Display discrete samples
This function displays samples from a discrete samples table of a geology database in the 3D graphics window. The purpose of this function is to draw the sample positions 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 Database > Display > Display discrete samples, or...
Once samples have been displayed using this function they are selectable by any graphics function that selects points. The samples are also selectable using point snap mode.
If a geology database is not currently open the Select database form will be displayed so that a database can be opened.
Enter the name of the geology database to be opened and choose Apply to open the database and display the Display discrete samples form.
Discrete sample table
Choose the discrete sample table from which sample data is to be retrieved for displaying in the 3D graphics window. Note that it is only possible to display data from 1 discrete sample table in a single graphics session.
Rescale
Tick the checkbox if the graphics display is to be rescaled after the samples have been drawn.
Colour stations by
It is necessary to make use of the styles table when drawing samples 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 samples 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 samples 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 value ranges for the sample table and field of interest to achieve the required colouring of sample markers and labels.
Default rendering styles
If there is no entry in the styles table that matches the Colour stations by field for a sample then these default rendering styles will be used to display the sample.
Colour
Enter the default colour to be used for rendering samples for which no style definition exists in the styles table.
Marker style
Enter the default marker style to be used for rendering samples for which no style definition exists in the styles table.
Display labels
Apart from the basic rendering characteristics of colour and marker it is possible to define which labels are to be drawn to signify the samples.
The inputs below describe how the labels are defined. Up to 9 labels at different locations relative to the sample coordinates may be drawn.
Field
Choose the field from the discrete sample 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 samples. 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 sample marker.
- below - The label will be drawn below the sample marker.
- left - The label will be drawn to the left of the sample marker.
- right - The label will be drawn to the right of the sample 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 Query constraints form.
A subset of the samples that exist in the table may be drawn by defining constraints to restrict the selection. If no constraints are entered then all samples will be drawn. Complete the Define query constraints form and choose Apply to display the samples.
The samples retrieved from the database are remembered so that, if the samples are erased from the graphics display either by using the Clear Screen or Hide Discrete Samples functions, they can be quickly redrawn using the Refresh Discrete Samples function without having to retrieve them from the database again.
It is possible that some labels may not appear next to the sample marker as you might expect. This will only occur if there is no value stored in the database table for the sample in question. If this happens you will find that this is because there is no value stored, that is, it is NULL, for those samples which are missing the label.