Full frontal area is an Android application that can run on any Android device, version 3.0 or higher, with a camera, to measure the frontal area of things. Cyclists, triathletes, and other aero-speed athletes like speed skaters can use it to measure the relative difference between various positions, or equipment. If you use the calibration feature you can even get accurate absolute frontal area measurements for comparison with others.
The app will work best with a uniform background, preferably a solid bright color though a simple white wall may work for some. Arrange the lighting in the room so that there are minimal shadows casting against the backdrop. Perhaps set your bike trainer up in front of a blank wall, or hang a sheet. Make sure that whatever you are measuring is of a different color than the background. Once you are set, just follow these steps:
Opening the app brings you to a camera preview screen, simply point and press the camera icon to snap a picture. If your camera has a flash, you may be able to active it by selecting the flash option from the settings menu at the upper right. The first picture you take will set the background, and that will remain as the background until you clear it from the menu.
The next picture you take will be the one whose frontal area will be measured, by subtracting out the background image. For this reason you must use a tripod or other method of solidly mounting your camera so that it does not move between the background picture and the test picture. If you are working alone, and need time to get from the camera, to the backdrop, you can select a recording delay in the settings menu. You can also choose to load images from your Gallery, if you don't have a camera on your device, or want to use a better one. The background and test images must be exactly the same size.
Once your picture is taken you come to the fine tuning screen. Areas that are being identified as the test object will be highlighted in transparent green or red. You can change the color from the settings menu. Once the background is selected you can use the tolerance slider at the bottom to adjust how picky the matching algorithm is. Slide it until only the intended object is being matched. You can bring up a cropping tool from the settings menu if you need to crop out trouble areas. If there are a few speckles of stray pixels, you can try the filter setting to cull them. If nothing works you may need to adjust the lighting conditions or background color.
Once you are satisfied with the match, select Save from the settings menu. When you save the App will do the area calculations on a higher resolution image than was used in the preview stage, so it may take a few moments. Once complete you arrive at the results screen. This will show you a list of all the results you have saved. They will persist until you choose to delete them. Each result includes an image so keep an eye on how much space you are using. Press on any row to bring up a detail page. This provides a pinch-zoomable image of the given position or object, and it's frontal area data. You can press Show-Mask to review how good the area matching was, and you can email the image and results to yourself, or others.
If you want to compare data over the long term, or with other people, you may use the calibration feature. First, take a picture of an object whose area is known. From the fine tuning screen choose Calibrate from the settings. After processing you will get a dialog asking you to enter the area of the object. Once you enter the area, the app will compute how much area each pixel represents. This data will be applied to all subsequent images until you clear the calibration setting from the setting menu. You can back out of this screen to the camera preview screen to begin taking test images. For the data to be accurate, you must keep the camera at the same distance for all images, and you must not adjust image size options. It is safe to use the crop feature, this will not affect the calibration.