Tag Archives: Layer

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 of 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 ArcGIS 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)