Managing and importing topography from the field into InRoads is a critical stage before beginning any design process. Making sure that the surface (DTM) accurately depicts your survey is a must to begin any job. However, the raw data being imported into InRoads can contain "spikes" or erroneous data that needs to be removed from the model. These "spikes" can occur for many reasons, but they need to be quickly rectified in creating an accurate model to work with.
This situation can occur particularly from a scanned survey. The scan can contain an area where the elevation values of the ground shots are incorrect, producing a spike in your terrain model that obviously does not exist. To complicate matters, the scan can generate several thousand points that are contained in a single feature, preventing you from simply deleting the feature entirely from the DTM. Also, editing each point individually with the Edit Feature Point tool can be time consuming, and be deemed as a non-viable workflow.
A solution to this issue is to use the Surface > Edit Surface > Delete Feature tool in conjunction with a MicroStation fence. The user would simply place a fence around the points with the bad elevation values, select the feature from the pick list that contains the bad points, and then apply the tool.
In conclusion, the feature that had the bad elevation values for several points in a particular region also had thousands of points outside this region which are good. So, the use of the fence limited the points deleted in that feature without affecting all the other points. Another advantage to this procedure is that it will not alter other features within the MicroStation fence area that do not need to be modified, since the only feature selected from the pick list in the Delete Feature tool is the one that contains the erroneous data. This ability to focus your attention to a particular feature in a particular area proves to be an effective method in editing your surface data.
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