Frequently Asked Questions

This page contains a list of Frequently asked questions along with the answers to those questions. The questions are listed in no particular order.

Questions:

  1. How do I download the newest version of VisIt?

  2. What do I need in order to run VisIt?

  3. I have a Windows machine. Can I run VisIt?

  4. Where can I find sample data files to plot in VisIt?

  5. How can I access files on a remote computer?

  6. How do I create a plot?

  7. What kinds of data can VisIt read?

  8. I can't get VisIt to recognize that I have a time-varying database. The VCR controls never activate. Why?

  9. How do I report a bug or request a new feature?

  10. How do I know what changed from version to version?

  11. How do I use VisIt with Python?

  12. Is VisIt parallel?

Answers:

  1. How do I download the newest version of VisIt? The newest version of VisIt can be downloaded by anonymous ftp from ftp://ftp.llnl.gov/pub/visit. Just type that URL into your web browser and a list of directories, containing the available versions of VisIt, will appear in your browser. Choose the version of VisIt that runs on your system and download it. You can then follow the installation instructions in the INSTALL_NOTES file.

  2. What do I need in order to run VisIt? VisIt runs on many platforms, including PCs running Windows and Linux. If you plan to run VisIt on a PC, we recommend at least a Pentium III with 128MB RAM and hardware accelerated graphics. VisIt also runs on many flavors of UNIX, including: Linux, IRIX, AIX, and Tru64. Our installations for IRIX and AIX include parallel versions of our compute engine so that VisIt can make use of several processors.

  3. I have a Windows machine. Can I run VisIt? Yes you can. As of version 0.9.10, you can download Windows 2000 version which is complete with an installation program. The executable program that you download extracts its contents to a temporary folder, which is usually C:\VISITTEMP. From there, you can double click on the setup.exe installation program to install VisIt.

  4. Where can I find sample data files to plot in VisIt? VisIt reads a number of common file formats for storing scientific data. This includes but is not limited to Silo, Exodus, VTK, Plot3D, Ensight, and Alias Wavefront OBJ formats. When you download a VisIt distribution, you actually get sample Silo data files to use when trying VisIt out. If you installed a UNIX version and put it in /usr/local, then the data files would be located in /usr/local/visit/data. If you installed a Windows version, let's say version 1.1.4, and it installed in C:\Program Files\LLNL\VisIt 1.1.4\, then the sample data files would be located in C:\Program Files\LLNL\VisIt 1.1.4\data\.You can also create your own data files by writing programs to write data in any of the formats that VisIt can read. You can also write new VisIt database reader plugins if you are interested in having VisIt read your own data file format. For more information on this, send e-mail to visit-developers@ornl.gov.

  5. How can I access files on a remote computer? Open the file selection window and type the name of the computer that you want to access into the "host" text field. Doing this will launch part of VisIt on the remote computer and allow you to access your files. Note that doing this sometimes requires you to type in a  password.

  6. How do I create a plot?In order to create a plot, first you must open a file. This is done by selecting a file from the file panel area of the main window and clicking the open button. Next, click on the plots menu in the middle of the main window and choose a plot type and a variable for that plot type. Once you've made your selection, release the mouse button and the plot will be added to the plot list. Finally, click the Draw button to get the plot to draw.

  7. What kinds of data can VisIt read? VisIt can read and operate on scalar, vector, and material data that is stored in a variety of files formats. The file formats that VisIt currently understands are: Silo, Exodus, Ensight Gold, VTK, Plot3D, Alias Wavefront. VisIt also reads certain formats of ascii text files. If you want to have VisIt read your data, you can write a database reader plugin.

  8. I can't get VisIt to recognize that I have a time-varying database. The VCR controls never activate. Why? You know that those files are part of a time-varying database by the file naming convention that you used. VisIt can guess using the automatic file grouping feature, which is new in version 1.1.3, but it may guess incorrectly. You can either use automatic file grouping and provide a suitable file filter to remove any files that don't fit your naming convention, or you can create a .visit file. A .visit file is a text file that contains a list of file names (one per line) where each filename corresponds to one time state in your time-varying database. When you open a .visit file, VisIt knows that you are trying to open a set of related files and it works without any guessing.

  9. How do I report a bug or request a new feature? You can let us know about bugs or ask for feature enhancements by sending e-mail to visit-users@ornl.gov.

  10. How do I know what changed from version to version? We provide release notes with VisIt which give details on what we fixed or added for a release. You can read the release notes by selecting the Release notes option from the Main Window's Help menu.

  11. How do I use VisIt with Python? There are two ways of using VisIt with Python. The first way is to use VisIt's cli program, which is actually a Python interpreter with VisIt extensions. To invoke the cli, type "visit -cli" at the command line prompt. The cli launches VisIt's viewer and then drops back into a regular Python command line session in which you can do any sort of Python processing. If you have a Python script that you want to run, you can also type: visit -cli -s filename, where filename is the name of the Python script that you want to execute. Another way to run VisIt in Python is to import the visit module by inserting "import visit" in your Python script. This method is not widely supported because we cannot be sure which version of Python is used on your system. There are also issues with VisIt being able to find its support libraries when running in it in this manner.

  12. Is VisIt parallel? The short answer is yes. In fact, most VisIt components are serial applications, with the exception of the parallel version of the compute engine. The compute engine is the VisIt component that does all of the hard data processing work and it can be run on as many processors as are available. This comes in handy when you want to run VisIt on your desktop but connect to a remote machine where you want to run the compute engine in parallel to process a large database quickly. We designed VisIt to leverage remote compute power of large parallel computers with the interactivity of local desktop machines with fast graphics hardware.