Measuring Long Term Movement
Moiré Tell Tales can be left in place for long periods. Long term movement can
then be monitored simply by occasional recording using a camera or mobile phone.
Compared with other means of long term crack monitoring, Moiré Tell Tales have some significant advantages:
- Read movements of as little as 0.1 mm in two directions.
- No additional equipment required to read the tell tale. Only a standard camera is needed to make a record.
- Readings of a correctly installed Moiré Tell Tale are not sensitive to the technique of the person recording.
- Records can be made from considerable distances.
- Dynamic response can be monitored using the same simple device as long term trend.
Each Moiré Tell Tale has a unique ID, encoded in a QR Code. Photographs of
Moiré Tell Tales can be filed automatically by searching images for these codes.
Monitoring Movement in Difficult to Access Locations
Because Moiré Tell Tales indicate movement by means of a bold pattern, they can
be photographed from considerable distances. A long telephoto lens will allow
recording from some tens of metres. Even greater distances can be achieved by
attaching a camera to a telescope using a digiscoping adaptor.