Display survey stations
This function displays stations from a survey stations database in the 3D graphics window. The purpose of this function is to draw the survey stations on the graphics screen with some recognisable symbol so that they can be selected when performing various graphics query functions.
To run this function: Choose Display > Survey stations, or Survey > Stations > Display stations from database, or...
After stations have been displayed using this function they are selectable by any graphics function that selects points. The stations are also selectable using point snap mode.
If a survey database is not currently open the Select database form will be displayed so that a database can be opened.
Enter the name of the survey database to be opened and choose Apply to open the database and display the Display survey stations form.
Fields on the Display Survey Stations form
Rescale
Tick the checkbox if the graphics display is to be rescaled after the stations have been drawn.
Display traverse connections
If stations have been created using the Underground Traverse function, or certain other functions that record an entry in the station_from field a line may be drawn between stations to indicate the traverse connections between stations. Tick the check box if the traverse connections are to be drawn. If there is no entry in the station_from field for a station then a traverse connection cannot be drawn.
Traverse arrow direction
If the traverse connections between stations are being drawn then you may choose to draw an arrow indicating the direction of the traverse. The arrow is drawn at the midpoint of each traverse connection line. Choose one of the three buttons to achieve the desired arrow display style:
Forward
The arrow will point in the direction in which the traverse was performed, that is, from the original setup station to each new station.
Reverse
The arrow will point towards the station from which each station was surveyed.
None
No arrow will be displayed on the traverse connection line.
Colour stations by
It is necessary to make use of the styles table when drawing stations to ensure that they are drawn as required. The styles table permits you to define, for a table and field of interest, a range of rendering attributes (colours, marker styles, etc.) so that stations will always be drawn in a certain way.
It is permissible to leave this field empty. If no entry is made in this field the stations will be rendered using the default colour, line style and marker style described below.
The most common way to define styles is to have one entry in the styles table to match the each of the codes that are present in the level_area field of the survey_stations table. Each level or area will then always be rendered the same way each time they are drawn.
You can use standard wildcard characters to match more than a single code. The valid characters are:
- ? match any single character.
- * match any string of zero or more characters
- [..] match any single character from the enclosed set. For example [a-z] would match any character in the inclusive range 'a' to 'z'. If the first character after the initial bracket is the exclamation '!' then the effect of the range is negated. For example [!m-n] would match all characters other than 'm' and 'n'.
Default rendering styles
If there is no entry in the styles table that matches the Colour stations by field for a station then these default rendering styles will be used to display the station.
Colour
Enter the default colour to be used for rendering stations for which no style definition exists in the styles table.
Line style
Enter the default line style to be used for rendering stations for which no style definition exists in the styles table.
Marker style
Enter the default marker style to be used for rendering stations for which no style definition exists in the styles table.
Display labels
Apart from the basic rendering characteristics of colour, marker, etc., it is possible to define which labels are to be drawn to signify the stations. The inputs below describe how the labels are defined. Up to 9 labels at different locations relative to the station coordinates may be drawn.
Field
Choose the field from the survey_stations table from which the label is to be obtained.
Decimals
The number of decimal places used for formatting floating point numeric fields can be defined to achieve the desired effect.
Font
Choose the font with which the label is to be drawn.
Size
Choose the size of the text label. Enter a numeric value in this field. The size of the rendered text is dependent on this field and the units field described below.
Units
The font size units may be either:
oru
This means object relative units. The size is interpreted as being expressed in the same units as that of the coordinate system of the stations. Consequently the text will increase and decrease in size as the scale of the view changes.
sru
This means screen relative units. A value of 0.02 is equivalent to approximately 2% of the containing window height. In this case the text size remains constant regardless of the scale of the view.
Position
The position of each of the text labels may be defined using simple codes. These codes are:
- above - The label will be drawn above the station marker.
- below - The label will be drawn below the station marker.
- left - The label will be drawn to the left of the station marker.
- right - The label will be drawn to the right of the station marker.
Multiple labels may be defined to be drawn at any of these positions. Multiple labels are stacked at each position to produce a tidy presentation.
Complete the Display survey stations form and choose Apply to display Define Query Constraints form.
A subset of the stations that exist in the database may be drawn by defining constraints to restrict the selection. If no constraints are entered then all stations will be drawn. Complete the Define query constraints form and choose Apply to display the stations.
The stations retrieved from the database are remembered so that, if the stations are erased from the graphics display either by using the Clear Screen or Erase Survey Stations functions, they can be quickly redrawn using the Redraw Survey Stations function without having to retrieve them from the database again.
It is possible that some labels may not appear next to the station marker as you might expect. This will only occur if there is no value stored in the database table for the station in question. For example, if the reverse bearing is to be drawn but you find that some of the values are missing, you will find that this is because there is no value stored, that is, it is NULL, for those stations which are missing the label.