Animation

When images found on the "net" need to be saved and then animated to gain a "change through time" perspective, the following instructions should be helpful:

• After the image has been downloaded to your computer screen go to File on the menu bar. Scroll down to Save As..., and save the image as a Source file. When naming the images, be sure to number them in chronological order. This will assure you of a true representation of the data change as a function of time. The images will need to be "opened" in the proper order for this to take place.

• When you have the data set you desire (We suggest between 5 and 7 images) you will need to open them with the software GIF Converter or Paint Shop Pro (for PC's).
• Double-click on the icon, click on O.K. on the order form. Go to the menu bar and choose Open.
• Then you click on the file you wish to open. Go to Save As... and choose TIFF file from the choices provided under File Type. The images must be in TIFF or PICT format to allow you to use the NIH software to animate your images. Converting the images to TIFF format will use a lot of memory. That is the reason for limiting the number of images to between 5 and 7.
• After they have been saved as TIFF or PICT files, close GIF Converter program.

• Open the NIH Image software. You will have better results if you have the FPU (floating point unit) version. If you don't have the FPU version, go to the NIH site and download the fat binary version. These directions are written for the FPU version.

• After NIH is open then go to File and choose Open. Open the images in chronological order.

• After this is complete, go to Stacks and choose Windows to Stack. Then go to Stacks and choose Animate. You should see the images presented on your screen one after the other giving the illusion of movement.

• The numbers 1-9 slow down or speed up the animation respectively. You can use the < or > keys to scroll through the images one at a time.

Measurement

Another feature of NIH Image, is the ability to make measurements on the images that are accurate. These include but by no means are limited to lengths, areas and densities of pixels. Once you start to explore this software you can find many applications for it. Here are instructions for setting the software up to make length and area measurements. You can then use these to predict the speed of air masses, or crustal plates for instance. The areas of air masses or volcanic features can also be determined. Feel free to have the students do ALL of these after you familiarize yourself with the techniques.

These brief instructions will allow you to calibrate NIH and make measurements of features found on an image.

• Open NIH and choose the Line Tool (diagonal dashed line with an arrow head under it).
• Next, measure a prominent feature (sometimes there is a scale) on the image, by drawing a line with the Line Tool.
• Go to Analyze, and Set Scale. The length that corresponds to the line you drew (in number of pixels) is displayed in "Measured Distance". The "Known Distance" catagory is highlighted. Enter the known distance here (from a map or other source) then choose the correct units from the choices given... kilometers, etc.

To determine velocity, determine the total distance the storm travels and divide that by the total time in hours between the first and last image. The movie will look better if images are downloaded at about the same time each day.