User guide

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SenseCam v2.3 User Guide Page 12 of 31 10/03/2009

image similarity data that is generated is cached (in the image.dat file) so that it is available

subsequently without requiring re-generation. When textons have been generated, a number

of marks appear under the image playback progress bar – these indicate points in the image

sequence where the scene appears to change significantly – and they therefore effectively

split the image sequence into segments of related images. The sensitivity of this

segmentation is adjustable using the slider to the right of the „Calculate Textons‟ option.

3.5. Sequence of operations when the SenseCam Image Importer runs

The Image Importer performs the following sequence of actions:

1. Saves a copy of the current PC time for later use (step 6 below).

2. Creates a new directory on the PC into which to store everything from the

SenseCam.

3. Iterates over every file on the SenseCam in any directory under \DATA:

a. Copies JPG files to the PC. Images may be rotated if necessary. EXIF

timestamps and TIFF manufacturer ("Microsoft") and model ("SenseCam")

headers are added as files are copied across

b. Copies the one and only log (SENSOR.CSV) file to the PC

4. Deletes everything under \DATA and including the DATA directory itself. (This is

extremely time consuming despite the USB 2.0 connection. This is not due to any

aspect of SenseCam firmware, but is because of the nature of the FAT file system

on flash memory devices.)

5. Deletes any existing \SYSTEM\TIME.* and writes a new \SYSTEM\TIME.CSV

with the time recorded in step 1 above. In this way, TIME.CSV will contain the

time at which the SenseCam was connected to the PC (to a reasonable

approximation).

6. Finally, invokes the viewer (or other application) on the copied directory.

3.6. SenseCam Viewer configuration file

Several aspects of the SenseCam Viewer operation may be controlled by altering the XML

format configuration file in the install directory (by default <program files>\Microsoft

Research Ltd\SenseCam). Do be careful when editing this file: if the viewer application

cannot read it, it will not start. Note that the file is only read when the program starts, so

changing it while the viewer is running will have no effect until you restart.

Viewer.SlowInterval/Viewer.FastInterval:

There is some limited playback speed control via the two lines: