cells (or pixels) of equal size, organized into rows and columns (or a grid). Each cell contains a value representing information, such as elevation or temperature. Rasters can represent digital aerial photographs, imagery from satellites, gridded layers, or even scanned maps. You can use raster data as a background (basemap) to visually analyse other data (you’ll be doing this in Part 3), and you can also use it in an analysis operations.
There are many ways to use raster data in analysis operations. When performing these operations, your main concern will likely be with the data represented by the values of the cells; therefore, you will be performing operations that manipulate these values. To utilize raster data within an analysis operation, you will need the following extension:
ArcGIS Spatial Analyst - This extension provides a comprehensive set of advanced spatial modeling and analysis tools that allow you to perform integrated raster and vector analysis.
In Part 2, you will be using the ArcGIS Spatial Analyst extension. Make sure this extension is turned on by selecting ‘Customize Extensions’ in the Main Menu of ArcMap.
It is also worth checking that the background geoprocessing option is still disabled.
By the end of Part 2 you will be able to:
1. Derive statistics from raster data via integration with vector data using the ‘Zonal Statistics’ tool.
2. Perform a reclassification of raster data.
3. Use ‘Raster Calculator’.
4. Resample a raster
You have been asked by the Australian Federal and Queensland State Governments to help them understand where Dugongs are found (i.e. what characteristics may be used to determine their likely habitats and whether the current protection zones are sufficient for the species protection). As part of this endeavour they have provided you with the following datasets:
Dugdensity – a raster grid of dugong density (dugongs/km2) in Moreton Bay, Queensland.
Moreton_Bay_marine_park_zoning_2008 – a vector polygon of marine park zones in Moreton Bay, Queensland.
Seagrass – a raster grid of seagrass presence in Moreton Bay.
Moreton_Bay_Bathymetry_Bil_2009 – Bathymetry (i.e. water depth) for Moreton Bay. Derived from the Geoscience Australia: Australian Bathymetry and Topography Grid (2009). Queensland – a vector base layer of the spatial extent of Queensland.
Background information: The dugong (Dugong dugon) is the only strictly marine herbivorous mammal. They live for about 70 years, and reach a maximum size of between 2 – 3 metres. Dugongs graze predominantly on tropical and subtropical seagrass meadows. Around a quarter of global dugong habitats occur in northern Australia’s waters between Moreton Bay in Queensland and Shark Bay in Western Australia. The major threats to dugongs in Moreton Bay are vessel strike, seagrass dieback and entanglement in fishing nets. In Australia the Dugong dugon is protected under the Environment Protection and Biodiversity Conservation Act 1999 (Cwth).
Start ArcMap 10.5, and add the four layers contained within the Part2 folder of Assignment2Data.zip to your map. Once the layers have been added zoom into the extent of the dugdensity raster.
HINT: You can use the Identify tool to get pixel value information for a single pixel of a raster grid, just like you can use it to get information on features within a shapefile. Try using the Identify tool on the Dugdensity and Moreton Bay Bathymetry rasters.
Task 1: Zonal statistics
In Task 1 you will undertake an analysis of the effectiveness of the current framework of protection zones. Open the attribute table of ‘Moreton_Bay_marine_park_zoning_2008’. The ‘ZONE_TYPE’ column provides information on the designated marine park zone for each feature: General Use zones allow all types of fishing; Habitat Protection zones allow all types of fishing except trawling; Conservation Park zones allow only recreational fishing (i.e. commercial fishing such as trawling and netting is not allowed), and Marine National Park zones don’t allow any type of fishing.
In this task, we are focusing on marine park zone types. There are many different features (74) in the marine park layer, but only four types of zones. You are going to learn how to use the ‘Dissolve’ tool to simplify the marine park layer.
In ArcToolbox, select ‘Data Management Tools Generalization Dissolve’. The ‘Input Feature’ is
‘Moreton_Bay_marine_park_zoning_2008’, the ‘Output Feature Class’ is the new dissolved shapefile (save it to your working directory and give it an appropriate name, e.g. ‘Moreton_Bay_MPdissolve’) and the ‘Dissolve Field’ is ‘ZONE_TYPE’. Leave the rest of the options as default. Select ‘OK’ to finish.
Open the attribute table of ‘Moreton_Bay_MPdissolve’ to see what the ‘Dissolve’ tool has done to the original layer.
The raster grid ‘dugdensity’ contains information on the number of dugongs/km2.
Q2.1: What is the resolution (i.e. cell size) of dugdensity? (1 mark)
You are now going to calculate the number of dugongs in each of the different marine park zones using the ‘Zonal Statistics as Table’ tool.
In ArcToolbox, select ‘Spatial Analyst Tools Zonal Zonal Statistics as Table’. The ‘Input Raster or
Feature Zone Data’ is ‘Moreton_Bay_MPdissolve’, the ‘Zone Field’ is ‘ZONE_TYPE’ and the ‘Input Value Raster’ is ‘dugdensity’. The ‘Output Table’ is the new zonal statistics table (save it to your working directory and give it an appropriate name, e.g. StatsdugMP). Leave all the other options as default (but note that you could select a single statistics type if you only need one type of statistic. Select ‘OK’ to finish.
Open the table ‘StatsdugMP’.
Q2.2: Fill in the table below. (2 marks)
General Use Habitat Protection Conservation Park Marine National Park
Number of dugongs
Q2.3: What proportion of the dugong population of Moreton Bay is in zones where commercial netting is allowed? (1 mark)
The Queensland Government wants to know how many dugongs are within 10 kilometres of the mainland.
Q2.4: Use the analysis techniques you learned above and in Assignment 1 to calculate the number of dugongs within 10 kilometres of the mainland. Note: The Queensland Shapefile includes islands so make sure you only perform your analysis on the mainland (1 mark)
Q2.5: Draw a data flow diagram of the analysis process you used to calculate the number of dugongs within 10 kilometres of land. (3 marks)
Task 2: Reclassification
The Queensland Government has requested a layer that shows areas of low, medium and high dugong density. They have stated that you must use a natural breaks (jenk’s) classification with 3 classes.
To reclassify a raster, the ‘Reclassify’ tool is used.
In ArcToolbox, select ‘Spatial Analyst Tools Reclass Reclassify’. The ‘Input Raster’ is ‘dugdensity’, and the ‘Reclass Field’ is ‘Value’. Select the ‘Classify’ button. Change the ‘Classification Method:’ to ‘Natural Breaks (Jenks)’ and ‘Classes’ to 3.
The Output Raster is the new reclassified raster grid (save it to your working directory and give it an appropriate name, e.g. dugreclass). Leave the text under New Values as the default 1, 2 and 3, but remember that 1 = low density, 2 = medium density, and 3 = high density.
Select OK to finish. Since this raster is a integer raster, it can have an attribute table. Open the attribute table of dugreclass.
Q2.6: What is the area (in km2) of low, medium and high dugong density in Moreton Bay? (3 marks)
Task 3: Map algebra
Geoprocessing functions (e.g. clip, intersect and union) can only be performed on vector layers. Reducing the size of a raster grid to an area of interest (like a clip) requires you to use a different set of analysis tools.
The raster grid seagrass contains information on the location of seagrass habitats in Moreton Bay. The Queensland Government wants to know how many dugongs are on top of seagrass habitats. You are going to use the ‘Raster Calculator’ tool to figure this out.
In ArcToolbox, select ‘Spatial Analyst Tools Map Algebra Raster Calculator’. The Map Algebra expression is -seagrass- * -dugdensity-. The Output Raster is the new raster grid which shows the output of your algebraic expression (save it to your working directory and give it an appropriate name, e.g. dugseagrass).
The output layer dugseagrass shows only those grid cells of dugdensity that overlap seagrass habitats.
Q2.7: Why in the output does only the overlapping areas produce a cell in the output? (1 mark)
You are now going to convert ‘dugseagrass’ into a point shapefile, where one point will be located at the centroid of each cell. In ArcToolbox, select ‘Conversion Tools From Raster Raster to Point’. The ‘Input Raster’ is ‘dugseagrass’, the ‘Field’ is ‘Value’, and the ‘Output Point Features’ is the new point layer (save it to your working directory and give it an appropriate name, e.g. ‘dugseagrass_point.shp’). Select ‘OK’ to finish.
Q2.8: How many dugongs are on top of seagrass habitats? (1 mark)
Q2.9: How many seagrass points do not have dugongs associated with them? (1 mark)
Task 4: Resampling a raster
Clear any selected features and turn off all layers except the ‘seagrass’ and
‘Moreton_Bay_Bathymetry_Bil_2009.tif’. Zoom into a region of the
‘Moreton_Bay_Bathymetry_Bil_2009.tif’ where there is both sea grass and bathymetry values. You will notice that the cellsize of the seagrass and bathymetry rasters are different. This is a common occurrence when dealing with different sources/types of data. In this task we will resample the
‘Moreton_Bay_Bathymetry_Bil_2009.tif’ raster so that it has the same cellsize as the seagrass raster.
Using the search pane type in and then open the ‘Resample’ tool. The ‘Input Raster’ is
‘Moreton_Bay_Bathymetry_Bil_2009.tif’. In the ‘Output Raster Dataset’ navigate to your working directory and call the output ‘Moreton_Bathymetry_1km.tif’ and in the ‘Output Cell Size (optional)’ dropdown menu select ‘Same as layer seagrass’. For the ‘Resampling Technique (optional)’ choose ‘Bilinear’. Click Ok to run the tool.
Have a close look at the output. The cell size appears to be the same (can be checked through looking at the layer properties, however does the extent/locations of each cell correspond to a seagrass cell?
The reason why the cells don’t match up is due to the fact that the raster’s cells have not been snapped to the same location; this happens due to the fact that you have merely resampled the cells so that they have the same cellsize, not the same location.
Lets fix this issue now, open the ‘Resample’ tool and set it up the same as we did before (call the output
Moreton_Bathymetry_1kmsnap.tif’), however this time we will snap the raster. To do this, click on ‘Environments ? Processing Extent’ and then in the ‘Snap Raster’ drop down menu select the ‘seagrass’ raster and click Ok and then Ok to run the tool. Zoom into the output raster and have a look at the cellsize/location. The output raster and the ‘seagrass’ raster’s cells should be the same size and location (note: some ‘Seagrass’ cells may not have a corresponding bathymetry cell due to the extents of each dataset.
Using the analyses undertaken within this Part undertake the following questions:
Q2.10: Using the snapped bathymetry raster (‘Moreton_Bathymetry_1kmsnap.tif’) and the ‘seagrass’ raster calculate the mean, minimum and maximum depths of ‘seagrass’ cells within Moreton Bay. (3 marks)
Q2.11: What is the average, minimum and maximum depths that dugongs are found (dugreclass) layer within Moreton Bay? (1.5 marks)
Create an A4 map of Moreton Bay that shows the raster grid of the spatial extent of dugongs that are on top of seagrass habitats and the Queensland base layer. Insert a title, scale bar (in kilometers), north arrow, and legend.
Q2.9: Export the map of dugongs on seagrass habitats in a jpeg file format and insert it in your assignment template. (2.5 marks)
Part 2 Total: 21 marks
Part 3: Digitizing in ArcGIS
Geocoding is the process of finding geographic coordinates from features in space, and the conversion of geographic information into a digital format. There are multiple methods that enable the production of referenced digital data (see your Week 5 lecture for further information). One of methods is onscreen digitizing using a georeferenced image or map as a base layer. And that’s exactly what you’ll be doing today.
By the end of Part 3 you will be able to:
1. Create an empty shapefile for data capture and digitizing.
2. Use onscreen digitizing to create a new polygon shapefile.
3. Add fields and enter information into an attribute table.
Task 1: Creating an empty shapefile and onscreen digitizing
You are going to learn how to perform onscreen digitizing by digitizing the spatial extent of buildings on the Macquarie University campus. You have been provided with a georectified image of the campus (MU_Map.tif) to use as your digitizing base layer. You have also been provided with a roads and paths layer (MU_Roads_Paths.shp; polyline), and a layer of the campus boundary (MU_Campus_Boundary.shp; polygon).
Start ArcMap 10.5, and add the three layers contained within the Part3 folder of Assignment2Data.zip to your map.
Before you can digitize, you must first create a new, empty shapefile that will store your polygon features. In ‘ArcCatalog’, right click on your working directory folder and select ‘New Shapefile’.
Name your new shapefile ‘MU_Buildings.shp’. The ‘Feature Type’ is polygon. Under ‘Spatial Reference’, select Edit. This is where you set the co-ordinate system for the new data layer.
Select ‘Projected Coordinate Systems National Grids Australia GDA_1994_MGA_Zone56’
Press Ok and then Ok again in the ‘Create New Shapefile’ window.
The new shapefile should automatically add to your map. To edit the new shapefile, select ‘Editor Start Editing’ from the ‘Editor’ toolbar.
Make sure ‘MU_Buildings.shp’ is the editing layer by selecting its name in the ‘Start Editing’ window.
The create features dialog box contains all the tools you need to edit your new layer. To open the Create Features editing box (if it isn’t already opened), select ‘Editor Editing Windows Create Features’.
Select the name of your editing layer (i.e. MU_Buildings) in the ‘Create Features’ window.
The buildings you need to digitize are listed below. Multiple buildings are grouped together when they are adjacent (touch) or are connected. You need to create ONE feature (polygon) per group (i.e. a total of 14 features).
1. E7B E7A (14SCO, 12WW)
2. E5A E5B (11WW, 10SCO)
3. E3B E3A (8SCO, 10MW)
4. F9A (15RPD)
5. F9B (3SR)
6. F9C (13RPD)
7. F7B (4WW)
8. E4B E4A (6ER, 4ER)
9. E6A E6B (9WW, 7WW)
10. E8A E8B E8C (14ER, 6SR, 6WW)
11. E12A (5MD)
12. E12B (6MD)
13. E12C (7MD)
14. E14B E14A (3MD,1MD)
Zoom to the area where you will begin digitizing. The recommended zoom (map scale) for digitizing is 1:1,000.
Select ‘Polygon’ in the ‘Constructions Tools’ panel of the ‘Create Features’ window. In the ‘Editor’ toolbar, make sure the ‘Straight Segment’ tool is selected (it should be selected by default). You will be using point-to-point digitizing in this exercise.
Position the digitizing cursor over a corner point of the first building to be captured, and then click once to mark the point. Drag and click around the building, adding enough points to give the correct shape. Double click the final corner to finish the polygon.
If you are unhappy with your shape and want to delete it, click the ‘Select Features’ tool and then select the feature (building) you want to delete. Press the ‘Delete’ button on your keyboard to delete the feature.
Repeat the above steps for all 14 buildings. Use the Zoom out or Pan buttons to find all the buildings
When you are finished digitizing, select ‘Editor Save Edits’ then ‘Editor Stop Editing’.
Task 2. Adding feature attributes
In this task, you will add the building names and their area (metres2) to the attribute table of ‘MU_Buildings.shp’.
Open the attribute table of ‘MU_Buildings.shp’. Select the ‘Table Options’ icon and then ‘Add Field’.
Name your new field ‘Area_M2’, and stipulate the ‘Type’ as ‘Float’. Keep the default values of Precision and Scale. This will allow you to create a numeric field with an unlimited number of decimal places (opposed to a short or long integer field with no decimal places).
You should now be able to see a new field in ‘MU_Buildings.shp’ with the fieldname ‘Area_M2’. All the records have the same attribute value (i.e. 0).
You will now use the ‘Calculate Geometry’ tool to populate the Area_M2 field. Right-click the fieldname Area_M2 and select ‘Calculate Geometry’. The ‘Property’ is Area, and the ‘Units’ are Square Meters.
Select the ‘Table Options’ icon and then ‘Add Field’. Name your new field ‘Building’, and stipulate the Type as Text. This will allow you to create a text field that can hold the building names.
To add the building names to the attribute table, select ‘Editor Start Editing’ from the ‘Editor’ toolbar. Make sure ‘MU_Buildings.shp’ is the editing layer by selecting its name in the ‘Start Editing’ box.
Use your keyboard to type the name of buildings into the ‘Buildings’ field of the ‘MU_Buildings.shp’ attribute table, e.g. E7B E7A
When you have finished adding all the names, select ‘Editor Save Edits’ then ‘Editor Stop Editing’.
Remember to save your ‘MU_Buildings.shp’ layer and map (.mxd) file to your working directory!
Create an A4 map of your buildings in the Layout View. Zoom to the spatial extent of ‘MU_Buildings.shp’. Give each building a unique symbol. Use symbology to differentiate between roads and paths, and the different campus regions (i.e. eastern, western etc.). Include your initials in the title of the map (e.g. AG). Do not show ‘MU_Map.tif’ in your map.
Q3.1: Export the map of your buildings in a jpeg file format and insert it in your template. (5 marks)
Q3.2: What is the area (in m2) of each building? (7 marks)
Q3.3: What is the total length (in metres) of paths at Macquarie University? (0.5 marks). What is the total length of roads? (0.5 marks)
Q3.4a: How many buildings are within 20 metres of a path? (1 mark).
Q3.4b: Draw a data flow diagram of the analysis process you used to calculate the number of buildings within 20 metres of a path. (3 marks).
Q3.5a: What is the total length of paths in the Eastern campus? (1 point).
Q3.5b: Draw a data flow diagram of the analysis process you used to calculate the total length of paths in the Eastern campus. (3 marks)
Part 3 Total: 21 marks
Part 4: Advanced mapping in ArcGIS
A key function of GIS is its ability to facilitate the visualization and presentation of spatial information. Mapping in GIS combines science, aesthetics and technique to model reality and communicate spatial information. A map consists of a collection of spatial information (or geographic elements), plus descriptive information (or cartographic elements) that helps the reader interpret the information on the map (e.g. labels, legend, north arrow etc.). Map layouts can include multiple maps at different scales to enable the reader to view the study area in context, or to see finer detail in an important area. In Part 4, you will learn how to communicate spatial information effectively using advanced mapping techniques.
By the end of Part 4 you will be able to:
1. Manipulate map layouts within ArcMap.
2. Use labelling functions.
3. Make awesome maps.
Task 1: Manipulating map layouts in ArcMap 10.5
The data that you need to complete Part 4 is contained within the ‘Part4’ folder of ‘Assignment2Data.zip’. You will also need ‘MU_Roads_Paths.shp’ and ‘MU_Campus_Boundary.shp’ contained within the Part 3 folder, and the ‘MU_Buildings.shp’ layer that you created in Part 3. Your map will include:
1. A map of Macquarie University’s campus with sculpture locations, campus regions, roads and paths; and
2. An inset map showing a magnified view of sculpture locations, campus regions, roads, paths and buildings in the eastern campus.
Start ArcMap 10.5, and add the layers from Part 3 and the sculpture layer contained within the Part 4 folder to your map.
Switch to the ‘Layout View’. Your ‘Data Frame’ automatically covers the entire ‘sheet of paper’.
In the TOC, click the Data Frame’s name (Layers) twice (slowly), and rename it ‘Map 1’.
Decide whether you prefer a portrait or landscape orientation. To change the orientation, select from the main menu ‘File ? Page and Print Setup’. Under ‘Paper’, check A4 paper size is specified, and change to ‘Landscape’. Click OK to apply the change.
You can change the size and position of the Data Frame in Layout View by clicking and dragging the corners of the frame to resize the map area. Map 1 should occupy about two thirds of the ‘sheet of paper’.
Use the zoom tools to Zoom to Layer ‘MU_Campus_Boundary.shp’. The recommended map scale of Map
1 is 1:8,500.
Now you will create an inset map to show a magnified view of the eastern campus. Multiple Data Frames are used to display multiple maps in one layout. There are two ways to create a new Data Frame:
1. In the ‘Layout View’, select the ‘Map 1’ Data Frame and then copy (Ctrl c) and paste (Ctrl p);
2. Select from the main menu ‘Insert ? Data Frame’. Then add layers to the new data frame.
In the TOC, click the name ‘New Data Frame’ twice (slowly) and rename it ‘Inset’.
Your inset map needs to contain the following layers: ‘MU_Roads_Paths.shp’, ‘MU_Campus_Boundary.shp’, ‘Sculpt_XY.shp’AND’ ‘MU_Buildings.shp’.
Adjust the size of your inset map so that it covers the remaining one third of your layout. Use the zoom tools to zoom to the eastern campus shown in ‘MU_Campus_Boundary.shp’. The recommended map scale of Inset is 1:3,000.
A Data Frame needs to be active to add layers, edit, zoom etc. You activate a Data Frame by:
1. Right clicking the Data Frame’s name in the TOC and selecting ‘Activate’; or
2. In the ‘Layout View’, select the ‘Data Frame’ you want to activate using he select button .
Use ‘Symbology’ to change the appearance of your layers. Ensure that the layers in your two maps share the same symbology. Give each building a unique symbol. Use symbology to differentiate between roads and paths, and the different campus regions (i.e. eastern, western etc.).
Add an imagery basemap to both of your maps by selecting the drop down arrow next to the ‘Add Data’ button and then ‘Add Basemap’.
You can make the ‘MU_Campus_Boundary.shp’ transparent by using the ‘Effects’ toolbar.
Add the ‘Effects’ toolbar by right clicking in the grey area at the top of your ArcMap window, and selecting Effects. Make sure that ‘MU_Campus_Boundary’ appears in the ‘Effects’ toolbar window. Use the Adjust Transparency tool to change the transparency level.
Task 2: Adding labels to a map
‘Annotation’ is text added to a map that identifies or describes a geographic feature. Annotation has many different properties, including size, font, colour and spatial arrangement (for example at an angle, or curved along the side of a river). Annotation is created by using the ‘Label Features’ function.
You will now label the buildings in the inset map with their names. In the TOC of the Inset data frame, right click ‘MU_Buildings.shp’ and select ‘Label Features’. Labels will automatically add to your inset map. If the labels are from the wrong field, right click the ‘MU_Buildings.shp’ in the TOC and select ‘Properties’. Click the ‘Labels’ tab. Set the ‘Label Field:’ to ‘Building’. You can change the appearance of your labels in the ‘Labels’ tab under ‘Text Symbol’.
‘Map 1’ and ‘Inset’ require their own north arrow, scale bar, and title. However, the two maps can share a legend (just make sure you have included all the layers in your shared legend). Do not include the basemap in your legend. You also need to add a title to your ‘sheet of paper’. Select ‘Insert ? Text’ to add a title. Remember to include your initials in the title (e.g. AG).
Remember to save your map (.mxd) file!
Q4.1: Export your awesome map in a jpeg file format and insert it in your assignment template. (10 marks)
Q4.2: Fill in the table below. (4 marks)
Eastern Northern Western Central
Number of sculptures
Q4.3: How many sculptures are within 30 metres of ‘MU_Buildings.shp’? (1 mark)
Q4.4: Fill in the table below. (2 marks)
Eastern Northern Western Central
Total length of roads (metres)
Part 4 Total: 17 marks