thanks sir for replying..... sir , i am using bundler software in window .how can i add my camera database so that are able to estimate the focal length of my camera. i read somethinG *FAQ ................* A. There are many reasons why Bundler might produce erroneous results. However, there are a few common failure modes. The first is that there is not enough overlap between the images. A good rule of thumb is that each point in the scene needs to be visible in at least three images, and that when walking around an object, you should take photos at least every 15 degrees (i.e., 24 photos when capturing a full 360 view of an object). A second common failure mode is that Bundler can't get a good focal length estimate (though it will still try hard to produce a usually wrong result). Your camera may need to be added to the CCD width database in bin/ extract_focal.pl. To tell if this is a problem, look at the generated list.txt file for your dataset. Each line should have three entries: the image name, a zero, and a focal length. If this isn't the case, either (a) your camera model needs to be registered (possible with most still cameras) or (b) you are using a video camera and therfore Bundler can't automatically detect focal lengths from the Exif tags in your images. Here are some instructions for handling these cases: - *Case (a): I am using a still digital camera*: First, you will need to find the sensor width (in millimeters (mm)) of your camera. Sensor widths for most cameras can be found on dpreview; see this page <http://www.cs.cornell.edu/~snavely/bundler/focal.html> for more information. Once you have found the sensor width in mm, you must add a line to the sensor width database in bin/extract_focal.pl. First, use the provided jhead tool to find the camera make and model as listed in the Exif tags. You will then add a line to bin/extract_focal.pl of the form: "[Camera make] [Camera model]" => [Sensor width] See the existing entries for examples. with regards RAKESH KUMAR RAY ELECTRONICS AND COMMUNICATION ENGINEERING TEZPUR UNIVERSITY ASSAM