Fire Testing Deformation Measurement PDF

The Linearis3D Stereo system simplifies dynamic deformation measurements of large objects ranging from two to twelve meters in size — for example furnaces up to 6 x 10 meters. The object shown in Fig. 3 has a size of 6 x 6 meters, with the marked measuring points displayed in blue.

It is ideally suited for vertical fire testing applications thanks to its non-contact measurement, robustness against smoke and dust, and high precision. As a result, it offers a major benefit for work safety.

The system has been in continuous use for over 10 years at fire testing laboratories across Europe, including test and research facilities, manufacturers of construction elements, and regulatory agencies.

Features

Two high-resolution DSLR or video cameras
Resolution between 12 and 24 megapixels
Measuring frequency up to 0.1 Hz (higher frame rates possible with video cameras)
Unlimited number of measurement points
Free positioning of the cameras in front of the measuring object
Unlimited measurement time
Live evaluation of results
Accuracy in the order of a few tenths of millimeters
Calibration certificate included
Completely wireless configuration (Wi-Fi, battery power) possible
Fully automatable measurement process

Environment

Standard room lighting is sufficient
Smoke and dust do not affect the measurement
Bumps and shocks during measurement are compensated

Calibration

Reference markers are placed to the left and right of the test object (see Fig. 2). The stereo cameras use these markers to determine their position in space, so that small camera movements during the test do not affect measurement accuracy. Depending on the application, either a mobile calibration device or a set of calibration markers is used; their 3D positions are determined with the system's integrated photogrammetry module from around 50 images and take only a few minutes to set up.

Measurement procedure

The cameras can be freely positioned in front of the target. The points to be measured are identified with self-adhesive markers (see Fig. 3). Measurements are triggered manually or automatically at defined intervals, and images can optionally be transferred live via Wi-Fi for real-time evaluation.

Technology

The system is based on state-of-the-art photogrammetric methods. Sophisticated image processing algorithms extract the markers from the images, and an integrated bundle adjustment — the gold standard for photogrammetric precision — computes the 3D deformations, which can be tracked live in the evaluation software (see Fig. 4).