Features in ArcGIS can be points, lines, or polygons. Enumeration areas are displayed as polygons, while buildings such as schools, hospitals, or places of worship are usually displayed as points. Buildings can be used as geolocation points, which help census workers find enumeration areas.
First, you'll create and modify point data representing geolocation points and household clusters. Household clusters represent groups of households and can also be used to guide enumerators.
Open the project
First, you'll download and open an ArcGIS Pro project package containing geographic and census information for Zambia, your area of interest.
- Download the Southern Lusaka Enumeration Areas project package.
A file named Southern_Lusaka_Enumeration_Areas.ppkx is downloaded to your computer. A .ppkx file is an ArcGIS Pro project package and may contain maps, data, and other files that you can open in ArcGIS Pro.
- Start ArcGIS Pro. If prompted, sign in using your licensed ArcGIS organizational account.
If you don't have access to ArcGIS Pro or an ArcGIS organizational account, see options for software access.
When you open ArcGIS Pro, you're given the option to create a new project or open an existing one. If you've created a project before, you'll see a list of recentprojects.
- If necessary, click Open another project.
- In the Open Project window, browse to and double-click the Southern_Lusaka_Enumeration_Areas project package that you downloaded.
The project opens. It shows the boundaries of the Southern and Lusaka provinces in southern Zambia. It also shows the OpenStreetMap basemap. A basemap contains basic geographic information about an area, such as roads, political boundaries, and water bodies.
The Contents pane lists all layers on the map. The map includes a point layer named Southern and Lusaka Households (the yellow points on the map) that represents household clusters and a layer named Enumeration Areas. The household cluster and enumeration area data are fictionalized for the purposes of this tutorial.
Create a point feature class
Next, you'll navigate to an area of interest using a bookmark that was included in the project. Then, you'll create a point feature class to contain geolocation points that census workers can use to locate enumeration areas.
- On the ribbon, on the Map tab, click Bookmarks and choose Itezhi-Tezhi.
The map navigates to the location of the bookmark, an area in the Southern province called Itezhi-Tezhi that is near a large lake.
When the map zooms in, three blue polygons become visible. These polygons represent enumeration areas.
Census workers in the field typically use points of interest to locate enumeration areas, but not all census workers have accurate GPS devices and some areas may have limited or no cellular coverage. Adding point features to the map to represent points of interest is essential because census workers can view these points even when offline.
You'll create a layer to capture these geolocation points of interest.
- In the Catalog pane, expand the Databases folder. Expand southern_lusaka_enumeration_areas.gdb.
If you don't see the Catalog pane, click the View tab on the ribbon. In the Windows group, click Catalog Pane.
A .gdb file is a geodatabase. Geodatabases are a type of file folder that primarily contains spatial data you can add to a map in ArcGIS. The southern_lusaka_enumeration_areas geodatabase contains two feature classes, both of which are on the map. You'll create the geolocation points feature class in this geodatabase.
- Right-click the southern_lusaka_enumeration_areas geodatabase, point to New, and choose Feature Class.
The Create Feature Class pane appears. This pane guides you step-by-step through the process of creating a feature class.
First, you'll name the feature class. The name of a feature class cannot contain spaces or several other types of special characters. However, you can add an optional alias that contains any characters you want. The alias is displayed in most locations instead of the name.
- For Name, type Geolocation_Points (including underscore). For Alias, type Geolocation Points (with no underscore).
Next, you'll choose the feature class type. There are a few options to choose from, but the main types of feature classes are points, lines, and polygons. Lines are best for roads or rivers, while polygons are best for areas or geographic boundaries. Points are best for data that only covers a single point on the map, such as a building or a point of interest.
- For Feature Class Type, choose Point.
- At the bottom of the Create Feature Class pane, click Next.
Next, you'll add attribute fields to the feature class. Attributes are textual or numerical data associated with each feature. They can include information such as names or coordinates.
For the geolocation points feature class, you'll add an ID field, a field to track who added each point, and a general field for additional comments.
- Click Click here to add a new field. For Field Name, type ID and confirm that Data Type is Text.
You can also change the field's alias, add a default value, and adjust the field length. The IDs that you'll use for the geolocation points will be five characters long, so you'll change the length accordingly.
- Click the gray box next to the ID field to select the field. At the bottom, under Field Properties, for Length, type 5.
- Add a field with the following information:
- For Field Name, type Plotted_By.
- Confirm that Data Type is set to Text.
- For Alias, type Plotted By.
- For Length, type 30.
- Add a field with the following information:
- For Field Name, type Comments.
- Confirm that Data Type is set to Text.
- For Length, type 150.
You can also import fields from another feature class. To do so, click Import and browse to the feature class with the fields you want to add. This method is useful for keeping fields consistent between similar layers.
- Click Next.
The next pane is for choosing the coordinate system used by the feature class. Coordinate systems are mathematical models for defining locations on the earth.
You'll choose the default option, WGS 1984, which is the coordinate system used by most GPS devices. While not every census worker has access to accurate GPS, some do, so using a compatible coordinate system is useful.
To learn more about coordinate systems and how to choose the best one for your map, try Geographic vs Projected Coordinate Systems.
- Click Next.
The next pane determines the feature class's tolerance, or the minimum distance between coordinates before they are considered equal. The default tolerance (an extremely small fraction of a degree) is appropriate for most datasets, so you'll leave it unchanged.
- Click Next.
The next pane determines the resolution. Like the tolerance, the default value (which is also an extremely small fraction of a degree) is appropriate for most datasets.
- Click Next.
Lastly, you have the option to specify the database storage configuration. The default configuration is appropriate for most datasets.
- Click Finish.
The Geolocation_Points feature class is created. It is added to the geodatabase in the Catalog pane and to the map in the Contents pane. No point features appear on the map because you haven't added any features yet.
Digitize geolocation points
The process of creating new features is called digitizing. You'll digitize one geolocation point per enumeration area. Because field workers need to be able to locate the points, it's best to place them at obvious landmarks, such as major street intersections.
- On the map, zoom to the three enumeration areas.
To zoom in or out, use the mouse wheel button. Alternatively, press Shift and draw a box around the area you want to zoom to.
- On the ribbon, click the Edit tab. In the Features group, click Create.
The Create Features pane appears. It contains a list of all editable feature classes on the map.
- In the Create Features pane, click Geolocation Points.
The color of the geolocation point symbol is random. Your symbol may differ from the example images.
The layer is selected and options for editing become available. The default option, Point, allows you to add a point anywhere that you click on the map. You'll use this editing option to add geolocation points for each enumeration area.
By default, you may have snapping turned on. Snapping causes the features you digitize to snap to existing features, ensuring that two features are exactly adjacent with no gaps or slivers between them. While snapping is useful for editing adjacent features (and you'll use it later in the tutorial), you don't want to snap the geolocation points to the edges of the enumeration areas, so you'll turn snapping off.
- On the Edit tab, in the Snapping group, click Snapping and confirm that the Snapping is off. If the Snapping is on, click the button next to it to turn it off.
Next, you'll add the first geolocation point.
- In the rightmost enumeration area, click the street intersection.
A geolocation point is added at the location you clicked.
- In the middle enumeration area, click the street intersection.
The remaining enumeration area has no paved roads or intersections inside of it. The only road is an unpaved or dirt road, symbolized on the basemap by a brown dotted line. Instead of at an intersection, you'll place a geolocation point at the bend in the road, which occurs in the center of the enumeration area. While not an ideal location, there are few other points of interest, so in this case it is acceptable.
- In the leftmost enumeration area, click the bend in the dashed line.
You've added a geolocation point to each enumeration area.
- Close the Create Features pane.
Closing the pane ends the editing session and returns your pointer to normal. Next, you'll open the attribute table for the layer and edit the attribute information for each point you added.
- In the Contents pane, right-click Geolocation Points and choose Attribute Table.
You can also access the Attribute Table by pressing Ctrl+T.
The table appears. It contains five fields. The OBJECTID and Shape fields are default fields that are automatically populated. The other three fields are the ones you added when you created the feature class.
You'll add information for the ID and Plotted By fields. The ID field value will match the ID field for the geolocation point's enumeration area. You can check each enumeration area's ID by clicking it on the map, but for the purposes of this tutorial, you'll be provided the correct ID. Each ID is an alphanumeric string that combines the letters EZ with a three-digit number.
- For the first entry in the table, in the ID column, double-click <Null> and type EZ003. Press Enter.
The attribute information is updated.
- For the first entry in the table, in the Plotted By column, double-click <Null> and type your name or initials (or a fictitious name).
- Edit the following attribute information:
- For the second entry, for ID, type EZ002. For Plotted By, type your name or initials.
- For the third entry, for ID, type EZ001. For Plotted By, type your name or initials.
You'll leave the Comments column unchanged, as you have no comments about any of the points.
- Close the attribute table.
You've made several edits, including digitizing three points and adding attribute information. It's important to save your edits once you're finished editing. Saving your edits is different than saving your project.
- On the ribbon, on the Edit tab, in the Manage Edits group, click Save.
- In the Save Edits window, click Yes.
Your edits are saved to the dataset. If you add the same Geolocation Points layer to a different map, you'll still see the points you digitized.
Modify points to remove errors
You've digitized new point features. Next, you'll edit existing point features. Sometimes, a feature may be located in an incorrect location. Moving and deleting features may be necessary to ensure your data is accurate.
- On the ribbon, click the Map tab. In the Navigate group, click Bookmarks and choose the Kazungula bookmark.
The map navigates to an area on the southwestern border of Southern province.
This location has three enumeration areas. It also has five household cluster points. The household cluster points aggregate demographic information about households in an enumeration area. You can also use these household cluster points as geolocation points. However, none of the household clusters in this location are located in enumeration areas.
Two of the household cluster points are located outside of the neighborhood. You'll change the basemap to try to understand why.
- On the Map tab, in the Layer group, click Basemap and choose Imagery.
The basemap changes to one that shows satellite imagery of the area.
Based on the map, the two household cluster points located outside of the neighborhood are positioned in a river. It's likely that these points have been added erroneously.
- Change the basemap back to OpenStreetMap.
Ordinarily, it is not recommended that you delete data from an original dataset without making a copy first. For the purposes of this tutorial, however, you'll assume that the two points located in the river are erroneous and that you verified this fact by contacting the field worker who originally collected the points.
Now that you have absolute certainty that they are erroneous, you'll delete the two household clusters that are not located in an area where people live. Then, you'll move the other three household clusters into the corresponding enumeration areas.
- Click the Edit tab. In the Selection group, click the Select tool.
- On the map, click the household cluster point near Kazungula Bridge.
The point is selected (highlighted blue). You can delete the point individually and then select the second erroneous point and delete it, or you can select both points and delete them at once. The second option is more efficient.
- Press Shift and click the household cluster near the Zambezi line south of the enumeration areas.
By pressing Shift, you can select multiple features at the same time. Both points are selected.
If you click the wrong area, you may select a different feature than intended. To clear the selection, in the Selection group, click Clear.
- On the Edit tab, in the Features group, click Delete.
Deleting data is permanent. Once you save your edits, the deleted features are removed from the dataset completely. In an ordinary workflow, it's recommended that you first make a copy of the original dataset before deleting any features.
The points are removed from the map and the dataset. Next, you'll move the other household clusters into a central location in each enumeration area.
- On the Edit tab, in the Tools group, click Move.
The Modify Features pane appears. The pane prompts you to select one or more features.
- On the map, select the household cluster point south of the three enumeration areas.
The point is selected and the pointer changes. You can now move the point by dragging it on the map.
- Drag the selected point to the center of the nearest enumeration area.
If you need to zoom in or pan the map, you can temporarily revert the pointer to navigation mode by pressing the C key.
Next, you'll move the other two points.
- In the Modify Features pane, click Change the selection.
- Select the household cluster point to the northwest of the enumeration areas. Move the point to the center of the road in the nearest enumeration area.
- Click Change the selection. Select the household cluster point to the north of the enumeration areas and move the point to the center of the nearest enumeration area, at the end of the cul-de-sac.
- Close the Modify Features pane.
You've moved the three household cluster points.
- On the Edit tab, in the Manage Edits group, click Save. In the Save Edits window, click Yes.
The edits you made in this section are saved. You'll also save the project.
- On the Quick Access Toolbar, click the Save button.
You've learned how to create, modify, and delete point features using editing tools in ArcGIS Pro. Next, you'll edit enumeration area polygons and learn a few of the more advanced techniques for editing.
Enumeration areas are meant to be relatively small areas, usually covered by one of more enumerators on foot. Mapping and sizing enumeration areas appropriately is essential to census efforts. You'll digitize new enumeration areas and also modify areas to eliminate errors.
Digitize an enumeration area
First, you'll navigate to an area of interest and digitize an enumeration area based on standard criteria.
- If necessary, open your Southern Lusaka Enumeration Areas project in ArcGIS Pro.
- On the ribbon, click the Map tab. In the Navigate group, click Bookmarks and choose the Gabon bookmark.
The map navigates to Gabon township in Lusaka, the capital of Zambia.
Like the other areas you've navigated to in this tutorial, this area already has some enumeration areas. Enumeration areas are typically drawn around point locations. Previously, you created geolocation points for each enumeration area, but you can also base the enumeration areas around the household cluster points that appear on the map. (The location of each point is typically determined using a statistical sampling process to ensure the locations are representative of the wider region.)
Enumeration areas adhere to the following criteria:
- The area must be between 3 and 5 hectares (to ensure it is walkable by a survey team).
- The area's boundaries should not cross rivers.
- The area's boundaries should be contiguous with roads, when possible.
You'll create an enumeration area for one of the points on the map. First, you'll measure an area between 3 and 5 hectares around the point to help plan the dimensions of the enumeration area.
- Zoom to the household cluster point in the northwestern corner of the study area.
The roads around this area may provide a boundary for the enumeration area. You'll perform your measurement here.
- On the ribbon, on the Map tab, in the Inquiry group, click the drop-down arrow for the Measure tool and choose Measure Area.
The Measure Area window appears and the pointer changes. You can draw a polygon by clicking locations on the map and the tool will calculate the polygon's area.
You'll measure the tall, somewhat rectangular area enclosed by roads around the household cluster point.
- On the map, click the southwest corner of the neighborhood around the household cluster point.
Now, when you move the pointer, a line connects your pointer to the point you clicked. By clicking subsequent points, you'll draw a polygon. (Your drawing does not have to be perfect; you're only estimating the area.)
- Following the roads, click points to draw a tall, slanted rectangular polygon around the point. For the final point, double-click to complete the drawing.
The Measure Area window displays the area of the polygon, although in your organization's default unit of measurement, which is probably either imperial or metric. You'll change it to hectares.
- In the Measure Area window, click the unit of measurement and choose Hectares.
The unit of measurement changes. While the exact number you receive may vary slightly, the area of the polygon you drew is about 3.25 hectares. This area is within the recommended range of 3 to 5 hectares. This area also crosses no rivers and uses roads for all of its boundaries, meaning it's an acceptable enumeration area.
- Close the Measure Area window.
Closing the window also removes your drawing from the map. You'll draw the area again, this time while digitizing a new enumeration area feature.
The process for digitizing a polygon is similar to the process for digitizing a point. Instead of clicking a single point on the map, however, you'll draw the polygon similar to how you drew the measurement area, by clicking multiple points that serve as the vertices of the polygon.
- On the ribbon, click the Edit tab. In the Features group, click Create.
- In the Create Features pane, click the Enumeration Areas feature template.
The default editing tool for this template is Polygon. Other templates provide the option to draw specific geometric shapes or draw freehand. The Polygon tool functions the same way as the Measure tool.
- On the map, draw a polygon similar to the polygon you drew with the Measure tool, using the roads as the boundaries. Double-click the final vertex to complete the polygon.
You've digitized the enumeration area.
- Close the Create Features pane.
- Save your edits.
Remove gaps between areas
The enumeration area you digitized is not adjacent to any other areas. However, the other enumeration areas on the map are. It's important to ensure the boundaries of adjacent areas match exactly. Otherwise, there may be gaps or slivers in your data that can lead to issues in analysis or navigation.
Next, you'll edit the vertices of an enumeration area using snapping to remove a gap.
- On the map, pan to the boundary between the two eastmost enumeration areas.
The boundary looks somewhat irregular. It's possible that there was an error when digitizing these enumeration areas, leading to a gap.
- Zoom in to the boundary.
When zoomed in, the gap becomes visible. Several vertices do not match exactly. You'll edit the vertices so they line up.
- On the ribbon, on the Edit tab, in the Tools group, click Edit Vertices.
The Modify Features pane appears with the Edit Vertices tool. The tool prompts you to select the feature you want to edit.
- On the map, click the southern enumeration area to select it.
The feature's vertices, represented by green and red squares, appear.
Three vertices are misaligned. With the vertices active, you can drag them on the map to move them. But even if you drag them to match up perfectly with the other enumeration area's vertices, the features may be misaligned once you zoom in. To ensure the vertices match exactly, you'll turn on snapping.
As you learned before, snapping causes the points and vertices you create or modify to snap to parts of other features. They're convenient for creating or editing adjacent features.
- On the ribbon, on the Edit tab, in the Snapping group, click Snapping. Turn on Snapping.
Snapping turns on.
The other buttons in the Snapping menu determine the parts of features to which you'll snap. You can snap to point features, endpoints of polygon or polyline features, vertices, edges, intersections, midpoints, or points of tangency. Which snapping settings are turned on or off depends on your default settings and whether you've used snapping before. The only snapping setting you need is the setting to snap to vertices.
- In the Snapping menu, confirm that Vertex snaps to the nearest vertex of a polyline or polygon feature is turned on.
The other snapping settings won't matter for this tutorial, but they may be useful to you in other contexts. Next, you'll modify the vertices on the map so they snap together.
- On the map, drag the eastmost misaligned vertex so that it snaps to the nearest vertex.
Because of snapping, the two vertices match up exactly.
- Drag the other two misaligned vertices so they snap to the nearest vertex.
The highlighted blue line shows the original location of the polygon boundary, while the dashed line shows the new location. The boundary between the two enumeration areas now lines up exactly.
- Close the Modify Features pane. On the ribbon, on the Edit tab, in the Selection group, click Clear.
- Save your edits.
Modify shared boundaries
What if you wanted to edit a boundary shared by two or more features? It's inconvenient to edit the vertices for one feature and then repeat the same edits for the adjacent features. Using topological editing, you can edit the edges and vertices of adjacent features at the same time. Topological editing reduces repetition in a common editing workflow and helps ensure you don't introduce errors such as gaps or slivers when you edit.
You'll use map topology to modify a shared boundary between two enumeration areas.
- Navigate to the Gabon bookmark.
- Zoom to the shared boundary between the enumeration areas at the southern end of the bookmark, near the United Church of Zambia on the basemap.
This boundary is meant to be contiguous with a road, but the boundary doesn't match the road very well. You'll edit the edge using map topology.
- On the Edit tab, in the Manage Edits group, click No Topology and choose Map Topology.
Turning on Map Topology gives you more options when using a tool to modify features. These options involve maintaining the contiguity between adjacent features when editing.
- In the Tools group, click Edit Vertices.
The Modify Features pane appears. You used this pane previously, but now it includes an option to edit edges between features instead of individual features.
- In the Modify Features pane, click the Edges tab.
The pane prompts you to select an edge. The edges of all features on the map are highlighted purple, indicating which edges you can select.
- On the map, click the edge between the two enumeration areas.
The edge is selected. It contains two vertices, one at either end. You'll adjust the position of these vertices to better match the road on the basemap. You'll also add a new vertex to match the slight bend in the road.
For this editing, you'll only want to snap to edges, not vertices, so you'll adjust the snapping options.
- On the ribbon, on the Edit tab, in the Snapping group, click Snapping. Turn off all snapping options except Edge snaps to the nearest edge of a polyline or polygon segment.
- On the map, drag the edge's west endpoint up to the location of the road.
The dashed line shows the location of the boundary based on the moved vertex. It still doesn't match the location of the road because the road bends slightly near the middle. You'll add a new vertex to include this bend.
- Right-click the middle of the dashed line and choose Add Vertex. (If necessary, zoom in.)
A vertex is added at the point you clicked. You can move this vertex like any other vertex. The location to which you want to move this vertex is close to the location of the original line, so snapping may make it difficult to move the vertex to the correct location.
- Turn snapping off.
- Drag the new vertex to the bend in the road, located at the intersection.
The edge now incorporates the slight bend in the road. It's possible to make the boundary even more accurate with the road by adding another vertex, but the boundary you've created is sufficient for the purposes of this tutorial.
- If necessary, zoom out until you can see the entire boundary.
- At the bottom of the map, click the Finish button.
The edit is applied and the new edge is displayed.
Because you turned on map topology, the edit is applied to both of the adjacent enumeration area features. The boundary remains contiguous and there are no gaps, slivers, or other editing errors.
- Close the Modify Features pane and save the edits.
Merge and split features
You've edited features by modifying vertices and edges. Next, you'll merge two features into one and split one feature into two.
- Navigate to the Gabon bookmark.
Some of the enumeration areas in this region don't follow the criteria for enumeration areas. For instance, the two small enumeration area in the middle of the study area are both smaller than the recommended size of 3 to 5 hectares for enumeration areas. You'll merge these areas into one.
- On the ribbon, on the Edit tab, in the Tools group, click Merge.
The Modify Features pane appears. It prompts you to select two or more features that you want to merge.
- On the map, press Shift and select the two small enumeration areas near the middle of the study area.
The pane updates with attributes for the feature that will be created when you confirm the merge. You can edit the attributes in the pane, but the default attributes are fine for this feature.
- In the Modify Features pane, click Merge.
The selected features are merged into a single feature.
The enumeration area directly north of the merged feature is larger than the recommended maximum size of 5 hectares. Additionally, the enumeration area has a river running through the middle of it that may make it difficult for census workers to traverse.
In this instance, it's possible the river is a canal that was built after the enumeration area was created. It's also possible that the enumeration area is so large because the area did not contain as much housing in the past as it does now, or that there is a bridge or crossing that makes it possible to traverse the river. As it stands in the current state, the enumeration area is too large, so you'll split it in two.
- On the Edit tab, in the Tools group, click Split.
In the Modify Features pane, the Split tool appears.
- Click Change the selection. On the map, select the large enumeration area in the northeast corner of the study area.
To split the feature, you'll digitize a line in the middle of it. You'll digitize this line to follow the river in the center of the feature.
- Turn on Snapping.
- On the map, digitize a line that follows the river in the middle of the selected enumeration area. Make sure your line connects exactly to the top and bottom edge of the feature and double-click when the drawing is finished.
If you attempt to split a feature without drawing a line from one edge of the feature to another, the split will not work.
As soon as you finish the drawing, the split is applied.
Both enumeration areas are similar to the size of the other enumeration areas on the map.
- Close the Modify Features pane, clear the selection, and save your edits.
- Save the project.
Throughout this tutorial, you created and edited data related to census workers in the field. You worked with both point and polygon data in ArcGIS Pro and learned how to create a feature class; how to add, move, and delete features; and how to edit vertices. You also used map topology to edit edges without leaving gaps or overlaps. You digitized enumeration areas and split and merged enumeration areas to better adhere to size standards.
Although you learned a lot in this workflow, there are many more editing tools available. You're encouraged to explore some of these tools on your own, and you can learn more about them at Editing in ArcGIS Pro.
You can find more tutorials in the tutorialgallery.