
abort condition is a much simpler strategy and can
also reduce the number of computations. Although
the angle-based criteria with a 15
◦
condition lead to
a near-perfect accuracy, it may fail depending on the
terrain regarded. We can see that Karsava in Latvia
has so many trees and so many quite short values for
FVP, that the simple strategy to abort as soon as 1
◦
slope is achieved is very difficult to beat in terms of
accuracy. A high deviation of absolute errors, seen in
Figure 6b, leads to a significantly higher percentage
of needed computations. But also for other regions,
the 1
◦
max slope criterion can only be outperformed
only by means of a safety margin, and at a cost of
necessary computations. However, in Table 2, we dis-
played the mean values, which are susceptible for the
outliers. Taking into account the 5% quantile, the 1
◦
criterion achieves 0.99 for Latvia, but 0.98 for Bavaria
and Hesse. The network with a safety margin of 250
achieves 1 for Latvia and Hesse and 0.99 for Bavaria.
This is why the apparently good performance of the
simple max slope criterion is misleading.
Overall, the computing time is hardware- and
implementation-dependent. With an Intel
®
Xeon
®
Gold 6154 CPU, the time needed to infer the FVP for
one LoS is approximately 0.03ms, when the input-
data contains 10000 LoSs.
6 CONCLUSION
In this paper, we presented a novel approach to accel-
erate the viewshed computation. For each LoS, the
FVP is estimated, after which the viewshed compu-
tation is aborted. Before the FVP the viewshed com-
putation is exactly as before. Ideally, this results in
no loss of accuracy compared to traditional methods.
Since the distance towards the FVP is significantly
smaller than the desired maximum visibility distance,
in most cases substantial speed gains can be achieved.
We achieve an accuracy of ±250m. Our test data
shows that we could save more than 90% of the com-
putations, whilst maintaining a high accuracy when
dealing with large viewshed distances or high resolu-
tion datasets. This efficiency cannot be achieved by
traditional LoS algorithms and even with the simple
1
◦
criterion, we achieved much less points to be tested
with comparable accuracy.
As this is our initial study with this approach, we
are confident that further improvements in accuracy
and speed are achievable. There are many possibil-
ities within network architecture, making it unlikely
that we have found the optimal solution in the first
attempt.
In future studies, we aim to enhance performance
through skip connections or parallel network architec-
tures. Additionally, we plan to investigate the aptitude
of convolutional neural networks. Deeper networks
are not currently planned due to performance consid-
erations.
ACKNOWLEDGEMENTS
Freely available AI-based text generation techniques
helped summarize Section 2. The sources were se-
lected by the authors who also carefully double-
checked the resulting text. We also thank the review-
ers for their insightful comments.
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