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
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.
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.
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
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
Break lines 3D polyline
Planfeature 2D polyline
Splined lines NA
PointsList 2D / 3D CAD points
Plan feature Block
TIN 3D Faces
Alignment geometry Polylines for straight elements, Arcs for curves. Spirals would have to be broken into straights at a interval provided
8 freelancers are bidding on average £2381 for this job
Hello There, I have been in CAD development domain for over 2 decades. I have worked on format conversions and have good hands on over such activities. Look forward to hear from you Many Thanks