Extract sections
This function takes sections of any orientation through the block model and creates one string file containing either block outlines or block centroids for each section. Sections can be defined by either nominating the northing, easting, elevation or defining an axis with start and end points or an axis bearing and dip.
To run this function: Choose Block model > Sections > Create, or...
Note:If the section plane is exactly coincident with the face of a block in the model the string file which is created will have the closed segment or centroid point from each block which shares that section and a warning message to that effect will be given. To prevent this from occurring simply ensure that the section plane passes through the middle of the blocks rather than being coincident with the block extremities.
See Define Sections for further information about defining the section orientation.
Complete the SECTION GROUP DEFINITION form and choose Apply to display the SECTIONS FROM BLOCK MODEL form.
Define section files to create:
Location
Enter the location name for the section files to be created. The ID numbers of the section files are determined by the section range.
Extract
Enter what type of output you require:
- Block Outlines provides the outline of each block that the section plane intersects.
- Centroids provides a string file of points where each point represents the centroid of the block intersected by the section plane.
Coordinates (Section View/Real World Coordinates)
If oblique or dipping sections are defined then the output strings can be stored in real world coordinates or coordinates relative to the defined oblique section. In the latter case the Y and X fields of the string file will be relative to the lower left hand corner of the section plane or to the defined axis.
Constrain (Y/N)
Enter `Y' if you wish to constrain the current block model or `N' for an unconstrained block model.
See Make Constraint.
All Attributes ?
This field determines whether all attributes are output with the sections, or whether only a select group of them are output. Selecting 'Y' for this field will output every attribute in the model, in the order that the attributes were created. Selecting 'N' for this field will will cause the cursor focus to move to the Output Attributes scrolling region, where you should enter the attributes you want exported with the sections. The attributes will be exported in the order selected in the scrolling region.
Define the String Classification attribute:
Greater meaning can be conveyed when viewing or plotting the string files which are created containing the section outlines or centroids if the data has been classified into different string numbers thus permitting different colours to be used.
The method of classifying the data into different strings is to specify a Model Attribute from which values will be obtained to classify the data into different strings and by defining either a range of numeric values, if the attribute field is numeric, or a number of discrete character values if the attribute field is a character field.
Model Attribute
Enter the name of the block model attribute field which is to be used to perform the classification of the output strings.
Numeric range
If the attribute name entered above is a numeric attribute, then you must enter the range of numeric values which are required in the output string file. The range which you enter is interpreted as successive pairs of From and To values, e.g.:
Numeric range = 0,10,2;999
The string numbers used for the results and the manner in which the range is interpreted to obtain the From and To values is shown in the table below:
| String | From | To |
|---|---|---|
| 1 | >= 0 | < 2 |
| 2 | >= 2 | < 4 |
| 3 | >= 4 | < 6 |
| 4 | >= 6 | < 8 |
| 5 | >= 8 | < 10 |
| 6 | >= 10 | < 999 |
Any blocks whose attribute value is not within any of the defined From and To values are assigned to the highest required string number + 1. For example, if a block had an attribute value of 1000 it would be placed in string 7 of the string file.
Character Range, Character Value and String No.
If the attribute name entered above is a character attribute then you must enter both a character value, which is to be used for the comparison, and the string number which is to be assigned to the blocks which have this character value.
Any blocks whose attribute value is not defined explicitly will be placed in string 1 of the string file.
Result
One string file is created for each ID number in the section range entered, provided of course that the section intersects with the block model. The string file will contain either the block outlines as closed segments, or points which represent the centroid of the block outline at the intersection with the section plane.
The description field in both cases contains the values from ALL of the model attribute fields, with D1 containing the first attribute, D2 the second attribute etc.
One of the inputs for the section extraction process is the option to create the results in Section View coordinates or in Real World coordinates. The coordinates which you choose are saved to the Y, X and Z fields of the string file while the alternate coordinates are stored in the last 3 description fields of the string file. Therefore, if you choose to save Section View coordinates, the last 3 description fields will contain the real world Y, X and Z values in that order.
You may find this useful to later use the String Maths function to quickly swap the coordinate system of the resultant sections.