Tag Archives: Edit
Cleaning up line data with geoprocessing
Editing and data compilation are less commonly thought of as operations that can be automated through geoprocessing. However, ArcGIS 10 introduced the Editing toolbox, which contains a set of geoprocessing tools to perform bulk edits. These tools combined with others in the geoprocessing environment can automate data import and maintenance work. Automated data compilation tools are especially useful for importing data into a geodatabase but can also be employed on a regular schedule to perform routine quality assurance (QA) checks. In this entry, I will discuss the use of geoprocessing to clean CAD line data as part of the import process.
Importing data with geoprocessing
Lines that are created without the use of spatial integrity measures, such as snapping or topology, almost always contain some inconsistencies. These errors are likely in data that originated in formats such as CAD, shapefile, or KML. Fortunately, many common topological issues can be resolved in an automated manner by using ModelBuilder to link together tools that will import data into a geodatabase and perform standard data cleanup techniques.
I have a CAD file for a new subdivision that needs to be integrated with my existing GIS parcel data. The GIS data must be kept to stringent accuracy standards, so I need to fix any issues where lines do not connect to each other, overlap, or are duplicated. Rather than risk reducing the quality of the main parcels geodatabase, I can create a local temporary geodatabase where I can preprocess the CAD lines before introducing the features into the production geodatabase. Although the CAD file contains buildings, roads, text, registration tic marks, and other features, I plan to use only the parcel lot lines.
I have built a model that imports the CAD lines into a temporary scratch workspace, cleans and processes the lines, and then copies the corrected lines into an output file geodatabase. When importing CAD data into a geodatabase, I can choose from several available tools, including CAD to Geodatabase or Feature Class to Feature Class. The CAD to Geodatabase tool converts all the geometries in a drawing to individual feature classes, such as a line feature class for the parcel lines, annotation feature class for CAD text, and so on. In my case, I am using Feature Class to Feature Class tool because I need only the lot line geometry from the CAD file. This tool makes the model reusable because it can import many different formats and not simply CAD. In addition, the Feature Class to Feature Class tool allows for an SQL expression so I can further refine the import to include only the CAD features that satisfy an attribute query for lot lines (in this case, “Layer” = ‘LOT-L’).
Performing automated quality assurance on lines
Once the CAD parcel lot lines are imported into a geodatabase feature class, I can begin running tools to perform automated QA processes. Many tools are found in the Editing toolbox, although other toolboxes can be purposed for data compilation QA tasks. For example, I can start by using the Integrate tool in the Data Management toolbox to address minor inconsistencies in the line work. Integrate makes features coincident if they fall within the specified x,y tolerance. By using a small tolerance on Integrate (and other similar tools), I can avoid editing the data beyond the level of cleanup I intended. In addition, since I am running the tools on a copy of the data outside my production database, I can run the tools repeatedly to refine tolerance values to fix more issues in an automated manner. The intermediate data created as the model runs is maintained and can be reviewed in the scratch geodatabase.
After the dataset is integrated, I check for duplicated lines with the Delete Identical tool (Data Management toolbox). The dashed lines connecting to this tool represent preconditions, which are used to control the order of operations in a model. For example, the Integrated Lines output is a precondition to the Delete Identical tool. This way, the Delete Identical tool will not execute until the lines have been integrated.
The next part of the model identifies lines that are dangles. With the Feature Vertices to Points tool in the Data Management toolbox, I create a new point feature class containing the line endpoints that are not connected to any other lines. I can then use Select Layer By Location to identify the lines that intersect these dangling endpoints. The resulting selection represents lines with dangles.
Many of these dangle errors can be fixed by running the Editing toolbox’s Trim Line, Extend Line, and Snap tools. Effective use of the Editing toolbox geoprocessing tools can improve productivity because the tools apply edits in bulk, such as to all features or all selected features. In most cases, the similar editing function applies to only one feature at a time. Because I exposed the tolerances as variables and model parameters, I can easily run the model with different values because the tolerance settings appear as input boxes on the tool’s dialog box. For example, I am willing to extend or trim the lines from this CAD dataset initially up to a maximum length of five feet. After that procedure, I want to inspect the lines visually to see how many issues remain to ensure that I will not be making incorrect edits if I increase the tolerance value. I can change the tolerance as needed depending on the accuracy of the lines I am importing.
In addition, since my organization’s spatial integrity rules indicate the parcel lines should be split and not intersect themselves, I can use a sequence of spatial and attribute queries to find the locations where lines have intersecting endpoints. Lines are often split so that each length can be attributed separately.
Once these processes have run, the lines are output into a feature dataset in a geodatabase and are much cleaner topologically. After the model completes, I can run the Feature Vertices to Points tool again on the cleaned output to see the remaining dangles and compare the current number of endpoints that are dangles (the yellow circles in the graphic) to the number in the original CAD lines (the red circles). While there may be a few remaining issues, there are less than before running the model. At this point, I can build a geodatabase topology to check for and repair any other errors. When I am satisfied that the lines meet the standards for our spatial data, I can import it into the production database.
For more information:
The sample tools and data can be downloaded from the Editing Labs group on ArcGIS.com. An ArcInfo license in required to run the tools.
Editing tips and tricks: Part 2
This is part 2 of tips for editing with ArcGIS 10. This content comes from a User Conference session presented by the Editing Team at the 2011 conference. For tips 1 – 5 see this this post.
6. Trace edges when cutting polygons.
The current park design is landscaped with shrubs along the entire western border. However, I want the area to be three different types of vegetation, each separated by a foot path. I draw features for the new path lines first so I can use them to split the large polygon. Then, I select the polygon and click the Cut Polygons tool, change the construction method to Trace on the Feature Construction toolbar, and follow along the edge of the overlapping foot path feature. I need to make sure that the trace goes all the way across the polygon so the cut is successful. When I finish the sketch, the polygon is split and its edge exactly matches the shape of the path.
Another method I can use to split the shrub patch polygon by the overlapping foot path line is to snap to the edge of the polygon, right-click directly over the foot path line, click Replace Sketch, and finish the sketch. Replace Sketch pulls the shape of the underlying feature into the sketch used to cut the polygon.
7. Change attributes for multiple features in the Attributes window.
With the shrub patch polygon now split into three features, I want to make two of them flower beds by using the Attributes window to change the landscaping type. To update just two of the three selected polygons, I hold down CTRL and click the feature entries (listed by display expression) at the top of the window, then change their landscaping from Shrub Patch to Flower Bed. If I click the layer name, all selected features are updated; clicking just one feature updates just that feature’s values.
8. Extend lines by sketching with the Continue Feature tool.
The new foot path across the western landscaping needs to be extended eastward across the open space so it connects with another foot path. I can use the Continue Feature tool to extend a line by drawing a sketch. Since the path was digitized from the west originally, I flip the direction of the line so it will be extended toward the east instead. Continue Feature is available starting with ArcGIS 10 Service Pack 2, but must be added to a toolbar from the Customize dialog box because it is not on the default user interface.
9. Use Find Text to provide the text for annotation.
With my park features placed on the map, I want to add some annotation to describe them. To make the text string for a new annotation feature come from the attributes of an existing feature on the map, I can use the Find Text tool on the Annotation Construction window. For example, I click Find Text, click a recreational polygon, and it populates the text box with Athletic Field from the attributes of the polygon. This saves me from typing words manually.
10. Use the Topology toolbar to update multiple features at once.
I want to expand the area of vegetation around the recreational area so it goes closer to the eastern sidewalk of the park. This edge is shared by flower bed polygons, a foot path line, and open space polygons. I can build a map topology to make edits to all these features at the same time, including moving edges, reshaping edges, and modifying the vertices on the edges. I select the shared edge with the Topology Edit tool and use the Reshape Edge tool to update simultaneously all the features that share the common boundary.
The Shared Features window lists which features are part of the selected edge. By default, all shared features are updated when an edge is modified; I can exclude features from edits by unchecking the boxes next to the feature. Once I reshape the edge, the features are still coincident.
If I attempt to perform this edit with the Reshape Feature tool on the Editor toolbar, only one feature is updated at a time and gaps and overlaps will form among my features. With Reshape Edge, they are all modified together. Be sure to use the topology editing tools when making edits to features that share edges.
For the slides from this User Conference session click here.
Content provided by Rhonda from the Editing Team
Editing tips and tricks: Part 1
3. Set a feature template’s default attribute values.
Editing representation marker symbols in ArcMap
By Jaynya Richards, Esri Research Cartographer
Modifying existing representation marker symbols in an ArcGIS style is easier than you’d think. Follow along to learn how you can do this, too. Start with any of the Esri styles that don’t already contain representation markers, like the NPS style that we have blogged about on Mapping Center. Make a copy of the style for backup. Continue reading
Preparing a map for editing: Using basemap layers effectively
When editing, you can incorporate basemap layers into your map to increase productivity. If you have a complicated map, such as a water utility network containing many detailed features and underlying background layers, you can spend a lot of time waiting for the map to refresh whenever you pan or zoom. With ArcGIS 10, you can minimize this by creating a basemap layer containing the contextual reference layers that you are not editing, such as imagery or streets.
A basemap layer is a special type of group layer that is drawn using optimized map display logic that utilizes a local cache to refresh the map quickly. Basemap layers also help reduce network traffic since ArcMap does not need to contact the server repeatedly to retrieve the map extent. To create a basemap layer, right-click the data frame name in the table of contents, click New Basemap Layer, and drag the layers into it. Although a basemap layer can contain any layer format, such as feature classes, shapefiles, Web services, or rasters, some content types are more appropriate for use in basemaps. This post shows you how to identify layers suitable for basemaps, use the editing environment with basemaps, and improve your basemap performance.
Choosing the layers to be in a basemap layer
To use basemap layers effectively, they should truly form a basemap beneath the layers that you are editing. If you edit data for a water district, your operational layers, such as manholes, water main lines, and valves, cannot be part of a basemap layer because you need to edit them and have the features be drawn dynamically to access the latest updates from their data sources. However, any supporting reference layers that you normally display underneath the utility data can be placed in a basemap layer for enhanced performance. For example, you could include a land base of parcel boundaries, buildings, streets, and other built features, as well as imagery layers, in one or more basemap layers. The layers in the basemap look the same as they did before; they just draw faster now. Here is an example table of contents showing the kinds of underlying layers that could be basemap layers.
Basemaps tend to be relatively static and typically are updated on an infrequent basis. Rasters and service layers are good candidates for basemap layers because they are stable and can benefit greatly from improved drawing speed. ArcGIS Online, for example, provides imagery, topography, streets, and other content from several different sources that you can use in your maps. If you click the arrow next to the Add Data button and click Add Basemap, you can add layers from ArcGIS Online directly into a new basemap layer.
Editing when basemap layers are in the map
Because basemap layers are cached, there are limitations on what you can do with them. For example, you cannot edit the layers in a basemap or change the layer symbology. If you need to make edits or layer updates, drag the layer out of your basemap, make the changes, and drag the updated layer back into the basemap layer.
If you attempt to start an edit session with an editable layer in the basemap, ArcMap shows you a warning message. You can edit all the other layers in that workspace, but you cannot edit the layers in the basemap even if they belong to the same geodatabase. If the basemap contains any layers that are related to other editable layers through relationship classes, topologies, geometric networks, or parcel fabrics, or shares data sources with layers outside the basemap, you cannot start editing at all until you move the layer out of the basemap. You can double-click an entry in the Start Editing dialog box to open an ArcGIS Desktop Help topic containing more information on how to fix these and other issues that occur when you start editing.
Although you cannot edit the layers inside a basemap, you can snap to feature layers in a basemap layer. For example, if you were creating a new waterline in relation to building locations, you can still snap to the Building Footprints layer even though it is inside the basemap.
Improving basemap layer display and performance
With basemap layers, you can pan continuously and smoothly by pressing the Q key or holding down the mouse wheel. The rest of the map layers are redrawn once you release the key or the wheel button. If you find that the layers on top of the basemap are difficult to see, you can dim the display of the basemap using the Effects toolbar. This makes the basemap appear washed out and partially transparent, helping your operational layers stand out more. This can be useful for editing, especially in cases where your basemap layers contain orthographic images or other richly colored content that may obscure the details of layers on top of them.
Once you create a basemap layer, you can run diagnostic tests to check its performance. You can do this by right-clicking the basemap layer and clicking Analyze Basemap Layer to display a window listing ways you can speed it up even further. You might see messages indicating that the layer is being projected on the fly or uses complex symbology, which can slow down drawing. For example, the message “Layer draws at all scale ranges” is a suggestion to set a visible scale range on the layer since there is no need to display the layer when the features are too detailed or too coarse at certain map scales. You can right-click an entry to open the Layer Properties dialog box, where you can resolve many of the issues to get the most out of basemap layers.
Data used in the examples is modified from the Water Network Utilities Template by Esri and Fort Pierce, Florida.
For more information, see Working with basemap layers and About edit sessions in the ArcGIS Desktop Help.
3D Analyst at 10
3D Analyst 10 makes ArcGIS a complete system for 3D GIS.
That is a big statement so let me explain. Not only can you view your geospatial data in 3D Analyst, at 10 you can edit your data in 3D and analyze your data in 3D. Now that is pretty huge. Most companies focus on 3D visualization of geospatial data and some are very good at it. However you can only look at your data on a globe for so long. After awhile, the WOW factor starts wearing off and you’ll want to edit and analyze your data in 3D. This is what makes 3D Analyst different from 3D viewers.
So what does that mean: Edit in 3D and 3D Analysis?
We have enabled the standard ArcGIS editing environment inside both ArcGlobe and ArcScene. You can create and delete individual features, move, rotate, scale and replace feature geometry. This includes the ability to place 3D models (e.g.: COLLADA files) directly into the 3D view as new multipatch features, and then move / scale / rotate them on the landscape. All the standard editing options – Undo, Redo, Edit Templates, etc – are supported, as is the classic Snapping environment.
We’ve also made huge improvements in the analysis of 3D vector features. We have added 3D boolean operators such as Intersect 3D, Union 3D, Difference3D and Inside 3D to be used with closed multipatches, new GP tools that expose 3D vector analysis specifically for virtual city workflows, such as Skyline and Skyline Barrier and enhanced existing GP tools to work better with 3D – ‘Select by Location’ dialog uses 3D distances, multipatch objects can participate in the Line of Sight tool.
edit in 3D Analyze in 3D
So what does this all mean?
It means that 3DAnalyst 10 is a big leap forward for the handling of 3D GIS data. Not only can you view huge volumes of your data in 3D, you can edit your data in 3D, analyze it in 3D and easily share it with your colleagues or the public.
That sounds great but what can you actually do with it?
I’ll get into that in more detail next time.
Gert van Maren
3D Product Manager
Using snapping effectively in ArcGIS 10
Snapping allows you to create features that connect to each other so your edits are more accurate, with fewer errors. In ArcGIS 10, you can choose from one of two snapping environments to use when you are editing. The default is the new Snapping toolbar, which is flexible, easy-to-use, and has more snapping types, more options, and better feedback. Alternatively, you can enable classic snapping, which provides fine-grained control over the snapping environment. This post provides an overview of each environment, so you can decide which one allows you to get your editing done most effectively.
Snapping toolbar (the default snapping environment)
The Snapping toolbar is the central location where you manage the snapping settings. There is minimal setup required, since the most common snapping types are enabled by default. The Snapping toolbar environment is used by the editing tools, but is also available outside of an edit session and is used by other parts of ArcGIS, such as georeferencing and the Measure tool. Snapping is also part of ArcGIS Engine, so you can build custom applications that utilize snapping.
Snapping is managed at the map level, so whenever a snap type is turned on, you can snap to any visible feature layer. This also includes layer types that are not editable, such as basemap layers or CAD files. You cannot snap to features that are hidden from the map, though, including when the layer is turned off, has a definition query (visible features in the layer can still be snapped to), and is beyond the layer scale range. Snapping is useful when creating new features or when editing existing ones, such as by reshaping edges, splitting lines or polygons, moving features, or editing features in a topology.
The Snapping toolbar has buttons to enable snapping to points, edges, vertices, and ends, which are all on by default. The order in which snapping occurs to certain types is determined automatically; the highest priority is given to snapping to sketch elements. To turn on or off individual snap types, click them on the toolbar. If you want to stop snapping temporarily, hold down the space-bar. To turn off snapping altogether, uncheck Use Snapping on the Snapping menu.
To set options for working with the ArcGIS 10 snapping environment, click the Snapping menu and click Options. From there, you can set the snapping tolerance in pixels, which is the distance your pointer needs to be from a feature for snapping to occur, or customize the snapping feedback. As you move your mouse pointer, you get visual cues in the form of pop-up SnapTips and the pointer icon to tell you the layer you are snapping to and with which snapping type. You can change the color of the icon and the content, font, and color of SnapTips. When you are working over imagery, add a background to the SnapTip to place a solid fill behind the text so it is easier to read. Your snapping settings apply to all your ArcMap sessions since they are saved in the registry for the application.
Each snapping type (vertex, edge, endpoint, intersection, and so on) has its own pointer icon, which matches the buttons on the Snapping toolbar. For example, the pointer is a square with lines inside it when you are snapping to an endpoint and becomes a box with diagonal lines when you are snapping to an edge. In the following example graphics showing streets and parcels, you can see the SnapTips with the layer name and the snap type. When creating a new road, snap to the existing endpoint (Streets: Endpoint) so the segment connects to it. If you need to create a building footprint at a parcel boundary, snap to the Parcels: Edge.
On the Snapping menu, you can enable snapping to an intersection, segment midpoint, or curve tangent point. These additional snap types are only available with the new snapping environment. For example, intersection snapping allows snapping to locations where two features intersect but there may not be any defined vertex or endpoint there. You might use intersection snapping when you are adding points at street intersections or dividing a feature where it meets another feature. If you need to split a park where a stream crosses it, you can turn on intersection snapping, then select the park polygon, click the Cut Polygons tool on the Editor toolbar, snap to the first intersection, and use Trace to follow along the stream’s edge. When you have traced across the park, snap to the other intersection and finish the sketch to cut the park into two features.
Since you can snap to any visible features in a layer, you may need to spend some time authoring your map. If you find you are snapping to layers you don’t want to snap to, make sure you need that layer to be displayed in the first place. By turning off unnecessary layers, disabling certain snap types, setting layer scale ranges, and making sure your labels and symbols are as descriptive as they can be, you can use the Snapping toolbar more effectively.
Classic snapping
Classic snapping is the snapping environment that you may be familiar with from ArcGIS 9. Classic snapping is available to you in cases where you need more control over the way snapping occurs or if you are working with a part of ArcGIS that uses only classic snapping, such as tracing with the ArcScan for ArcGIS extension and editing in ArcScene and ArcGlobe. When classic snapping is enabled on the Editing Options > General tab, editing tools only use the classic snapping environment. However, georeferencing tools, the Measure tool, and other non editing tools continue to use the snap settings on the Snapping toolbar.
Classic snapping allows you to manage the individual snapping types, layers, and priorities. In classic snapping, snapping settings are specified for each layer and type (vertex, edge, or end) in the Snapping Environment window, which you open by clicking the Editor menu, pointing to Snapping, and clicking Snapping Window. No snapping occurs until you check some boxes in the window. You can drag and drop layers up and down the list to change the snapping order; layers at the top will be snapped to before layers further down the list. To snap to points, check the Vertex box since there is no specific point snap type in classic snapping.
To set options for classic snapping, click the Editor menu, point to Snapping, and click Options. From there, you can change the snapping tolerance in either pixels or map units and turn on SnapTips, which are off by default. SnapTips with classic snapping cannot be customized (they will always show the layer and type) and are opaque yellow, rather than the semitransparent SnapTips available with the Snapping toolbar. The setting for enabling classic snapping is stored in a map document; its options are saved in the ArcGIS registry.
Enabling classic snapping is most useful for complicated maps with lots of overlapping layers. When working with complex utility data, for example, classic snapping may be beneficial because you have many features in one location, but need to snap easily to a particular feature and in a certain order. If you are creating water mains, you could move that layer up in the list so new mains snap to existing mains first and set whether they should snap at vertices, edges, or ends. Since utility data often has many point features, you can reorder the point layers in the list so new lines connect to certain points, such as system valves or hydrants, before they snap to other types of point features. If you do not want to snap to a particular layer at all, uncheck it from the list. However, features not visible because of definition queries can still be snapped to when you are using classic snapping.
This kind of fine management of the snapping environment is only possible with classic snapping. However, this also takes a lot of work to maintain and set up, considering that each layer in the map is listed in the window and has three separate boxes to check. So, if you are trying to snap to a feature but no snapping occurs, you have to sort through a potentially lengthy list of layers and checkboxes to enable the snapping. With the Snapping toolbar, snapping is on for all layers.
Summary
Each snapping environment has trade-offs of ease versus control that you need to evaluate. Some users have reported that they were skeptical of the Snapping toolbar at first and immediately went back to classic snapping because they were familiar with it, but eventually spent time using the Snapping toolbar and loved it. The Snapping toolbar might take some time to get used to, but its simplicity and power should meet the needs of most editing tasks. However, you can switch between the snapping environments at any time on the Editing Options dialog box so you can use the one that is most appropriate for your current work.
Data credits:
Data used in the examples is from the Water Network Utilities Template by Esri and Fort Pierce, Florida.
For more information:
About snapping
About the editing classic snapping environment
Content provided by Rhonda (Editing Team)
Preparing a map for editing: Setting layer properties
To get the most out of editing in ArcGIS 10, use the
Layer Properties dialog box to (1) prepare symbology, (2) simplify attribute
fields, and (3) set a display expression. Doing these things for each layer you
plan to edit can help make your data compilation tasks easier and
straightforward. This post walks you through setting up a parcels land-use
layer so you can create and edit features in it.
Preparing the layer’s symbology
The Layer Properties > Symbology tab allows you to set the symbols
used to draw the layer. Since feature templates are based on the symbols used
in the map, be sure to symbolize your layers appropriately before you start
editing for the first time on a map since ArcMap creates feature templates for
you then, or anytime you create feature templates yourself. If you change the renderer
type after you create feature templates, you will end up with templates that do
not reflect the features you want to create.
When creating features, you should use either the Single Symbol or
Unique Values renderer. If you are symbolizing with unique values, make the
labels for your symbols meaningful, as the symbol labels become the names for
the feature templates. For example, the parcels layer has symbol category
labels taken from the raw attributes of AGR, COM, IND, RES, and UNK, which are
shortened versions of various types of land-uses. Expanding the text of the
symbol labels to Agricultural, Commercial, Industrial, Residential, and Unknown
will reduce the cleanup needed on your feature templates after they are created
and help other editors understand which features they are creating. The symbol
labels are also used in the entries in the table of contents and the map layout
legend, so there are additional reasons to do this. These graphics show the
Layer Properties > Symbology tab and the resulting feature templates in the
Create Features window.
When there is a problem with the symbol for a feature template, the
Template Properties dialog box displays an exclamation point icon in the
preview area. The template is also shown in the Create Features window as a
silver layer icon, rather than the symbol that will be assigned to the new
feature. This often happens when the symbology was changed dramatically after
the feature template was created, such as switching renderers or symbol
categories. If this occurs, look at the feature template’s default attributes
to ensure they match the current symbology or symbol category. You can also
simply delete the template and re-create it to synchronize the symbols.
Simplifying the attribute fields
When you look at your parcels layer in the Attributes
window, by default, all the fields are displayed in their original order and
with their names as they appear in the data source. The field names are hard to
read and understand since they use capital letters and underscores because
spaces are not possible in the actual field names. Fields that you cannot even
edit are displayed, which makes it harder to find the fields you want. This is
a lot of junk content to wade through when you want to edit these attributes! This
layer could benefit from some work on the Layer Properties > Fields tab.
The Fields tab is the central place for you to set up the
display properties of fields. Spending time organizing fields makes your
editing and overall ArcGIS experience more productive because the settings are
used throughout ArcMap, including in the attributes table, the Attributes
window, and the Identify window. In addition, they are maintained when you
share layers with others through layer files, layer packages, map packages, and
Web services.
The left side of the Fields tab contains a list of all
the fields in the feature class or table, including any fields that have been
joined to it. If you have a long list of fields but only plan to edit the
attribute values for a few fields, hide the ones you do not need to by
unchecking them in the list. For the parcels layer, you might be only
interested in seeing information about the land-uses and the IDs, so you can turn
off nearly everything else. To save even more space, hide system fields that
ArcGIS does not allow you to edit anyway, such as the Object ID, Shape, Shape_Length,
and Shape_Area. This does not delete the fields; it simply turns them off to
make it easier to access the fields you want. Many dialog boxes have option
buttons that allow you to view all fields in a layer if you need to see them
again temporarily.
The order of the fields list is the default order in
which they are displayed throughout ArcMap. You can change the order to promote
to the top of the list the fields you use most often. To reorder a field, click
it in the list and drag it to the position you want, or click the arrow buttons
to move it up or down the list. You can also select multiple fields and reorder
them at the same time. With the parcels layer, move up the IDs and land-use
code fields since you plan to edit them.
When you click a field in the list on the left, the individual field’s properties are displayed on the right side o
f the tab (the
right side will be blank when you have multiple fields selected). You can change
the properties that are shown in the Appearance section, which specify how the
contents of the field are displayed in ArcMap, but not the system information
under Field Details. When you click a row on the right side, an explanation of
the property is provided in the box at the bottom of the tab.
In the Appearance section, you should give your fields
aliases to specify an alternate field name that is descriptive and user-friendly.
Field aliases do not have to adhere to geodatabase naming conventions, so
aliases can have spaces between words or be as long as necessary. For example, for
the field, “LAND_USE,” set the field alias as, “Type of land-use.” The alias is
a lot simpler to read and understand than the source field name.
You can also set a field to be read-only, which means you
can view but cannot edit that field, regardless of the file or database
permissions. This is useful when you need to see the value of a field for
context, but do not want to inadvertently update its value. If you want to
distinguish certain fields-for example, to make them easier to see when editing
in the Attributes window-set the Highlight property to Yes. This will add
background shading so those fields will stand out from the others.
After a little cleanup, the list is a lot easier to
manage and edit. Only the most useful fields are shown, with clearer alias
names and a more appropriate order.
Two of the most popular requests on the ArcGIS Ideas site, where you can submit and
vote for A
rcGIS software enhancements, are the ability to rename fields and
reorder them after they have been created. Although this functionality may not
be available in the underlying database, you can get the same result by
authoring your map and setting the field properties.
You should follow these guidelines when working with
stand-alone tables, since the field properties are used with tables, too. If
you create a relationship class to relate a table of landowner information to
the parcel layer, you can navigate through the related records to edit the
landowner table in the Attributes window. If you turn off unwanted fields, reorder
fields, and set other properties in the landowner table, it will be easier to find
and edit the table’s values, too.
Setting the display expression
The display expression is new with ArcGIS 10 and is found
on the Layer Properties > Display tab. Setting the display expression
ensures that the most useful information is displayed when representing a
feature in the Attributes window, the Identify window, in HTML Pop-ups, and
other places across ArcGIS. The display expression can simply be the contents of
a field by itself, which is similar to the primary display field from previous
releases. However, the display expression is more powerful because you can
customize the text. This allows you to enter your own text or combine the
contents of multiple fields. For example, you could write an expression that
would include the text, “Land-use type:” before the field value. This would be
entered on the Display Expression dialog box as, “Land-use type: ” + [Land-use
field name].
When editing, the display expression makes it easier to
navigate the Attributes window tree. Stand-alone tables have a display
expression property, so setting it on the table can help when viewing related
records, too. The display expression is also shown in the Edit tool selection
chip, which is a small pop-up that appears on-screen to help you select the
correct feature when you click multiple overlapping features with the Edit
tool. For example, you are trying to select a road that overlaps a parcel
polygon. If you click the road, the selection chip appears, allowing you to
choose whether to you want to select the road line or the parcel polygon.
Content provided by Rhonda (Editing Team)
Preparing a map for editing: Assembling the data to edit
It’s a good idea to spend a little time preparing your map for editing. You’ll be a lot more productive and save clicks if you set up your map and data before you really get in and make edits. This post is part of a series on the subject.
Choosing where to store your data
ArcGIS allows you to create and edit several kinds of data. You can edit feature data stored in geodatabases and shapefiles, as well as various tabular formats. When gathering your data in preparation for a geographic information system (GIS) project, make sure all the data you want to edit is stored in the same workspace, which is a single geodatabase or a folder of shapefiles, since you can only edit one workspace at a time. If you are still using shapefiles, consider migrating to a geodatabase, such as a file geodatabase, which provides more functionality and storage capacity with as much speed and simplicity as shapefiles. You can use the geoprocessing tools for importing and exporting data, as well as often simply copying and pasting feature classes in the Catalog tree, to get data into a geodatabase.
With the Catalog window now embedded in ArcMap, you can perform data management tasks and access your data without having to open the separate ArcCatalog application. This is useful in itself, but a few additional settings can make your use of the Catalog window even more productive. For example, the directory where you save a map document is tagged as the Home location and is always promoted to the top of the Catalog window when that map is open. Therefore, if you put the geodatabase in the same folder as the map document you are working on, you can quickly find your data in the Home location without having to navigate through the whole folder tree. Doing this also keeps your GIS project better organized since all the data, maps, and other supporting materials are in the same place. In addition, you can set your geodatabase as the map’s default geodatabase (right-click it in the Catalog window and click Make Default Geodatabase) so any outputs will be saved in that location automatically.
Choosing the projection for your data
As you compile your data, you need to consider the projections. First, you should make sure the feature classes that you will be editing all have the same coordinate system. In addition, if you have data in a geographic coordinate system, you may want to change to an appropriate local projection. This will improve accuracy when editing and make it easier to enter lengths and other measurements since values are specified in the map units of the coordinate system by default. For example, if your map uses the geographic coordinate system of WGS 1984, when you are editing, ArcMap interprets any entered values as decimal degrees because those are the map units for that coordinate system. So when you type 100 for the length of a segment, as shown below, ArcMap interprets that as 100 degrees and will likely present you with a series of error messages. On the other hand, with a projected coordinate system, the map units will be in a more useful unit, such as meters or feet. Also, a projected coordinate system is flexible because it allows you to specify distances in units other than the map units by including an abbreviation with the value; you can only enter values in the coordinate system’s map units (typically, decimal degrees, as just discussed) when working with a geographic coordinate system.
The coordinate systems of the layers also need to match the coordinate system of the data frame. If the coordinate systems of the data frame and layers are different, the layers will be projected on the fly to the coordinate system of the data frame. Projecting on the fly can be problematic because it may cause unexpected alignment issues when making edits. For example, when editing, you may digitize some lines that look like they connect to other lines. While the lines appear to be snapped to edges when projecting on the fly, the lines may be dangling when you display them in their native projection. In addition, you cannot perform shared editing of coincident features through a map topology for layers that are being projected on the fly.
To avoid all these issues, make sure you are not projecting on the fly while editing. When you have an empty data frame, it automatically takes on the 
coordinate system of the first layer added to it. To change the data frame’s coordinate system, right-click the data frame name in the table of contents, click Properties, then click the Coordinate System tab. In the Select a coordinate system box, you can quickly set the coordinate system of the data frame to match that of a layer in it by clicking the Layers folder and navigating to the coordinate system listed underneath one of the layer names. Since the coordinate system of the data frame and the layers will now match, the layers will not be projected on the fly.
Starting an edit session
When you are finally ready to edit your data, turn on the Editor toolbar (if it’s not already displayed), click the Editor 
menu, then click Start Editing. This begins an edit session, which you will end when you are done. When you start an edit session on a geodatabase workspace, you have the ability to edit all the feature classes and tables in that geodatabase at the same time. With an edit session on a shapefile folder workspace, you can edit all the shapefiles that are stored in that directory.
If you start editing in a map that contains data from more than one workspace, you are prompted to choose the workspace you want to edit. On the dialog box, click a layer at the top to select its workspace source at the bottom of the window (notice that the database symbols change color), or click a workspace at the bottom of the window to view the layers in it at the top. Once you have picked the workspace, click OK to start the edit session. Later, if you need to edit data in the other workspace, stop editing, then start a new edit session and choose that workspace. Keep in mind that you can also right-click a layer in the table of contents, point to Edit Features, then click Start Editing, which automatically starts an edit session on the entire workspace containing that layer.
Once you choose the workspace to edit, sometimes you may see another dialog box appear about problems that ArcMap encountered when you started editing. This dialog box will list the layers that are being projected on the fly, as well as any other issues such as missing licensing, layers that cannot be edited because they are read-only or inside a basemap layer, and so on. You can double-click each message to open a help topic with more information.
For more on the Catalog window, projection considerations, and edit sessions in ArcGIS 10, see the following:
What’s new for accessing your data in ArcGIS 10
About editing data in a different projection (projecting on the fly)
About edit sessions
