Mobile and Pervasive Construction Visualization Using Outdoor Augmented Reality - Mobile and Pervasive Computing in Construction - page 64

Figure 5.6 Automated generation of an ARVISCOPE animation trace file
contain other lines of text that will be written out when other parts of the modeled
operation take place. Thus, the time ordered sequence of animation statements
written out by all the activities in the model during a simulation run constitutes the
trace file required to visualize the modeled operations in AR.
T he algorithm used in the designed AR application to read, extract, and interpret
the contents of an animation trace file is shown in Figure 5.7. As shown in this
figure, once the animation trace file is opened and the animation clock is started,
the first available SIMTIME statement is read and the specified time argument is
extracted. This argument is then compared to the continuously progressing
animation time.
If the time argument is less than or equal to the current animation time, the
entire block of statements between the current and next SIMTIME statements are
read and stored in an empty list. Otherwise, the application suspends the processing
of the trace file until the above condition holds. At this point, each statement inside
the list is separately processed and the contents of the augmented scene are
accordingly updated. This process continues until the end of animation trace
file is reached.
Figure 5.8 presents a small portion of the animation trace file of the earthmoving
operation shown in Figure 5.5 in the ARVISCOPE language. By referring to
Tables 5.1 and 5.2, the result of processing each statement in this figure can be
explained. Firstly, a route called ReturnRoad is defined by specifying the
beginning, ending, and two intermediate points in terms of global values of
longitude, latitude, and altitude. The 3D models of a hauler and its bucket are
then loaded. An instance of each of these models is then created and the bucket is