Create From Elements tool

Used to create a terrain model from 3D graphical elements that is ruled.

Found on the Civil ribbon in the Terrain Model group.

Ruled Terrains update dynamically if the source elements are changed. Each element or group of elements of a terrain feature type can be selected individually or via selection set. This tool is useful if the elements do not have consistency symbology or attributes (where the Create From Graphical Filter Group tool may be a better option). After the terrain model is created from the first grouping of elements, the software prompts to append another terrain feature (by defining another selection set of elements) or to create another terrain model. The models are named Terrain Model (Element), Terrain Model (Element) 1, etcetera.

With a selection set of all elements of a type (e.g., all break lines) to be made into a model, select the tool. You are prompted with how many elements in the selection set. Data point to accept. Set the type of elements to be extracted and the edge options.

If no objects are selected when you select the tool, select the elements and then reset to complete the selection set.

Tool Settings

Setting

Description

Feature Type

The concept of feature types is used throughout the Terrain Model tools.

Spot or Spot Elevation – Points (with X,Y,Z data) that have no functional relationship to any other point. Random survey shots in open terrain would be an example of random spots. Point elements such as cells, circles, and text strings are typical MicroStation elements used to graphically define spot elevations. Lines, line strings, and other longitudinal elements are equally valid. The software creates a spot elevation for each vertex of each longitudinal element.
Break Line – Breaks are used to designate linear features such as edges of pavement, ditch bottoms, ridges, etcetera where an abrupt change of slope occurs. Any longitudinal element may be defined as a break line. Triangles will not cross a break line in the terrain model.
Soft Break Line – A soft break line is a break line, however, if it crosses a break line, it will not affect the triangulation and is ignored.
Contour – Element or set of elements of the same elevation. Contours may be used as source data to generate a terrain model, or may be computed (drawn based on terrain model). Contour interval is the elevation difference between two adjacent contours.
Hole – An area defined by a closed shape that demarcates a region where the current terrain is ignored and the underlying terrain is utilized.
Boundary – The external boundary of the surface.
Drape Boundary – A surface boundary that determines its elevations by draping on the underlying surface.
Void – An area defined by a closed shape that demarcates a region of missing data or obscure areas. No point or break data located within the void area is utilized and no triangles are created inside the void areas. The Void coordinates are included in the triangulation and void lines between successive void coordinates are inserted as drape lines on the surface. Therefore, they do not change the slope or elevations of the surface.
Drape Void – An area defined by a closed shape that demarcates a region of missing data or obscure areas. No point or break data located within the void area is utilized and no triangles are created inside the void areas. In the drape void, the void coordinates are not included in the triangulation. Voids are inserted post triangulation. The void coordinates and lines are draped on the terrain model surface. Even though a user must provide an elevation for Drape Void vertices, the user elevations are changed to the elevation of the terrain model surface at the XY Drape Void coordinate position.
Break Void – An area defined by a closed shape that demarcates a region of missing data or obscure areas. No point or break data located within the void area is utilized and no triangles are created inside the void areas. It differs from Voids and Drape Voids in that it utilizes the vertex elevations of the graphical element, while the void lines between successive void coordinates are inserted as break lines. Therefore, break voids change the slope and elevations of the surface.
Island – An area defined by a closed shape that demarcates a region of data wholly within a void. Example, islands in the middle of rivers, lakes, etcetera.

Triangulation Options group

Several of the terrain model tools utilize the triangulation options section where the Edge Method is specified.

Many of the external edge triangles are thin and narrow and not representative of the surface. This is particularly evident where the edge of the data set is concave in nature. One approach to eliminate these triangles is the use of the Edge Method.

No Removal – No external triangles are deleted. Note the Maximum Triangle Length is ignored. There are no user defined parameters.
Remove Slivers – Long, thin triangles are dissolved based on a formula hard coded within the software. Note the Maximum Triangle Length is ignored. There are no user defined parameters.
Max Triangle Length – External triangles whose external edge is longer in length than the user specified distance are deleted. Note the option does not apply to internal triangles, only those on the edge of the model. Specify the Maximum Triangle Length in master units.

Feature group

Setting	Description
Feature Definition	Select an existing feature definition from the drop-down list to use for object being placed.
Name Prefix	Type a prefix value to use for all objects set using this Feature Definition, which are useful in quickly identifying features in a group.

Key-in: terrainmodel create fromelements