The Comma Codes button from the Survey Code Prefixes Dialog allows you to define which single character to expect for some of the available comma codes. Currently, some of the comma codes that can be used are fixed to a certain character. When selected, the dialog shown below will be displayed.
Comma codes are referred to as such because the comma is what n4ce uses to separate the comma codes from the main part of the code string. However, on some survey instruments and data loggers, it can take a few key presses to produce a comma character. The Separators field allows you to specify one or more alternative characters that can be used. When survey information is imported, the existence of any one of the specified characters will allow n4ce to recognise comma codes. When n4ce displays comma codes, it always uses a comma character.
Some of the comma codes in the above dialog refer to a specific type of feature display and these will be described in the appropriate section of this chapter. Those that are not specific are described below.
The No Model comma code, normally X, specifies that you do not wish the point to be included into the DTM triangles. This is necessary where the level of the point would have an adverse effect on the model, such as an observation to the eaves of a building or an underground service. If this comma code is set, the height of the point may still be displayed.
The 2D comma code, normally Y, specifies that the point does not have a valid height and is to be treated as 2D. If it is a surveyed observation, no height will be calculated when survey reduction takes places. If the point has been created by other means, any height assigned to the point is ignored. Therefore, the point will not be used in the DTM triangles and any height cannot be displayed as an annotation.
The No Height comma code, normally Z, overrides any display of the point height. If the point code prefix requires the display of a height, it will not be. The point can still be used in the DTM triangles. The automatic addition of this comma code is an option when using some of the feature editing tools in the model.
Other Comma Codes
The New Code comma code, normally N, specifies the start of a new feature string. This is used where two successive features use the same code and is useful in the field where you do not wish to use feature string numbers. Whilst it normally applies to line features, it can be used on any type of feature. This comma code can also be defined for a point by the addition of a ‘+’ character to the end of the point code. This only works when data is being imported. Once imported, the plus character will be removed and the normal comma code displayed in its place.
The Ignore comma code, normally I, only applies to surveyed observations. If used, the observation will be ignored when creating a model from the survey or when performing the calculations for reductions, traverses and resections. When a survey is reduced, the co-ordinates of the ignored points will be displayed in the data grids.