VAPOR

VAPOR is the Visualization and Analysis Platform for Ocean, Atmosphere, and Solar Researchers. VAPOR provides an interactive 3D visualization environment that runs on most UNIX and Windows systems equipped with modern 3D graphics cards. It has been developed by ​NCAR and is freely available at ​http://www.vapor.ucar.edu.

Official manuals are available ​here (GUI guide) and ​here (rendering).

System requirements

The official VAPOR FAQ say (May, 2018):

• We recommend a minimum of 512 MBs of main memory. VAPOR relies heavily on RAM for caching data in order to improve performance. So the more memory you have, the better the performance, in general.This is particularly true when animating through temporal data.

• A graphics card with 3D hardware texture support and an OpenGL driver that can take advantage of the card are a must. Note that standard Linux distributions come with a generic driver that will work on all systems, but this will usually not give adequate performance. For best performance a driver provided by the graphics card vendor is essential. If you plan to use Linux and have not yet purchased a graphics card, you should check that the card you are considering purchasing has a driver optimized for Linux.

Conversion of NetCDF to VDF data

VAPOR has its own mechanism for storing field data and its associated attributes (metadata). The components of a VAPOR Data Collection (VDC) are distributed across different disk files. All metadata for a VDC are stored in a single .vdf file. See ​here for more information.

Via command-line tools (ncdfvdfcreate, ncdf2vdf), NetCDF data can be converted to VDC format. Please refer to the ​official documentation for details.

Starting VAPOR at IMUK

VAPOR (version 2.4.2) is installed on the Linux server at IMUK and can be started from the terminal:

module load vapor; vaporgui&.

The VAPOR window will appear. In case your graphics card (or your graphics card driver) is inappropriate, you might experience error message when rendering 3D data.

Recommended User preferences & advice

• The user preferences can be opened from the "Edit" menu. We recommend to set the following settings:
  • Cache Size (Megabytes): depending on your RAM, allow VAPOR to block 70-80% of your total RAM.
  • Specify graphics texture size: the performance of VAPOR can be improved by setting a value for the texture size (​see here).

• Save your work regularly! Use the "Save Session" option to save your visualizer settings to file. Our experience is that VAPOR tends to crash from time to time and you will lose all your settings. Saving your settings allows you not only to restore your last session (you just need to load the data manually), but it also allows to visualize several data sets with the same visualizer settings.

• Play! There are unlimited possibilities of presenting your data. Try out different approaches for visualizing interesting features of your simulated flow. Toy around with the lighting setup, transparency, viewing angles etc..

• Flow Rendering: Be careful when using "Field line advection". This type is used to show trajectories of your flow field, but it requires enormous computational time (which can make VAPOR crash). Make sure that "Auto-refresh flow" is disabled and you know what you are doing. It is also a good idea to save your session before using flow rendering.