Camera Ruler

This is the first camera ruler in the android market that allows you to take a picture of an object and accurately measure the size of it. You can save the measurement to a picture and share it with your family and friends through Email, Facebook, Pinterest, etc. This camera ruler uses a coin as a reference to calibrate itself, and the calibration process is fully automatic. The current version supports coins in US dollar, Euro, and Canadian dollar.

Please leave your rating and comments on Google Play to help us improve the app. If you'd like to request for more functionality or the support for more countries of coins, please let us know in your comments.

Some tips for accurate measurement:
1. Place your item on the ground or a flat / level surface such as a desk top. Place the coin next to or on the item.
2. You can also hold the item vertically, and place the coin on or next to it.
3. Hold your camera parallel to the item. Keep the item and the coin at / close to the center of the camera's field of view.
4. Pay attention to the level at the lower-right corner. Tune it to the center by slightly rolling your phone. The level dot will turn green when centered.
5. The app will try to find the coin automatically. Once it finds it, it will lock the coin by drawing a red circle on it.
6. If the app is not able to lock the coin, please try to change a coin or the background. Basically, please try to increase the color difference between the background and the coin. Sometimes, some extra light helps too.
7. Once the coin is locked, tap on the coin.
8. Zoom, rotate, and move the item to the center; measure it by sliding the two red lines.
9. You've made a good measurement!
10. Double-tap on the screen to bring up the menu. You can save it or share it with your friends. You can also choose to change the color of the ruler, or add annotations to the picture. You will be able to browse the saved pictures within the app.

Updates history:

Important updates in Version 2.2:

Added a level to improve the ruler's accuracy. Camera ruler inaccuracy is mainly caused by the perspective distortion of the camera. In this update, a level has been added to help the user adjust the position of the phone so as to mitigate the perspective distortion. Both level and vertical positions are supported.

Version 2.1:

Circle detection algorithm has been improved to reduce false detections.

Version 2.02
Fixed minor visual misalignment in older phones.

Important updates in version 2.0.

1. Physical menu button is disabled.
Double tap on screen to show and hide the option menu.

2. Added the function of annotation.
User is able to add text to the picture, such as name, time, and location.

3. Added the browsing function.
User is able to browse all the saved pictures within the app.

Version 1.4-1.5

Fixed a bug in image conversion.
Fixed a bug in coin selection.
Known issues with OpenCV remain.

Version 1.3
Fixed the "cannot read external storage error" on some devices with external storage.

Version 1.2
Fixed the "cannot read external storage error" on devices with no external storage.
The software has been changed to remember the previously used coin type。

Known issues:
This software uses the OpenCV toolbox, which does not work on certain devices, such as some Motorola devices, HTC One S, and Zopo zp500+. It will be fixed in the future updates.