Author Topic: How can I improve the look of the 3-d view?  (Read 1629 times)


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How can I improve the look of the 3-d view?
« on: June 19, 2017, 02:03:17 PM »
I am seeing vertical 'cliff edges' in the 3-d view, which are not really there.  I have also found that some objects seem to be the wrong height above the ground. This is not helpful when I am trying to check the accuracy of the model.  And does it mean that the results are wrong?

Generating the 3-d view is a complex process - the features of the model - which are entered as a few lines - have to be turned into surfaces. The lines are regarded as the edges of features, and the first step is to generate points (called vertices) to define where these separate features can be joined to adjacent features. Then the vertices are joined in a series of triangular facets, such that all vertices are joined without leaving any gaps and without any of the facets overlapping.  This process requires many iterations, making it slow. But there can be ambiguity, especially where there is sparse data, sometimes causing sub-optimal facetting resulting in the issues described. 

Whilst it may be right to describe the result as 'unhelpful', it is as much a symptom of the lack of data as it is of errors in the 3-d creation process.  Do not automatically assume that it is just a bug in the 3-d facetting - quite often they can reveal genuine errors in the model. You may well find it helps if you add into the model some ground profiles (we can't call them contours) normal to the original contours.  NoiseMap can get their height from the original ground model.  Be sure to add enough points on each of these new profiles to adequately represent any changes in the slope of the ground. If you are getting errors around buildings, try to ensure that you are modelling any ground levelling work that may have been done in these areas. You may need to add more ground contours or profiles adjacent to buildings.

Be careful when making these enhancements - if you do it badly, you could make the situation worse.

Do these facetting errors mean that the results are wrong? No, because the noise calculations are not based on the 3-d facets.  All the heights are evaluated at calculation time from the actual ground model and object heights. As long as these are correct, then the results will be fine. However, beware of sparse data - the accuracy of the height data will have an effect on the accuracy of the final calculations.
« Last Edit: June 27, 2017, 11:24:43 AM by roger »