When NoiseMap was first written, noise models were created by hand digitising and computers were slow, so one of the compromises was that we limited the number of barriers that would be considered in any part of the angle of view of a segment. The original limit was 30 barriers - and when you could only have a total of 100 barriers in a model, that was fine.
But when you use automatic model creation, you can have tens of thousands of noise barriers, including building outline and ground contours, and this makes it much more likely that important screening effects could be overlooked if you only consider a small number of barriers in each part of the angle of view.
So in Version 5.0.22, we added a Calculation Parameter that lets you select the maximum number of effective barriers in any part of the angle of view. The highest number you can have is 5000, the Default value is 2000, but for backwards compatibility, you can set the maximum number of barriers to only 100. This is not recommended for general use, though.
The value you choose can affect the result. If you find that you have improved the barrier screening but the noise level has not gone down (or it might even have gone up!) increase the limit on number of effective barriers.
Of course, if you are running NoiseMap Enterprise, you can't increase the limit, so perhaps it is time to upgrade to five?
