DXF to LandXML convertor

Introduction NRG Surveys develops software for Civil Engineering, our website [login to view URL] presents the various modules that we offer. The current software has been in development since 1987 and since 1991 has been developed using VB6 We are currently upgrading some of the software using .Net and taking advantage of the improved speed of execution Project Overview The module we are currently upgrading is our existing DTM_Map which processes topographic surveys and creates triangle meshes from which it can provide visualisation, contour and calculate volumes. Many of our users also use Autocad and most of the output from the software is to Autocad compatible drawing files. Autocad uses DWG as it’s native format but DWG is not documented and requires a licence from Autocad to use their SDK in reading and writing. We have therefore elected to use DXF which is an industry standard ‘drawing exchange format’ and is well documented with a lot of open source code already available. LandXML is a well documented format and is used widely in Civil Engineering and topographic mapping. A schema is available on the [login to view URL] website We need to be able to import the points and lines from a DXF file into our object model. However our resources are currently engaged on other aspects of the development and we feel that this element could be contracted out, and since we already import Land XML files we see the opportunity to outsource someone to develop a DXF to XML / XML to DXF convertor 1. File Open Open and preview DXF file with ability to switch layers on and off with automatic redraw as they are changed, including zoom and pan options on preview. Import options will be available from the preview window. 2. Units The units will be specified in the drawing file and the user should have the option to convert into their own units, i.e. Millimetres to Metres, or feet to meters etc. 3. UCS The DXF file may contain elements which are in a user defined coordinate system, these should be translated to the ‘world’ system on export to XML 4. Elements DXF to XML DXF element type XML element type UCS Have to be resolved / transformed prior to XML conversion. OLE Not supported currently in LandXML 3D Polylines Describe the line style Assign 3D line to XML file 2D Polylines Describe the line style Assign 2D line to XML file Splined lines Would have to be turned into straights at a given interval prior to conversion. Points PointList2d or PointList3d tags Blocks Point geometry tag Arcs Point geometry tag Ellipses Point geometry tag 3D Faces TIN tag 3D Polymesh TIN tag Hatching NA Text Survey//Annotation tag Text as Spot heights Special case for a 2D drawing which has heights as text on the drawing. A separate option is needed to filter the values of the text and if the values fall within limits set by the user then it is imported as a 3D point at the text insertion position and the user has an option to give the points a global label   5. Converting XML to DXF The reverse process will be required to convert XML to DXF XML element type DXF element type UCS NA OLE NA Break lines 3D polyline Planfeature 2D polyline Splined lines NA PointsList 2D / 3D CAD points Plan feature Block Arcs NA Ellipses NA TIN 3D Faces Alignment geometry Polylines for straight elements, Arcs for curves. Spirals would have to be broken into straights at a interval provided Annotation Text.