Error in profiling

During noise calculations, you can get a warning on the AutoCAD command line about "Error in profiling". This will always be accompanied by a red line on the noise module's layer for temporary data (which is set in Global Settings). If this line is shorter than 50m, a red circle will also be drawn around it.

These lines and circles are drawn to help locate the problem.

The error message means that the program could not find any terrain profile between two points. Terrain profiles are calculated by finding crossings between lines in the specified terrain data and the line you want to find the heights for. To find a profile from A to B in the model, the program adds the "Search width" (set in Global Settings) on both ends of the line. The drawing below shows how the  program looks for the profile between A' and B' to find the profile between A and B. The point is to make it more likely to cross some terrain lines.

If there are no terrain lines between A and A' or between B and B', there is not enough information to do any correct calculation for this profile. So the calculation is not done and and error message is issued. The current calculation point will not be calculated, but the program continues with the next calculation point.

A typical case where this can happen, is if the calculation basis specified in the noise task consists only of terrain contours and the terrain is more or less flat. Normally it is recommended to create a terrain surface, which basically eliminates this problem (as long as the terrain surface covers all necessary area).

An example of flat terrain specified by terrain contour lines is shown below. You can see there are no terrain lines between A and A', which is 100m further away. If you increase the "Search width" to 500m (giving A''), the problem will be solved.

Another typical example is defining a road all the way to the edge of the terrain data. The drawing to the right shows two red lines as a result of this problem. If you continue these lines, you will see they do not hit any terrain lines.

This problem can be solved by drawing a help line in the terrain module. Or even better by specifying a terrain surface and using this as calculation basis.

Another typical example is during calculation with reflections, if there is a building outline at the edge of the terrain model. The drawing to the right shows this.

This problem can be solved in two ways:

2. You can extend the terrain.

After you have fixed all problems with calculation, you can recalculate the so far uncalculated points like this: