Page 72 - Riem-Vol6_nº3

417 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 3
A. P. Martins | J. C. Pizolato Junior | V. L. Belini
The proposed method objective is to achieve the percentual index
of the crack area on the structure on masonry or concrete image.
The block diagram in the Figure 3 shows the proposed method.
The entry of the proposed method (block 1 in Figure 3) corre-
sponds to a masonry or concrete structure with crack as shown
in Figure 1 (masonry structure).
The block 2 on Figure 3 represents the capture of a cracked struc-
ture’s image using a mobile phone, and this image is digitally pro-
cessed on block 3. The digital processing final result, whose algo-
rithm will be detailed on Section 4, consists on the identification
of the pixels that represent a crack region on the image. Starting
from this information it is possible to indentify a crack region on
the image.
The block 4 of Figure 3 has as function calculating the percentual
index of occupation of the crack on the monitored structure image.
However, the proposed method is sensitive to sideways displace-
ment and to the distance of the mobile phone to the structure with
the crack being analyzed. Thereby, it was proposed the application
of a support base for the positioning and alignment of the mobile
phone’s photographic camera in relation to the crack region, as
shown in Figure 4(a). Figure 4(b) illustrates in detail the structure’s
directional guide and the acquisition system’s support base from
Figure 4(a). This guide was proposed with the objective of aligning
correctly the image acquisition system to the masonry structure.
Thereby, the acquisition system’s support base allows keeping a
constant positioning of the mobile phone camera in relation to the
monitored structure on periodic inspections.
concrete. The next section presents the proposed method for the
crack monitoring and the image acquisition.
3. Proposed methodology
This paper work fundaments itself on the application of digital pro-
cessing techniques on images in the spatial domain using a mobile
phone. As a result, the implemented algorithm works directly math-
ematical morphology of the pixels on images previously converted
to binary matrix.
Figure 3 – Block diagram of the proposed
method for the identification of crack growth
Figure 4 – Image acquisition of the proposed vision system. (a). mobile phone positioned on the support
base on a masonry structure. In this case a 200 mm focal length was
adjusted between the mobile phone's camera and the masonry structure.
(b). Masonry structure directional guide put on the support base of the proposed image acquisition system.
(c). Internal view of the proposed system's support base and the detail
of the opening for the device's camera localized behind the illumination
A B C