flipbook measurement tool beta
instructions
To use this tool first select which flipbook you would like to analyze from the drop-down box. Then enter the frame numbers for the frames to be analyzed. These frame numbers can be found by clicking on the image when the frame of interest is shown on the original flipbook page. The frame number should be shown in the address bar after the # symbol.
The first frame should contain an object of known dimensions that is about the same distance from the lens and parallel to the direction of motion of the object of interest. If there is a reference available that I know then I will probably mention it in the flipbook description. The first frame should also contain one reference point to the position of the object of interest. The second frame should contain the second reference point for the object's motion.
To set the 4 reference points click on the selection button next to the point you want to set and click the location on the image where you want to set the point. The on-screen arrow buttons, manually entering coordinates, or the "w", "a", "s", and "d" keys on the keyboard can be used to fine tune the point location. Note that the image in the upper right is a zoomed view to aid in precision selection. The first three points should be set on the first frame and the last point should be set in the other frame.
Input the known reference distance and the frames per second of the recording. The resulting speed will be given in terms of whatever unit you used for distance per second.
usage tips
If you can't get the distance reference and the first speed reference in the same frame then you can set the distance reference first and then change to the first speed reference frame.
The numbers on the images are the actual frame numbers output from the camera. This can be useful to check for dropped frames. If a dropped frame is found you can set all your reference points, make a note of the frame numbers in the images, and then change the frame input values to the actual frame numbers. It won't matter that the images you used to set the values will no longer be shown for the calculation.
You can measure distance instead of speed with this tool as well. Set your speed references to the distance you want measured and set your frame rate to the difference between your two frame numbers and the output will be a distance measurement in the same units as your reference distance.
browser compatibility
I haven't done extensive compatibility testing with this application. I have tested it in the current browser editions as of the program's creation: Firefox 3, Opera 9.27, and IE 7.
It seems to work best with Firefox. It does have some known issues. IE has some alignment issues in the zoomed image, but as long as you are set you don't use the non-zoomed image to set one point and the zoomed image to set another it should still give good results. The point movement hot-keys interfere with Opera's default hot-keys, and Firefox sometimes moves two pixels at a time when using the hot-keys.