Microstation DGN

Microstation DGN files from Microstation versions predating version 8.0 are supported for reading (a DGNv8 driver, using Teigha libraries, is available to read and write DGN v8 files). The entire file is represented as one layer (named "elements").

DGN files are considered to have no georeferencing information through OGR. Features will all have the following generic attributes:

DGN files do not contain spatial indexes; however, the DGN driver does take advantage of the extents information at the beginning of each element to minimize processing of elements outside the current spatial filter window when in effect.

Supported Elements

The following element types are supported:

Generally speaking any concept of complex objects, and cells as associated components is lost. Each component of a complex object or cell is treated as a independent feature.

Styling Information

Some drawing information about features can be extracted from the ColorIndex, Weight and Style generic attributes; however, for all features an OGR style string has been prepared with the values encoded in ready-to-use form for applications supporting OGR style strings.

The various kinds of linear geometries will carry style information indicating the color, thickness and line style (i.e. dotted, solid, etc).

Polygons (Shape elements) will carry styling information for the edge as well as a fill color if provided. Fill patterns are not supported.

Text elements will contain the text, angle, color and size information (expressed in ground units) in the style string.

Creation Issues

2D DGN files may be written with OGR with significant limitations:

The dataset creation supports the following options: