To ensure that you're dealing with the right information you need a clear view of your data at every stage of the transformation process.
Data inspection meets this need: it is the act of viewing data for verification and debugging purposes, before, during, or after a translation.
In FME Desktop, you can use two data inspection tools: in Workbench via the Visual Preview window, or in a complementary application called the FME Data Inspector. In this course we will discuss both, but will primarily use Visual Preview.
Data Inspection Tools
FME data inspection tools let you view data in any supported format. They are used primarily to preview data before translation or to verify it after translation. You can use them to set up and debug workspaces by inspecting data during the translation.
FME data inspection tools are not designed to be full-featured spreadsheet, database, or mapping applications. They have no analysis or editing functionality, and the tools for symbology modification or printing are intended for data validation rather than producing output.
Visual Preview is an embedded version of FME Data Inspector that displays features in a Workbench window. Many - but not all - of the features available in the stand-alone Data Inspector application are available in Visual Preview. Visual Preview lets you inspect your data directly in Workbench as you build your workspace:
You can view features in Visual Preview in these ways:
Right-click on a reader feature type in the Navigator or Workbench Canvas, and select View Source Data (or View Written Data on a writer feature type):
On the canvas, click the View Source Data icon on the mini-toolbar over a feature type or some transformers (or View Written Data on a writer feature type):
Run a workspace with feature caching enabled and then select cached objects (we'll cover feature caching in the next section):
Drag and drop data files onto the pane:
In this course, we will primarily use Visual Preview in combination with feature caching, as explained in the next section.
Major Components of Visual Preview
The Visual Preview pane has options for toggling on and off several other windows to provide different ways of inspecting your data. You can do so using the buttons on the left side of the Visual Preview pane:
The Graphics window contains a toolbar. Some buttons are for navigating around the View window, some control selecting features, and others are for particular functions such as filtering data:
Display Control Window
The Toggle Display Control button controls the Display Control window, which shows a list of the open datasets and their feature types. Tools here let users turn these on or off in the display, alter their symbology, and adjust the display order:
Table View Window
You can change which table (feature type) is displayed by using the dropdown menu:
Feature Information Window
The Toggle Feature Information window button controls the Feature Information window. When you select a feature in the View window, the Information window shows information about that feature. This information includes the feature’s feature type, attributes, coordinate system, and details about its geometry:
FME Data Inspector
FME Workbench plus the FME Data Inspector (and several smaller utilities not covered here) comprise FME Desktop. FME Data Inspector is a standalone application for inspecting data. It has similar functionality to Visual Preview, but comes with a few more features.
Starting FME Data Inspector
To start the Data Inspector, locate it in the Windows start menu:
Major Components of FME Data Inspector
When FME Data Inspector opens a dataset, it looks something like this:
These components function the same as Visual Preview, with the following differences:
- There is a menu bar.
- The Graphics window is called the View window and can have multiple tabs called Views, each displaying different datasets.
- You can open data (File > Open Dataset), which opens it in a new View, or you can add data (File > Add Dataset), which adds data to the open View.
- Multiple tables (feature types) are still available in Table View using the dropdown menu, but once a new table is displayed, it is also shown as a tab in Table View.
- A few additional tools are available, including Mark Location and Measure Distances.