During the calculation process we use the viewing angles of your device camera that is why it is very important to assign these angles in the application settings. The application already has preinstalled settings of the viewing angles for the following devices: Acer Liquid, Google Nexus One, HTC Hero, HTC Legend, HTC Desire, HTC Droid Incredible, Samsung Galaxy S, Motorola Droid and Droid X. All you have to do is to check that your device is listed here. But if your device is not listed here, don’t worry. You need to set these angles manually through the "Settings" menu. There are many ways to determine them:

• The best way from the point of view of accuracy is to take some photos with your device and send them to us. Your photos have to contain calibration pattern. Please print it and make 20 or more photos from distinct viewpoints. Make photos with the highest resolution and the best quality. Send these photos to support@geo-mark.com indicating subject "Calibration". In e-mail please specify the model of your device. We will send you the answer during one working day, settings for your device will appear in the next version of GeoMark and in this table:

  Device name	Horizontal angle of view	Vertical angle of view
  HTC Legend	53.13 degrees	36.6 degrees
  HTC Desire	53.13 degrees	33.05 degrees
  HTC Hero	49.55 degrees	34.2 degrees
  HTC Droid Incredible	49.62 degrees	30.84 degrees
  Acer Liquid	57.2 degrees	44.54 degrees
  Google Nexus One	53.5 degrees	42.28 degrees
  Motorola Droid	54.3 degrees	42 degrees
  Motorola Droid X	47.37 degrees	37.7 degrees
  Samsung Galaxy S	53.81 degrees	41.61 degrees

• The second way to determine these angles is to take a ruler and take 2 photos (vertically and horizontally oriented) from a known distance. Determine which part of the ruler is in the photo and then measure the size of this part in meters. Now you can calculate the angles of view using the following formula:

  

  Note: the vertical angle must be less than the horizontal one.

  

  In this example the angle is 48.45 degrees.
• Also you can measure an object of known size by using GeoMark and change angles of view until satisfactory results are achieved. Note: accuracy of measurement depends not only on the angles of view, but on other parameters.

It often so happens that accelerometer and compass indicated values are improper to create a geophoto. In order to improve this situation you should move your device in the air several times in such a way so that its trajectory resembles number eight. And it is really worth doing!

In the next application version we intend to add support of devices with large screen and also a number of functions that will facilitate the measurement process.

GeoMark application developers’ team will appreciate any comments and suggestions concerning future development of our application.