What is Crayfish?

Crayfish is a plugin (extension) developed by Lutra Consulting for QGIS.

The Crayfish plugin provide extra functionalities to work with mesh data in QGIS.

In addition to rendering data, users can manipulate the temporal data using its built-in grid calcultor.

With Crayfish plugin, users can export their mesh data as an animation, raster or vector and plot graphs.

How to use Crayfish

You can install Crayfish plugin from the QGIS plugin repository. For loading and styling data, see QGIS documentation. Crayfish plugin provides the following functionalities:

Export to animation

You can create animations of the contours and vectors in the Crayfish layers. To generate an animation of contours and/or vectors, first you need to select the layer from QGIS layer tree. In QGIS, from the main menu, select Plugins, Crayfish and Export to animation.

A new window will appear:

• General: to set the output frame size, frame rate, start and end time, output location file. Note that the frame size is only used with the Default layout.
• Layout: Allows user to set layouts using Default or Custom layout
• Video: Set video resolution and path to the video maker software (ffmpeg).

Users have 2 options for setting up video layouts.

• Default layout: for this option, users can set title, time and legend within this sections. For each item, users can set font size, font colour and item's background colour. You can also set the location where time and legend appear on the layout.
• Custom layout (qpt): Using a print composer template gives users options to set very flexible and customised layout. You can add multiple map views, overviews, shapes, etc. in the same way you'd produce a printed output. For output time to appear on the layout, you need to add a text item and set the Item ID under Item properties in the print composer as time.

Plotting data

Users can generate plots of time series at a point or a cross section in Crayfish.

Time series plot (Click to enlarge).

To plot cross sections or time series from an existing line or point vector layer loaded in QGIS, you need to click on From Layer and select the layer first. You can then use the select tool from the main QGIS toolbar to display plot for each feature.

You can change various settings of the plot by right-clicking on the plot area. Crayfish plot also supports export to the following formats: image (png, jpg, etc.), scalable vector graphics and CSV.

Processing algorithms

Under the Projecessing toolbox, you should be able to access several algorithms to export your mesh data to raster or vector. You can also use the Mesh calcultor as a processing toolbox.

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