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XY-Plotter

Table of contents

  1. XY-Plotter
  2. Supported File Formats
  3. Visualization option
  4. Visualizing Lines and Areas

Displays arbitrary point data with attributes, optionally also lines or areas, all of them animated over time Requires a file contained coordinates and attributes (see below).

XY-Plotter

The XY-Plotter plots dots, lines or areas at specific locations given in a file (lines or areas are not available in the free version of Via). This layer serves two purposes: First, it allows to quickly visualize and test some data before or after conversion from other formats by simply plotting the points. Just dump some coordinate values into a file and have a look if their distribution makes visually sense and is what you expected. Second, due to its support to also visualize lines or areas, animate the visualized elements over time, and show text labels, it allows for complex data driven animations.

Supported File Formats

A variety of file formats are currently supported:

  • .txt, .xy Text files ending on .xy were traditionally the only format supported by Via. By now, the files can also end on .txt. Such files must contain at least two columns of data, separated with a tab. The first column contains usually the x-coordinate, while the second contains the y-coordinate. Arbitrary attributes can be included in additional columns. The first line can contain the column names.
  • .csv CSV (Comma separated values) files can often be created by spreadsheet or statistics applications. Each attribute, including x- and y-coordinates, should be stored in a separate column. Via supports CSV files that use comma or semicolon as field separator. The first line can contain the column names.
  • .gpx GPS devices often record points in GPX files. Via can load GPX files and extract the coordinates from recorded tracks and waypoints.
  • .xzy A very simple text file with three columns, no column headers, separated with a single space, where the first column corresponds to the x value, the second to y, and the last to a z value of a coordinate. This is often used for digital elevation models (DEM) in geographical information systems.

Visualization option

In the full version of Via, the layer offers a lot more functionality and supports additional attributes for each data point. When adding an xy data source, a dialog containing import options can be shown by clicking the corresponding button in the data sources view. In the dialog, attributes can be selected that should be imported, the name and data type can be specified for each attribute, and it can be specified with columns contain the X and Y values.

The layer settings offer a lot of functionality to work with the additional attributes. For example, it is possible to color the points based on an attribute’s value, or change the symbol or the size of the dot according to an attribute’s value. In addition, points can be displayed only during a specific time window, also based on attributes. If some of the points form a logical group, e.g. points from a GPS track of a single person, and group membership is available in an attribute, it is even possible to interpolate the location of time-dependent points along the time of day.

Visualized data can either be shown using the default spatial coordinate system Via uses to display all the other data as well, or it can be set relative to the viewing area. Using the default spatial coordinate system allows to show labels of places or special features in the simulation, while setting it to be relative to the viewing area allows to display overlay-like status information, e.g. some custom counter in the top-left of the visualization area.

Visualizing Lines and Areas

Via can display arbitrary lines or even areas, loaded from a CSV file or other data source supported by the XY layer. To display lines or areas, your input data needs to contain multiple columns that specify the X and Y coordinates. For example:

X1, Y1, X2, Y2, X3, Y3, ID, SPEED, LENGTH, …

Note the mulitple coordinate pairs X1 / Y1, X2 / Y2, X3 / Y3 in the input data.

In the XY settings dialog, define all the coordinate pairs in the Coordinates section. Next, select Lines & Areas and then select Line along Coordinate and add the coordinates in the order they should be connected with a line, or that should span up the area.

Lines and Areas can also by styled depending on the value of any available attribute.

A short video tutorial is available that explains how to visualize lines and areas with Via.