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Wasmer Consulting - NMPlot - User's Guide - Creating Movies


NMPlot User's Guide, Chapter 19: Creating Movies

Using NMPlot, you can create a movie from a group of grid files. The movie's frames consist of plots of your grid files.

As an example, consider the high temperature on January 1 of last year, as measured at a number of cities across the United States. You could make a grid file containing these measurements, and then use NMPlot to create a contour plot of the temperatures, displayed over a background map of the United States. This plot would show you the distribution of high temperatures on January 1.

Now assume that you have 365 of these grid files, each corresponding to a single day of last year. Using NMPlot, you could create a movie from these grids. This movie would display the plot of high temperatures mentioned in the previous paragraph. Only now, the plot would be animated. The contours would move, and you could see how the high temperatures varied throughout the year.

Steps in Creating a Movie

To make a movie, follow these steps.

  1. Create grid files from your data. See Quick-Start Guide to Importing Data into NMPlot, Introduction to Grids, and Introduction to the Noise Model Grid Format for information on creating grid files.

    All of the grid files must be located in the same directory, and must have identical file names, with the exception of a number just before the extension at the end of the file name. For example, the following list of grid file names would meet these conditions.

    • C:\temp\MyData1.grd

    • C:\temp\MyData2.grd

    • C:\temp\MyData3.grd

    The movie will display plots of your grid files, ordered by the numbers at the end of the grids' file names. Leading zeros in the file names (MyData009.grd, MyData010.grd, MyData011.grd) are allowed but not required.

  2. Create a plot of one of the grids (it does not matter which one). Set all plot options (contour levels, background maps, etc.) as desired. See Introduction to Plots.

    Tip:

    Pay particular attention to the plot's home view. By default, the home view displays the area covered by the largest contour. This works well for a single plot. However, for movies where the contours move, such a home view may cause the plot's background to also move. This can be distracting.

    For best results, set the home view to the primary grid and/or the define area polygon. Or, manually specify the home view. See The Home View for more information.

  3. Choose Create Movie from the File menu. The Create Movie dialog box appears.

    The Create Movie dialog box is a Multiple Page dialog box. See Multiple Page Dialog Boxes for more information.

    Set the various movie options as desired, and then press the OK button.

  4. NMPlot begins creating the movie. Depending on the options you selected, this can take anywhere from a few seconds to a few hours. A dialog box is displayed that shows NMPlot's progress.

    When the movie is finished, this dialog box disappears. The movie will be in the AVI file whose name you specified on the Movie File page of the Create Movie dialog box. You can display the movie using any third-party multimedia application capable of playing AVI files (for example, Microsoft Media Player). You can also post the movie on the Internet, or load it into a third-party movie editing program for editing.

Movie File

Use the Movie File page of the Create Movie dialog box to set the name of the file where your movie will be written.

In the box provided, type the name of file where your movie will be written. Press the Browse button , located to the right of the text box, to display the Open File dialog box, which allows you to browse for the file.

Your movie will be written as an AVI file. Typically, AVI files have the extension .avi.

Size

Use the Size page of the Create Movie dialog box to select the size, resolution, and format of the frames in your movie.

Movie Format

Select the format of the frames in your movie. This is a combination of the color depth (the maximum number of colors in each frame) and the compression method. You have the following choices.

Movie Frame Size

Select the method used to specify the dimensions of the frames in your movie (i.e., the width and height of your movie, in pixels). You have two choices.

Movie Frame Resolution

The resolution of a movie frame measures the size of the pixels. It is typically expressed in pixels per inch or pixels per centimeter.

As an example, assume that your movie has features that are drawn with 1-millimeter-wide lines. If your movie has a resolution of 100 pixels per centimeter, these lines will be 10 pixels wide.

Movies typically have the same resolution as computer monitors: i.e., 70 to 90 pixels per inch.

Select the method used to specify the resolution. You have two choices.

Playback Speed

Use the Playback Speed page of the Create Movie dialog box to set the rate at which your movie should be displayed.

In the box provided, type the speed at which your movie should be played, in frames per second. Typical speeds are between 8 and 36 frames per second.

Divide the total number of frames in your movie (i.e., the number of grid files) by the playback speed to determine the total length of your movie, in seconds.

Oversampling

NMPlot can use oversampling to improve the appearance your movie. Oversampling reduces jagged edges. In technical terms, it antialiases your movie's frames.

The amount of oversampling is controlled by the oversampling factor, an integer between one and eight. An oversampling factor of one means that oversampling is not performed. Higher factors result in smoother, higher-quality movies, but also dramatically increase the amount of memory required to create them.

Use the Oversampling page of the Create Movie dialog box to set the oversampling factor used when creating your movie.

Type the oversampling factor in the box provided.

When using oversampling, you should choose 24-bit true color or 8-bit grayscale color for your movie's color depth. See Movie Format.

Caution:

Oversampling dramatically increases the amount of memory needed to create your movie. The amount of memory required is proportional to the square of the oversampling factor.

Until you gain familiarity with your computer's capabilities, it is recommended that you initially create your movie using a low oversampling factor, and then attempt to create it with gradually increasing factors. If your computer takes an exceptionally long time to create your movie, you may not have enough memory. This is especially true if your hard drive light stays on constantly. Try reducing the oversampling factor.

Level of Detail

Use the Level of Detail page of the Create Movie dialog box to control how much background map detail is displayed in your movie.

Many background maps specify a minimum scale at which various features should be displayed. As you zoom in on such a map, additional detail appears. The intent is to prevent excessive detail from cluttering a plot when it is displayed at a small scale. See Background Map Formats.

Use the Level of Detail page to control how NMPlot uses this recommended scale information when you create your movie. You have four choices for how NMPlot determines how much detail to display.

Preview

Use the Preview page of the Create Movie dialog box to see a summary of the options that will be used to create your movie, and to preview selected frames.

The text presents a brief summary of the movie that will be created. This summary includes a listing of grid files associated with the first and last frames in the movie. To see a full listing of the grids files that will be used, press the Show All Grid File Names button.

Important:

Pay particular attention to the size of the AVI movie file that will be created. Movies can be very large: ensure that you have enough free hard disk space to hold the movie. Also, the AVI file must be smaller than 1.96 Gigabytes: a warning will be displayed if this limit may be exceeded.

To preview a frame from your movie, type the frame number in the box provided, then press the Preview Frame button. The requested frame will be displayed. There may be a delay before the frame appears.

Tip:

Movies can take a long time to create. Therefore, you should preview a representative sampling of your movie's frames to insure that you are satisfied with the options you have selected.


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