CAD to GIS with EV8 or theEngine
A logical and efficient way to build GIS from any CAD/DXF.
Unravel the Mess in 20 Seconds
This is a typical Microstation CAD 'fc1' drawing containing 19 layers of forestry data, including forest cover, property lines, roads, rivers, annotation or linkage text and many other items. In this example, the objective is to prepare attributed forest cover polygon, and polyline themes. But this could be any typical CAD data, parcels, pipelines, contours, etc.
The close up shows the polylines of various layers, and of course they are mixed in with one another, but are normally classified into appropriate layers. The first 'engine' job is to unravel these, and set them into a logical GIS structure.
AutoExtract CAD Data Logically
With EV8 or theEngine simply run 'AutoExtractCAD/Themes'. This function automatically creates an individual shapefile for each layer classification, or any field classification, or even legend classification. It will also automatically name each file, based on this class selection. In this case we get 19 files, made in a total of about 20 seconds. If you open a shapefile table you will see only the data that existed in one particular layer. One or two of these files will contain the text annotation as a field in a polyline shapefile. The shapefiles will be 2D or 3D depending on the geometry of the CAD drawing. Shown below are close ups of a few of these layers turned on. These can now be manipulated to suit the objective.
Turn on the forest cover polyline shapefile. In this case, it is actually a file made by merging three of the layer shapefiles into one by a batch file merge function in EV8 or theEngine. There were lines divided amongst 3 layers in the CAD (which of course yielded the three shapefiles).
Get a feel for the data by investigating the structure with some of EV8 or theEngine tools designed for that purpose. Then run one of the 'clean and build' functions in EV8 or theEngine, setting gap jump and/or extend tolerances. In this example, there were 4,200 lines segments. The result is a 1,100 record polygon shapefile, which has area, and length written automatically into the attribute table.
Point-in-Poly taken to its Logical Conclusion..Anything-to-Anything.
What remains to do is to write the appropriate annotation text and linkage numbers from the CAD to this database. To do that simply make this file and the appropriate polyline file (which contains the text or number layer) active, and run the 'Connect Attributes' function in EV8 or theEngine. This will automatically create the fields and populate them according to a spatial pattern you select. This is the 'point-in-poly' idea taken to its logical conclusion... point-in-poly, line-in-poly, poly-in-poly, line-to-line, point-to-point, distance between features, or all other possible pattern or selection combinations. This function can be run repeatedly using various combinations. It works on any 'attributed' theme type to any other theme type, and is automatic.
Here we build the rivers. In this case these were fractured, so they were 'cleaned and built', and re-noded using functions in EV8 or theEngine available for polyline building. And as for the polygons, you can attach attributes using the 'Connect Attributes' function from any of the text layer files, or from any file for that matter.
When EV8 or theEngine creates polygons or polylines from fractured data it also makes nodes at the intersections of any line segments. These can be archived into a shapefile with the XY location recorded as an attributes in the table. You can also re-node. Re-node is where only two lines exist at a point, they are re-built into one, and the node is removed. Nodes at the polygon intersections of the forest cover polygons are shown below. In the case of polygons, 'clean and build' also makes polylines which form the borders of the polygons, removing any overshoots or dangles. It is these that can be re-noded.
TIN using the CAD Data
With this CAD came a set of contour lines. You can use these to make a TIN. First use either EV8 or theEngine or tinShapeZ to explode the contour lines to a 3D pointZ shapefile as shown.
Legend for Colour
And then run EV8 or tinShapeZ to make a TIN in shapefile format.
Use EV8 or tinShapeZ to create a new shapefile in a 3D orientation. Note that the solar angle setting of you original shapefile is carried through to the new 3D view. This view is of a small section of the first file.